Add pickup of games from old history.
[remoteglot] / www / js / remoteglot.js
1 (function() {
2
3 /**
4  * Version of this script. If the server returns a version larger than
5  * this, it is a sign we should reload to upgrade ourselves.
6  *
7  * @type {Number}
8  * @const
9  * @private */
10 var SCRIPT_VERSION = 2016113007;
11
12 /**
13  * The current backend URL.
14  *
15  * @type {!string}
16  * @private
17  */
18 var backend_url = "/analysis.pl";
19 var backend_hash_url = "/hash";
20
21 /** @type {window.ChessBoard} @private */
22 var board = null;
23
24 /** @type {boolean} @private */
25 var board_is_animating = false;
26
27 /**
28  * The most recent analysis data we have from the server
29  * (about the most recent position).
30  *
31  * @type {?Object}
32  * @private */
33 var current_analysis_data = null;
34
35 /**
36  * If we are displaying previous analysis or from hash, this is non-null,
37  * and will override most of current_analysis_data.
38  *
39  * @type {?Object}
40  * @private
41  */
42 var displayed_analysis_data = null;
43
44 /**
45  * Games currently in progress, if any.
46  *
47  * @type {?Array.<{
48  *      name: string,
49  *      url: string,
50  *      hashurl: string,
51  *      id: string,
52  *      score: Object=,
53  *      result: string=,
54  * }>}
55  * @private
56  */
57 var current_games = null;
58
59 /** @type {Array.<{
60  *      from_col: number,
61  *      from_row: number,
62  *      to_col: number,
63  *      to_row: number,
64  *      line_width: number,
65  *      arrow_size: number,
66  *      fg_color: string
67  * }>}
68  * @private
69  */
70 var arrows = [];
71
72 /** @type {Array.<Array.<boolean>>} */
73 var occupied_by_arrows = [];
74
75 /** Currently displayed refutation lines (on-screen).
76  * Can either come from the current_analysis_data, displayed_analysis_data,
77  * or hash_refutation_lines.
78  */
79 var refutation_lines = [];
80
81 /** Refutation lines from current hash probe.
82  *
83  * If non-null, will override refutation lines from the base position.
84  * Note that these are relative to display_fen, not base_fen.
85  */
86 var hash_refutation_lines = null;
87
88 /** @type {!number} @private */
89 var move_num = 1;
90
91 /** @type {!string} @private */
92 var toplay = 'W';
93
94 /** @type {number} @private */
95 var ims = 0;
96
97 /** @type {boolean} @private */
98 var truncate_display_history = true;
99
100 /** @type {!string|undefined} @private */
101 var highlight_from = undefined;
102
103 /** @type {!string|undefined} @private */
104 var highlight_to = undefined;
105
106 /** The HTML object of the move currently being highlighted (in red).
107  * @type {?jQuery}
108  * @private */
109 var highlighted_move = null;
110
111 /** Currently suggested/recommended move when dragging.
112  * @type {?{from: !string, to: !string}}
113  * @private
114  */
115 var recommended_move = null;
116
117 /** If reverse-dragging (dragging from the destination square to the
118  * source square), the destination square.
119  * @type {?string}
120  * @private
121  */
122 var reverse_dragging_from = null;
123
124 /** @type {?number} @private */
125 var unique = null;
126
127 /** @type {boolean} @private */
128 var enable_sound = false;
129
130 /**
131  * Our best estimate of how many milliseconds we need to add to 
132  * new Date() to get the true UTC time. Calibrated against the
133  * server clock.
134  *
135  * @type {?number}
136  * @private
137  */
138 var client_clock_offset_ms = null;
139
140 var clock_timer = null;
141
142 /** The current position being analyzed, represented as a FEN string.
143  * Note that this is not necessarily the same as display_fen.
144  * @type {?string}
145  * @private
146  */
147 var base_fen = null;
148
149 /** The current position on the board, represented as a FEN string.
150  * Note that board.fen() does not contain e.g. who is to play.
151  * @type {?string}
152  * @private
153  */
154 var display_fen = null;
155
156 /** @typedef {{
157  *    start_fen: string,
158  *    pv: Array.<string>,
159  *    move_num: number,
160  *    toplay: string,
161  *    scores: Array<{first_move: number, score: Object}>,
162  *    start_display_move_num: number
163  * }} DisplayLine
164  *
165  * "start_display_move_num" is the (half-)move number to start displaying the PV at.
166  * "score" is also evaluated at this point.
167  */
168
169 /** All PVs that we currently know of.
170  *
171  * Element 0 is history (or null if no history).
172  * Element 1 is current main PV, or explored line if nowhere else on the screen.
173  * All remaining elements are refutation lines (multi-PV).
174  *
175  * @type {Array.<DisplayLine>}
176  * @private
177  */
178 var display_lines = [];
179
180 /** @type {?DisplayLine} @private */
181 var current_display_line = null;
182
183 /** @type {boolean} @private */
184 var current_display_line_is_history = false;
185
186 /** @type {?number} @private */
187 var current_display_move = null;
188
189 /**
190  * The current backend request to get main analysis (not history), if any,
191  * so that we can abort it.
192  *
193  * @type {?jqXHR}
194  * @private
195  */
196 var current_analysis_xhr = null;
197
198 /**
199  * The current timer to fire off a request to get main analysis (not history),
200  * if any, so that we can abort it.
201  *
202  * @type {?Number}
203  * @private
204  */
205 var current_analysis_request_timer = null;
206
207 /**
208  * The current backend request to get historic data, if any.
209  *
210  * @type {?jqXHR}
211  * @private
212  */
213 var current_historic_xhr = null;
214
215 /**
216  * The current backend request to get hash probes, if any, so that we can abort it.
217  *
218  * @type {?jqXHR}
219  * @private
220  */
221 var current_hash_xhr = null;
222
223 /**
224  * The current timer to display hash probe information (it could be waiting on the
225  * board to stop animating), if any, so that we can abort it.
226  *
227  * @type {?Number}
228  * @private
229  */
230 var current_hash_display_timer = null;
231
232 var supports_html5_storage = function() {
233         try {
234                 return 'localStorage' in window && window['localStorage'] !== null;
235         } catch (e) {
236                 return false;
237         }
238 }
239
240 // Make the unique token persistent so people refreshing the page won't count twice.
241 // Of course, you can never fully protect against people deliberately wanting to spam.
242 var get_unique = function() {
243         var use_local_storage = supports_html5_storage();
244         if (use_local_storage && localStorage['unique']) {
245                 return localStorage['unique'];
246         }
247         var unique = Math.random();
248         if (use_local_storage) {
249                 localStorage['unique'] = unique;
250         }
251         return unique;
252 }
253
254 var request_update = function() {
255         current_analysis_request_timer = null;
256
257         current_analysis_xhr = $.ajax({
258                 url: backend_url + "?ims=" + ims + "&unique=" + unique
259         }).done(function(data, textstatus, xhr) {
260                 sync_server_clock(xhr.getResponseHeader('Date'));
261                 ims = xhr.getResponseHeader('X-RGLM');
262                 var num_viewers = xhr.getResponseHeader('X-RGNV');
263                 var new_data;
264                 if (Array.isArray(data)) {
265                         new_data = JSON.parse(JSON.stringify(current_analysis_data));
266                         JSON_delta.patch(new_data, data);
267                 } else {
268                         new_data = data;
269                 }
270
271                 var minimum_version = xhr.getResponseHeader('X-RGMV');
272                 if (minimum_version && minimum_version > SCRIPT_VERSION) {
273                         // Upgrade to latest version with a force-reload.
274                         location.reload(true);
275                 }
276
277                 // Verify that the PV makes sense.
278                 var valid = true;
279                 if (new_data['pv']) {
280                         var hiddenboard = new Chess(new_data['position']['fen']);
281                         for (var i = 0; i < new_data['pv'].length; ++i) {
282                                 if (hiddenboard.move(new_data['pv'][i]) === null) {
283                                         valid = false;
284                                         break;
285                                 }
286                         }
287                 }
288
289                 var timeout = 100;
290                 if (valid) {
291                         possibly_play_sound(current_analysis_data, new_data);
292                         current_analysis_data = new_data;
293                         update_board();
294                         update_num_viewers(num_viewers);
295                 } else {
296                         console.log("Received invalid update, waiting five seconds and trying again.");
297                         location.reload(true);
298                 }
299
300                 // Next update.
301                 if (!backend_url.match(/history/)) {
302                         current_analysis_request_timer = setTimeout(function() { request_update(); }, timeout);
303                 }
304         }).fail(function(jqXHR, textStatus, errorThrown) {
305                 if (textStatus === "abort") {
306                         // Aborted because we are switching backends. Abandon and don't retry,
307                         // because another one is already started for us.
308                 } else {
309                         // Backend error or similar. Wait ten seconds, then try again.
310                         current_analysis_request_timer = setTimeout(function() { request_update(); }, 10000);
311                 }
312         });
313 }
314
315 var possibly_play_sound = function(old_data, new_data) {
316         if (!enable_sound) {
317                 return;
318         }
319         if (old_data === null) {
320                 return;
321         }
322         var ding = document.getElementById('ding');
323         if (ding && ding.play) {
324                 if (old_data['position'] && old_data['position']['fen'] &&
325                     new_data['position'] && new_data['position']['fen'] &&
326                     (old_data['position']['fen'] !== new_data['position']['fen'] ||
327                      old_data['position']['move_num'] !== new_data['position']['move_num'])) {
328                         ding.play();
329                 }
330         }
331 }
332
333 /**
334  * @type {!string} server_date_string
335  */
336 var sync_server_clock = function(server_date_string) {
337         var server_time_ms = new Date(server_date_string).getTime();
338         var client_time_ms = new Date().getTime();
339         var estimated_offset_ms = server_time_ms - client_time_ms;
340
341         // In order not to let the noise move us too much back and forth
342         // (the server only has one-second resolution anyway), we only
343         // change an existing skew if we are at least five seconds off.
344         if (client_clock_offset_ms === null ||
345             Math.abs(estimated_offset_ms - client_clock_offset_ms) > 5000) {
346                 client_clock_offset_ms = estimated_offset_ms;
347         }
348 }
349
350 var clear_arrows = function() {
351         for (var i = 0; i < arrows.length; ++i) {
352                 if (arrows[i].svg) {
353                         if (arrows[i].svg.parentElement) {
354                                 arrows[i].svg.parentElement.removeChild(arrows[i].svg);
355                         }
356                         delete arrows[i].svg;
357                 }
358         }
359         arrows = [];
360
361         occupied_by_arrows = [];
362         for (var y = 0; y < 8; ++y) {
363                 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
364         }
365 }
366
367 var redraw_arrows = function() {
368         for (var i = 0; i < arrows.length; ++i) {
369                 position_arrow(arrows[i]);
370         }
371 }
372
373 /** @param {!number} x
374  * @return {!number}
375  */
376 var sign = function(x) {
377         if (x > 0) {
378                 return 1;
379         } else if (x < 0) {
380                 return -1;
381         } else {
382                 return 0;
383         }
384 }
385
386 /** See if drawing this arrow on the board would cause unduly amount of confusion.
387  * @param {!string} from The square the arrow is from (e.g. e4).
388  * @param {!string} to The square the arrow is to (e.g. e4).
389  * @return {boolean}
390  */
391 var interfering_arrow = function(from, to) {
392         var from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
393         var from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
394         var to_col   = to.charCodeAt(0) - "a1".charCodeAt(0);
395         var to_row   = to.charCodeAt(1) - "a1".charCodeAt(1);
396
397         occupied_by_arrows[from_row][from_col] = true;
398
399         // Knight move: Just check that we haven't been at the destination before.
400         if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
401             (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
402                 return occupied_by_arrows[to_row][to_col];
403         }
404
405         // Sliding piece: Check if anything except the from-square is seen before.
406         var dx = sign(to_col - from_col);
407         var dy = sign(to_row - from_row);
408         var x = from_col;
409         var y = from_row;
410         do {
411                 x += dx;
412                 y += dy;
413                 if (occupied_by_arrows[y][x]) {
414                         return true;
415                 }
416                 occupied_by_arrows[y][x] = true;
417         } while (x != to_col || y != to_row);
418
419         return false;
420 }
421
422 /** Find a point along the coordinate system given by the given line,
423  * <t> units forward from the start of the line, <u> units to the right of it.
424  * @param {!number} x1
425  * @param {!number} x2
426  * @param {!number} y1
427  * @param {!number} y2
428  * @param {!number} t
429  * @param {!number} u
430  * @return {!string} The point in "x y" form, suitable for SVG paths.
431  */
432 var point_from_start = function(x1, y1, x2, y2, t, u) {
433         var dx = x2 - x1;
434         var dy = y2 - y1;
435
436         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
437         dx *= norm;
438         dy *= norm;
439
440         var x = x1 + dx * t + dy * u;
441         var y = y1 + dy * t - dx * u;
442         return x + " " + y;
443 }
444
445 /** Find a point along the coordinate system given by the given line,
446  * <t> units forward from the end of the line, <u> units to the right of it.
447  * @param {!number} x1
448  * @param {!number} x2
449  * @param {!number} y1
450  * @param {!number} y2
451  * @param {!number} t
452  * @param {!number} u
453  * @return {!string} The point in "x y" form, suitable for SVG paths.
454  */
455 var point_from_end = function(x1, y1, x2, y2, t, u) {
456         var dx = x2 - x1;
457         var dy = y2 - y1;
458
459         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
460         dx *= norm;
461         dy *= norm;
462
463         var x = x2 + dx * t + dy * u;
464         var y = y2 + dy * t - dx * u;
465         return x + " " + y;
466 }
467
468 var position_arrow = function(arrow) {
469         if (arrow.svg) {
470                 if (arrow.svg.parentElement) {
471                         arrow.svg.parentElement.removeChild(arrow.svg);
472                 }
473                 delete arrow.svg;
474         }
475         if (current_display_line !== null && !current_display_line_is_history) {
476                 return;
477         }
478
479         var zoom_factor = $("#board").width() / 400.0;
480         var line_width = arrow.line_width * zoom_factor;
481         var arrow_size = arrow.arrow_size * zoom_factor;
482
483         var square_width = $(".square-a8").width();
484         var pos, from_y, to_y, from_x, to_x;
485         if (board.orientation() === 'black') {
486                 pos = $(".square-h1").position();
487                 from_y = (arrow.from_row + 0.5)*square_width;
488                 to_y = (arrow.to_row + 0.5)*square_width;
489                 from_x = (7 - arrow.from_col + 0.5)*square_width;
490                 to_x = (7 - arrow.to_col + 0.5)*square_width;
491         } else {
492                 pos = $(".square-a8").position();
493                 from_y = (7 - arrow.from_row + 0.5)*square_width;
494                 to_y = (7 - arrow.to_row + 0.5)*square_width;
495                 from_x = (arrow.from_col + 0.5)*square_width;
496                 to_x = (arrow.to_col + 0.5)*square_width;
497         }
498
499         var SVG_NS = "http://www.w3.org/2000/svg";
500         var XHTML_NS = "http://www.w3.org/1999/xhtml";
501         var svg = document.createElementNS(SVG_NS, "svg");
502         svg.setAttribute("width", /** @type{number} */ ($("#board").width()));
503         svg.setAttribute("height", /** @type{number} */ ($("#board").height()));
504         svg.setAttribute("style", "position: absolute");
505         svg.setAttribute("position", "absolute");
506         svg.setAttribute("version", "1.1");
507         svg.setAttribute("class", "c1");
508         svg.setAttribute("xmlns", XHTML_NS);
509
510         var x1 = from_x;
511         var y1 = from_y;
512         var x2 = to_x;
513         var y2 = to_y;
514
515         // Draw the line.
516         var outline = document.createElementNS(SVG_NS, "path");
517         outline.setAttribute("d", "M " + point_from_start(x1, y1, x2, y2, arrow_size / 2, 0) + " L " + point_from_end(x1, y1, x2, y2, -arrow_size / 2, 0));
518         outline.setAttribute("xmlns", XHTML_NS);
519         outline.setAttribute("stroke", "#666");
520         outline.setAttribute("stroke-width", line_width + 2);
521         outline.setAttribute("fill", "none");
522         svg.appendChild(outline);
523
524         var path = document.createElementNS(SVG_NS, "path");
525         path.setAttribute("d", "M " + point_from_start(x1, y1, x2, y2, arrow_size / 2, 0) + " L " + point_from_end(x1, y1, x2, y2, -arrow_size / 2, 0));
526         path.setAttribute("xmlns", XHTML_NS);
527         path.setAttribute("stroke", arrow.fg_color);
528         path.setAttribute("stroke-width", line_width);
529         path.setAttribute("fill", "none");
530         svg.appendChild(path);
531
532         // Then the arrow head.
533         var head = document.createElementNS(SVG_NS, "path");
534         head.setAttribute("d",
535                 "M " +  point_from_end(x1, y1, x2, y2, 0, 0) +
536                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
537                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
538                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
539                 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
540         head.setAttribute("xmlns", XHTML_NS);
541         head.setAttribute("stroke", "#000");
542         head.setAttribute("stroke-width", "1");
543         head.setAttribute("fill", arrow.fg_color);
544         svg.appendChild(head);
545
546         $(svg).css({ top: pos.top, left: pos.left, 'pointer-events': 'none' });
547         document.body.appendChild(svg);
548         arrow.svg = svg;
549 }
550
551 /**
552  * @param {!string} from_square
553  * @param {!string} to_square
554  * @param {!string} fg_color
555  * @param {number} line_width
556  * @param {number} arrow_size
557  */
558 var create_arrow = function(from_square, to_square, fg_color, line_width, arrow_size) {
559         var from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
560         var from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
561         var to_col   = to_square.charCodeAt(0) - "a1".charCodeAt(0);
562         var to_row   = to_square.charCodeAt(1) - "a1".charCodeAt(1);
563
564         // Create arrow.
565         var arrow = {
566                 from_col: from_col,
567                 from_row: from_row,
568                 to_col: to_col,
569                 to_row: to_row,
570                 line_width: line_width,
571                 arrow_size: arrow_size,
572                 fg_color: fg_color
573         };
574
575         position_arrow(arrow);
576         arrows.push(arrow);
577 }
578
579 var compare_by_score = function(refutation_lines, invert, a, b) {
580         var sa = compute_score_sort_key(refutation_lines[b]['score'], refutation_lines[b]['depth'], invert);
581         var sb = compute_score_sort_key(refutation_lines[a]['score'], refutation_lines[a]['depth'], invert);
582         return sa - sb;
583 }
584
585 /**
586  * Fake multi-PV using the refutation lines. Find all “relevant” moves,
587  * sorted by quality, descending.
588  *
589  * @param {!Object} data
590  * @param {number} margin The maximum number of centipawns worse than the
591  *     best move can be and still be included.
592  * @param {boolean} invert Whether black is to play.
593  * @return {Array.<string>} The FEN representation (e.g. Ne4) of all
594  *     moves, in score order.
595  */
596 var find_nonstupid_moves = function(data, margin, invert) {
597         // First of all, if there are any moves that are more than 0.5 ahead of
598         // the primary move, the refutation lines are probably bunk, so just
599         // kill them all. 
600         var best_score = undefined;
601         var pv_score = undefined;
602         for (var move in data['refutation_lines']) {
603                 var line = data['refutation_lines'][move];
604                 var score = compute_score_sort_key(line['score'], line['depth'], invert, false);
605                 if (move == data['pv'][0]) {
606                         pv_score = score;
607                 }
608                 if (best_score === undefined || score > best_score) {
609                         best_score = score;
610                 }
611                 if (line['depth'] < 8) {
612                         return [];
613                 }
614         }
615
616         if (best_score - pv_score > 50) {
617                 return [];
618         }
619
620         // Now find all moves that are within “margin” of the best score.
621         // The PV move will always be first.
622         var moves = [];
623         for (var move in data['refutation_lines']) {
624                 var line = data['refutation_lines'][move];
625                 var score = compute_score_sort_key(line['score'], line['depth'], invert);
626                 if (move != data['pv'][0] && best_score - score <= margin) {
627                         moves.push(move);
628                 }
629         }
630         moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], data['position']['toplay'] === 'B', a, b) });
631         moves.unshift(data['pv'][0]);
632
633         return moves;
634 }
635
636 /**
637  * @param {number} x
638  * @return {!string}
639  */
640 var thousands = function(x) {
641         return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
642 }
643
644 /**
645  * @param {!string} start_fen
646  * @param {Array.<string>} pv
647  * @param {number} move_num
648  * @param {!string} toplay
649  * @param {Array<{ first_move: integer, score: Object }>} scores
650  * @param {number} start_display_move_num
651  * @param {number=} opt_limit
652  * @param {boolean=} opt_showlast
653  */
654 var add_pv = function(start_fen, pv, move_num, toplay, scores, start_display_move_num, opt_limit, opt_showlast) {
655         display_lines.push({
656                 start_fen: start_fen,
657                 pv: pv,
658                 move_num: parseInt(move_num),
659                 toplay: toplay,
660                 scores: scores,
661                 start_display_move_num: start_display_move_num
662         });
663         return print_pv(display_lines.length - 1, opt_limit, opt_showlast);
664 }
665
666 /**
667  * @param {number} line_num
668  * @param {number=} opt_limit If set, show at most this number of moves.
669  * @param {boolean=} opt_showlast If limit is set, show the last moves instead of the first ones.
670  */
671 var print_pv = function(line_num, opt_limit, opt_showlast) {
672         var display_line = display_lines[line_num];
673         var pv = display_line.pv;
674         var move_num = display_line.move_num;
675         var toplay = display_line.toplay;
676
677         // Truncate PV at the start if needed.
678         var start_display_move_num = display_line.start_display_move_num;
679         if (start_display_move_num > 0) {
680                 pv = pv.slice(start_display_move_num);
681                 var to_add = start_display_move_num;
682                 if (toplay === 'B') {
683                         ++move_num;
684                         toplay = 'W';
685                         --to_add;
686                 }
687                 if (to_add % 2 == 1) {
688                         toplay = 'B';
689                         --to_add;
690                 }
691                 move_num += to_add / 2;
692         }
693
694         var ret = '';
695         var i = 0;
696         if (opt_limit && opt_showlast && pv.length > opt_limit) {
697                 // Truncate the PV at the beginning (instead of at the end).
698                 // We assume here that toplay is 'W'. We also assume that if
699                 // opt_showlast is set, then it is the history, and thus,
700                 // the UI should be to expand the history.
701                 ret = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
702                 i = pv.length - opt_limit;
703                 if (i % 2 == 1) {
704                         ++i;
705                 }
706                 move_num += i / 2;
707         } else if (toplay == 'B' && pv.length > 0) {
708                 var move = "<a class=\"move\" id=\"automove" + line_num + "-0\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pv[0] + "</a>";
709                 ret = move_num + '. … ' + move;
710                 toplay = 'W';
711                 ++i;
712                 ++move_num;
713         }
714         for ( ; i < pv.length; ++i) {
715                 var move = "<a class=\"move\" id=\"automove" + line_num + "-" + i + "\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pv[i] + "</a>";
716
717                 if (toplay == 'W') {
718                         if (i > opt_limit && !opt_showlast) {
719                                 return ret + ' (…)';
720                         }
721                         if (ret != '') {
722                                 ret += ' ';
723                         }
724                         ret += move_num + '. ' + move;
725                         ++move_num;
726                         toplay = 'B';
727                 } else {
728                         ret += ' ' + move;
729                         toplay = 'W';
730                 }
731         }
732         return ret;
733 }
734
735 /** Update the highlighted to/from squares on the board.
736  * Based on the global "highlight_from" and "highlight_to" variables.
737  */
738 var update_board_highlight = function() {
739         $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
740         if ((current_display_line === null || current_display_line_is_history) &&
741             highlight_from !== undefined && highlight_to !== undefined) {
742                 $("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
743                 $("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
744         }
745 }
746
747 var update_history = function() {
748         if (display_lines[0] === null || display_lines[0].pv.length == 0) {
749                 $("#history").html("No history");
750         } else if (truncate_display_history) {
751                 $("#history").html(print_pv(0, 8, true));
752         } else {
753                 $("#history").html(
754                         '(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
755                         print_pv(0));
756         }
757 }
758
759 /**
760  * @param {!boolean} truncate_history
761  */
762 var collapse_history = function(truncate_history) {
763         truncate_display_history = truncate_history;
764         update_history();
765 }
766 window['collapse_history'] = collapse_history;
767
768 /** Update the HTML display of multi-PV from the global "refutation_lines".
769  *
770  * Also recreates the global "display_lines".
771  */
772 var update_refutation_lines = function() {
773         if (base_fen === null) {
774                 return;
775         }
776         if (display_lines.length > 2) {
777                 // Truncate so that only the history and PV is left.
778                 display_lines = [ display_lines[0], display_lines[1] ];
779         }
780         var tbl = $("#refutationlines");
781         tbl.empty();
782
783         // Find out where the lines start from.
784         var base_line = [];
785         var base_scores = display_lines[1].scores;
786         var start_display_move_num = 0;
787         if (hash_refutation_lines) {
788                 base_line = current_display_line.pv.slice(0, current_display_move + 1);
789                 base_scores = current_display_line.scores;
790                 start_display_move_num = base_line.length;
791         }
792
793         var moves = [];
794         for (var move in refutation_lines) {
795                 moves.push(move);
796         }
797
798         var invert = (toplay === 'B');
799         if (current_display_line && current_display_move % 2 == 0) {
800                 invert = !invert;
801         }
802         moves = moves.sort(function(a, b) { return compare_by_score(refutation_lines, invert, a, b) });
803         for (var i = 0; i < moves.length; ++i) {
804                 var line = refutation_lines[moves[i]];
805
806                 var tr = document.createElement("tr");
807
808                 var move_td = document.createElement("td");
809                 tr.appendChild(move_td);
810                 $(move_td).addClass("move");
811
812                 var scores = base_scores.concat([{ first_move: start_display_move_num, score: line['score'] }]);
813
814                 if (line['pv'].length == 0) {
815                         // Not found, so just make a one-move PV.
816                         var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['move'] + "</a>";
817                         $(move_td).html(move);
818                         var score_td = document.createElement("td");
819
820                         $(score_td).addClass("score");
821                         $(score_td).text("—");
822                         tr.appendChild(score_td);
823
824                         var depth_td = document.createElement("td");
825                         tr.appendChild(depth_td);
826                         $(depth_td).addClass("depth");
827                         $(depth_td).text("—");
828
829                         var pv_td = document.createElement("td");
830                         tr.appendChild(pv_td);
831                         $(pv_td).addClass("pv");
832                         $(pv_td).html(add_pv(base_fen, base_line.concat([ line['move'] ]), move_num, toplay, scores, start_display_move_num));
833
834                         tbl.append(tr);
835                         continue;
836                 }
837
838                 var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['move'] + "</a>";
839                 $(move_td).html(move);
840
841                 var score_td = document.createElement("td");
842                 tr.appendChild(score_td);
843                 $(score_td).addClass("score");
844                 $(score_td).text(format_short_score(line['score']));
845
846                 var depth_td = document.createElement("td");
847                 tr.appendChild(depth_td);
848                 $(depth_td).addClass("depth");
849                 if (line['depth'] && line['depth'] >= 0) {
850                         $(depth_td).text("d" + line['depth']);
851                 } else {
852                         $(depth_td).text("—");
853                 }
854
855                 var pv_td = document.createElement("td");
856                 tr.appendChild(pv_td);
857                 $(pv_td).addClass("pv");
858                 $(pv_td).html(add_pv(base_fen, base_line.concat(line['pv']), move_num, toplay, scores, start_display_move_num, 10));
859
860                 tbl.append(tr);
861         }
862
863         // Update the move highlight, as we've rewritten all the HTML.
864         update_move_highlight();
865 }
866
867 /**
868  * Create a Chess.js board object, containing the given position plus the given moves,
869  * up to the given limit.
870  *
871  * @param {?string} fen
872  * @param {Array.<string>} moves
873  * @param {number} last_move
874  */
875 var chess_from = function(fen, moves, last_move) {
876         var hiddenboard = new Chess();
877         if (fen !== null && fen !== undefined) {
878                 hiddenboard.load(fen);
879         }
880         for (var i = 0; i <= last_move; ++i) {
881                 if (moves[i] === '0-0') {
882                         hiddenboard.move('O-O');
883                 } else if (moves[i] === '0-0-0') {
884                         hiddenboard.move('O-O-O');
885                 } else {
886                         hiddenboard.move(moves[i]);
887                 }
888         }
889         return hiddenboard;
890 }
891
892 var update_game_list = function(games) {
893         $("#games").text("");
894         if (games === null) {
895                 return;
896         }
897
898         var games_div = document.getElementById('games');
899         for (var game_num = 0; game_num < games.length; ++game_num) {
900                 var game = games[game_num];
901                 var game_span = document.createElement("span");
902                 game_span.setAttribute("class", "game");
903
904                 var game_name = document.createTextNode(game['name']);
905                 if (game['url'] === backend_url) {
906                         // This game.
907                         game_span.appendChild(game_name);
908
909                         if (current_analysis_data && current_analysis_data['position']) {
910                                 var score;
911                                 if (current_analysis_data['position']['result']) {
912                                         score = " (" + current_analysis_data['position']['result'] + ")";
913                                 } else {
914                                         score = " (" + format_short_score(current_analysis_data['score']) + ")";
915                                 }
916                                 game_span.appendChild(document.createTextNode(score));
917                         }
918                 } else {
919                         // Some other game.
920                         var game_a = document.createElement("a");
921                         game_a.setAttribute("href", "#" + game['id']);
922                         game_a.appendChild(game_name);
923                         game_span.appendChild(game_a);
924
925                         var score;
926                         if (game['result']) {
927                                 score = " (" + game['result'] + ")";
928                         } else {
929                                 score = " (" + format_short_score(game['score']) + ")";
930                         }
931                         game_span.appendChild(document.createTextNode(score));
932                 }
933
934                 games_div.appendChild(game_span);
935         }
936 }
937
938 /**
939  * Try to find a running game that matches with the current hash,
940  * and switch to it if we're not already displaying it.
941  */
942 var possibly_switch_game_from_hash = function() {
943         var history_match = window.location.hash.match(/^#history=([a-zA-Z0-9_-]+)/);
944         if (history_match !== null) {
945                 var game_id = history_match[1];
946                 var fake_game = {
947                         url: '/history/' + game_id + '.json',
948                         hashurl: '',
949                         id: 'history=' + game_id
950                 };
951                 switch_backend(fake_game);
952                 return;
953         }
954
955         if (current_games === null) {
956                 return;
957         }
958
959         var hash = window.location.hash.replace(/^#/,'');
960         for (var i = 0; i < current_games.length; ++i) {
961                 if (current_games[i]['id'] === hash) {
962                         if (backend_url !== current_games[i]['url']) {
963                                 switch_backend(current_games[i]);
964                         }
965                         return;
966                 }
967         }
968 }
969
970 /**
971  * If this is a Chess960 castling which doesn't move the king,
972  * move the rook instead.
973 */
974 var patch_move = function(move) {
975         if (move === null) return null;
976         if (move.from !== move.to) return move;
977
978         var f = move.rook_sq & 15;
979         var r = move.rook_sq >> 4;
980         var from = ('abcdefgh'.substring(f,f+1) + '87654321'.substring(r,r+1));
981         var to = move.to;
982
983         if (move.to === 'g1') {
984                 to = 'f1';
985         } else if (move.to === 'g8') {
986                 to = 'f8';
987         } else if (move.to === 'b1') {
988                 to = 'c1';
989         } else if (move.to === 'b8') {
990                 to = 'c8';
991         }
992
993         return { from: from, to: to };
994 }
995
996 /** Update all the HTML on the page, based on current global state.
997  */
998 var update_board = function() {
999         var data = displayed_analysis_data || current_analysis_data;
1000         var current_data = current_analysis_data;  // Convenience alias.
1001
1002         display_lines = [];
1003
1004         // Print the history. This is pretty much the only thing that's
1005         // unconditionally taken from current_data (we're not interested in
1006         // historic history).
1007         if (current_data['position']['history']) {
1008                 var start = (current_data['position'] && current_data['position']['start_fen']) ? current_data['position']['start_fen'] : 'start';
1009                 add_pv(start, current_data['position']['history'], 1, 'W', null, 0, 8, true);
1010         } else {
1011                 display_lines.push(null);
1012         }
1013         update_history();
1014
1015         // Games currently in progress, if any.
1016         if (current_data['games']) {
1017                 current_games = current_data['games'];
1018                 possibly_switch_game_from_hash();
1019         } else {
1020                 current_games = null;
1021         }
1022         update_game_list(current_games);
1023
1024         // The headline. Names are always fetched from current_data;
1025         // the rest can depend a bit.
1026         var headline;
1027         if (current_data &&
1028             current_data['position']['player_w'] && current_data['position']['player_b']) {
1029                 headline = current_data['position']['player_w'] + '–' +
1030                         current_data['position']['player_b'] + ', analysis';
1031         } else {
1032                 headline = 'Analysis';
1033         }
1034
1035         // Credits, where applicable. Note that we don't want the footer to change a lot
1036         // when e.g. viewing history, so if any of these changed during the game,
1037         // use the current one still.
1038         if (current_data['using_lomonosov']) {
1039                 $("#lomonosov").show();
1040         } else {
1041                 $("#lomonosov").hide();
1042         }
1043
1044         // Credits: The engine name/version.
1045         if (current_data['engine'] && current_data['engine']['name'] !== null) {
1046                 $("#engineid").text(current_data['engine']['name']);
1047         }
1048
1049         // Credits: The engine URL.
1050         if (current_data['engine'] && current_data['engine']['url']) {
1051                 $("#engineid").attr("href", current_data['engine']['url']);
1052         } else {
1053                 $("#engineid").removeAttr("href");
1054         }
1055
1056         // Credits: Engine details.
1057         if (current_data['engine'] && current_data['engine']['details']) {
1058                 $("#enginedetails").text(" (" + current_data['engine']['details'] + ")");
1059         } else {
1060                 $("#enginedetails").text("");
1061         }
1062
1063         // Credits: Move source, possibly with URL.
1064         if (current_data['move_source'] && current_data['move_source_url']) {
1065                 $("#movesource").text("Moves provided by ");
1066                 var movesource_a = document.createElement("a");
1067                 movesource_a.setAttribute("href", current_data['move_source_url']);
1068                 var movesource_text = document.createTextNode(current_data['move_source']);
1069                 movesource_a.appendChild(movesource_text);
1070                 var movesource_period = document.createTextNode(".");
1071                 document.getElementById("movesource").appendChild(movesource_a);
1072                 document.getElementById("movesource").appendChild(movesource_period);
1073         } else if (current_data['move_source']) {
1074                 $("#movesource").text("Moves provided by " + current_data['move_source'] + ".");
1075         } else {
1076                 $("#movesource").text("");
1077         }
1078
1079         var last_move;
1080         if (displayed_analysis_data) {
1081                 // Displaying some non-current position, pick out the last move
1082                 // from the history. This will work even if the fetch failed.
1083                 if (current_display_move !== -1) {
1084                         last_move = format_halfmove_with_number(
1085                                 current_display_line.pv[current_display_move],
1086                                 current_display_move);
1087                         headline += ' after ' + last_move;
1088                 }
1089         } else if (data['position']['last_move'] !== 'none') {
1090                 // Find the previous move.
1091                 var previous_move_num, previous_toplay;
1092                 if (data['position']['toplay'] == 'B') {
1093                         previous_move_num = data['position']['move_num'];
1094                         previous_toplay = 'W';
1095                 } else {
1096                         previous_move_num = data['position']['move_num'] - 1;
1097                         previous_toplay = 'B';
1098                 }
1099
1100                 last_move = format_move_with_number(
1101                         data['position']['last_move'],
1102                         previous_move_num,
1103                         previous_toplay == 'W');
1104                 headline += ' after ' + last_move;
1105         } else {
1106                 last_move = null;
1107         }
1108         $("#headline").text(headline);
1109
1110         // The <title> contains a very brief headline.
1111         var title_elems = [];
1112         if (data['position'] && data['position']['result']) {
1113                 title_elems.push(data['position']['result']);
1114         } else if (data['score']) {
1115                 title_elems.push(format_short_score(data['score']));
1116         }
1117         if (last_move !== null) {
1118                 title_elems.push(last_move);
1119         }
1120
1121         if (title_elems.length != 0) {
1122                 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
1123         } else {
1124                 document.title = 'analysis.sesse.net';
1125         }
1126
1127         // The last move (shown by highlighting the from and to squares).
1128         if (data['position'] && data['position']['last_move_uci']) {
1129                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
1130                 highlight_to = data['position']['last_move_uci'].substr(2, 2);
1131         } else if (current_display_line_is_history && current_display_line && current_display_move >= 0) {
1132                 // We don't have historic analysis for this position, but we
1133                 // can reconstruct what the last move was by just replaying
1134                 // from the start.
1135                 var position = (data['position'] && data['position']['start_fen']) ? data['position']['start_fen'] : null;
1136                 var hiddenboard = chess_from(position, current_display_line.pv, current_display_move);
1137                 var moves = hiddenboard.history({ verbose: true });
1138                 last_move = moves.pop();
1139                 highlight_from = last_move.from;
1140                 highlight_to = last_move.to;
1141         } else {
1142                 highlight_from = highlight_to = undefined;
1143         }
1144         update_board_highlight();
1145
1146         if (data['failed']) {
1147                 $("#score").text("No analysis for this move");
1148                 $("#pvtitle").text("PV:");
1149                 $("#pv").empty();
1150                 $("#searchstats").html("&nbsp;");
1151                 $("#refutationlines").empty();
1152                 $("#whiteclock").empty();
1153                 $("#blackclock").empty();
1154                 refutation_lines = [];
1155                 update_refutation_lines();
1156                 clear_arrows();
1157                 update_displayed_line();
1158                 update_move_highlight();
1159                 return;
1160         }
1161
1162         update_clock();
1163
1164         // The score.
1165         if (current_display_line && !current_display_line_is_history) {
1166                 var score;
1167                 if (current_display_line.scores && current_display_line.scores.length > 0) {
1168                         for (var i = 0; i < current_display_line.scores.length; ++i) {
1169                                 if (current_display_move < current_display_line.scores[i].first_move) {
1170                                         break;
1171                                 }
1172                                 score = current_display_line.scores[i].score;
1173                         }
1174                 }
1175                 if (score) {
1176                         $("#score").text(format_long_score(score));
1177                 } else {
1178                         $("#score").text("No score for this line");
1179                 }
1180         } else if (data['score']) {
1181                 $("#score").text(format_long_score(data['score']));
1182         }
1183
1184         // The search stats.
1185         if (data['searchstats']) {
1186                 $("#searchstats").html(data['searchstats']);
1187         } else if (data['tablebase'] == 1) {
1188                 $("#searchstats").text("Tablebase result");
1189         } else if (data['nodes'] && data['nps'] && data['depth']) {
1190                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
1191                 if (data['seldepth']) {
1192                         stats += ' (' + data['seldepth'] + ' selective)';
1193                 }
1194                 if (data['tbhits'] && data['tbhits'] > 0) {
1195                         if (data['tbhits'] == 1) {
1196                                 stats += ', one Syzygy hit';
1197                         } else {
1198                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
1199                         }
1200                 }
1201
1202                 $("#searchstats").text(stats);
1203         } else {
1204                 $("#searchstats").text("");
1205         }
1206
1207         // Update the board itself.
1208         base_fen = data['position']['fen'];
1209         update_displayed_line();
1210
1211         // Print the PV.
1212         $("#pvtitle").text("PV:");
1213
1214         var scores = [{ first_move: -1, score: data['score'] }];
1215         $("#pv").html(add_pv(data['position']['fen'], data['pv'], data['position']['move_num'], data['position']['toplay'], scores, 0));
1216
1217         // Update the PV arrow.
1218         clear_arrows();
1219         if (data['pv'].length >= 1) {
1220                 var hiddenboard = new Chess(base_fen);
1221
1222                 // draw a continuation arrow as long as it's the same piece
1223                 var last_to;
1224                 for (var i = 0; i < data['pv'].length; i += 2) {
1225                         var move = patch_move(hiddenboard.move(data['pv'][i]));
1226
1227                         if ((i >= 2 && move.from != last_to) ||
1228                              interfering_arrow(move.from, move.to)) {
1229                                 break;
1230                         }
1231                         create_arrow(move.from, move.to, '#f66', 6, 20);
1232                         last_to = move.to;
1233                         hiddenboard.move(data['pv'][i + 1]);  // To keep continuity.
1234                 }
1235
1236                 var alt_moves = find_nonstupid_moves(data, 30, data['position']['toplay'] === 'B');
1237                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
1238                         hiddenboard = new Chess(base_fen);
1239                         var move = patch_move(hiddenboard.move(alt_moves[i]));
1240                         if (move !== null) {
1241                                 create_arrow(move.from, move.to, '#f66', 1, 10);
1242                         }
1243                 }
1244         }
1245
1246         // See if all semi-reasonable moves have only one possible response.
1247         if (data['pv'].length >= 2) {
1248                 var nonstupid_moves = find_nonstupid_moves(data, 300, data['position']['toplay'] === 'B');
1249                 var response;
1250                 {
1251                         var hiddenboard = new Chess(base_fen);
1252                         hiddenboard.move(data['pv'][0]);
1253                         response = hiddenboard.move(data['pv'][1]);
1254                 }
1255                 for (var i = 0; i < nonstupid_moves.length; ++i) {
1256                         if (nonstupid_moves[i] == data['pv'][0]) {
1257                                 // ignore the PV move for refutation lines.
1258                                 continue;
1259                         }
1260                         if (!data['refutation_lines'] ||
1261                             !data['refutation_lines'][nonstupid_moves[i]] ||
1262                             !data['refutation_lines'][nonstupid_moves[i]]['pv'] ||
1263                             data['refutation_lines'][nonstupid_moves[i]]['pv'].length < 1) {
1264                                 // Incomplete PV, abort.
1265                                 response = undefined;
1266                                 break;
1267                         }
1268                         var line = data['refutation_lines'][nonstupid_moves[i]];
1269                         hiddenboard = new Chess(base_fen);
1270                         hiddenboard.move(line['pv'][0]);
1271                         var this_response = hiddenboard.move(line['pv'][1]);
1272                         if (response.from !== this_response.from || response.to !== this_response.to) {
1273                                 // Different response depending on lines, abort.
1274                                 response = undefined;
1275                                 break;
1276                         }
1277                 }
1278
1279                 if (nonstupid_moves.length > 0 && response !== undefined) {
1280                         create_arrow(response.from, response.to, '#66f', 6, 20);
1281                 }
1282         }
1283
1284         // Update the refutation lines.
1285         base_fen = data['position']['fen'];
1286         move_num = parseInt(data['position']['move_num']);
1287         toplay = data['position']['toplay'];
1288         refutation_lines = hash_refutation_lines || data['refutation_lines'];
1289         update_refutation_lines();
1290
1291         // Update the sparkline last, since its size depends on how everything else reflowed.
1292         update_sparkline(data);
1293 }
1294
1295 var update_sparkline = function(data) {
1296         if (data && data['score_history']) {
1297                 var first_move_num = undefined;
1298                 for (var halfmove_num in data['score_history']) {
1299                         halfmove_num = parseInt(halfmove_num);
1300                         if (first_move_num === undefined || halfmove_num < first_move_num) {
1301                                 first_move_num = halfmove_num;
1302                         }
1303                 }
1304                 if (first_move_num !== undefined) {
1305                         var last_move_num = data['position']['move_num'] * 2 - 3;
1306                         if (data['position']['toplay'] === 'B') {
1307                                 ++last_move_num;
1308                         }
1309
1310                         // Possibly truncate some moves if we don't have enough width.
1311                         // FIXME: Sometimes width() for #scorecontainer (and by extent,
1312                         // #scoresparkcontainer) on Chrome for mobile seems to start off
1313                         // at something very small, and then suddenly snap back into place.
1314                         // Figure out why.
1315                         var max_moves = Math.floor($("#scoresparkcontainer").width() / 5) - 5;
1316                         if (last_move_num - first_move_num > max_moves) {
1317                                 first_move_num = last_move_num - max_moves;
1318                         }
1319
1320                         var min_score = -100;
1321                         var max_score = 100;
1322                         var last_score = null;
1323                         var scores = [];
1324                         for (var halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
1325                                 if (data['score_history'][halfmove_num]) {
1326                                         var score = compute_plot_score(data['score_history'][halfmove_num]);
1327                                         last_score = score;
1328                                         if (score < min_score) min_score = score;
1329                                         if (score > max_score) max_score = score;
1330                                 }
1331                                 scores.push(last_score);
1332                         }
1333                         if (data['score']) {
1334                                 scores.push(compute_plot_score(data['score']));
1335                         }
1336                         // FIXME: at some widths, calling sparkline() seems to push
1337                         // #scorecontainer under the board.
1338                         $("#scorespark").sparkline(scores, {
1339                                 type: 'bar',
1340                                 zeroColor: 'gray',
1341                                 chartRangeMin: min_score,
1342                                 chartRangeMax: max_score,
1343                                 tooltipFormatter: function(sparkline, options, fields) {
1344                                         // score_history contains the Nth _position_, but format_tooltip
1345                                         // wants to format the Nth _move_; thus the -1.
1346                                         return format_tooltip(data, fields[0].offset + first_move_num - 1);
1347                                 }
1348                         });
1349                         $('#scorespark').bind('sparklineClick', function(event) {
1350                                 var sparkline = event.sparklines[0];
1351                                 var region = sparkline.getCurrentRegionFields();
1352                                 if (region[0].offset !== undefined) {
1353                                         show_line(0, first_move_num + region[0].offset - 1);
1354                                 }
1355                         });
1356                 } else {
1357                         $("#scorespark").text("");
1358                 }
1359         } else {
1360                 $("#scorespark").text("");
1361         }
1362 }
1363
1364 /**
1365  * @param {number} num_viewers
1366  */
1367 var update_num_viewers = function(num_viewers) {
1368         if (num_viewers === null) {
1369                 $("#numviewers").text("");
1370         } else if (num_viewers == 1) {
1371                 $("#numviewers").text("You are the only current viewer");
1372         } else {
1373                 $("#numviewers").text(num_viewers + " current viewers");
1374         }
1375 }
1376
1377 var update_clock = function() {
1378         clearTimeout(clock_timer);
1379
1380         var data = displayed_analysis_data || current_analysis_data;
1381         if (!data) return;
1382
1383         if (data['position']) {
1384                 var result = data['position']['result'];
1385                 if (result === '1-0') {
1386                         $("#whiteclock").text("1");
1387                         $("#blackclock").text("0");
1388                         $("#whiteclock").removeClass("running-clock");
1389                         $("#blackclock").removeClass("running-clock");
1390                         return;
1391                 }
1392                 if (result === '1/2-1/2') {
1393                         $("#whiteclock").text("1/2");
1394                         $("#blackclock").text("1/2");
1395                         $("#whiteclock").removeClass("running-clock");
1396                         $("#blackclock").removeClass("running-clock");
1397                         return;
1398                 }       
1399                 if (result === '0-1') {
1400                         $("#whiteclock").text("0");
1401                         $("#blackclock").text("1");
1402                         $("#whiteclock").removeClass("running-clock");
1403                         $("#blackclock").removeClass("running-clock");
1404                         return;
1405                 }
1406         }
1407
1408         var white_clock_ms = null;
1409         var black_clock_ms = null;
1410
1411         // Static clocks.
1412         if (data['position'] &&
1413             data['position']['white_clock'] &&
1414             data['position']['black_clock']) {
1415                 white_clock_ms = data['position']['white_clock'] * 1000;
1416                 black_clock_ms = data['position']['black_clock'] * 1000;
1417         }
1418
1419         // Dynamic clock (only one, obviously).
1420         var color;
1421         if (data['position']['white_clock_target']) {
1422                 color = "white";
1423                 $("#whiteclock").addClass("running-clock");
1424                 $("#blackclock").removeClass("running-clock");
1425         } else if (data['position']['black_clock_target']) {
1426                 color = "black";
1427                 $("#whiteclock").removeClass("running-clock");
1428                 $("#blackclock").addClass("running-clock");
1429         } else {
1430                 $("#whiteclock").removeClass("running-clock");
1431                 $("#blackclock").removeClass("running-clock");
1432         }
1433         var remaining_ms;
1434         if (color) {
1435                 var now = new Date().getTime() + client_clock_offset_ms;
1436                 remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
1437                 if (color === "white") {
1438                         white_clock_ms = remaining_ms;
1439                 } else {
1440                         black_clock_ms = remaining_ms;
1441                 }
1442         }
1443
1444         if (white_clock_ms === null || black_clock_ms === null) {
1445                 $("#whiteclock").empty();
1446                 $("#blackclock").empty();
1447                 return;
1448         }
1449
1450         // If either player has twenty minutes or less left, add the second counters.
1451         // This matches what DGT clocks do.
1452         var show_seconds = (white_clock_ms < 60 * 20 * 1000 || black_clock_ms < 60 * 20 * 1000);
1453
1454         if (color) {
1455                 // See when the clock will change next, and update right after that.
1456                 var next_update_ms;
1457                 if (show_seconds) {
1458                         next_update_ms = remaining_ms % 1000 + 100;
1459                 } else {
1460                         next_update_ms = remaining_ms % 60000 + 100;
1461                 }
1462                 clock_timer = setTimeout(update_clock, next_update_ms);
1463         }
1464
1465         $("#whiteclock").text(format_clock(white_clock_ms, show_seconds));
1466         $("#blackclock").text(format_clock(black_clock_ms, show_seconds));
1467 }
1468
1469 /**
1470  * @param {Number} remaining_ms
1471  * @param {boolean} show_seconds
1472  */
1473 var format_clock = function(remaining_ms, show_seconds) {
1474         if (remaining_ms <= 0) {
1475                 if (show_seconds) {
1476                         return "00:00:00";
1477                 } else {
1478                         return "00:00";
1479                 }
1480         }
1481
1482         var remaining = Math.floor(remaining_ms / 1000);
1483         var seconds = remaining % 60;
1484         remaining = (remaining - seconds) / 60;
1485         var minutes = remaining % 60;
1486         remaining = (remaining - minutes) / 60;
1487         var hours = remaining;
1488         if (show_seconds) {
1489                 return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
1490         } else {
1491                 return format_2d(hours) + ":" + format_2d(minutes);
1492         }
1493 }
1494
1495 /**
1496  * @param {Number} x
1497  */
1498 var format_2d = function(x) {
1499         if (x >= 10) {
1500                 return x;
1501         } else {
1502                 return "0" + x;
1503         }
1504 }
1505
1506 /**
1507  * @param {string} move
1508  * @param {Number} move_num Move number of this move.
1509  * @param {boolean} white_to_play Whether white is to play this move.
1510  */
1511 var format_move_with_number = function(move, move_num, white_to_play) {
1512         var ret;
1513         if (white_to_play) {
1514                 ret = move_num + '. ';
1515         } else {
1516                 ret = move_num + '… ';
1517         }
1518         ret += move;
1519         return ret;
1520 }
1521
1522 /**
1523  * @param {string} move
1524  * @param {Number} halfmove_num Half-move number that is to be played,
1525  *   starting from 0.
1526  */
1527 var format_halfmove_with_number = function(move, halfmove_num) {
1528         return format_move_with_number(
1529                 move,
1530                 Math.floor(halfmove_num / 2) + 1,
1531                 halfmove_num % 2 == 0);
1532 }
1533
1534 /**
1535  * @param {Object} data
1536  * @param {Number} halfmove_num
1537  */
1538 var format_tooltip = function(data, halfmove_num) {
1539         if (data['score_history'][halfmove_num + 1] ||
1540             (halfmove_num + 1) === data['position']['history'].length) {
1541                 // Position is in the history, or it is the current position
1542                 // (which is implicitly tacked onto the history).
1543                 var move;
1544                 var short_score;
1545                 if ((halfmove_num + 1) === data['position']['history'].length) {
1546                         move = data['position']['last_move'];
1547                         short_score = format_short_score(data['score']);
1548                 } else {
1549                         move = data['position']['history'][halfmove_num];
1550                         short_score = format_short_score(data['score_history'][halfmove_num + 1]);
1551                 }
1552                 if (halfmove_num === -1) {
1553                         return "Start position: " + short_score;
1554                 } else {
1555                         var move_with_number = format_halfmove_with_number(move, halfmove_num);
1556                         return "After " + move_with_number + ": " + short_score;
1557                 }
1558         } else {
1559                 for (var i = halfmove_num; i --> -1; ) {
1560                         if (data['score_history'][i]) {
1561                                 var move = data['position']['history'][i];
1562                                 if (i === -1) {
1563                                         return "[Analysis kept from start position]";
1564                                 } else {
1565                                         return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
1566                                 }
1567                         }
1568                 }
1569         }
1570 }
1571
1572 /**
1573  * @param {boolean} truncate_history
1574  */
1575 var set_truncate_history = function(truncate_history) {
1576         truncate_display_history = truncate_history;
1577         update_refutation_lines();
1578 }
1579 window['set_truncate_history'] = set_truncate_history;
1580
1581 /**
1582  * @param {number} line_num
1583  * @param {number} move_num
1584  */
1585 var show_line = function(line_num, move_num) {
1586         if (line_num == -1) {
1587                 current_display_line = null;
1588                 current_display_move = null;
1589                 hash_refutation_lines = null;
1590                 if (displayed_analysis_data) {
1591                         // TODO: Support exiting to history position if we are in an
1592                         // analysis line of a history position.
1593                         displayed_analysis_data = null;
1594                 }
1595                 update_board();
1596                 return;
1597         } else {
1598                 current_display_line = jQuery.extend({}, display_lines[line_num]);  // Shallow clone.
1599                 current_display_move = move_num + current_display_line.start_display_move_num;
1600         }
1601         current_display_line_is_history = (line_num == 0);
1602
1603         update_historic_analysis();
1604         update_displayed_line();
1605         update_board_highlight();
1606         update_move_highlight();
1607         redraw_arrows();
1608 }
1609 window['show_line'] = show_line;
1610
1611 var prev_move = function() {
1612         if (current_display_line &&
1613             current_display_move >= current_display_line.start_display_move_num) {
1614                 --current_display_move;
1615         }
1616         update_historic_analysis();
1617         update_displayed_line();
1618         update_move_highlight();
1619 }
1620 window['prev_move'] = prev_move;
1621
1622 var next_move = function() {
1623         if (current_display_line &&
1624             current_display_move < current_display_line.pv.length - 1) {
1625                 ++current_display_move;
1626         }
1627         update_historic_analysis();
1628         update_displayed_line();
1629         update_move_highlight();
1630 }
1631 window['next_move'] = next_move;
1632
1633 var next_game = function() {
1634         if (current_games === null) {
1635                 return;
1636         }
1637
1638         // Try to find the game we are currently looking at.
1639         for (var game_num = 0; game_num < current_games.length; ++game_num) {
1640                 var game = current_games[game_num];
1641                 if (game['url'] === backend_url) {
1642                         var next_game_num = (game_num + 1) % current_games.length;
1643                         switch_backend(current_games[next_game_num]);
1644                         return;
1645                 }
1646         }
1647
1648         // Couldn't find it; give up.
1649 }
1650
1651 var update_historic_analysis = function() {
1652         if (!current_display_line_is_history) {
1653                 return;
1654         }
1655         if (current_display_move == current_display_line.pv.length - 1) {
1656                 displayed_analysis_data = null;
1657                 update_board();
1658         }
1659
1660         // Fetch old analysis for this line if it exists.
1661         var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pv, current_display_move);
1662         var filename = "/history/move" + (current_display_move + 1) + "-" +
1663                 hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
1664
1665         current_historic_xhr = $.ajax({
1666                 url: filename
1667         }).done(function(data, textstatus, xhr) {
1668                 displayed_analysis_data = data;
1669                 update_board();
1670         }).fail(function(jqXHR, textStatus, errorThrown) {
1671                 if (textStatus === "abort") {
1672                         // Aborted because we are switching backends. Don't do anything;
1673                         // we will already have been cleared.
1674                 } else {
1675                         displayed_analysis_data = {'failed': true};
1676                         update_board();
1677                 }
1678         });
1679 }
1680
1681 /**
1682  * @param {string} fen
1683  */
1684 var update_imbalance = function(fen) {
1685         var hiddenboard = new Chess(fen);
1686         var imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
1687         for (var row = 0; row < 8; ++row) {
1688                 for (var col = 0; col < 8; ++col) {
1689                         var col_text = String.fromCharCode('a1'.charCodeAt(0) + col);
1690                         var row_text = String.fromCharCode('a1'.charCodeAt(1) + row);
1691                         var square = col_text + row_text;
1692                         var contents = hiddenboard.get(square);
1693                         if (contents !== null) {
1694                                 if (contents.color === 'w') {
1695                                         ++imbalance[contents.type];
1696                                 } else {
1697                                         --imbalance[contents.type];
1698                                 }
1699                         }
1700                 }
1701         }
1702         var white_imbalance = '';
1703         var black_imbalance = '';
1704         for (var piece in imbalance) {
1705                 for (var i = 0; i < imbalance[piece]; ++i) {
1706                         white_imbalance += '<img src="img/chesspieces/wikipedia/w' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1707                 }
1708                 for (var i = 0; i < -imbalance[piece]; ++i) {
1709                         black_imbalance += '<img src="img/chesspieces/wikipedia/b' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1710                 }
1711         }
1712         $('#whiteimbalance').html(white_imbalance);
1713         $('#blackimbalance').html(black_imbalance);
1714 }
1715
1716 /** Mark the currently selected move in red.
1717  * Also replaces the PV with the current displayed line if it's not shown
1718  * anywhere else on the screen.
1719  */
1720 var update_move_highlight = function() {
1721         if (highlighted_move !== null) {
1722                 highlighted_move.removeClass('highlight'); 
1723         }
1724         if (current_display_line) {
1725                 var display_line_num = find_display_line_matching_num();
1726                 if (display_line_num === null) {
1727                         // Replace the PV with the (complete) line.
1728                         $("#pvtitle").text("Exploring:");
1729                         current_display_line.start_display_move_num = 0;
1730                         display_lines.push(current_display_line);
1731                         $("#pv").html(print_pv(display_lines.length - 1));
1732                         display_line_num = display_lines.length - 1;
1733
1734                         // Clear out the PV, so it's not selected by anything later.
1735                         display_lines[1].pv = [];
1736                 }
1737
1738                 highlighted_move = $("#automove" + display_line_num + "-" + (current_display_move - current_display_line.start_display_move_num));
1739                 highlighted_move.addClass('highlight');
1740         }
1741 }
1742
1743 /**
1744  * See if the current displayed line is identical to any of the ones
1745  * we have on screen. (It might not be if e.g. the analysis reloaded
1746  * since we started looking.)
1747  *
1748  * @return {?number}
1749  */
1750 var find_display_line_matching_num = function() {
1751         for (var i = 0; i < display_lines.length; ++i) {
1752                 var line = display_lines[i];
1753                 if (line.start_display_move_num > 0) continue;
1754                 if (current_display_line.start_fen !== line.start_fen) continue;
1755                 if (current_display_line.pv.length !== line.pv.length) continue;
1756                 var ok = true;
1757                 for (var j = 0; j < line.pv.length; ++j) {
1758                         if (current_display_line.pv[j] !== line.pv[j]) {
1759                                 ok = false;
1760                                 break;
1761                         }
1762                 }
1763                 if (ok) {
1764                         return i;
1765                 }
1766         }
1767         return null;
1768 }
1769
1770 /** Update the board based on the currently displayed line.
1771  * 
1772  * TODO: This should really be called only whenever something changes,
1773  * instead of all the time.
1774  */
1775 var update_displayed_line = function() {
1776         if (current_display_line === null) {
1777                 $("#linenav").hide();
1778                 $("#linemsg").show();
1779                 display_fen = base_fen;
1780                 set_board_position(base_fen);
1781                 update_imbalance(base_fen);
1782                 return;
1783         }
1784
1785         $("#linenav").show();
1786         $("#linemsg").hide();
1787
1788         if (current_display_move <= 0) {
1789                 $("#prevmove").html("Previous");
1790         } else {
1791                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
1792         }
1793         if (current_display_move == current_display_line.pv.length - 1) {
1794                 $("#nextmove").html("Next");
1795         } else {
1796                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
1797         }
1798
1799         var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pv, current_display_move);
1800         set_board_position(hiddenboard.fen());
1801         if (display_fen !== hiddenboard.fen() && !current_display_line_is_history) {
1802                 // Fire off a hash request, since we're now off the main position
1803                 // and it just changed.
1804                 explore_hash(hiddenboard.fen());
1805         }
1806         display_fen = hiddenboard.fen();
1807         update_imbalance(hiddenboard.fen());
1808 }
1809
1810 var set_board_position = function(new_fen) {
1811         board_is_animating = true;
1812         var old_fen = board.fen();
1813         board.position(new_fen);
1814         if (board.fen() === old_fen) {
1815                 board_is_animating = false;
1816         }
1817 }
1818
1819 /**
1820  * @param {boolean} param_enable_sound
1821  */
1822 var set_sound = function(param_enable_sound) {
1823         enable_sound = param_enable_sound;
1824         if (enable_sound) {
1825                 $("#soundon").html("<strong>On</strong>");
1826                 $("#soundoff").html("<a href=\"javascript:set_sound(false)\">Off</a>");
1827
1828                 // Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
1829                 // and also preload the file since the user has selected audio.
1830                 var ding = document.getElementById('ding');
1831                 if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
1832                         ding.src = 'ding.opus';
1833                         ding.load();
1834                 }
1835         } else {
1836                 $("#soundon").html("<a href=\"javascript:set_sound(true)\">On</a>");
1837                 $("#soundoff").html("<strong>Off</strong>");
1838         }
1839         if (supports_html5_storage()) {
1840                 localStorage['enable_sound'] = enable_sound ? 1 : 0;
1841         }
1842 }
1843 window['set_sound'] = set_sound;
1844
1845 /** Send off a hash probe request to the backend.
1846  * @param {string} fen
1847  */
1848 var explore_hash = function(fen) {
1849         // If we already have a backend response going, abort it.
1850         if (current_hash_xhr) {
1851                 current_hash_xhr.abort();
1852         }
1853         if (current_hash_display_timer) {
1854                 clearTimeout(current_hash_display_timer);
1855                 current_hash_display_timer = null;
1856         }
1857         $("#refutationlines").empty();
1858         current_hash_xhr = $.ajax({
1859                 url: backend_hash_url + "?fen=" + fen
1860         }).done(function(data, textstatus, xhr) {
1861                 show_explore_hash_results(data, fen);
1862         });
1863 }
1864
1865 /** Process the JSON response from a hash probe request.
1866  * @param {!Object} data
1867  * @param {string} fen
1868  */
1869 var show_explore_hash_results = function(data, fen) {
1870         if (board_is_animating) {
1871                 // Updating while the animation is still going causes
1872                 // the animation to jerk. This is pretty crude, but it will do.
1873                 current_hash_display_timer = setTimeout(function() { show_explore_hash_results(data, fen); }, 100);
1874                 return;
1875         }
1876         current_hash_display_timer = null;
1877         hash_refutation_lines = data['lines'];
1878         update_board();
1879 }
1880
1881 // almost all of this stuff comes from the chessboard.js example page
1882 var onDragStart = function(source, piece, position, orientation) {
1883         var pseudogame = new Chess(display_fen);
1884         if (pseudogame.game_over() === true ||
1885             (pseudogame.turn() === 'w' && piece.search(/^b/) !== -1) ||
1886             (pseudogame.turn() === 'b' && piece.search(/^w/) !== -1)) {
1887                 return false;
1888         }
1889
1890         recommended_move = get_best_move(pseudogame, source, null, pseudogame.turn() === 'b');
1891         if (recommended_move) {
1892                 var squareEl = $('#board .square-' + recommended_move.to);
1893                 squareEl.addClass('highlight1-32417');
1894         }
1895         return true;
1896 }
1897
1898 var mousedownSquare = function(e) {
1899         reverse_dragging_from = null;
1900         var square = $(this).attr('data-square');
1901
1902         var pseudogame = new Chess(display_fen);
1903         if (pseudogame.game_over() === true) {
1904                 return;
1905         }
1906
1907         // If the square is empty, or has a piece of the side not to move,
1908         // we handle it. If not, normal piece dragging will take it.
1909         var position = board.position();
1910         if (!position.hasOwnProperty(square) ||
1911             (pseudogame.turn() === 'w' && position[square].search(/^b/) !== -1) ||
1912             (pseudogame.turn() === 'b' && position[square].search(/^w/) !== -1)) {
1913                 reverse_dragging_from = square;
1914                 recommended_move = get_best_move(pseudogame, null, square, pseudogame.turn() === 'b');
1915                 if (recommended_move) {
1916                         var squareEl = $('#board .square-' + recommended_move.from);
1917                         squareEl.addClass('highlight1-32417');
1918                         squareEl = $('#board .square-' + recommended_move.to);
1919                         squareEl.addClass('highlight1-32417');
1920                 }
1921         }
1922 }
1923
1924 var mouseupSquare = function(e) {
1925         if (reverse_dragging_from === null) {
1926                 return;
1927         }
1928         var source = $(this).attr('data-square');
1929         var target = reverse_dragging_from;
1930         reverse_dragging_from = null;
1931         if (onDrop(source, target) !== 'snapback') {
1932                 onSnapEnd(source, target);
1933         }
1934         $("#board").find('.square-55d63').removeClass('highlight1-32417');
1935 }
1936
1937 var get_best_move = function(game, source, target, invert) {
1938         var moves = game.moves({ verbose: true });
1939         if (source !== null) {
1940                 moves = moves.filter(function(move) { return move.from == source; });
1941         }
1942         if (target !== null) {
1943                 moves = moves.filter(function(move) { return move.to == target; });
1944         }
1945         if (moves.length == 0) {
1946                 return null;
1947         }
1948         if (moves.length == 1) {
1949                 return moves[0];
1950         }
1951
1952         // More than one move. Use the display lines (if we have them)
1953         // to disambiguate; otherwise, we have no information.
1954         var move_hash = {};
1955         for (var i = 0; i < moves.length; ++i) {
1956                 move_hash[moves[i].san] = moves[i];
1957         }
1958
1959         // See if we're already exploring some line.
1960         if (current_display_line &&
1961             current_display_move < current_display_line.pv.length - 1) {
1962                 var first_move = current_display_line.pv[current_display_move + 1];
1963                 if (move_hash[first_move]) {
1964                         return move_hash[first_move];
1965                 }
1966         }
1967
1968         // History and PV take priority over the display lines.
1969         for (var i = 0; i < 2; ++i) {
1970                 var line = display_lines[i];
1971                 var first_move = line.pv[line.start_display_move_num];
1972                 if (move_hash[first_move]) {
1973                         return move_hash[first_move];
1974                 }
1975         }
1976
1977         var best_move = null;
1978         var best_move_score = null;
1979
1980         for (var move in refutation_lines) {
1981                 var line = refutation_lines[move];
1982                 if (!line['score']) {
1983                         continue;
1984                 }
1985                 var first_move = line['pv'][0];
1986                 if (move_hash[first_move]) {
1987                         var score = compute_score_sort_key(line['score'], line['depth'], invert);
1988                         if (best_move_score === null || score > best_move_score) {
1989                                 best_move = move_hash[first_move];
1990                                 best_move_score = score;
1991                         }
1992                 }
1993         }
1994         return best_move;
1995 }
1996
1997 var onDrop = function(source, target) {
1998         if (source === target) {
1999                 if (recommended_move === null) {
2000                         return 'snapback';
2001                 } else {
2002                         // Accept the move. It will be changed in onSnapEnd.
2003                         return;
2004                 }
2005         } else {
2006                 // Suggestion not asked for.
2007                 recommended_move = null;
2008         }
2009
2010         // see if the move is legal
2011         var pseudogame = new Chess(display_fen);
2012         var move = pseudogame.move({
2013                 from: source,
2014                 to: target,
2015                 promotion: 'q' // NOTE: always promote to a queen for example simplicity
2016         });
2017
2018         // illegal move
2019         if (move === null) return 'snapback';
2020 }
2021
2022 var onSnapEnd = function(source, target) {
2023         if (source === target && recommended_move !== null) {
2024                 source = recommended_move.from;
2025                 target = recommended_move.to;
2026         }
2027         recommended_move = null;
2028         var pseudogame = new Chess(display_fen);
2029         var move = pseudogame.move({
2030                 from: source,
2031                 to: target,
2032                 promotion: 'q' // NOTE: always promote to a queen for example simplicity
2033         });
2034
2035         if (current_display_line &&
2036             current_display_move < current_display_line.pv.length - 1 &&
2037             current_display_line.pv[current_display_move + 1] === move.san) {
2038                 next_move();
2039                 return;
2040         }
2041
2042         // Walk down the displayed lines until we find one that starts with
2043         // this move, then select that. Note that this gives us a good priority
2044         // order (history first, then PV, then multi-PV lines).
2045         for (var i = 0; i < display_lines.length; ++i) {
2046                 if (i == 1 && current_display_line) {
2047                         // Do not choose PV if not on it.
2048                         continue;
2049                 }
2050                 var line = display_lines[i];
2051                 if (line.pv[line.start_display_move_num] === move.san) {
2052                         show_line(i, 0);
2053                         return;
2054                 }
2055         }
2056
2057         // Shouldn't really be here if we have hash probes, but there's really
2058         // nothing we can do.
2059 }
2060 // End of dragging-related code.
2061
2062 var fmt_cp = function(v) {
2063         if (v === 0) {
2064                 return "0.00";
2065         } else if (v > 0) {
2066                 return "+" + (v / 100).toFixed(2);
2067         } else {
2068                 v = -v;
2069                 return "-" + (v / 100).toFixed(2);
2070         }
2071 }
2072
2073 var format_short_score = function(score) {
2074         if (!score) {
2075                 return "???";
2076         }
2077         if (score[0] === 'm') {
2078                 if (score[2]) {  // Is a bound.
2079                         return score[2] + "\u00a0M " + score[1];
2080                 } else {
2081                         return "M " + score[1];
2082                 }
2083         } else if (score[0] === 'd') {
2084                 return "TB draw";
2085         } else if (score[0] === 'cp') {
2086                 if (score[2]) {  // Is a bound.
2087                         return score[2] + "\u00a0" + fmt_cp(score[1]);
2088                 } else {
2089                         return fmt_cp(score[1]);
2090                 }
2091         }
2092         return null;
2093 }
2094
2095 var format_long_score = function(score) {
2096         if (!score) {
2097                 return "???";
2098         }
2099         if (score[0] === 'm') {
2100                 if (score[1] > 0) {
2101                         return "White mates in " + score[1];
2102                 } else {
2103                         return "Black mates in " + (-score[1]);
2104                 }
2105         } else if (score[0] === 'd') {
2106                 return "Theoretical draw";
2107         } else if (score[0] === 'cp') {
2108                 return "Score: " + format_short_score(score);
2109         }
2110         return null;
2111 }
2112
2113 var compute_plot_score = function(score) {
2114         if (score[0] === 'm') {
2115                 if (score[1] > 0) {
2116                         return 500;
2117                 } else {
2118                         return -500;
2119                 }
2120         } else if (score[0] === 'd') {
2121                 return 0;
2122         } else if (score[0] === 'cp') {
2123                 if (score[1] > 500) {
2124                         return 500;
2125                 } else if (score[1] < -500) {
2126                         return -500;
2127                 } else {
2128                         return score[1];
2129                 }
2130         }
2131         return null;
2132 }
2133
2134 /**
2135  * @param score The score digest tuple.
2136  * @param {?number} depth Depth the move has been computed to, or null.
2137  * @param {boolean} invert Whether black is to play.
2138  * @param {boolean=} depth_secondary_key
2139  * @return {number}
2140  */
2141 var compute_score_sort_key = function(score, depth, invert, depth_secondary_key) {
2142         var s;
2143         if (!score) {
2144                 return -10000000;
2145         }
2146         if (score[0] === 'm') {
2147                 if (score[1] > 0) {
2148                         // White mates.
2149                         s = 99999 - score[1];
2150                 } else {
2151                         // Black mates (note the double negative for score[1]).
2152                         s = -99999 - score[1];
2153                 }
2154         } else if (score[0] === 'd') {
2155                 s = 0;
2156         } else if (score[0] === 'cp') {
2157                 s = score[1];
2158         }
2159         if (s) {
2160                 if (invert) s = -s;
2161                 if (depth_secondary_key) {
2162                         return s * 200 + (depth || 0);
2163                 } else {
2164                         return s;
2165                 }
2166         } else {
2167                 return null;
2168         }
2169 }
2170
2171 /**
2172  * @param {Object} game
2173  */
2174 var switch_backend = function(game) {
2175         // Stop looking at historic data.
2176         current_display_line = null;
2177         current_display_move = null;
2178         displayed_analysis_data = null;
2179         if (current_historic_xhr) {
2180                 current_historic_xhr.abort();
2181         }
2182
2183         // If we already have a backend response going, abort it.
2184         if (current_analysis_xhr) {
2185                 current_analysis_xhr.abort();
2186         }
2187         if (current_hash_xhr) {
2188                 current_hash_xhr.abort();
2189         }
2190
2191         // Otherwise, we should have a timer going to start a new one.
2192         // Kill that, too.
2193         if (current_analysis_request_timer) {
2194                 clearTimeout(current_analysis_request_timer);
2195                 current_analysis_request_timer = null;
2196         }
2197         if (current_hash_display_timer) {
2198                 clearTimeout(current_hash_display_timer);
2199                 current_hash_display_timer = null;
2200         }
2201
2202         // Request an immediate fetch with the new backend.
2203         backend_url = game['url'];
2204         backend_hash_url = game['hashurl'];
2205         window.location.hash = '#' + game['id'];
2206         current_analysis_data = null;
2207         ims = 0;
2208         request_update();
2209 }
2210 window['switch_backend'] = switch_backend;
2211
2212 window['flip'] = function() { board.flip(); redraw_arrows(); };
2213
2214 var init = function() {
2215         unique = get_unique();
2216
2217         // Load settings from HTML5 local storage if available.
2218         if (supports_html5_storage() && localStorage['enable_sound']) {
2219                 set_sound(parseInt(localStorage['enable_sound']));
2220         } else {
2221                 set_sound(false);
2222         }
2223
2224         // Create board.
2225         board = new window.ChessBoard('board', {
2226                 onMoveEnd: function() { board_is_animating = false; },
2227
2228                 draggable: true,
2229                 onDragStart: onDragStart,
2230                 onDrop: onDrop,
2231                 onSnapEnd: onSnapEnd
2232         });
2233         $("#board").on('mousedown', '.square-55d63', mousedownSquare);
2234         $("#board").on('mouseup', '.square-55d63', mouseupSquare);
2235
2236         request_update();
2237         $(window).resize(function() {
2238                 board.resize();
2239                 update_sparkline(displayed_analysis_data || current_analysis_data);
2240                 update_board_highlight();
2241                 redraw_arrows();
2242         });
2243         $(window).keyup(function(event) {
2244                 if (event.which == 39) {  // Left arrow.
2245                         next_move();
2246                 } else if (event.which == 37) {  // Right arrow.
2247                         prev_move();
2248                 } else if (event.which >= 49 && event.which <= 57) {  // 1-9.
2249                         var num = event.which - 49;
2250                         if (current_games && current_games.length >= num) {
2251                                 switch_backend(current_games[num]);
2252                         }
2253                 } else if (event.which == 78) {  // N.
2254                         next_game();
2255                 }
2256         });
2257         window.addEventListener('hashchange', possibly_switch_game_from_hash, false);
2258         possibly_switch_game_from_hash();
2259 };
2260 $(document).ready(init);
2261
2262 })();