Add some support for listing games in progress, and switching between them. (Proper...
[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 = 2015062104;
11
12 /**
13  * The current backend URL.
14  *
15  * @type {!string}
16  * @private
17  */
18 var backend_url = "/analysis.pl";
19
20 /** @type {window.ChessBoard} @private */
21 var board = null;
22
23 /**
24  * The most recent analysis data we have from the server
25  * (about the most recent position).
26  *
27  * @type {?Object}
28  * @private */
29 var current_analysis_data = null;
30
31 /**
32  * If we are displaying previous analysis, this is non-null,
33  * and will override most of current_analysis_data.
34  *
35  * @type {?Object}
36  * @private
37  */
38 var displayed_analysis_data = null;
39
40 /** @type {Array.<{
41  *      from_col: number,
42  *      from_row: number,
43  *      to_col: number,
44  *      to_row: number,
45  *      line_width: number,
46  *      arrow_size: number,
47  *      fg_color: string
48  * }>}
49  * @private
50  */
51 var arrows = [];
52
53 /** @type {Array.<Array.<boolean>>} */
54 var occupied_by_arrows = [];
55
56 var refutation_lines = [];
57
58 /** @type {!number} @private */
59 var move_num = 1;
60
61 /** @type {!string} @private */
62 var toplay = 'W';
63
64 /** @type {number} @private */
65 var ims = 0;
66
67 /** @type {boolean} @private */
68 var sort_refutation_lines_by_score = true;
69
70 /** @type {boolean} @private */
71 var truncate_display_history = true;
72
73 /** @type {!string|undefined} @private */
74 var highlight_from = undefined;
75
76 /** @type {!string|undefined} @private */
77 var highlight_to = undefined;
78
79 /** @type {?jQuery} @private */
80 var highlighted_move = null;
81
82 /** @type {?number} @private */
83 var unique = null;
84
85 /** @type {boolean} @private */
86 var enable_sound = false;
87
88 /**
89  * Our best estimate of how many milliseconds we need to add to 
90  * new Date() to get the true UTC time. Calibrated against the
91  * server clock.
92  *
93  * @type {?number}
94  * @private
95  */
96 var client_clock_offset_ms = null;
97
98 var clock_timer = null;
99
100 /** The current position on the board, represented as a FEN string.
101  * @type {?string}
102  * @private
103  */
104 var fen = null;
105
106 /** @typedef {{
107  *    start_fen: string,
108  *    uci_pv: Array.<string>,
109  *    pretty_pv: Array.<string>,
110  *    line_num: number
111  * }} DisplayLine
112  */
113
114 /** @type {Array.<DisplayLine>}
115  * @private
116  */
117 var display_lines = [];
118
119 /** @type {?DisplayLine} @private */
120 var current_display_line = null;
121
122 /** @type {boolean} @private */
123 var current_display_line_is_history = false;
124
125 /** @type {?number} @private */
126 var current_display_move = null;
127
128 /**
129  * The current backend request to get main analysis (not history), if any,
130  * so that we can abort it.
131  *
132  * @type {?jqXHR}
133  * @private
134  */
135 var current_analysis_xhr = null;
136
137 /**
138  * The current timer to fire off a request to get main analysis (not history),
139  * if any, so that we can abort it.
140  *
141  * @type {?Number}
142  * @private
143  */
144 var current_analysis_request_timer = null;
145
146 /**
147  * The current backend request to get historic data, if any.
148  *
149  * @type {?jqXHR}
150  * @private
151  */
152 var current_historic_xhr = null;
153
154 var supports_html5_storage = function() {
155         try {
156                 return 'localStorage' in window && window['localStorage'] !== null;
157         } catch (e) {
158                 return false;
159         }
160 }
161
162 // Make the unique token persistent so people refreshing the page won't count twice.
163 // Of course, you can never fully protect against people deliberately wanting to spam.
164 var get_unique = function() {
165         var use_local_storage = supports_html5_storage();
166         if (use_local_storage && localStorage['unique']) {
167                 return localStorage['unique'];
168         }
169         var unique = Math.random();
170         if (use_local_storage) {
171                 localStorage['unique'] = unique;
172         }
173         return unique;
174 }
175
176 var request_update = function() {
177         current_analysis_request_timer = null;
178
179         current_analysis_xhr = $.ajax({
180                 url: backend_url + "?ims=" + ims + "&unique=" + unique
181         }).done(function(data, textstatus, xhr) {
182                 sync_server_clock(xhr.getResponseHeader('Date'));
183                 ims = xhr.getResponseHeader('X-RGLM');
184                 var num_viewers = xhr.getResponseHeader('X-RGNV');
185                 var new_data;
186                 if (Array.isArray(data)) {
187                         new_data = JSON.parse(JSON.stringify(current_analysis_data));
188                         JSON_delta.patch(new_data, data);
189                 } else {
190                         new_data = data;
191                 }
192
193                 var minimum_version = xhr.getResponseHeader('X-RGMV');
194                 if (minimum_version && minimum_version > SCRIPT_VERSION) {
195                         // Upgrade to latest version with a force-reload.
196                         location.reload(true);
197                 }
198
199                 possibly_play_sound(current_analysis_data, new_data);
200                 current_analysis_data = new_data;
201                 update_board(current_analysis_data, displayed_analysis_data);
202                 update_num_viewers(num_viewers);
203
204                 // Next update.
205                 current_analysis_request_timer = setTimeout(function() { request_update(); }, 100);
206         }).fail(function(jqXHR, textStatus, errorThrown) {
207                 if (textStatus === "abort") {
208                         // Aborted because we are switching backends. Abandon and don't retry,
209                         // because another one is already started for us.
210                 } else {
211                         // Backend error or similar. Wait ten seconds, then try again.
212                         current_analysis_request_timer = setTimeout(function() { request_update(); }, 10000);
213                 }
214         });
215 }
216
217 var possibly_play_sound = function(old_data, new_data) {
218         if (!enable_sound) {
219                 return;
220         }
221         if (old_data === null) {
222                 return;
223         }
224         var ding = document.getElementById('ding');
225         if (ding && ding.play) {
226                 if (old_data['position'] && old_data['position']['fen'] &&
227                     new_data['position'] && new_data['position']['fen'] &&
228                     (old_data['position']['fen'] !== new_data['position']['fen'] ||
229                      old_data['position']['move_num'] !== new_data['position']['move_num'])) {
230                         ding.play();
231                 }
232         }
233 }
234
235 /**
236  * @type {!string} server_date_string
237  */
238 var sync_server_clock = function(server_date_string) {
239         var server_time_ms = new Date(server_date_string).getTime();
240         var client_time_ms = new Date().getTime();
241         var estimated_offset_ms = server_time_ms - client_time_ms;
242
243         // In order not to let the noise move us too much back and forth
244         // (the server only has one-second resolution anyway), we only
245         // change an existing skew if we are at least five seconds off.
246         if (client_clock_offset_ms === null ||
247             Math.abs(estimated_offset_ms - client_clock_offset_ms) > 5000) {
248                 client_clock_offset_ms = estimated_offset_ms;
249         }
250 }
251
252 var clear_arrows = function() {
253         for (var i = 0; i < arrows.length; ++i) {
254                 if (arrows[i].svg) {
255                         if (arrows[i].svg.parentElement) {
256                                 arrows[i].svg.parentElement.removeChild(arrows[i].svg);
257                         }
258                         delete arrows[i].svg;
259                 }
260         }
261         arrows = [];
262
263         occupied_by_arrows = [];
264         for (var y = 0; y < 8; ++y) {
265                 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
266         }
267 }
268
269 var redraw_arrows = function() {
270         for (var i = 0; i < arrows.length; ++i) {
271                 position_arrow(arrows[i]);
272         }
273 }
274
275 /** @param {!number} x
276  * @return {!number}
277  */
278 var sign = function(x) {
279         if (x > 0) {
280                 return 1;
281         } else if (x < 0) {
282                 return -1;
283         } else {
284                 return 0;
285         }
286 }
287
288 /** See if drawing this arrow on the board would cause unduly amount of confusion.
289  * @param {!string} from The square the arrow is from (e.g. e4).
290  * @param {!string} to The square the arrow is to (e.g. e4).
291  * @return {boolean}
292  */
293 var interfering_arrow = function(from, to) {
294         var from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
295         var from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
296         var to_col   = to.charCodeAt(0) - "a1".charCodeAt(0);
297         var to_row   = to.charCodeAt(1) - "a1".charCodeAt(1);
298
299         occupied_by_arrows[from_row][from_col] = true;
300
301         // Knight move: Just check that we haven't been at the destination before.
302         if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
303             (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
304                 return occupied_by_arrows[to_row][to_col];
305         }
306
307         // Sliding piece: Check if anything except the from-square is seen before.
308         var dx = sign(to_col - from_col);
309         var dy = sign(to_row - from_row);
310         var x = from_col;
311         var y = from_row;
312         do {
313                 x += dx;
314                 y += dy;
315                 if (occupied_by_arrows[y][x]) {
316                         return true;
317                 }
318                 occupied_by_arrows[y][x] = true;
319         } while (x != to_col || y != to_row);
320
321         return false;
322 }
323
324 /** Find a point along the coordinate system given by the given line,
325  * <t> units forward from the start of the line, <u> units to the right of it.
326  * @param {!number} x1
327  * @param {!number} x2
328  * @param {!number} y1
329  * @param {!number} y2
330  * @param {!number} t
331  * @param {!number} u
332  * @return {!string} The point in "x y" form, suitable for SVG paths.
333  */
334 var point_from_start = function(x1, y1, x2, y2, t, u) {
335         var dx = x2 - x1;
336         var dy = y2 - y1;
337
338         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
339         dx *= norm;
340         dy *= norm;
341
342         var x = x1 + dx * t + dy * u;
343         var y = y1 + dy * t - dx * u;
344         return x + " " + y;
345 }
346
347 /** Find a point along the coordinate system given by the given line,
348  * <t> units forward from the end of the line, <u> units to the right of it.
349  * @param {!number} x1
350  * @param {!number} x2
351  * @param {!number} y1
352  * @param {!number} y2
353  * @param {!number} t
354  * @param {!number} u
355  * @return {!string} The point in "x y" form, suitable for SVG paths.
356  */
357 var point_from_end = function(x1, y1, x2, y2, t, u) {
358         var dx = x2 - x1;
359         var dy = y2 - y1;
360
361         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
362         dx *= norm;
363         dy *= norm;
364
365         var x = x2 + dx * t + dy * u;
366         var y = y2 + dy * t - dx * u;
367         return x + " " + y;
368 }
369
370 var position_arrow = function(arrow) {
371         if (arrow.svg) {
372                 if (arrow.svg.parentElement) {
373                         arrow.svg.parentElement.removeChild(arrow.svg);
374                 }
375                 delete arrow.svg;
376         }
377         if (current_display_line !== null && !current_display_line_is_history) {
378                 return;
379         }
380
381         var pos = $(".square-a8").position();
382
383         var zoom_factor = $("#board").width() / 400.0;
384         var line_width = arrow.line_width * zoom_factor;
385         var arrow_size = arrow.arrow_size * zoom_factor;
386
387         var square_width = $(".square-a8").width();
388         var from_y = (7 - arrow.from_row + 0.5)*square_width;
389         var to_y = (7 - arrow.to_row + 0.5)*square_width;
390         var from_x = (arrow.from_col + 0.5)*square_width;
391         var to_x = (arrow.to_col + 0.5)*square_width;
392
393         var SVG_NS = "http://www.w3.org/2000/svg";
394         var XHTML_NS = "http://www.w3.org/1999/xhtml";
395         var svg = document.createElementNS(SVG_NS, "svg");
396         svg.setAttribute("width", /** @type{number} */ ($("#board").width()));
397         svg.setAttribute("height", /** @type{number} */ ($("#board").height()));
398         svg.setAttribute("style", "position: absolute");
399         svg.setAttribute("position", "absolute");
400         svg.setAttribute("version", "1.1");
401         svg.setAttribute("class", "c1");
402         svg.setAttribute("xmlns", XHTML_NS);
403
404         var x1 = from_x;
405         var y1 = from_y;
406         var x2 = to_x;
407         var y2 = to_y;
408
409         // Draw the line.
410         var outline = document.createElementNS(SVG_NS, "path");
411         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));
412         outline.setAttribute("xmlns", XHTML_NS);
413         outline.setAttribute("stroke", "#666");
414         outline.setAttribute("stroke-width", line_width + 2);
415         outline.setAttribute("fill", "none");
416         svg.appendChild(outline);
417
418         var path = document.createElementNS(SVG_NS, "path");
419         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));
420         path.setAttribute("xmlns", XHTML_NS);
421         path.setAttribute("stroke", arrow.fg_color);
422         path.setAttribute("stroke-width", line_width);
423         path.setAttribute("fill", "none");
424         svg.appendChild(path);
425
426         // Then the arrow head.
427         var head = document.createElementNS(SVG_NS, "path");
428         head.setAttribute("d",
429                 "M " +  point_from_end(x1, y1, x2, y2, 0, 0) +
430                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
431                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
432                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
433                 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
434         head.setAttribute("xmlns", XHTML_NS);
435         head.setAttribute("stroke", "#000");
436         head.setAttribute("stroke-width", "1");
437         head.setAttribute("fill", arrow.fg_color);
438         svg.appendChild(head);
439
440         $(svg).css({ top: pos.top, left: pos.left });
441         document.body.appendChild(svg);
442         arrow.svg = svg;
443 }
444
445 /**
446  * @param {!string} from_square
447  * @param {!string} to_square
448  * @param {!string} fg_color
449  * @param {number} line_width
450  * @param {number} arrow_size
451  */
452 var create_arrow = function(from_square, to_square, fg_color, line_width, arrow_size) {
453         var from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
454         var from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
455         var to_col   = to_square.charCodeAt(0) - "a1".charCodeAt(0);
456         var to_row   = to_square.charCodeAt(1) - "a1".charCodeAt(1);
457
458         // Create arrow.
459         var arrow = {
460                 from_col: from_col,
461                 from_row: from_row,
462                 to_col: to_col,
463                 to_row: to_row,
464                 line_width: line_width,
465                 arrow_size: arrow_size,
466                 fg_color: fg_color
467         };
468
469         position_arrow(arrow);
470         arrows.push(arrow);
471 }
472
473 var compare_by_sort_key = function(refutation_lines, a, b) {
474         var ska = refutation_lines[a]['sort_key'];
475         var skb = refutation_lines[b]['sort_key'];
476         if (ska < skb) return -1;
477         if (ska > skb) return 1;
478         return 0;
479 };
480
481 var compare_by_score = function(refutation_lines, a, b) {
482         var sa = parseInt(refutation_lines[b]['score_sort_key'], 10);
483         var sb = parseInt(refutation_lines[a]['score_sort_key'], 10);
484         return sa - sb;
485 }
486
487 /**
488  * Fake multi-PV using the refutation lines. Find all “relevant” moves,
489  * sorted by quality, descending.
490  *
491  * @param {!Object} data
492  * @param {number} margin The maximum number of centipawns worse than the
493  *     best move can be and still be included.
494  * @return {Array.<string>} The UCI representation (e.g. e1g1) of all
495  *     moves, in score order.
496  */
497 var find_nonstupid_moves = function(data, margin) {
498         // First of all, if there are any moves that are more than 0.5 ahead of
499         // the primary move, the refutation lines are probably bunk, so just
500         // kill them all. 
501         var best_score = undefined;
502         var pv_score = undefined;
503         for (var move in data['refutation_lines']) {
504                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
505                 if (move == data['pv_uci'][0]) {
506                         pv_score = score;
507                 }
508                 if (best_score === undefined || score > best_score) {
509                         best_score = score;
510                 }
511                 if (!(data['refutation_lines'][move]['depth'] >= 8)) {
512                         return [];
513                 }
514         }
515
516         if (best_score - pv_score > 50) {
517                 return [];
518         }
519
520         // Now find all moves that are within “margin” of the best score.
521         // The PV move will always be first.
522         var moves = [];
523         for (var move in data['refutation_lines']) {
524                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
525                 if (move != data['pv_uci'][0] && best_score - score <= margin) {
526                         moves.push(move);
527                 }
528         }
529         moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], a, b) });
530         moves.unshift(data['pv_uci'][0]);
531
532         return moves;
533 }
534
535 /**
536  * @param {number} x
537  * @return {!string}
538  */
539 var thousands = function(x) {
540         return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
541 }
542
543 /**
544  * @param {!string} fen
545  * @param {Array.<string>} pretty_pv
546  * @param {number} move_num
547  * @param {!string} toplay
548  * @param {number=} opt_limit
549  * @param {boolean=} opt_showlast
550  */
551 var add_pv = function(fen, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
552         display_lines.push({
553                 start_fen: fen,
554                 pretty_pv: pretty_pv,
555                 line_number: display_lines.length
556         });
557         return print_pv(display_lines.length - 1, pretty_pv, move_num, toplay, opt_limit, opt_showlast);
558 }
559
560 /**
561  * @param {number} line_num
562  * @param {Array.<string>} pretty_pv
563  * @param {number} move_num
564  * @param {!string} toplay
565  * @param {number=} opt_limit
566  * @param {boolean=} opt_showlast
567  */
568 var print_pv = function(line_num, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
569         var pv = '';
570         var i = 0;
571         if (opt_limit && opt_showlast && pretty_pv.length > opt_limit) {
572                 // Truncate the PV at the beginning (instead of at the end).
573                 // We assume here that toplay is 'W'. We also assume that if
574                 // opt_showlast is set, then it is the history, and thus,
575                 // the UI should be to expand the history.
576                 pv = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
577                 i = pretty_pv.length - opt_limit;
578                 if (i % 2 == 1) {
579                         ++i;
580                 }
581                 move_num += i / 2;
582         } else if (toplay == 'B' && pretty_pv.length > 0) {
583                 var move = "<a class=\"move\" id=\"automove" + line_num + "-0\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
584                 pv = move_num + '. … ' + move;
585                 toplay = 'W';
586                 ++i;
587                 ++move_num;
588         }
589         for ( ; i < pretty_pv.length; ++i) {
590                 var move = "<a class=\"move\" id=\"automove" + line_num + "-" + i + "\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pretty_pv[i] + "</a>";
591
592                 if (toplay == 'W') {
593                         if (i > opt_limit && !opt_showlast) {
594                                 return pv + ' (…)';
595                         }
596                         if (pv != '') {
597                                 pv += ' ';
598                         }
599                         pv += move_num + '. ' + move;
600                         ++move_num;
601                         toplay = 'B';
602                 } else {
603                         pv += ' ' + move;
604                         toplay = 'W';
605                 }
606         }
607         return pv;
608 }
609
610 var update_highlight = function() {
611         $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
612         if ((current_display_line === null || current_display_line_is_history) &&
613             highlight_from !== undefined && highlight_to !== undefined) {
614                 $("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
615                 $("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
616         }
617 }
618
619 var update_history = function() {
620         if (display_lines[0] === null || display_lines[0].pretty_pv.length == 0) {
621                 $("#history").html("No history");
622         } else if (truncate_display_history) {
623                 $("#history").html(print_pv(0, display_lines[0].pretty_pv, 1, 'W', 8, true));
624         } else {
625                 $("#history").html(
626                         '(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
627                         print_pv(0, display_lines[0].pretty_pv, 1, 'W'));
628         }
629 }
630
631 /**
632  * @param {!boolean} truncate_history
633  */
634 var collapse_history = function(truncate_history) {
635         truncate_display_history = truncate_history;
636         update_history();
637 }
638 window['collapse_history'] = collapse_history;
639
640 var update_refutation_lines = function() {
641         if (fen === null) {
642                 return;
643         }
644         if (display_lines.length > 2) {
645                 display_lines = [ display_lines[0], display_lines[1] ];
646         }
647
648         var tbl = $("#refutationlines");
649         tbl.empty();
650
651         var moves = [];
652         for (var move in refutation_lines) {
653                 moves.push(move);
654         }
655         var compare = sort_refutation_lines_by_score ? compare_by_score : compare_by_sort_key;
656         moves = moves.sort(function(a, b) { return compare(refutation_lines, a, b) });
657         for (var i = 0; i < moves.length; ++i) {
658                 var line = refutation_lines[moves[i]];
659
660                 var tr = document.createElement("tr");
661
662                 var move_td = document.createElement("td");
663                 tr.appendChild(move_td);
664                 $(move_td).addClass("move");
665                 if (line['pv_pretty'].length == 0) {
666                         $(move_td).text(line['pretty_move']);
667                 } else {
668                         var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['pretty_move'] + "</a>";
669                         $(move_td).html(move);
670                 }
671
672                 var score_td = document.createElement("td");
673                 tr.appendChild(score_td);
674                 $(score_td).addClass("score");
675                 $(score_td).text(line['pretty_score']);
676
677                 var depth_td = document.createElement("td");
678                 tr.appendChild(depth_td);
679                 $(depth_td).addClass("depth");
680                 $(depth_td).text("d" + line['depth']);
681
682                 var pv_td = document.createElement("td");
683                 tr.appendChild(pv_td);
684                 $(pv_td).addClass("pv");
685                 $(pv_td).html(add_pv(fen, line['pv_pretty'], move_num, toplay, 10));
686
687                 tbl.append(tr);
688         }
689
690         // Make one of the links clickable and the other nonclickable.
691         if (sort_refutation_lines_by_score) {
692                 $("#sortbyscore0").html("<a href=\"javascript:resort_refutation_lines(false)\">Move</a>");
693                 $("#sortbyscore1").html("<strong>Score</strong>");
694         } else {
695                 $("#sortbyscore0").html("<strong>Move</strong>");
696                 $("#sortbyscore1").html("<a href=\"javascript:resort_refutation_lines(true)\">Score</a>");
697         }
698 }
699
700 /**
701  * @param {?string} fen
702  * @param {Array.<string>} moves
703  * @param {number} last_move
704  */
705 var chess_from = function(fen, moves, last_move) {
706         var hiddenboard = new Chess();
707         if (fen !== null) {
708                 hiddenboard.load(fen);
709         }
710         for (var i = 0; i <= last_move; ++i) {
711                 if (moves[i] === '0-0') {
712                         hiddenboard.move('O-O');
713                 } else if (moves[i] === '0-0-0') {
714                         hiddenboard.move('O-O-O');
715                 } else {
716                         hiddenboard.move(moves[i]);
717                 }
718         }
719         return hiddenboard;
720 }
721
722 /**
723  * @param {Object} data
724  * @param {?Object} display_data
725  */
726 var update_board = function(current_data, display_data) {
727         var data = display_data || current_data;
728
729         display_lines = [];
730
731         // Print the history. This is pretty much the only thing that's
732         // unconditionally taken from current_data (we're not interested in
733         // historic history).
734         if (current_data['position']['pretty_history']) {
735                 add_pv('start', current_data['position']['pretty_history'], 1, 'W', 8, true);
736         } else {
737                 display_lines.push(null);
738         }
739         update_history();
740
741         // Games currently in progress, if any.
742         $("#games").text("");
743         if (current_data['games']) {
744                 var games_div = document.getElementById('games');
745                 for (var game_num = 0; game_num < current_data['games'].length; ++game_num) {
746                         var game = current_data['games'][game_num];
747                         var game_span = document.createElement("span");
748                         game_span.setAttribute("class", "game");
749
750                         var game_name = document.createTextNode(game['name']);
751                         if (game['url'] === backend_url) {
752                                 game_span.appendChild(game_name);
753                         } else {
754                                 var game_a = document.createElement("a");
755                                 game_a.setAttribute("href", "javascript:switch_backend('" + game['url'] + "')");
756                                 game_a.appendChild(game_name);
757                                 game_span.appendChild(game_a);
758                         }
759                         games_div.appendChild(game_span);
760                 }
761         }
762
763         // The headline. Names are always fetched from current_data;
764         // the rest can depend a bit.
765         var headline;
766         if (current_data &&
767             current_data['position']['player_w'] && current_data['position']['player_b']) {
768                 headline = current_data['position']['player_w'] + '–' +
769                         current_data['position']['player_b'] + ', analysis';
770         } else {
771                 headline = 'Analysis';
772         }
773
774         var last_move;
775         if (display_data) {
776                 // Displaying some non-current position, pick out the last move
777                 // from the history. This will work even if the fetch failed.
778                 last_move = format_halfmove_with_number(
779                         current_display_line.pretty_pv[current_display_move],
780                         current_display_move + 1);
781                 headline += ' after ' + last_move;
782         } else if (data['position']['last_move'] !== 'none') {
783                 last_move = format_move_with_number(
784                         data['position']['last_move'],
785                         data['position']['move_num'],
786                         data['position']['toplay'] == 'W');
787                 headline += ' after ' + last_move;
788         } else {
789                 last_move = null;
790         }
791         $("#headline").text(headline);
792
793         // The <title> contains a very brief headline.
794         var title_elems = [];
795         if (data['short_score'] !== undefined && data['short_score'] !== null) {
796                 title_elems.push(data['short_score'].replace(/^ /, ""));
797         }
798         if (last_move !== null) {
799                 title_elems.push(last_move);
800         }
801
802         if (title_elems.length != 0) {
803                 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
804         } else {
805                 document.title = 'analysis.sesse.net';
806         }
807
808         // The last move (shown by highlighting the from and to squares).
809         if (data['position'] && data['position']['last_move_uci']) {
810                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
811                 highlight_to = data['position']['last_move_uci'].substr(2, 2);
812         } else if (current_display_line_is_history && current_display_move >= 0) {
813                 // We don't have historic analysis for this position, but we
814                 // can reconstruct what the last move was by just replaying
815                 // from the start.
816                 var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
817                 var moves = hiddenboard.history({ verbose: true });
818                 var last_move = moves.pop();
819                 highlight_from = last_move.from;
820                 highlight_to = last_move.to;
821         } else {
822                 highlight_from = highlight_to = undefined;
823         }
824         update_highlight();
825
826         if (data['failed']) {
827                 $("#score").text("No analysis for this move");
828                 $("#pv").empty();
829                 $("#searchstats").html("&nbsp;");
830                 $("#refutationlines").empty();
831                 $("#whiteclock").empty();
832                 $("#blackclock").empty();
833                 refutation_lines = [];
834                 update_refutation_lines();
835                 clear_arrows();
836                 update_displayed_line();
837                 return;
838         }
839
840         update_clock();
841
842         // The engine id.
843         if (data['id'] && data['id']['name'] !== null) {
844                 $("#engineid").text(data['id']['name']);
845         }
846
847         // The score.
848         if (data['score'] !== null) {
849                 $("#score").text(data['score']);
850         }
851
852         // The search stats.
853         if (data['tablebase'] == 1) {
854                 $("#searchstats").text("Tablebase result");
855         } else if (data['nodes'] && data['nps'] && data['depth']) {
856                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
857                 if (data['seldepth']) {
858                         stats += ' (' + data['seldepth'] + ' selective)';
859                 }
860                 if (data['tbhits'] && data['tbhits'] > 0) {
861                         if (data['tbhits'] == 1) {
862                                 stats += ', one Syzygy hit';
863                         } else {
864                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
865                         }
866                 }
867
868                 $("#searchstats").text(stats);
869         } else {
870                 $("#searchstats").text("");
871         }
872
873         // Update the board itself.
874         fen = data['position']['fen'];
875         update_displayed_line();
876
877         // Print the PV.
878         $("#pv").html(add_pv(data['position']['fen'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
879
880         // Update the PV arrow.
881         clear_arrows();
882         if (data['pv_uci'].length >= 1) {
883                 // draw a continuation arrow as long as it's the same piece
884                 for (var i = 0; i < data['pv_uci'].length; i += 2) {
885                         var from = data['pv_uci'][i].substr(0, 2);
886                         var to = data['pv_uci'][i].substr(2,4);
887                         if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 2)) ||
888                              interfering_arrow(from, to)) {
889                                 break;
890                         }
891                         create_arrow(from, to, '#f66', 6, 20);
892                 }
893
894                 var alt_moves = find_nonstupid_moves(data, 30);
895                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
896                         create_arrow(alt_moves[i].substr(0, 2),
897                                      alt_moves[i].substr(2, 2), '#f66', 1, 10);
898                 }
899         }
900
901         // See if all semi-reasonable moves have only one possible response.
902         if (data['pv_uci'].length >= 2) {
903                 var nonstupid_moves = find_nonstupid_moves(data, 300);
904                 var response = data['pv_uci'][1];
905                 for (var i = 0; i < nonstupid_moves.length; ++i) {
906                         if (nonstupid_moves[i] == data['pv_uci'][0]) {
907                                 // ignore the PV move for refutation lines.
908                                 continue;
909                         }
910                         if (!data['refutation_lines'] ||
911                             !data['refutation_lines'][nonstupid_moves[i]] ||
912                             !data['refutation_lines'][nonstupid_moves[i]]['pv_uci'] ||
913                             data['refutation_lines'][nonstupid_moves[i]]['pv_uci'].length < 1) {
914                                 // Incomplete PV, abort.
915                                 response = undefined;
916                                 break;
917                         }
918                         var this_response = data['refutation_lines'][nonstupid_moves[i]]['pv_uci'][1];
919                         if (response !== this_response) {
920                                 // Different response depending on lines, abort.
921                                 response = undefined;
922                                 break;
923                         }
924                 }
925
926                 if (nonstupid_moves.length > 0 && response !== undefined) {
927                         create_arrow(response.substr(0, 2),
928                                      response.substr(2, 2), '#66f', 6, 20);
929                 }
930         }
931
932         // Update the refutation lines.
933         fen = data['position']['fen'];
934         move_num = data['position']['move_num'];
935         toplay = data['position']['toplay'];
936         refutation_lines = data['refutation_lines'];
937         update_refutation_lines();
938
939         // Update the sparkline last, since its size depends on how everything else reflowed.
940         update_sparkline(data);
941 }
942
943 var update_sparkline = function(data) {
944         if (data && data['score_history']) {
945                 var first_move_num = undefined;
946                 for (var halfmove_num in data['score_history']) {
947                         halfmove_num = parseInt(halfmove_num);
948                         if (first_move_num === undefined || halfmove_num < first_move_num) {
949                                 first_move_num = halfmove_num;
950                         }
951                 }
952                 if (first_move_num !== undefined) {
953                         var last_move_num = data['position']['move_num'] * 2 - 3;
954                         if (data['position']['toplay'] === 'B') {
955                                 ++last_move_num;
956                         }
957
958                         // Possibly truncate some moves if we don't have enough width.
959                         // FIXME: Sometimes width() for #scorecontainer (and by extent,
960                         // #scoresparkcontainer) on Chrome for mobile seems to start off
961                         // at something very small, and then suddenly snap back into place.
962                         // Figure out why.
963                         var max_moves = Math.floor($("#scoresparkcontainer").width() / 5) - 5;
964                         if (last_move_num - first_move_num > max_moves) {
965                                 first_move_num = last_move_num - max_moves;
966                         }
967
968                         var min_score = -100;
969                         var max_score = 100;
970                         var last_score = null;
971                         var scores = [];
972                         for (var halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
973                                 if (data['score_history'][halfmove_num]) {
974                                         var score = data['score_history'][halfmove_num][0];
975                                         if (score < min_score) min_score = score;
976                                         if (score > max_score) max_score = score;
977                                         last_score = data['score_history'][halfmove_num][0];
978                                 }
979                                 scores.push(last_score);
980                         }
981                         if (data['plot_score']) {
982                                 scores.push(data['plot_score']);
983                         }
984                         // FIXME: at some widths, calling sparkline() seems to push
985                         // #scorecontainer under the board.
986                         $("#scorespark").sparkline(scores, {
987                                 type: 'bar',
988                                 zeroColor: 'gray',
989                                 chartRangeMin: min_score,
990                                 chartRangeMax: max_score,
991                                 tooltipFormatter: function(sparkline, options, fields) {
992                                         return format_tooltip(data, fields[0].offset + first_move_num);
993                                 }
994                         });
995                 } else {
996                         $("#scorespark").text("");
997                 }
998         } else {
999                 $("#scorespark").text("");
1000         }
1001 }
1002
1003 /**
1004  * @param {number} num_viewers
1005  */
1006 var update_num_viewers = function(num_viewers) {
1007         if (num_viewers === null) {
1008                 $("#numviewers").text("");
1009         } else if (num_viewers == 1) {
1010                 $("#numviewers").text("You are the only current viewer");
1011         } else {
1012                 $("#numviewers").text(num_viewers + " current viewers");
1013         }
1014 }
1015
1016 var update_clock = function() {
1017         clearTimeout(clock_timer);
1018
1019         var data = displayed_analysis_data || current_analysis_data;
1020         if (data['position']) {
1021                 var result = data['position']['result'];
1022                 if (result === '1-0') {
1023                         $("#whiteclock").text("1");
1024                         $("#blackclock").text("0");
1025                         $("#whiteclock").removeClass("running-clock");
1026                         $("#blackclock").removeClass("running-clock");
1027                         return;
1028                 }
1029                 if (result === '1/2-1/2') {
1030                         $("#whiteclock").text("1/2");
1031                         $("#blackclock").text("1/2");
1032                         $("#whiteclock").removeClass("running-clock");
1033                         $("#blackclock").removeClass("running-clock");
1034                         return;
1035                 }       
1036                 if (result === '0-1') {
1037                         $("#whiteclock").text("0");
1038                         $("#blackclock").text("1");
1039                         $("#whiteclock").removeClass("running-clock");
1040                         $("#blackclock").removeClass("running-clock");
1041                         return;
1042                 }
1043         }
1044
1045         var white_clock_ms = null;
1046         var black_clock_ms = null;
1047         var show_seconds = false;
1048
1049         // Static clocks.
1050         if (data['position'] &&
1051             data['position']['white_clock'] &&
1052             data['position']['black_clock']) {
1053                 white_clock_ms = data['position']['white_clock'] * 1000;
1054                 black_clock_ms = data['position']['black_clock'] * 1000;
1055         }
1056
1057         // Dynamic clock (only one, obviously).
1058         var color;
1059         if (data['position']['white_clock_target']) {
1060                 color = "white";
1061                 $("#whiteclock").addClass("running-clock");
1062                 $("#blackclock").removeClass("running-clock");
1063         } else if (data['position']['black_clock_target']) {
1064                 color = "black";
1065                 $("#whiteclock").removeClass("running-clock");
1066                 $("#blackclock").addClass("running-clock");
1067         } else {
1068                 $("#whiteclock").removeClass("running-clock");
1069                 $("#blackclock").removeClass("running-clock");
1070         }
1071         var remaining_ms;
1072         if (color) {
1073                 var now = new Date().getTime() + client_clock_offset_ms;
1074                 remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
1075                 if (color === "white") {
1076                         white_clock_ms = remaining_ms;
1077                 } else {
1078                         black_clock_ms = remaining_ms;
1079                 }
1080         }
1081
1082         if (white_clock_ms === null || black_clock_ms === null) {
1083                 $("#whiteclock").empty();
1084                 $("#blackclock").empty();
1085                 return;
1086         }
1087
1088         // If either player has ten minutes or less left, add the second counters.
1089         var show_seconds = (white_clock_ms < 60 * 10 * 1000 || black_clock_ms < 60 * 10 * 1000);
1090
1091         if (color) {
1092                 // See when the clock will change next, and update right after that.
1093                 var next_update_ms;
1094                 if (show_seconds) {
1095                         next_update_ms = remaining_ms % 1000 + 100;
1096                 } else {
1097                         next_update_ms = remaining_ms % 60000 + 100;
1098                 }
1099                 clock_timer = setTimeout(update_clock, next_update_ms);
1100         }
1101
1102         $("#whiteclock").text(format_clock(white_clock_ms, show_seconds));
1103         $("#blackclock").text(format_clock(black_clock_ms, show_seconds));
1104 }
1105
1106 /**
1107  * @param {Number} remaining_ms
1108  * @param {boolean} show_seconds
1109  */
1110 var format_clock = function(remaining_ms, show_seconds) {
1111         if (remaining_ms <= 0) {
1112                 if (show_seconds) {
1113                         return "00:00:00";
1114                 } else {
1115                         return "00:00";
1116                 }
1117         }
1118
1119         var remaining = Math.floor(remaining_ms / 1000);
1120         var seconds = remaining % 60;
1121         remaining = (remaining - seconds) / 60;
1122         var minutes = remaining % 60;
1123         remaining = (remaining - minutes) / 60;
1124         var hours = remaining;
1125         if (show_seconds) {
1126                 return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
1127         } else {
1128                 return format_2d(hours) + ":" + format_2d(minutes);
1129         }
1130 }
1131
1132 /**
1133  * @param {Number} x
1134  */
1135 var format_2d = function(x) {
1136         if (x >= 10) {
1137                 return x;
1138         } else {
1139                 return "0" + x;
1140         }
1141 }
1142
1143 /**
1144  * @param {string} move
1145  * @param {Number} move_num
1146  * @param {boolean} white_to_play
1147  */
1148 var format_move_with_number = function(move, move_num, white_to_play) {
1149         var ret;
1150         if (white_to_play) {
1151                 ret = (move_num - 1) + '… ';
1152         } else {
1153                 ret = move_num + '. ';
1154         }
1155         ret += move;
1156         return ret;
1157 }
1158
1159 /**
1160  * @param {string} move
1161  * @param {Number} halfmove_num
1162  */
1163 var format_halfmove_with_number = function(move, halfmove_num) {
1164         return format_move_with_number(
1165                 move,
1166                 Math.floor(halfmove_num / 2) + 1,
1167                 halfmove_num % 2 == 0);
1168 }
1169
1170 /**
1171  * @param {Object} data
1172  * @param {Number} halfmove_num
1173  */
1174 var format_tooltip = function(data, halfmove_num) {
1175         if (data['score_history'][halfmove_num] ||
1176             halfmove_num === data['position']['pretty_history'].length) {
1177                 var move;
1178                 var short_score;
1179                 if (halfmove_num === data['position']['pretty_history'].length) {
1180                         move = data['position']['last_move'];
1181                         short_score = data['short_score'];
1182                 } else {
1183                         move = data['position']['pretty_history'][halfmove_num];
1184                         short_score = data['score_history'][halfmove_num][1];
1185                 }
1186                 var move_with_number = format_halfmove_with_number(move, halfmove_num);
1187
1188                 return "After " + move_with_number + ": " + short_score;
1189         } else {
1190                 for (var i = halfmove_num; i --> 0; ) {
1191                         if (data['score_history'][i]) {
1192                                 var move = data['position']['pretty_history'][i];
1193                                 return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
1194                         }
1195                 }
1196         }
1197 }
1198
1199 /**
1200  * @param {boolean} sort_by_score
1201  */
1202 var resort_refutation_lines = function(sort_by_score) {
1203         sort_refutation_lines_by_score = sort_by_score;
1204         if (supports_html5_storage()) {
1205                 localStorage['sort_refutation_lines_by_score'] = sort_by_score ? 1 : 0;
1206         }
1207         update_refutation_lines();
1208 }
1209 window['resort_refutation_lines'] = resort_refutation_lines;
1210
1211 /**
1212  * @param {boolean} truncate_history
1213  */
1214 var set_truncate_history = function(truncate_history) {
1215         truncate_display_history = truncate_history;
1216         update_refutation_lines();
1217 }
1218 window['set_truncate_history'] = set_truncate_history;
1219
1220 /**
1221  * @param {number} line_num
1222  * @param {number} move_num
1223  */
1224 var show_line = function(line_num, move_num) {
1225         if (line_num == -1) {
1226                 current_display_line = null;
1227                 current_display_move = null;
1228                 if (displayed_analysis_data) {
1229                         // TODO: Support exiting to history position if we are in an
1230                         // analysis line of a history position.
1231                         displayed_analysis_data = null;
1232                         update_board(current_analysis_data, displayed_analysis_data);
1233                 }
1234         } else {
1235                 current_display_line = display_lines[line_num];
1236                 current_display_move = move_num;
1237         }
1238         current_display_line_is_history = (line_num == 0);
1239
1240         update_historic_analysis();
1241         update_displayed_line();
1242         update_highlight();
1243         redraw_arrows();
1244 }
1245 window['show_line'] = show_line;
1246
1247 var prev_move = function() {
1248         if (current_display_move > -1) {
1249                 --current_display_move;
1250         }
1251         update_historic_analysis();
1252         update_displayed_line();
1253 }
1254 window['prev_move'] = prev_move;
1255
1256 var next_move = function() {
1257         if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
1258                 ++current_display_move;
1259         }
1260         update_historic_analysis();
1261         update_displayed_line();
1262 }
1263 window['next_move'] = next_move;
1264
1265 var update_historic_analysis = function() {
1266         if (!current_display_line_is_history) {
1267                 return;
1268         }
1269         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1270                 displayed_analysis_data = null;
1271                 update_board(current_analysis_data, displayed_analysis_data);
1272         }
1273
1274         // Fetch old analysis for this line if it exists.
1275         var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
1276         var filename = "/history/move" + (current_display_move + 1) + "-" +
1277                 hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
1278
1279         current_historic_xhr = $.ajax({
1280                 url: filename
1281         }).done(function(data, textstatus, xhr) {
1282                 displayed_analysis_data = data;
1283                 update_board(current_analysis_data, displayed_analysis_data);
1284         }).fail(function(jqXHR, textStatus, errorThrown) {
1285                 if (textStatus === "abort") {
1286                         // Aborted because we are switching backends. Don't do anything;
1287                         // we will already have been cleared.
1288                 } else {
1289                         displayed_analysis_data = {'failed': true};
1290                         update_board(current_analysis_data, displayed_analysis_data);
1291                 }
1292         });
1293 }
1294
1295 /**
1296  * @param {string} fen
1297  */
1298 var update_imbalance = function(fen) {
1299         var hiddenboard = new Chess(fen);
1300         var imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
1301         for (var row = 0; row < 8; ++row) {
1302                 for (var col = 0; col < 8; ++col) {
1303                         var col_text = String.fromCharCode('a1'.charCodeAt(0) + col);
1304                         var row_text = String.fromCharCode('a1'.charCodeAt(1) + row);
1305                         var square = col_text + row_text;
1306                         var contents = hiddenboard.get(square);
1307                         if (contents !== null) {
1308                                 if (contents.color === 'w') {
1309                                         ++imbalance[contents.type];
1310                                 } else {
1311                                         --imbalance[contents.type];
1312                                 }
1313                         }
1314                 }
1315         }
1316         var white_imbalance = '';
1317         var black_imbalance = '';
1318         for (var piece in imbalance) {
1319                 for (var i = 0; i < imbalance[piece]; ++i) {
1320                         white_imbalance += '<img src="img/chesspieces/wikipedia/w' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1321                 }
1322                 for (var i = 0; i < -imbalance[piece]; ++i) {
1323                         black_imbalance += '<img src="img/chesspieces/wikipedia/b' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1324                 }
1325         }
1326         $('#whiteimbalance').html(white_imbalance);
1327         $('#blackimbalance').html(black_imbalance);
1328 }
1329
1330 var update_displayed_line = function() {
1331         if (highlighted_move !== null) {
1332                 highlighted_move.removeClass('highlight'); 
1333         }
1334         if (current_display_line === null) {
1335                 $("#linenav").hide();
1336                 $("#linemsg").show();
1337                 board.position(fen);
1338                 update_imbalance(fen);
1339                 return;
1340         }
1341
1342         $("#linenav").show();
1343         $("#linemsg").hide();
1344
1345         if (current_display_move <= 0) {
1346                 $("#prevmove").html("Previous");
1347         } else {
1348                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
1349         }
1350         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1351                 $("#nextmove").html("Next");
1352         } else {
1353                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
1354         }
1355
1356         highlighted_move = $("#automove" + current_display_line.line_number + "-" + current_display_move);
1357         highlighted_move.addClass('highlight'); 
1358
1359         var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pretty_pv, current_display_move);
1360         board.position(hiddenboard.fen());
1361         update_imbalance(hiddenboard.fen());
1362 }
1363
1364 /**
1365  * @param {boolean} param_enable_sound
1366  */
1367 var set_sound = function(param_enable_sound) {
1368         enable_sound = param_enable_sound;
1369         if (enable_sound) {
1370                 $("#soundon").html("<strong>On</strong>");
1371                 $("#soundoff").html("<a href=\"javascript:set_sound(false)\">Off</a>");
1372
1373                 // Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
1374                 // and also preload the file since the user has selected audio.
1375                 var ding = document.getElementById('ding');
1376                 if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
1377                         ding.src = 'ding.opus';
1378                         ding.load();
1379                 }
1380         } else {
1381                 $("#soundon").html("<a href=\"javascript:set_sound(true)\">On</a>");
1382                 $("#soundoff").html("<strong>Off</strong>");
1383         }
1384         if (supports_html5_storage()) {
1385                 localStorage['enable_sound'] = enable_sound ? 1 : 0;
1386         }
1387 }
1388 window['set_sound'] = set_sound;
1389
1390 /**
1391  * @param {string} new_backend_url
1392  */
1393 var switch_backend = function(new_backend_url) {
1394         // Stop looking at historic data.
1395         current_display_line = null;
1396         current_display_move = null;
1397         displayed_analysis_data = null;
1398         if (current_historic_xhr) {
1399                 current_historic_xhr.abort();
1400         }
1401
1402         // If we already have a backend response going, abort it.
1403         if (current_analysis_xhr) {
1404                 current_analysis_xhr.abort();
1405         }
1406
1407         // Otherwise, we should have a timer going to start a new one.
1408         // Kill that, too.
1409         if (current_analysis_request_timer) {
1410                 clearTimeout(current_analysis_request_timer);
1411                 current_analysis_request_timer = null;
1412         }
1413
1414         // Request an immediate fetch with the new backend.
1415         backend_url = new_backend_url;
1416         current_analysis_data = null;
1417         ims = 0;
1418         request_update();
1419 }
1420 window['switch_backend'] = switch_backend;
1421
1422 var init = function() {
1423         unique = get_unique();
1424
1425         // Load settings from HTML5 local storage if available.
1426         if (supports_html5_storage() && localStorage['enable_sound']) {
1427                 set_sound(parseInt(localStorage['enable_sound']));
1428         } else {
1429                 set_sound(false);
1430         }
1431         if (supports_html5_storage() && localStorage['sort_refutation_lines_by_score']) {
1432                 sort_refutation_lines_by_score = parseInt(localStorage['sort_refutation_lines_by_score']);
1433         } else {
1434                 sort_refutation_lines_by_score = true;
1435         }
1436
1437         // Create board.
1438         board = new window.ChessBoard('board', 'start');
1439
1440         request_update();
1441         $(window).resize(function() {
1442                 board.resize();
1443                 update_sparkline(displayed_analysis_data || current_analysis_data);
1444                 update_highlight();
1445                 redraw_arrows();
1446         });
1447         $(window).keyup(function(event) {
1448                 if (event.which == 39) {
1449                         next_move();
1450                 } else if (event.which == 37) {
1451                         prev_move();
1452                 }
1453         });
1454 };
1455 $(document).ready(init);
1456
1457 })();