Some refactorings out of update_board().
[remoteglot] / www / js / remoteglot.js
1 (function() {
2
3 /** @type {window.ChessBoard} @private */
4 var board = null;
5
6 /** @type {Array.<{
7  *      from_col: number,
8  *      from_row: number,
9  *      to_col: number,
10  *      to_row: number,
11  *      line_width: number,
12  *      arrow_size: number,
13  *      fg_color: string
14  * }>}
15  * @private
16  */
17 var arrows = [];
18
19 /** @type {Array.<Array.<boolean>>} */
20 var occupied_by_arrows = [];
21
22 var refutation_lines = [];
23
24 /** @type {!number} @private */
25 var move_num = 1;
26
27 /** @type {!string} @private */
28 var toplay = 'W';
29
30 /** @type {number} @private */
31 var ims = 0;
32
33 /** @type {boolean} @private */
34 var sort_refutation_lines_by_score = true;
35
36 /** @type {boolean} @private */
37 var truncate_display_history = true;
38
39 /** @type {!string|undefined} @private */
40 var highlight_from = undefined;
41
42 /** @type {!string|undefined} @private */
43 var highlight_to = undefined;
44
45 /** @type {?jQuery} @private */
46 var highlighted_move = null;
47
48 /** @type {?number} @private */
49 var unique = null;
50
51 /** The current position on the board, represented as a FEN string.
52  * @type {?string}
53  * @private
54  */
55 var fen = null;
56
57 /** @typedef {{
58  *    start_fen: string,
59  *    uci_pv: Array.<string>,
60  *    pretty_pv: Array.<string>,
61  *    line_num: number
62  * }} DisplayLine
63  */
64
65 /** @type {Array.<DisplayLine>}
66  * @private
67  */
68 var display_lines = [];
69
70 /** @type {?DisplayLine} @private */
71 var current_display_line = null;
72
73 /** @type {?number} @private */
74 var current_display_move = null;
75
76 var supports_html5_storage = function() {
77         try {
78                 return 'localStorage' in window && window['localStorage'] !== null;
79         } catch (e) {
80                 return false;
81         }
82 }
83
84 // Make the unique token persistent so people refreshing the page won't count twice.
85 // Of course, you can never fully protect against people deliberately wanting to spam.
86 var get_unique = function() {
87         var use_local_storage = supports_html5_storage();
88         if (use_local_storage && localStorage['unique']) {
89                 return localStorage['unique'];
90         }
91         var unique = Math.random();
92         if (use_local_storage) {
93                 localStorage['unique'] = unique;
94         }
95         return unique;
96 }
97
98 var request_update = function() {
99         $.ajax({
100                 url: "/analysis.pl?ims=" + ims + "&unique=" + unique
101         }).done(function(data, textstatus, xhr) {
102                 ims = xhr.getResponseHeader('X-Remoteglot-Last-Modified');
103                 var num_viewers = xhr.getResponseHeader('X-Remoteglot-Num-Viewers');
104                 update_board(data);
105                 update_num_viewers(num_viewers);
106
107                 // Next update.
108                 setTimeout(function() { request_update(); }, 100);
109         }).fail(function() {
110                 // Wait ten seconds, then try again.
111                 setTimeout(function() { request_update(); }, 10000);
112         });
113 }
114
115 var clear_arrows = function() {
116         for (var i = 0; i < arrows.length; ++i) {
117                 if (arrows[i].svg) {
118                         arrows[i].svg.parentElement.removeChild(arrows[i].svg);
119                         delete arrows[i].svg;
120                 }
121         }
122         arrows = [];
123
124         occupied_by_arrows = [];
125         for (var y = 0; y < 8; ++y) {
126                 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
127         }
128 }
129
130 var redraw_arrows = function() {
131         for (var i = 0; i < arrows.length; ++i) {
132                 position_arrow(arrows[i]);
133         }
134 }
135
136 /** @param {!number} x
137  * @return {!number}
138  */
139 var sign = function(x) {
140         if (x > 0) {
141                 return 1;
142         } else if (x < 0) {
143                 return -1;
144         } else {
145                 return 0;
146         }
147 }
148
149 /** See if drawing this arrow on the board would cause unduly amount of confusion.
150  * @param {!string} from The square the arrow is from (e.g. e4).
151  * @param {!string} to The square the arrow is to (e.g. e4).
152  * @return {boolean}
153  */
154 var interfering_arrow = function(from, to) {
155         var from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
156         var from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
157         var to_col   = to.charCodeAt(0) - "a1".charCodeAt(0);
158         var to_row   = to.charCodeAt(1) - "a1".charCodeAt(1);
159
160         occupied_by_arrows[from_row][from_col] = true;
161
162         // Knight move: Just check that we haven't been at the destination before.
163         if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
164             (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
165                 return occupied_by_arrows[to_row][to_col];
166         }
167
168         // Sliding piece: Check if anything except the from-square is seen before.
169         var dx = sign(to_col - from_col);
170         var dy = sign(to_row - from_row);
171         var x = from_col;
172         var y = from_row;
173         do {
174                 x += dx;
175                 y += dy;
176                 if (occupied_by_arrows[y][x]) {
177                         return true;
178                 }
179                 occupied_by_arrows[y][x] = true;
180         } while (x != to_col || y != to_row);
181
182         return false;
183 }
184
185 /** Find a point along the coordinate system given by the given line,
186  * <t> units forward from the start of the line, <u> units to the right of it.
187  * @param {!number} x1
188  * @param {!number} x2
189  * @param {!number} y1
190  * @param {!number} y2
191  * @param {!number} t
192  * @param {!number} u
193  * @return {!string} The point in "x y" form, suitable for SVG paths.
194  */
195 var point_from_start = function(x1, y1, x2, y2, t, u) {
196         var dx = x2 - x1;
197         var dy = y2 - y1;
198
199         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
200         dx *= norm;
201         dy *= norm;
202
203         var x = x1 + dx * t + dy * u;
204         var y = y1 + dy * t - dx * u;
205         return x + " " + y;
206 }
207
208 /** Find a point along the coordinate system given by the given line,
209  * <t> units forward from the end of the line, <u> units to the right of it.
210  * @param {!number} x1
211  * @param {!number} x2
212  * @param {!number} y1
213  * @param {!number} y2
214  * @param {!number} t
215  * @param {!number} u
216  * @return {!string} The point in "x y" form, suitable for SVG paths.
217  */
218 var point_from_end = function(x1, y1, x2, y2, t, u) {
219         var dx = x2 - x1;
220         var dy = y2 - y1;
221
222         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
223         dx *= norm;
224         dy *= norm;
225
226         var x = x2 + dx * t + dy * u;
227         var y = y2 + dy * t - dx * u;
228         return x + " " + y;
229 }
230
231 var position_arrow = function(arrow) {
232         if (arrow.svg) {
233                 arrow.svg.parentElement.removeChild(arrow.svg);
234                 delete arrow.svg;
235         }
236         if (current_display_line !== null) {
237                 return;
238         }
239
240         var pos = $(".square-a8").position();
241
242         var zoom_factor = $("#board").width() / 400.0;
243         var line_width = arrow.line_width * zoom_factor;
244         var arrow_size = arrow.arrow_size * zoom_factor;
245
246         var square_width = $(".square-a8").width();
247         var from_y = (7 - arrow.from_row + 0.5)*square_width;
248         var to_y = (7 - arrow.to_row + 0.5)*square_width;
249         var from_x = (arrow.from_col + 0.5)*square_width;
250         var to_x = (arrow.to_col + 0.5)*square_width;
251
252         var SVG_NS = "http://www.w3.org/2000/svg";
253         var XHTML_NS = "http://www.w3.org/1999/xhtml";
254         var svg = document.createElementNS(SVG_NS, "svg");
255         svg.setAttribute("width", /** @type{number} */ ($("#board").width()));
256         svg.setAttribute("height", /** @type{number} */ ($("#board").height()));
257         svg.setAttribute("style", "position: absolute");
258         svg.setAttribute("position", "absolute");
259         svg.setAttribute("version", "1.1");
260         svg.setAttribute("class", "c1");
261         svg.setAttribute("xmlns", XHTML_NS);
262
263         var x1 = from_x;
264         var y1 = from_y;
265         var x2 = to_x;
266         var y2 = to_y;
267
268         // Draw the line.
269         var outline = document.createElementNS(SVG_NS, "path");
270         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));
271         outline.setAttribute("xmlns", XHTML_NS);
272         outline.setAttribute("stroke", "#666");
273         outline.setAttribute("stroke-width", line_width + 2);
274         outline.setAttribute("fill", "none");
275         svg.appendChild(outline);
276
277         var path = document.createElementNS(SVG_NS, "path");
278         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));
279         path.setAttribute("xmlns", XHTML_NS);
280         path.setAttribute("stroke", arrow.fg_color);
281         path.setAttribute("stroke-width", line_width);
282         path.setAttribute("fill", "none");
283         svg.appendChild(path);
284
285         // Then the arrow head.
286         var head = document.createElementNS(SVG_NS, "path");
287         head.setAttribute("d",
288                 "M " +  point_from_end(x1, y1, x2, y2, 0, 0) +
289                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
290                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
291                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
292                 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
293         head.setAttribute("xmlns", XHTML_NS);
294         head.setAttribute("stroke", "#000");
295         head.setAttribute("stroke-width", "1");
296         head.setAttribute("fill", arrow.fg_color);
297         svg.appendChild(head);
298
299         $(svg).css({ top: pos.top, left: pos.left });
300         document.body.appendChild(svg);
301         arrow.svg = svg;
302 }
303
304 /**
305  * @param {!string} from_square
306  * @param {!string} to_square
307  * @param {!string} fg_color
308  * @param {number} line_width
309  * @param {number} arrow_size
310  */
311 var create_arrow = function(from_square, to_square, fg_color, line_width, arrow_size) {
312         var from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
313         var from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
314         var to_col   = to_square.charCodeAt(0) - "a1".charCodeAt(0);
315         var to_row   = to_square.charCodeAt(1) - "a1".charCodeAt(1);
316
317         // Create arrow.
318         var arrow = {
319                 from_col: from_col,
320                 from_row: from_row,
321                 to_col: to_col,
322                 to_row: to_row,
323                 line_width: line_width,
324                 arrow_size: arrow_size,
325                 fg_color: fg_color
326         };
327
328         position_arrow(arrow);
329         arrows.push(arrow);
330 }
331
332 var compare_by_sort_key = function(refutation_lines, a, b) {
333         var ska = refutation_lines[a]['sort_key'];
334         var skb = refutation_lines[b]['sort_key'];
335         if (ska < skb) return -1;
336         if (ska > skb) return 1;
337         return 0;
338 };
339
340 var compare_by_score = function(refutation_lines, a, b) {
341         var sa = parseInt(refutation_lines[b]['score_sort_key'], 10);
342         var sb = parseInt(refutation_lines[a]['score_sort_key'], 10);
343         return sa - sb;
344 }
345
346 /**
347  * Fake multi-PV using the refutation lines. Find all “relevant” moves,
348  * sorted by quality, descending.
349  *
350  * @param {!Object} data
351  * @param {number} margin The maximum number of centipawns worse than the
352  *     best move can be and still be included.
353  * @return {Array.<string>} The UCI representation (e.g. e1g1) of all
354  *     moves, in score order.
355  */
356 var find_nonstupid_moves = function(data, margin) {
357         // First of all, if there are any moves that are more than 0.5 ahead of
358         // the primary move, the refutation lines are probably bunk, so just
359         // kill them all. 
360         var best_score = undefined;
361         var pv_score = undefined;
362         for (var move in data['refutation_lines']) {
363                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
364                 if (move == data['pv_uci'][0]) {
365                         pv_score = score;
366                 }
367                 if (best_score === undefined || score > best_score) {
368                         best_score = score;
369                 }
370                 if (!(data['refutation_lines'][move]['depth'] >= 8)) {
371                         return [];
372                 }
373         }
374
375         if (best_score - pv_score > 50) {
376                 return [];
377         }
378
379         // Now find all moves that are within “margin” of the best score.
380         // The PV move will always be first.
381         var moves = [];
382         for (var move in data['refutation_lines']) {
383                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
384                 if (move != data['pv_uci'][0] && best_score - score <= margin) {
385                         moves.push(move);
386                 }
387         }
388         moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], a, b) });
389         moves.unshift(data['pv_uci'][0]);
390
391         return moves;
392 }
393
394 /**
395  * @param {number} x
396  * @return {!string}
397  */
398 var thousands = function(x) {
399         return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
400 }
401
402 /**
403  * @param {!string} fen
404  * @param {Array.<string>} uci_pv
405  * @param {number} move_num
406  * @param {!string} toplay
407  * @param {number=} opt_limit
408  * @param {boolean=} opt_showlast
409  */
410 var add_pv = function(fen, uci_pv, move_num, toplay, opt_limit, opt_showlast) {
411         var hiddenboard = new Chess();
412         hiddenboard.load(fen);
413         for (var i = 0; i < uci_pv.length; ++i) {
414                 hiddenboard.move(ucimove_to_chessjs_move(uci_pv[i]));
415         }
416         var pretty_pv = hiddenboard.history();
417
418         display_lines.push({
419                 start_fen: fen,
420                 uci_pv: uci_pv,
421                 pretty_pv: pretty_pv,
422                 line_number: display_lines.length
423         });
424         return print_pv(display_lines.length - 1, pretty_pv, move_num, toplay, opt_limit, opt_showlast);
425 }
426
427 /**
428  * @param {number} line_num
429  * @param {Array.<string>} pretty_pv
430  * @param {number} move_num
431  * @param {!string} toplay
432  * @param {number=} opt_limit
433  * @param {boolean=} opt_showlast
434  */
435 var print_pv = function(line_num, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
436         var pv = '';
437         var i = 0;
438         if (opt_limit && opt_showlast && pretty_pv.length > opt_limit) {
439                 // Truncate the PV at the beginning (instead of at the end).
440                 // We assume here that toplay is 'W'. We also assume that if
441                 // opt_showlast is set, then it is the history, and thus,
442                 // the UI should be to expand the history.
443                 pv = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
444                 i = pretty_pv.length - opt_limit;
445                 if (i % 2 == 1) {
446                         ++i;
447                 }
448                 move_num += i / 2;
449         } else if (toplay == 'B' && pretty_pv.length > 0) {
450                 var move = "<a class=\"move\" id=\"automove" + line_num + "-0\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
451                 pv = move_num + '. … ' + move;
452                 toplay = 'W';
453                 ++i;
454                 ++move_num;
455         }
456         for ( ; i < pretty_pv.length; ++i) {
457                 var move = "<a class=\"move\" id=\"automove" + line_num + "-" + i + "\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pretty_pv[i] + "</a>";
458
459                 if (toplay == 'W') {
460                         if (i > opt_limit && !opt_showlast) {
461                                 return pv + ' (…)';
462                         }
463                         if (pv != '') {
464                                 pv += ' ';
465                         }
466                         pv += move_num + '. ' + move;
467                         ++move_num;
468                         toplay = 'B';
469                 } else {
470                         pv += ' ' + move;
471                         toplay = 'W';
472                 }
473         }
474         return pv;
475 }
476
477 var update_highlight = function() {
478         $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
479         if (current_display_line === null && highlight_from !== undefined && highlight_to !== undefined) {
480                 $("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
481                 $("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
482         }
483 }
484
485 var update_history = function() {
486         if (display_lines[0] === null || display_lines[0].pretty_pv.length == 0) {
487                 $("#history").html("No history");
488         } else if (truncate_display_history) {
489                 $("#history").html(print_pv(0, display_lines[0].pretty_pv, 1, 'W', 8, true));
490         } else {
491                 $("#history").html(
492                         '(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
493                         print_pv(0, display_lines[0].pretty_pv, 1, 'W'));
494         }
495 }
496
497 /**
498  * @param {!boolean} truncate_history
499  */
500 var collapse_history = function(truncate_history) {
501         truncate_display_history = truncate_history;
502         update_history();
503 }
504 window['collapse_history'] = collapse_history;
505
506 var update_refutation_lines = function() {
507         if (fen === null) {
508                 return;
509         }
510         if (display_lines.length > 2) {
511                 display_lines = [ display_lines[0], display_lines[1] ];
512         }
513
514         var tbl = $("#refutationlines");
515         tbl.empty();
516
517         var moves = [];
518         for (var move in refutation_lines) {
519                 moves.push(move);
520         }
521         var compare = sort_refutation_lines_by_score ? compare_by_score : compare_by_sort_key;
522         moves = moves.sort(function(a, b) { return compare(refutation_lines, a, b) });
523         for (var i = 0; i < moves.length; ++i) {
524                 var line = refutation_lines[moves[i]];
525
526                 var tr = document.createElement("tr");
527
528                 var move_td = document.createElement("td");
529                 tr.appendChild(move_td);
530                 $(move_td).addClass("move");
531                 if (line['pv_uci'].length == 0) {
532                         $(move_td).text(line['pretty_move']);
533                 } else {
534                         var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['pretty_move'] + "</a>";
535                         $(move_td).html(move);
536                 }
537
538                 var score_td = document.createElement("td");
539                 tr.appendChild(score_td);
540                 $(score_td).addClass("score");
541                 $(score_td).text(line['pretty_score']);
542
543                 var depth_td = document.createElement("td");
544                 tr.appendChild(depth_td);
545                 $(depth_td).addClass("depth");
546                 $(depth_td).text("d" + line['depth']);
547
548                 var pv_td = document.createElement("td");
549                 tr.appendChild(pv_td);
550                 $(pv_td).addClass("pv");
551                 $(pv_td).html(add_pv(fen, line['pv_uci'], move_num, toplay, 10));
552
553                 tbl.append(tr);
554         }
555
556         // Make one of the links clickable and the other nonclickable.
557         if (sort_refutation_lines_by_score) {
558                 $("#sortbyscore0").html("<a href=\"javascript:resort_refutation_lines(false)\">Move</a>");
559                 $("#sortbyscore1").html("<strong>Score</strong>");
560         } else {
561                 $("#sortbyscore0").html("<strong>Move</strong>");
562                 $("#sortbyscore1").html("<a href=\"javascript:resort_refutation_lines(true)\">Score</a>");
563         }
564 }
565
566 /**
567  * @param {Object} data
568  */
569 var update_board = function(data) {
570         display_lines = [];
571
572         // The headline.
573         var headline;
574         if (data['position']['player_w'] && data['position']['player_b']) {
575                 headline = data['position']['player_w'] + '–' +
576                         data['position']['player_b'] + ', analysis';
577         } else {
578                 headline = 'Analysis';
579         }
580         var last_move;
581         if (data['position']['last_move'] !== 'none') {
582                 if (data['position']['toplay'] == 'W') {
583                         last_move = (data['position']['move_num']-1) + '… ';
584                 } else {
585                         last_move = data['position']['move_num'] + '. ';
586                 }
587                 last_move += data['position']['last_move'];
588
589                 headline += ' after ' + last_move;
590         } else {
591                 last_move = null;
592         }
593
594         $("#headline").text(headline);
595
596         // The engine id.
597         if (data['id'] && data['id']['name'] !== null) {
598                 $("#engineid").text(data['id']['name']);
599         }
600
601         // The score.
602         if (data['score'] !== null) {
603                 $("#score").text(data['score']);
604         }
605
606         var title_elems = [];
607         if (data['short_score'] !== undefined && data['short_score'] !== null) {
608                 title_elems.push(data['short_score']);
609         }
610         if (last_move !== null) {
611                 title_elems.push(last_move);
612         }
613
614         if (title_elems.length != 0) {
615                 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
616         } else {
617                 document.title = 'analysis.sesse.net';
618         }
619
620         // The search stats.
621         if (data['tablebase'] == 1) {
622                 $("#searchstats").text("Tablebase result");
623         } else if (data['nodes'] && data['nps'] && data['depth']) {
624                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
625                 if (data['seldepth']) {
626                         stats += ' (' + data['seldepth'] + ' selective)';
627                 }
628                 if (data['tbhits'] && data['tbhits'] > 0) {
629                         if (data['tbhits'] == 1) {
630                                 stats += ', one Syzygy hit';
631                         } else {
632                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
633                         }
634                 }
635
636                 $("#searchstats").text(stats);
637         } else {
638                 $("#searchstats").text("");
639         }
640
641         // Update the board itself.
642         fen = data['position']['fen'];
643         update_displayed_line();
644
645         if (data['position']['last_move_uci']) {
646                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
647                 highlight_to = data['position']['last_move_uci'].substr(2, 2);
648         } else {
649                 highlight_from = highlight_to = undefined;
650         }
651         update_highlight();
652
653         // Print the history.
654         if (data['position']['history']) {
655                 add_pv('start', data['position']['history'], 1, 'W', 8, true);
656         } else {
657                 display_lines.push(null);
658         }
659         update_history();
660
661         // Print the PV.
662         $("#pv").html(add_pv(data['position']['fen'], data['pv_uci'], data['position']['move_num'], data['position']['toplay']));
663
664         // Update the PV arrow.
665         clear_arrows();
666         if (data['pv_uci'].length >= 1) {
667                 // draw a continuation arrow as long as it's the same piece
668                 for (var i = 0; i < data['pv_uci'].length; i += 2) {
669                         var from = data['pv_uci'][i].substr(0, 2);
670                         var to = data['pv_uci'][i].substr(2,4);
671                         if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 2)) ||
672                              interfering_arrow(from, to)) {
673                                 break;
674                         }
675                         create_arrow(from, to, '#f66', 6, 20);
676                 }
677
678                 var alt_moves = find_nonstupid_moves(data, 30);
679                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
680                         create_arrow(alt_moves[i].substr(0, 2),
681                                      alt_moves[i].substr(2, 2), '#f66', 1, 10);
682                 }
683         }
684
685         // See if all semi-reasonable moves have only one possible response.
686         if (data['pv_uci'].length >= 2) {
687                 var nonstupid_moves = find_nonstupid_moves(data, 300);
688                 var response = data['pv_uci'][1];
689                 for (var i = 0; i < nonstupid_moves.length; ++i) {
690                         if (nonstupid_moves[i] == data['pv_uci'][0]) {
691                                 // ignore the PV move for refutation lines.
692                                 continue;
693                         }
694                         if (!data['refutation_lines'] ||
695                             !data['refutation_lines'][nonstupid_moves[i]] ||
696                             !data['refutation_lines'][nonstupid_moves[i]]['pv_uci'] ||
697                             data['refutation_lines'][nonstupid_moves[i]]['pv_uci'].length < 1) {
698                                 // Incomplete PV, abort.
699                                 response = undefined;
700                                 break;
701                         }
702                         var this_response = data['refutation_lines'][nonstupid_moves[i]]['pv_uci'][1];
703                         if (response !== this_response) {
704                                 // Different response depending on lines, abort.
705                                 response = undefined;
706                                 break;
707                         }
708                 }
709
710                 if (nonstupid_moves.length > 0 && response !== undefined) {
711                         create_arrow(response.substr(0, 2),
712                                      response.substr(2, 2), '#66f', 6, 20);
713                 }
714         }
715
716         // Update the refutation lines.
717         fen = data['position']['fen'];
718         move_num = data['position']['move_num'];
719         toplay = data['position']['toplay'];
720         refutation_lines = data['refutation_lines'];
721         update_refutation_lines();
722 }
723
724 /**
725  * @param {number} num_viewers
726  */
727 var update_num_viewers = function(num_viewers) {
728         if (num_viewers === null) {
729                 $("#numviewers").text("");
730         } else if (num_viewers == 1) {
731                 $("#numviewers").text("You are the only current viewer");
732         } else {
733                 $("#numviewers").text(num_viewers + " current viewers");
734         }
735 }
736
737 /**
738  * @param {boolean} sort_by_score
739  */
740 var resort_refutation_lines = function(sort_by_score) {
741         sort_refutation_lines_by_score = sort_by_score;
742         update_refutation_lines();
743 }
744 window['resort_refutation_lines'] = resort_refutation_lines;
745
746 /**
747  * @param {boolean} truncate_history
748  */
749 var set_truncate_history = function(truncate_history) {
750         truncate_display_history = truncate_history;
751         update_refutation_lines();
752 }
753 window['set_truncate_history'] = set_truncate_history;
754
755 /**
756  * @param {number} line_num
757  * @param {number} move_num
758  */
759 var show_line = function(line_num, move_num) {
760         if (line_num == -1) {
761                 current_display_line = null;
762                 current_display_move = null;
763         } else {
764                 current_display_line = display_lines[line_num];
765                 current_display_move = move_num;
766         }
767         update_displayed_line();
768         update_highlight();
769         redraw_arrows();
770 }
771 window['show_line'] = show_line;
772
773 var prev_move = function() {
774         if (current_display_move > -1) {
775                 --current_display_move;
776         }
777         update_displayed_line();
778 }
779 window['prev_move'] = prev_move;
780
781 var next_move = function() {
782         if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
783                 ++current_display_move;
784         }
785         update_displayed_line();
786 }
787 window['next_move'] = next_move;
788
789 var update_displayed_line = function() {
790         if (highlighted_move !== null) {
791                 highlighted_move.removeClass('highlight'); 
792         }
793         if (current_display_line === null) {
794                 $("#linenav").hide();
795                 $("#linemsg").show();
796                 board.position(fen);
797                 return;
798         }
799
800         $("#linenav").show();
801         $("#linemsg").hide();
802
803         if (current_display_move <= 0) {
804                 $("#prevmove").html("Previous");
805         } else {
806                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
807         }
808         if (current_display_move == current_display_line.uci_pv.length - 1) {
809                 $("#nextmove").html("Next");
810         } else {
811                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
812         }
813
814         var hiddenboard = new Chess();
815         hiddenboard.load(current_display_line.start_fen);
816         for (var i = 0; i <= current_display_move; ++i) {
817                 hiddenboard.move(ucimove_to_chessjs_move(current_display_line.uci_pv[i]));
818         }
819
820         highlighted_move = $("#automove" + current_display_line.line_number + "-" + current_display_move);
821         highlighted_move.addClass('highlight'); 
822
823         board.position(hiddenboard.fen());
824 }
825
826 var ucimove_to_chessjs_move = function(move) {
827         var source = move.substr(0, 2);
828         var target = move.substr(2, 2);
829         var promo = move.substr(4, 1);
830
831         if (promo === '') {
832                 return { from: source, to: target };
833         } else {
834                 return { from: source, to: target, promotion: promo };
835         }
836 }
837
838 var init = function() {
839         unique = get_unique();
840
841         // Create board.
842         board = new window.ChessBoard('board', 'start');
843
844         request_update();
845         $(window).resize(function() {
846                 board.resize();
847                 update_highlight();
848                 redraw_arrows();
849         });
850         $(window).keyup(function(event) {
851                 if (event.which == 39) {
852                         next_move();
853                 } else if (event.which == 37) {
854                         prev_move();
855                 }
856         });
857 };
858 $(document).ready(init);
859
860 })();