git.sesse.net Git - remoteglot/blob - 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         // The headline. Names are always fetched from current_data;
 742         // the rest can depend a bit.
 743         var headline;
 744         if (current_data &&
 745             current_data['position']['player_w'] && current_data['position']['player_b']) {
 746                 headline = current_data['position']['player_w'] + '–' +
 747                         current_data['position']['player_b'] + ', analysis';
 748         } else {
 749                 headline = 'Analysis';
 750         }
 751
 752         var last_move;
 753         if (display_data) {
 754                 // Displaying some non-current position, pick out the last move
 755                 // from the history. This will work even if the fetch failed.
 756                 last_move = format_halfmove_with_number(
 757                         current_display_line.pretty_pv[current_display_move],
 758                         current_display_move + 1);
 759                 headline += ' after ' + last_move;
 760         } else if (data['position']['last_move'] !== 'none') {
 761                 last_move = format_move_with_number(
 762                         data['position']['last_move'],
 763                         data['position']['move_num'],
 764                         data['position']['toplay'] == 'W');
 765                 headline += ' after ' + last_move;
 766         } else {
 767                 last_move = null;
 768         }
 769         $("#headline").text(headline);
 770
 771         // The <title> contains a very brief headline.
 772         var title_elems = [];
 773         if (data['short_score'] !== undefined && data['short_score'] !== null) {
 774                 title_elems.push(data['short_score'].replace(/^ /, ""));
 775         }
 776         if (last_move !== null) {
 777                 title_elems.push(last_move);
 778         }
 779
 780         if (title_elems.length != 0) {
 781                 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
 782         } else {
 783                 document.title = 'analysis.sesse.net';
 784         }
 785
 786         // The last move (shown by highlighting the from and to squares).
 787         if (data['position'] && data['position']['last_move_uci']) {
 788                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
 789                 highlight_to = data['position']['last_move_uci'].substr(2, 2);
 790         } else if (current_display_line_is_history && current_display_move >= 0) {
 791                 // We don't have historic analysis for this position, but we
 792                 // can reconstruct what the last move was by just replaying
 793                 // from the start.
 794                 var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
 795                 var moves = hiddenboard.history({ verbose: true });
 796                 var last_move = moves.pop();
 797                 highlight_from = last_move.from;
 798                 highlight_to = last_move.to;
 799         } else {
 800                 highlight_from = highlight_to = undefined;
 801         }
 802         update_highlight();
 803
 804         if (data['failed']) {
 805                 $("#score").text("No analysis for this move");
 806                 $("#pv").empty();
 807                 $("#searchstats").html("&nbsp;");
 808                 $("#refutationlines").empty();
 809                 $("#whiteclock").empty();
 810                 $("#blackclock").empty();
 811                 refutation_lines = [];
 812                 update_refutation_lines();
 813                 clear_arrows();
 814                 update_displayed_line();
 815                 return;
 816         }
 817
 818         update_clock();
 819
 820         // The engine id.
 821         if (data['id'] && data['id']['name'] !== null) {
 822                 $("#engineid").text(data['id']['name']);
 823         }
 824
 825         // The score.
 826         if (data['score'] !== null) {
 827                 $("#score").text(data['score']);
 828         }
 829
 830         // The search stats.
 831         if (data['tablebase'] == 1) {
 832                 $("#searchstats").text("Tablebase result");
 833         } else if (data['nodes'] && data['nps'] && data['depth']) {
 834                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
 835                 if (data['seldepth']) {
 836                         stats += ' (' + data['seldepth'] + ' selective)';
 837                 }
 838                 if (data['tbhits'] && data['tbhits'] > 0) {
 839                         if (data['tbhits'] == 1) {
 840                                 stats += ', one Syzygy hit';
 841                         } else {
 842                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
 843                         }
 844                 }
 845
 846                 $("#searchstats").text(stats);
 847         } else {
 848                 $("#searchstats").text("");
 849         }
 850
 851         // Update the board itself.
 852         fen = data['position']['fen'];
 853         update_displayed_line();
 854
 855         // Print the PV.
 856         $("#pv").html(add_pv(data['position']['fen'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
 857
 858         // Update the PV arrow.
 859         clear_arrows();
 860         if (data['pv_uci'].length >= 1) {
 861                 // draw a continuation arrow as long as it's the same piece
 862                 for (var i = 0; i < data['pv_uci'].length; i += 2) {
 863                         var from = data['pv_uci'][i].substr(0, 2);
 864                         var to = data['pv_uci'][i].substr(2,4);
 865                         if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 2)) ||
 866                              interfering_arrow(from, to)) {
 867                                 break;
 868                         }
 869                         create_arrow(from, to, '#f66', 6, 20);
 870                 }
 871
 872                 var alt_moves = find_nonstupid_moves(data, 30);
 873                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
 874                         create_arrow(alt_moves[i].substr(0, 2),
 875                                      alt_moves[i].substr(2, 2), '#f66', 1, 10);
 876                 }
 877         }
 878
 879         // See if all semi-reasonable moves have only one possible response.
 880         if (data['pv_uci'].length >= 2) {
 881                 var nonstupid_moves = find_nonstupid_moves(data, 300);
 882                 var response = data['pv_uci'][1];
 883                 for (var i = 0; i < nonstupid_moves.length; ++i) {
 884                         if (nonstupid_moves[i] == data['pv_uci'][0]) {
 885                                 // ignore the PV move for refutation lines.
 886                                 continue;
 887                         }
 888                         if (!data['refutation_lines'] ||
 889                             !data['refutation_lines'][nonstupid_moves[i]] ||
 890                             !data['refutation_lines'][nonstupid_moves[i]]['pv_uci'] ||
 891                             data['refutation_lines'][nonstupid_moves[i]]['pv_uci'].length < 1) {
 892                                 // Incomplete PV, abort.
 893                                 response = undefined;
 894                                 break;
 895                         }
 896                         var this_response = data['refutation_lines'][nonstupid_moves[i]]['pv_uci'][1];
 897                         if (response !== this_response) {
 898                                 // Different response depending on lines, abort.
 899                                 response = undefined;
 900                                 break;
 901                         }
 902                 }
 903
 904                 if (nonstupid_moves.length > 0 && response !== undefined) {
 905                         create_arrow(response.substr(0, 2),
 906                                      response.substr(2, 2), '#66f', 6, 20);
 907                 }
 908         }
 909
 910         // Update the refutation lines.
 911         fen = data['position']['fen'];
 912         move_num = data['position']['move_num'];
 913         toplay = data['position']['toplay'];
 914         refutation_lines = data['refutation_lines'];
 915         update_refutation_lines();
 916
 917         // Update the sparkline last, since its size depends on how everything else reflowed.
 918         update_sparkline(data);
 919 }
 920
 921 var update_sparkline = function(data) {
 922         if (data && data['score_history']) {
 923                 var first_move_num = undefined;
 924                 for (var halfmove_num in data['score_history']) {
 925                         halfmove_num = parseInt(halfmove_num);
 926                         if (first_move_num === undefined || halfmove_num < first_move_num) {
 927                                 first_move_num = halfmove_num;
 928                         }
 929                 }
 930                 if (first_move_num !== undefined) {
 931                         var last_move_num = data['position']['move_num'] * 2 - 3;
 932                         if (data['position']['toplay'] === 'B') {
 933                                 ++last_move_num;
 934                         }
 935
 936                         // Possibly truncate some moves if we don't have enough width.
 937                         // FIXME: Sometimes width() for #scorecontainer (and by extent,
 938                         // #scoresparkcontainer) on Chrome for mobile seems to start off
 939                         // at something very small, and then suddenly snap back into place.
 940                         // Figure out why.
 941                         var max_moves = Math.floor($("#scoresparkcontainer").width() / 5) - 5;
 942                         if (last_move_num - first_move_num > max_moves) {
 943                                 first_move_num = last_move_num - max_moves;
 944                         }
 945
 946                         var min_score = -100;
 947                         var max_score = 100;
 948                         var last_score = null;
 949                         var scores = [];
 950                         for (var halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
 951                                 if (data['score_history'][halfmove_num]) {
 952                                         var score = data['score_history'][halfmove_num][0];
 953                                         if (score < min_score) min_score = score;
 954                                         if (score > max_score) max_score = score;
 955                                         last_score = data['score_history'][halfmove_num][0];
 956                                 }
 957                                 scores.push(last_score);
 958                         }
 959                         if (data['plot_score']) {
 960                                 scores.push(data['plot_score']);
 961                         }
 962                         // FIXME: at some widths, calling sparkline() seems to push
 963                         // #scorecontainer under the board.
 964                         $("#scorespark").sparkline(scores, {
 965                                 type: 'bar',
 966                                 zeroColor: 'gray',
 967                                 chartRangeMin: min_score,
 968                                 chartRangeMax: max_score,
 969                                 tooltipFormatter: function(sparkline, options, fields) {
 970                                         return format_tooltip(data, fields[0].offset + first_move_num);
 971                                 }
 972                         });
 973                 } else {
 974                         $("#scorespark").text("");
 975                 }
 976         } else {
 977                 $("#scorespark").text("");
 978         }
 979 }
 980
 981 /**
 982  * @param {number} num_viewers
 983  */
 984 var update_num_viewers = function(num_viewers) {
 985         if (num_viewers === null) {
 986                 $("#numviewers").text("");
 987         } else if (num_viewers == 1) {
 988                 $("#numviewers").text("You are the only current viewer");
 989         } else {
 990                 $("#numviewers").text(num_viewers + " current viewers");
 991         }
 992 }
 993
 994 var update_clock = function() {
 995         clearTimeout(clock_timer);
 996
 997         var data = displayed_analysis_data || current_analysis_data;
 998         if (data['position']) {
 999                 var result = data['position']['result'];
1000                 if (result === '1-0') {
1001                         $("#whiteclock").text("1");
1002                         $("#blackclock").text("0");
1003                         $("#whiteclock").removeClass("running-clock");
1004                         $("#blackclock").removeClass("running-clock");
1005                         return;
1006                 }
1007                 if (result === '1/2-1/2') {
1008                         $("#whiteclock").text("1/2");
1009                         $("#blackclock").text("1/2");
1010                         $("#whiteclock").removeClass("running-clock");
1011                         $("#blackclock").removeClass("running-clock");
1012                         return;
1013                 }
1014                 if (result === '0-1') {
1015                         $("#whiteclock").text("0");
1016                         $("#blackclock").text("1");
1017                         $("#whiteclock").removeClass("running-clock");
1018                         $("#blackclock").removeClass("running-clock");
1019                         return;
1020                 }
1021         }
1022
1023         var white_clock_ms = null;
1024         var black_clock_ms = null;
1025         var show_seconds = false;
1026
1027         // Static clocks.
1028         if (data['position'] &&
1029             data['position']['white_clock'] &&
1030             data['position']['black_clock']) {
1031                 white_clock_ms = data['position']['white_clock'] * 1000;
1032                 black_clock_ms = data['position']['black_clock'] * 1000;
1033         }
1034
1035         // Dynamic clock (only one, obviously).
1036         var color;
1037         if (data['position']['white_clock_target']) {
1038                 color = "white";
1039                 $("#whiteclock").addClass("running-clock");
1040                 $("#blackclock").removeClass("running-clock");
1041         } else if (data['position']['black_clock_target']) {
1042                 color = "black";
1043                 $("#whiteclock").removeClass("running-clock");
1044                 $("#blackclock").addClass("running-clock");
1045         } else {
1046                 $("#whiteclock").removeClass("running-clock");
1047                 $("#blackclock").removeClass("running-clock");
1048         }
1049         var remaining_ms;
1050         if (color) {
1051                 var now = new Date().getTime() + client_clock_offset_ms;
1052                 remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
1053                 if (color === "white") {
1054                         white_clock_ms = remaining_ms;
1055                 } else {
1056                         black_clock_ms = remaining_ms;
1057                 }
1058         }
1059
1060         if (white_clock_ms === null || black_clock_ms === null) {
1061                 $("#whiteclock").empty();
1062                 $("#blackclock").empty();
1063                 return;
1064         }
1065
1066         // If either player has ten minutes or less left, add the second counters.
1067         var show_seconds = (white_clock_ms < 60 * 10 * 1000 || black_clock_ms < 60 * 10 * 1000);
1068
1069         if (color) {
1070                 // See when the clock will change next, and update right after that.
1071                 var next_update_ms;
1072                 if (show_seconds) {
1073                         next_update_ms = remaining_ms % 1000 + 100;
1074                 } else {
1075                         next_update_ms = remaining_ms % 60000 + 100;
1076                 }
1077                 clock_timer = setTimeout(update_clock, next_update_ms);
1078         }
1079
1080         $("#whiteclock").text(format_clock(white_clock_ms, show_seconds));
1081         $("#blackclock").text(format_clock(black_clock_ms, show_seconds));
1082 }
1083
1084 /**
1085  * @param {Number} remaining_ms
1086  * @param {boolean} show_seconds
1087  */
1088 var format_clock = function(remaining_ms, show_seconds) {
1089         if (remaining_ms <= 0) {
1090                 if (show_seconds) {
1091                         return "00:00:00";
1092                 } else {
1093                         return "00:00";
1094                 }
1095         }
1096
1097         var remaining = Math.floor(remaining_ms / 1000);
1098         var seconds = remaining % 60;
1099         remaining = (remaining - seconds) / 60;
1100         var minutes = remaining % 60;
1101         remaining = (remaining - minutes) / 60;
1102         var hours = remaining;
1103         if (show_seconds) {
1104                 return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
1105         } else {
1106                 return format_2d(hours) + ":" + format_2d(minutes);
1107         }
1108 }
1109
1110 /**
1111  * @param {Number} x
1112  */
1113 var format_2d = function(x) {
1114         if (x >= 10) {
1115                 return x;
1116         } else {
1117                 return "0" + x;
1118         }
1119 }
1120
1121 /**
1122  * @param {string} move
1123  * @param {Number} move_num
1124  * @param {boolean} white_to_play
1125  */
1126 var format_move_with_number = function(move, move_num, white_to_play) {
1127         var ret;
1128         if (white_to_play) {
1129                 ret = (move_num - 1) + '… ';
1130         } else {
1131                 ret = move_num + '. ';
1132         }
1133         ret += move;
1134         return ret;
1135 }
1136
1137 /**
1138  * @param {string} move
1139  * @param {Number} halfmove_num
1140  */
1141 var format_halfmove_with_number = function(move, halfmove_num) {
1142         return format_move_with_number(
1143                 move,
1144                 Math.floor(halfmove_num / 2) + 1,
1145                 halfmove_num % 2 == 0);
1146 }
1147
1148 /**
1149  * @param {Object} data
1150  * @param {Number} halfmove_num
1151  */
1152 var format_tooltip = function(data, halfmove_num) {
1153         if (data['score_history'][halfmove_num] ||
1154             halfmove_num === data['position']['pretty_history'].length) {
1155                 var move;
1156                 var short_score;
1157                 if (halfmove_num === data['position']['pretty_history'].length) {
1158                         move = data['position']['last_move'];
1159                         short_score = data['short_score'];
1160                 } else {
1161                         move = data['position']['pretty_history'][halfmove_num];
1162                         short_score = data['score_history'][halfmove_num][1];
1163                 }
1164                 var move_with_number = format_halfmove_with_number(move, halfmove_num);
1165
1166                 return "After " + move_with_number + ": " + short_score;
1167         } else {
1168                 for (var i = halfmove_num; i --> 0; ) {
1169                         if (data['score_history'][i]) {
1170                                 var move = data['position']['pretty_history'][i];
1171                                 return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
1172                         }
1173                 }
1174         }
1175 }
1176
1177 /**
1178  * @param {boolean} sort_by_score
1179  */
1180 var resort_refutation_lines = function(sort_by_score) {
1181         sort_refutation_lines_by_score = sort_by_score;
1182         if (supports_html5_storage()) {
1183                 localStorage['sort_refutation_lines_by_score'] = sort_by_score ? 1 : 0;
1184         }
1185         update_refutation_lines();
1186 }
1187 window['resort_refutation_lines'] = resort_refutation_lines;
1188
1189 /**
1190  * @param {boolean} truncate_history
1191  */
1192 var set_truncate_history = function(truncate_history) {
1193         truncate_display_history = truncate_history;
1194         update_refutation_lines();
1195 }
1196 window['set_truncate_history'] = set_truncate_history;
1197
1198 /**
1199  * @param {number} line_num
1200  * @param {number} move_num
1201  */
1202 var show_line = function(line_num, move_num) {
1203         if (line_num == -1) {
1204                 current_display_line = null;
1205                 current_display_move = null;
1206                 if (displayed_analysis_data) {
1207                         // TODO: Support exiting to history position if we are in an
1208                         // analysis line of a history position.
1209                         displayed_analysis_data = null;
1210                         update_board(current_analysis_data, displayed_analysis_data);
1211                 }
1212         } else {
1213                 current_display_line = display_lines[line_num];
1214                 current_display_move = move_num;
1215         }
1216         current_display_line_is_history = (line_num == 0);
1217
1218         update_historic_analysis();
1219         update_displayed_line();
1220         update_highlight();
1221         redraw_arrows();
1222 }
1223 window['show_line'] = show_line;
1224
1225 var prev_move = function() {
1226         if (current_display_move > -1) {
1227                 --current_display_move;
1228         }
1229         update_historic_analysis();
1230         update_displayed_line();
1231 }
1232 window['prev_move'] = prev_move;
1233
1234 var next_move = function() {
1235         if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
1236                 ++current_display_move;
1237         }
1238         update_historic_analysis();
1239         update_displayed_line();
1240 }
1241 window['next_move'] = next_move;
1242
1243 var update_historic_analysis = function() {
1244         if (!current_display_line_is_history) {
1245                 return;
1246         }
1247         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1248                 displayed_analysis_data = null;
1249                 update_board(current_analysis_data, displayed_analysis_data);
1250         }
1251
1252         // Fetch old analysis for this line if it exists.
1253         var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
1254         var filename = "/history/move" + (current_display_move + 1) + "-" +
1255                 hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
1256
1257         current_historic_xhr = $.ajax({
1258                 url: filename
1259         }).done(function(data, textstatus, xhr) {
1260                 displayed_analysis_data = data;
1261                 update_board(current_analysis_data, displayed_analysis_data);
1262         }).fail(function(jqXHR, textStatus, errorThrown) {
1263                 if (textStatus === "abort") {
1264                         // Aborted because we are switching backends. Don't do anything;
1265                         // we will already have been cleared.
1266                 } else {
1267                         displayed_analysis_data = {'failed': true};
1268                         update_board(current_analysis_data, displayed_analysis_data);
1269                 }
1270         });
1271 }
1272
1273 /**
1274  * @param {string} fen
1275  */
1276 var update_imbalance = function(fen) {
1277         var hiddenboard = new Chess(fen);
1278         var imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
1279         for (var row = 0; row < 8; ++row) {
1280                 for (var col = 0; col < 8; ++col) {
1281                         var col_text = String.fromCharCode('a1'.charCodeAt(0) + col);
1282                         var row_text = String.fromCharCode('a1'.charCodeAt(1) + row);
1283                         var square = col_text + row_text;
1284                         var contents = hiddenboard.get(square);
1285                         if (contents !== null) {
1286                                 if (contents.color === 'w') {
1287                                         ++imbalance[contents.type];
1288                                 } else {
1289                                         --imbalance[contents.type];
1290                                 }
1291                         }
1292                 }
1293         }
1294         var white_imbalance = '';
1295         var black_imbalance = '';
1296         for (var piece in imbalance) {
1297                 for (var i = 0; i < imbalance[piece]; ++i) {
1298                         white_imbalance += '<img src="img/chesspieces/wikipedia/w' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1299                 }
1300                 for (var i = 0; i < -imbalance[piece]; ++i) {
1301                         black_imbalance += '<img src="img/chesspieces/wikipedia/b' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1302                 }
1303         }
1304         $('#whiteimbalance').html(white_imbalance);
1305         $('#blackimbalance').html(black_imbalance);
1306 }
1307
1308 var update_displayed_line = function() {
1309         if (highlighted_move !== null) {
1310                 highlighted_move.removeClass('highlight');
1311         }
1312         if (current_display_line === null) {
1313                 $("#linenav").hide();
1314                 $("#linemsg").show();
1315                 board.position(fen);
1316                 update_imbalance(fen);
1317                 return;
1318         }
1319
1320         $("#linenav").show();
1321         $("#linemsg").hide();
1322
1323         if (current_display_move <= 0) {
1324                 $("#prevmove").html("Previous");
1325         } else {
1326                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
1327         }
1328         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1329                 $("#nextmove").html("Next");
1330         } else {
1331                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
1332         }
1333
1334         highlighted_move = $("#automove" + current_display_line.line_number + "-" + current_display_move);
1335         highlighted_move.addClass('highlight');
1336
1337         var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pretty_pv, current_display_move);
1338         board.position(hiddenboard.fen());
1339         update_imbalance(hiddenboard.fen());
1340 }
1341
1342 /**
1343  * @param {boolean} param_enable_sound
1344  */
1345 var set_sound = function(param_enable_sound) {
1346         enable_sound = param_enable_sound;
1347         if (enable_sound) {
1348                 $("#soundon").html("<strong>On</strong>");
1349                 $("#soundoff").html("<a href=\"javascript:set_sound(false)\">Off</a>");
1350
1351                 // Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
1352                 // and also preload the file since the user has selected audio.
1353                 var ding = document.getElementById('ding');
1354                 if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
1355                         ding.src = 'ding.opus';
1356                         ding.load();
1357                 }
1358         } else {
1359                 $("#soundon").html("<a href=\"javascript:set_sound(true)\">On</a>");
1360                 $("#soundoff").html("<strong>Off</strong>");
1361         }
1362         if (supports_html5_storage()) {
1363                 localStorage['enable_sound'] = enable_sound ? 1 : 0;
1364         }
1365 }
1366 window['set_sound'] = set_sound;
1367
1368 /**
1369  * @param {string} new_backend_url
1370  */
1371 var switch_backend = function(new_backend_url) {
1372         // Stop looking at historic data.
1373         current_display_line = null;
1374         current_display_move = null;
1375         displayed_analysis_data = null;
1376         if (current_historic_xhr) {
1377                 current_historic_xhr.abort();
1378         }
1379
1380         // If we already have a backend response going, abort it.
1381         if (current_analysis_xhr) {
1382                 current_analysis_xhr.abort();
1383         }
1384
1385         // Otherwise, we should have a timer going to start a new one.
1386         // Kill that, too.
1387         if (current_analysis_request_timer) {
1388                 clearTimeout(current_analysis_request_timer);
1389                 current_analysis_request_timer = null;
1390         }
1391
1392         // Request an immediate fetch with the new backend.
1393         backend_url = new_backend_url;
1394         current_analysis_data = null;
1395         ims = 0;
1396         request_update();
1397 }
1398 window['switch_backend'] = switch_backend;
1399
1400 var init = function() {
1401         unique = get_unique();
1402
1403         // Load settings from HTML5 local storage if available.
1404         if (supports_html5_storage() && localStorage['enable_sound']) {
1405                 set_sound(parseInt(localStorage['enable_sound']));
1406         } else {
1407                 set_sound(false);
1408         }
1409         if (supports_html5_storage() && localStorage['sort_refutation_lines_by_score']) {
1410                 sort_refutation_lines_by_score = parseInt(localStorage['sort_refutation_lines_by_score']);
1411         } else {
1412                 sort_refutation_lines_by_score = true;
1413         }
1414
1415         // Create board.
1416         board = new window.ChessBoard('board', 'start');
1417
1418         request_update();
1419         $(window).resize(function() {
1420                 board.resize();
1421                 update_sparkline(displayed_analysis_data || current_analysis_data);
1422                 update_highlight();
1423                 redraw_arrows();
1424         });
1425         $(window).keyup(function(event) {
1426                 if (event.which == 39) {
1427                         next_move();
1428                 } else if (event.which == 37) {
1429                         prev_move();
1430                 }
1431         });
1432 };
1433 $(document).ready(init);
1434
1435 })();