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 /**
  41  * Games currently in progress, if any.
  42  *
  43  * @type {?Array.<{
  44  *      name: string,
  45  *      url: string,
  46  *      id: string,
  47  * }>}
  48  * @private
  49  */
  50 var current_games = null;
  51
  52 /** @type {Array.<{
  53  *      from_col: number,
  54  *      from_row: number,
  55  *      to_col: number,
  56  *      to_row: number,
  57  *      line_width: number,
  58  *      arrow_size: number,
  59  *      fg_color: string
  60  * }>}
  61  * @private
  62  */
  63 var arrows = [];
  64
  65 /** @type {Array.<Array.<boolean>>} */
  66 var occupied_by_arrows = [];
  67
  68 var refutation_lines = [];
  69
  70 /** @type {!number} @private */
  71 var move_num = 1;
  72
  73 /** @type {!string} @private */
  74 var toplay = 'W';
  75
  76 /** @type {number} @private */
  77 var ims = 0;
  78
  79 /** @type {boolean} @private */
  80 var sort_refutation_lines_by_score = true;
  81
  82 /** @type {boolean} @private */
  83 var truncate_display_history = true;
  84
  85 /** @type {!string|undefined} @private */
  86 var highlight_from = undefined;
  87
  88 /** @type {!string|undefined} @private */
  89 var highlight_to = undefined;
  90
  91 /** The HTML object of the move currently being highlighted (in red).
  92  * @type {?jQuery}
  93  * @private */
  94 var highlighted_move = null;
  95
  96 /** @type {?number} @private */
  97 var unique = null;
  98
  99 /** @type {boolean} @private */
 100 var enable_sound = false;
 101
 102 /**
 103  * Our best estimate of how many milliseconds we need to add to
 104  * new Date() to get the true UTC time. Calibrated against the
 105  * server clock.
 106  *
 107  * @type {?number}
 108  * @private
 109  */
 110 var client_clock_offset_ms = null;
 111
 112 var clock_timer = null;
 113
 114 /** The current position on the board, represented as a FEN string.
 115  * @type {?string}
 116  * @private
 117  */
 118 var fen = null;
 119
 120 /** @typedef {{
 121  *    start_fen: string,
 122  *    uci_pv: Array.<string>,
 123  *    pretty_pv: Array.<string>,
 124  *    line_num: number
 125  * }} DisplayLine
 126  */
 127
 128 /** All PVs that we currently know of.
 129  *
 130  * Element 0 is history (or null if no history).
 131  * Element 1 is current main PV.
 132  * All remaining elements are refutation lines (multi-PV).
 133  *
 134  * @type {Array.<DisplayLine>}
 135  * @private
 136  */
 137 var display_lines = [];
 138
 139 /** @type {?DisplayLine} @private */
 140 var current_display_line = null;
 141
 142 /** @type {boolean} @private */
 143 var current_display_line_is_history = false;
 144
 145 /** @type {?number} @private */
 146 var current_display_move = null;
 147
 148 /**
 149  * The current backend request to get main analysis (not history), if any,
 150  * so that we can abort it.
 151  *
 152  * @type {?jqXHR}
 153  * @private
 154  */
 155 var current_analysis_xhr = null;
 156
 157 /**
 158  * The current timer to fire off a request to get main analysis (not history),
 159  * if any, so that we can abort it.
 160  *
 161  * @type {?Number}
 162  * @private
 163  */
 164 var current_analysis_request_timer = null;
 165
 166 /**
 167  * The current backend request to get historic data, if any.
 168  *
 169  * @type {?jqXHR}
 170  * @private
 171  */
 172 var current_historic_xhr = null;
 173
 174 var supports_html5_storage = function() {
 175         try {
 176                 return 'localStorage' in window && window['localStorage'] !== null;
 177         } catch (e) {
 178                 return false;
 179         }
 180 }
 181
 182 // Make the unique token persistent so people refreshing the page won't count twice.
 183 // Of course, you can never fully protect against people deliberately wanting to spam.
 184 var get_unique = function() {
 185         var use_local_storage = supports_html5_storage();
 186         if (use_local_storage && localStorage['unique']) {
 187                 return localStorage['unique'];
 188         }
 189         var unique = Math.random();
 190         if (use_local_storage) {
 191                 localStorage['unique'] = unique;
 192         }
 193         return unique;
 194 }
 195
 196 var request_update = function() {
 197         current_analysis_request_timer = null;
 198
 199         current_analysis_xhr = $.ajax({
 200                 url: backend_url + "?ims=" + ims + "&unique=" + unique
 201         }).done(function(data, textstatus, xhr) {
 202                 sync_server_clock(xhr.getResponseHeader('Date'));
 203                 ims = xhr.getResponseHeader('X-RGLM');
 204                 var num_viewers = xhr.getResponseHeader('X-RGNV');
 205                 var new_data;
 206                 if (Array.isArray(data)) {
 207                         new_data = JSON.parse(JSON.stringify(current_analysis_data));
 208                         JSON_delta.patch(new_data, data);
 209                 } else {
 210                         new_data = data;
 211                 }
 212
 213                 var minimum_version = xhr.getResponseHeader('X-RGMV');
 214                 if (minimum_version && minimum_version > SCRIPT_VERSION) {
 215                         // Upgrade to latest version with a force-reload.
 216                         location.reload(true);
 217                 }
 218
 219                 possibly_play_sound(current_analysis_data, new_data);
 220                 current_analysis_data = new_data;
 221                 update_board(current_analysis_data, displayed_analysis_data);
 222                 update_num_viewers(num_viewers);
 223
 224                 // Next update.
 225                 current_analysis_request_timer = setTimeout(function() { request_update(); }, 100);
 226         }).fail(function(jqXHR, textStatus, errorThrown) {
 227                 if (textStatus === "abort") {
 228                         // Aborted because we are switching backends. Abandon and don't retry,
 229                         // because another one is already started for us.
 230                 } else {
 231                         // Backend error or similar. Wait ten seconds, then try again.
 232                         current_analysis_request_timer = setTimeout(function() { request_update(); }, 10000);
 233                 }
 234         });
 235 }
 236
 237 var possibly_play_sound = function(old_data, new_data) {
 238         if (!enable_sound) {
 239                 return;
 240         }
 241         if (old_data === null) {
 242                 return;
 243         }
 244         var ding = document.getElementById('ding');
 245         if (ding && ding.play) {
 246                 if (old_data['position'] && old_data['position']['fen'] &&
 247                     new_data['position'] && new_data['position']['fen'] &&
 248                     (old_data['position']['fen'] !== new_data['position']['fen'] ||
 249                      old_data['position']['move_num'] !== new_data['position']['move_num'])) {
 250                         ding.play();
 251                 }
 252         }
 253 }
 254
 255 /**
 256  * @type {!string} server_date_string
 257  */
 258 var sync_server_clock = function(server_date_string) {
 259         var server_time_ms = new Date(server_date_string).getTime();
 260         var client_time_ms = new Date().getTime();
 261         var estimated_offset_ms = server_time_ms - client_time_ms;
 262
 263         // In order not to let the noise move us too much back and forth
 264         // (the server only has one-second resolution anyway), we only
 265         // change an existing skew if we are at least five seconds off.
 266         if (client_clock_offset_ms === null ||
 267             Math.abs(estimated_offset_ms - client_clock_offset_ms) > 5000) {
 268                 client_clock_offset_ms = estimated_offset_ms;
 269         }
 270 }
 271
 272 var clear_arrows = function() {
 273         for (var i = 0; i < arrows.length; ++i) {
 274                 if (arrows[i].svg) {
 275                         if (arrows[i].svg.parentElement) {
 276                                 arrows[i].svg.parentElement.removeChild(arrows[i].svg);
 277                         }
 278                         delete arrows[i].svg;
 279                 }
 280         }
 281         arrows = [];
 282
 283         occupied_by_arrows = [];
 284         for (var y = 0; y < 8; ++y) {
 285                 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
 286         }
 287 }
 288
 289 var redraw_arrows = function() {
 290         for (var i = 0; i < arrows.length; ++i) {
 291                 position_arrow(arrows[i]);
 292         }
 293 }
 294
 295 /** @param {!number} x
 296  * @return {!number}
 297  */
 298 var sign = function(x) {
 299         if (x > 0) {
 300                 return 1;
 301         } else if (x < 0) {
 302                 return -1;
 303         } else {
 304                 return 0;
 305         }
 306 }
 307
 308 /** See if drawing this arrow on the board would cause unduly amount of confusion.
 309  * @param {!string} from The square the arrow is from (e.g. e4).
 310  * @param {!string} to The square the arrow is to (e.g. e4).
 311  * @return {boolean}
 312  */
 313 var interfering_arrow = function(from, to) {
 314         var from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
 315         var from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
 316         var to_col   = to.charCodeAt(0) - "a1".charCodeAt(0);
 317         var to_row   = to.charCodeAt(1) - "a1".charCodeAt(1);
 318
 319         occupied_by_arrows[from_row][from_col] = true;
 320
 321         // Knight move: Just check that we haven't been at the destination before.
 322         if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
 323             (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
 324                 return occupied_by_arrows[to_row][to_col];
 325         }
 326
 327         // Sliding piece: Check if anything except the from-square is seen before.
 328         var dx = sign(to_col - from_col);
 329         var dy = sign(to_row - from_row);
 330         var x = from_col;
 331         var y = from_row;
 332         do {
 333                 x += dx;
 334                 y += dy;
 335                 if (occupied_by_arrows[y][x]) {
 336                         return true;
 337                 }
 338                 occupied_by_arrows[y][x] = true;
 339         } while (x != to_col || y != to_row);
 340
 341         return false;
 342 }
 343
 344 /** Find a point along the coordinate system given by the given line,
 345  * <t> units forward from the start of the line, <u> units to the right of it.
 346  * @param {!number} x1
 347  * @param {!number} x2
 348  * @param {!number} y1
 349  * @param {!number} y2
 350  * @param {!number} t
 351  * @param {!number} u
 352  * @return {!string} The point in "x y" form, suitable for SVG paths.
 353  */
 354 var point_from_start = function(x1, y1, x2, y2, t, u) {
 355         var dx = x2 - x1;
 356         var dy = y2 - y1;
 357
 358         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
 359         dx *= norm;
 360         dy *= norm;
 361
 362         var x = x1 + dx * t + dy * u;
 363         var y = y1 + dy * t - dx * u;
 364         return x + " " + y;
 365 }
 366
 367 /** Find a point along the coordinate system given by the given line,
 368  * <t> units forward from the end of the line, <u> units to the right of it.
 369  * @param {!number} x1
 370  * @param {!number} x2
 371  * @param {!number} y1
 372  * @param {!number} y2
 373  * @param {!number} t
 374  * @param {!number} u
 375  * @return {!string} The point in "x y" form, suitable for SVG paths.
 376  */
 377 var point_from_end = function(x1, y1, x2, y2, t, u) {
 378         var dx = x2 - x1;
 379         var dy = y2 - y1;
 380
 381         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
 382         dx *= norm;
 383         dy *= norm;
 384
 385         var x = x2 + dx * t + dy * u;
 386         var y = y2 + dy * t - dx * u;
 387         return x + " " + y;
 388 }
 389
 390 var position_arrow = function(arrow) {
 391         if (arrow.svg) {
 392                 if (arrow.svg.parentElement) {
 393                         arrow.svg.parentElement.removeChild(arrow.svg);
 394                 }
 395                 delete arrow.svg;
 396         }
 397         if (current_display_line !== null && !current_display_line_is_history) {
 398                 return;
 399         }
 400
 401         var pos = $(".square-a8").position();
 402
 403         var zoom_factor = $("#board").width() / 400.0;
 404         var line_width = arrow.line_width * zoom_factor;
 405         var arrow_size = arrow.arrow_size * zoom_factor;
 406
 407         var square_width = $(".square-a8").width();
 408         var from_y = (7 - arrow.from_row + 0.5)*square_width;
 409         var to_y = (7 - arrow.to_row + 0.5)*square_width;
 410         var from_x = (arrow.from_col + 0.5)*square_width;
 411         var to_x = (arrow.to_col + 0.5)*square_width;
 412
 413         var SVG_NS = "http://www.w3.org/2000/svg";
 414         var XHTML_NS = "http://www.w3.org/1999/xhtml";
 415         var svg = document.createElementNS(SVG_NS, "svg");
 416         svg.setAttribute("width", /** @type{number} */ ($("#board").width()));
 417         svg.setAttribute("height", /** @type{number} */ ($("#board").height()));
 418         svg.setAttribute("style", "position: absolute");
 419         svg.setAttribute("position", "absolute");
 420         svg.setAttribute("version", "1.1");
 421         svg.setAttribute("class", "c1");
 422         svg.setAttribute("xmlns", XHTML_NS);
 423
 424         var x1 = from_x;
 425         var y1 = from_y;
 426         var x2 = to_x;
 427         var y2 = to_y;
 428
 429         // Draw the line.
 430         var outline = document.createElementNS(SVG_NS, "path");
 431         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));
 432         outline.setAttribute("xmlns", XHTML_NS);
 433         outline.setAttribute("stroke", "#666");
 434         outline.setAttribute("stroke-width", line_width + 2);
 435         outline.setAttribute("fill", "none");
 436         svg.appendChild(outline);
 437
 438         var path = document.createElementNS(SVG_NS, "path");
 439         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));
 440         path.setAttribute("xmlns", XHTML_NS);
 441         path.setAttribute("stroke", arrow.fg_color);
 442         path.setAttribute("stroke-width", line_width);
 443         path.setAttribute("fill", "none");
 444         svg.appendChild(path);
 445
 446         // Then the arrow head.
 447         var head = document.createElementNS(SVG_NS, "path");
 448         head.setAttribute("d",
 449                 "M " +  point_from_end(x1, y1, x2, y2, 0, 0) +
 450                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
 451                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
 452                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
 453                 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
 454         head.setAttribute("xmlns", XHTML_NS);
 455         head.setAttribute("stroke", "#000");
 456         head.setAttribute("stroke-width", "1");
 457         head.setAttribute("fill", arrow.fg_color);
 458         svg.appendChild(head);
 459
 460         $(svg).css({ top: pos.top, left: pos.left });
 461         document.body.appendChild(svg);
 462         arrow.svg = svg;
 463 }
 464
 465 /**
 466  * @param {!string} from_square
 467  * @param {!string} to_square
 468  * @param {!string} fg_color
 469  * @param {number} line_width
 470  * @param {number} arrow_size
 471  */
 472 var create_arrow = function(from_square, to_square, fg_color, line_width, arrow_size) {
 473         var from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
 474         var from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
 475         var to_col   = to_square.charCodeAt(0) - "a1".charCodeAt(0);
 476         var to_row   = to_square.charCodeAt(1) - "a1".charCodeAt(1);
 477
 478         // Create arrow.
 479         var arrow = {
 480                 from_col: from_col,
 481                 from_row: from_row,
 482                 to_col: to_col,
 483                 to_row: to_row,
 484                 line_width: line_width,
 485                 arrow_size: arrow_size,
 486                 fg_color: fg_color
 487         };
 488
 489         position_arrow(arrow);
 490         arrows.push(arrow);
 491 }
 492
 493 var compare_by_sort_key = function(refutation_lines, a, b) {
 494         var ska = refutation_lines[a]['sort_key'];
 495         var skb = refutation_lines[b]['sort_key'];
 496         if (ska < skb) return -1;
 497         if (ska > skb) return 1;
 498         return 0;
 499 };
 500
 501 var compare_by_score = function(refutation_lines, a, b) {
 502         var sa = parseInt(refutation_lines[b]['score_sort_key'], 10);
 503         var sb = parseInt(refutation_lines[a]['score_sort_key'], 10);
 504         return sa - sb;
 505 }
 506
 507 /**
 508  * Fake multi-PV using the refutation lines. Find all “relevant” moves,
 509  * sorted by quality, descending.
 510  *
 511  * @param {!Object} data
 512  * @param {number} margin The maximum number of centipawns worse than the
 513  *     best move can be and still be included.
 514  * @return {Array.<string>} The UCI representation (e.g. e1g1) of all
 515  *     moves, in score order.
 516  */
 517 var find_nonstupid_moves = function(data, margin) {
 518         // First of all, if there are any moves that are more than 0.5 ahead of
 519         // the primary move, the refutation lines are probably bunk, so just
 520         // kill them all.
 521         var best_score = undefined;
 522         var pv_score = undefined;
 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]) {
 526                         pv_score = score;
 527                 }
 528                 if (best_score === undefined || score > best_score) {
 529                         best_score = score;
 530                 }
 531                 if (!(data['refutation_lines'][move]['depth'] >= 8)) {
 532                         return [];
 533                 }
 534         }
 535
 536         if (best_score - pv_score > 50) {
 537                 return [];
 538         }
 539
 540         // Now find all moves that are within “margin” of the best score.
 541         // The PV move will always be first.
 542         var moves = [];
 543         for (var move in data['refutation_lines']) {
 544                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
 545                 if (move != data['pv_uci'][0] && best_score - score <= margin) {
 546                         moves.push(move);
 547                 }
 548         }
 549         moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], a, b) });
 550         moves.unshift(data['pv_uci'][0]);
 551
 552         return moves;
 553 }
 554
 555 /**
 556  * @param {number} x
 557  * @return {!string}
 558  */
 559 var thousands = function(x) {
 560         return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
 561 }
 562
 563 /**
 564  * @param {!string} fen
 565  * @param {Array.<string>} pretty_pv
 566  * @param {number} move_num
 567  * @param {!string} toplay
 568  * @param {number=} opt_limit
 569  * @param {boolean=} opt_showlast
 570  */
 571 var add_pv = function(fen, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 572         display_lines.push({
 573                 start_fen: fen,
 574                 pretty_pv: pretty_pv,
 575                 line_number: display_lines.length
 576         });
 577         return print_pv(display_lines.length - 1, pretty_pv, move_num, toplay, opt_limit, opt_showlast);
 578 }
 579
 580 /**
 581  * @param {number} line_num
 582  * @param {Array.<string>} pretty_pv
 583  * @param {number} move_num
 584  * @param {!string} toplay
 585  * @param {number=} opt_limit
 586  * @param {boolean=} opt_showlast
 587  */
 588 var print_pv = function(line_num, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 589         var pv = '';
 590         var i = 0;
 591         if (opt_limit && opt_showlast && pretty_pv.length > opt_limit) {
 592                 // Truncate the PV at the beginning (instead of at the end).
 593                 // We assume here that toplay is 'W'. We also assume that if
 594                 // opt_showlast is set, then it is the history, and thus,
 595                 // the UI should be to expand the history.
 596                 pv = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
 597                 i = pretty_pv.length - opt_limit;
 598                 if (i % 2 == 1) {
 599                         ++i;
 600                 }
 601                 move_num += i / 2;
 602         } else if (toplay == 'B' && pretty_pv.length > 0) {
 603                 var move = "<a class=\"move\" id=\"automove" + line_num + "-0\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
 604                 pv = move_num + '. … ' + move;
 605                 toplay = 'W';
 606                 ++i;
 607                 ++move_num;
 608         }
 609         for ( ; i < pretty_pv.length; ++i) {
 610                 var move = "<a class=\"move\" id=\"automove" + line_num + "-" + i + "\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pretty_pv[i] + "</a>";
 611
 612                 if (toplay == 'W') {
 613                         if (i > opt_limit && !opt_showlast) {
 614                                 return pv + ' (…)';
 615                         }
 616                         if (pv != '') {
 617                                 pv += ' ';
 618                         }
 619                         pv += move_num + '. ' + move;
 620                         ++move_num;
 621                         toplay = 'B';
 622                 } else {
 623                         pv += ' ' + move;
 624                         toplay = 'W';
 625                 }
 626         }
 627         return pv;
 628 }
 629
 630 /** Update the highlighted to/from squares on the board.
 631  * Based on the global "highlight_from" and "highlight_to" variables.
 632  */
 633 var update_board_highlight = function() {
 634         $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
 635         if ((current_display_line === null || current_display_line_is_history) &&
 636             highlight_from !== undefined && highlight_to !== undefined) {
 637                 $("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
 638                 $("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
 639         }
 640 }
 641
 642 var update_history = function() {
 643         if (display_lines[0] === null || display_lines[0].pretty_pv.length == 0) {
 644                 $("#history").html("No history");
 645         } else if (truncate_display_history) {
 646                 $("#history").html(print_pv(0, display_lines[0].pretty_pv, 1, 'W', 8, true));
 647         } else {
 648                 $("#history").html(
 649                         '(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
 650                         print_pv(0, display_lines[0].pretty_pv, 1, 'W'));
 651         }
 652 }
 653
 654 /**
 655  * @param {!boolean} truncate_history
 656  */
 657 var collapse_history = function(truncate_history) {
 658         truncate_display_history = truncate_history;
 659         update_history();
 660 }
 661 window['collapse_history'] = collapse_history;
 662
 663 /** Update the HTML display of multi-PV from the global "refutation_lines".
 664  *
 665  * Also recreates the global "display_lines".
 666  */
 667 var update_refutation_lines = function() {
 668         if (fen === null) {
 669                 return;
 670         }
 671         if (display_lines.length > 2) {
 672                 // Truncate so that only the history and PV is left.
 673                 display_lines = [ display_lines[0], display_lines[1] ];
 674         }
 675
 676         var tbl = $("#refutationlines");
 677         tbl.empty();
 678
 679         var moves = [];
 680         for (var move in refutation_lines) {
 681                 moves.push(move);
 682         }
 683         var compare = sort_refutation_lines_by_score ? compare_by_score : compare_by_sort_key;
 684         moves = moves.sort(function(a, b) { return compare(refutation_lines, a, b) });
 685         for (var i = 0; i < moves.length; ++i) {
 686                 var line = refutation_lines[moves[i]];
 687
 688                 var tr = document.createElement("tr");
 689
 690                 var move_td = document.createElement("td");
 691                 tr.appendChild(move_td);
 692                 $(move_td).addClass("move");
 693                 if (line['pv_pretty'].length == 0) {
 694                         $(move_td).text(line['pretty_move']);
 695                 } else {
 696                         var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['pretty_move'] + "</a>";
 697                         $(move_td).html(move);
 698                 }
 699
 700                 var score_td = document.createElement("td");
 701                 tr.appendChild(score_td);
 702                 $(score_td).addClass("score");
 703                 $(score_td).text(line['pretty_score']);
 704
 705                 var depth_td = document.createElement("td");
 706                 tr.appendChild(depth_td);
 707                 $(depth_td).addClass("depth");
 708                 $(depth_td).text("d" + line['depth']);
 709
 710                 var pv_td = document.createElement("td");
 711                 tr.appendChild(pv_td);
 712                 $(pv_td).addClass("pv");
 713                 $(pv_td).html(add_pv(fen, line['pv_pretty'], move_num, toplay, 10));
 714
 715                 tbl.append(tr);
 716         }
 717
 718         // Make one of the links clickable and the other nonclickable.
 719         if (sort_refutation_lines_by_score) {
 720                 $("#sortbyscore0").html("<a href=\"javascript:resort_refutation_lines(false)\">Move</a>");
 721                 $("#sortbyscore1").html("<strong>Score</strong>");
 722         } else {
 723                 $("#sortbyscore0").html("<strong>Move</strong>");
 724                 $("#sortbyscore1").html("<a href=\"javascript:resort_refutation_lines(true)\">Score</a>");
 725         }
 726 }
 727
 728 /**
 729  * Create a Chess.js board object, containing the given position plus the given moves,
 730  * up to the given limit.
 731  *
 732  * @param {?string} fen
 733  * @param {Array.<string>} moves
 734  * @param {number} last_move
 735  */
 736 var chess_from = function(fen, moves, last_move) {
 737         var hiddenboard = new Chess();
 738         if (fen !== null) {
 739                 hiddenboard.load(fen);
 740         }
 741         for (var i = 0; i <= last_move; ++i) {
 742                 if (moves[i] === '0-0') {
 743                         hiddenboard.move('O-O');
 744                 } else if (moves[i] === '0-0-0') {
 745                         hiddenboard.move('O-O-O');
 746                 } else {
 747                         hiddenboard.move(moves[i]);
 748                 }
 749         }
 750         return hiddenboard;
 751 }
 752
 753 var update_game_list = function(games) {
 754         $("#games").text("");
 755         if (games === null) {
 756                 return;
 757         }
 758
 759         var games_div = document.getElementById('games');
 760         for (var game_num = 0; game_num < games.length; ++game_num) {
 761                 var game = games[game_num];
 762                 var game_span = document.createElement("span");
 763                 game_span.setAttribute("class", "game");
 764
 765                 var game_name = document.createTextNode(game['name']);
 766                 if (game['url'] === backend_url) {
 767                         game_span.appendChild(game_name);
 768                 } else {
 769                         var game_a = document.createElement("a");
 770                         game_a.setAttribute("href", "#" + game['id']);
 771                         game_a.appendChild(game_name);
 772                         game_span.appendChild(game_a);
 773                 }
 774                 games_div.appendChild(game_span);
 775         }
 776 }
 777
 778 /**
 779  * Try to find a running game that matches with the current hash,
 780  * and switch to it if we're not already displaying it.
 781  */
 782 var possibly_switch_game_from_hash = function() {
 783         if (current_games === null) {
 784                 return;
 785         }
 786
 787         var hash = window.location.hash.replace(/^#/,'');
 788         for (var i = 0; i < current_games.length; ++i) {
 789                 if (current_games[i]['id'] === hash) {
 790                         if (backend_url !== current_games[i]['url']) {
 791                                 switch_backend(current_games[i]['url']);
 792                         }
 793                         return;
 794                 }
 795         }
 796 }
 797
 798 /**
 799  * @param {Object} data
 800  * @param {?Object} display_data
 801  */
 802 var update_board = function(current_data, display_data) {
 803         var data = display_data || current_data;
 804
 805         display_lines = [];
 806
 807         // Print the history. This is pretty much the only thing that's
 808         // unconditionally taken from current_data (we're not interested in
 809         // historic history).
 810         if (current_data['position']['pretty_history']) {
 811                 add_pv('start', current_data['position']['pretty_history'], 1, 'W', 8, true);
 812         } else {
 813                 display_lines.push(null);
 814         }
 815         update_history();
 816
 817         // Games currently in progress, if any.
 818         if (current_data['games']) {
 819                 current_games = current_data['games'];
 820                 possibly_switch_game_from_hash();
 821                 update_game_list(current_data['games']);
 822         } else {
 823                 current_games = null;
 824                 update_game_list(null);
 825         }
 826
 827         // The headline. Names are always fetched from current_data;
 828         // the rest can depend a bit.
 829         var headline;
 830         if (current_data &&
 831             current_data['position']['player_w'] && current_data['position']['player_b']) {
 832                 headline = current_data['position']['player_w'] + '–' +
 833                         current_data['position']['player_b'] + ', analysis';
 834         } else {
 835                 headline = 'Analysis';
 836         }
 837
 838         // Credits, where applicable. Note that we don't want the footer to change a lot
 839         // when e.g. viewing history, so if any of these changed during the game,
 840         // use the current one still.
 841         if (current_data['using_lomonosov']) {
 842                 $("#lomonosov").show();
 843         } else {
 844                 $("#lomonosov").hide();
 845         }
 846
 847         // Credits: The engine name/version.
 848         if (current_data['engine'] && current_data['engine']['name'] !== null) {
 849                 $("#engineid").text(current_data['engine']['name']);
 850         }
 851
 852         // Credits: The engine URL.
 853         if (current_data['engine'] && current_data['engine']['url']) {
 854                 $("#engineid").attr("href", current_data['engine']['url']);
 855         } else {
 856                 $("#engineid").removeAttr("href");
 857         }
 858
 859         // Credits: Engine details.
 860         if (current_data['engine'] && current_data['engine']['details']) {
 861                 $("#enginedetails").text(" (" + current_data['engine']['details'] + ")");
 862         } else {
 863                 $("#enginedetails").text("");
 864         }
 865
 866         // Credits: Move source, possibly with URL.
 867         if (current_data['move_source'] && current_data['move_source_url']) {
 868                 $("#movesource").text("Moves provided by ");
 869                 var movesource_a = document.createElement("a");
 870                 movesource_a.setAttribute("href", current_data['move_source_url']);
 871                 var movesource_text = document.createTextNode(current_data['move_source']);
 872                 movesource_a.appendChild(movesource_text);
 873                 var movesource_period = document.createTextNode(".");
 874                 document.getElementById("movesource").appendChild(movesource_a);
 875                 document.getElementById("movesource").appendChild(movesource_period);
 876         } else if (current_data['move_source']) {
 877                 $("#movesource").text("Moves provided by " + current_data['move_source'] + ".");
 878         } else {
 879                 $("#movesource").text("");
 880         }
 881
 882         var last_move;
 883         if (display_data) {
 884                 // Displaying some non-current position, pick out the last move
 885                 // from the history. This will work even if the fetch failed.
 886                 last_move = format_halfmove_with_number(
 887                         current_display_line.pretty_pv[current_display_move],
 888                         current_display_move + 1);
 889                 headline += ' after ' + last_move;
 890         } else if (data['position']['last_move'] !== 'none') {
 891                 last_move = format_move_with_number(
 892                         data['position']['last_move'],
 893                         data['position']['move_num'],
 894                         data['position']['toplay'] == 'W');
 895                 headline += ' after ' + last_move;
 896         } else {
 897                 last_move = null;
 898         }
 899         $("#headline").text(headline);
 900
 901         // The <title> contains a very brief headline.
 902         var title_elems = [];
 903         if (data['short_score'] !== undefined && data['short_score'] !== null) {
 904                 title_elems.push(data['short_score'].replace(/^ /, ""));
 905         }
 906         if (last_move !== null) {
 907                 title_elems.push(last_move);
 908         }
 909
 910         if (title_elems.length != 0) {
 911                 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
 912         } else {
 913                 document.title = 'analysis.sesse.net';
 914         }
 915
 916         // The last move (shown by highlighting the from and to squares).
 917         if (data['position'] && data['position']['last_move_uci']) {
 918                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
 919                 highlight_to = data['position']['last_move_uci'].substr(2, 2);
 920         } else if (current_display_line_is_history && current_display_move >= 0) {
 921                 // We don't have historic analysis for this position, but we
 922                 // can reconstruct what the last move was by just replaying
 923                 // from the start.
 924                 var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
 925                 var moves = hiddenboard.history({ verbose: true });
 926                 var last_move = moves.pop();
 927                 highlight_from = last_move.from;
 928                 highlight_to = last_move.to;
 929         } else {
 930                 highlight_from = highlight_to = undefined;
 931         }
 932         update_board_highlight();
 933
 934         if (data['failed']) {
 935                 $("#score").text("No analysis for this move");
 936                 $("#pv").empty();
 937                 $("#searchstats").html("&nbsp;");
 938                 $("#refutationlines").empty();
 939                 $("#whiteclock").empty();
 940                 $("#blackclock").empty();
 941                 refutation_lines = [];
 942                 update_refutation_lines();
 943                 clear_arrows();
 944                 update_displayed_line();
 945                 update_move_highlight();
 946                 return;
 947         }
 948
 949         update_clock();
 950
 951         // The score.
 952         if (data['score'] !== null) {
 953                 $("#score").text(data['score']);
 954         }
 955
 956         // The search stats.
 957         if (data['tablebase'] == 1) {
 958                 $("#searchstats").text("Tablebase result");
 959         } else if (data['nodes'] && data['nps'] && data['depth']) {
 960                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
 961                 if (data['seldepth']) {
 962                         stats += ' (' + data['seldepth'] + ' selective)';
 963                 }
 964                 if (data['tbhits'] && data['tbhits'] > 0) {
 965                         if (data['tbhits'] == 1) {
 966                                 stats += ', one Syzygy hit';
 967                         } else {
 968                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
 969                         }
 970                 }
 971
 972                 $("#searchstats").text(stats);
 973         } else {
 974                 $("#searchstats").text("");
 975         }
 976
 977         // Update the board itself.
 978         fen = data['position']['fen'];
 979         update_displayed_line();
 980         update_move_highlight();
 981
 982         // Print the PV.
 983         $("#pv").html(add_pv(data['position']['fen'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
 984
 985         // Update the PV arrow.
 986         clear_arrows();
 987         if (data['pv_uci'].length >= 1) {
 988                 // draw a continuation arrow as long as it's the same piece
 989                 for (var i = 0; i < data['pv_uci'].length; i += 2) {
 990                         var from = data['pv_uci'][i].substr(0, 2);
 991                         var to = data['pv_uci'][i].substr(2,4);
 992                         if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 2)) ||
 993                              interfering_arrow(from, to)) {
 994                                 break;
 995                         }
 996                         create_arrow(from, to, '#f66', 6, 20);
 997                 }
 998
 999                 var alt_moves = find_nonstupid_moves(data, 30);
1000                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
1001                         create_arrow(alt_moves[i].substr(0, 2),
1002                                      alt_moves[i].substr(2, 2), '#f66', 1, 10);
1003                 }
1004         }
1005
1006         // See if all semi-reasonable moves have only one possible response.
1007         if (data['pv_uci'].length >= 2) {
1008                 var nonstupid_moves = find_nonstupid_moves(data, 300);
1009                 var response = data['pv_uci'][1];
1010                 for (var i = 0; i < nonstupid_moves.length; ++i) {
1011                         if (nonstupid_moves[i] == data['pv_uci'][0]) {
1012                                 // ignore the PV move for refutation lines.
1013                                 continue;
1014                         }
1015                         if (!data['refutation_lines'] ||
1016                             !data['refutation_lines'][nonstupid_moves[i]] ||
1017                             !data['refutation_lines'][nonstupid_moves[i]]['pv_uci'] ||
1018                             data['refutation_lines'][nonstupid_moves[i]]['pv_uci'].length < 1) {
1019                                 // Incomplete PV, abort.
1020                                 response = undefined;
1021                                 break;
1022                         }
1023                         var this_response = data['refutation_lines'][nonstupid_moves[i]]['pv_uci'][1];
1024                         if (response !== this_response) {
1025                                 // Different response depending on lines, abort.
1026                                 response = undefined;
1027                                 break;
1028                         }
1029                 }
1030
1031                 if (nonstupid_moves.length > 0 && response !== undefined) {
1032                         create_arrow(response.substr(0, 2),
1033                                      response.substr(2, 2), '#66f', 6, 20);
1034                 }
1035         }
1036
1037         // Update the refutation lines.
1038         fen = data['position']['fen'];
1039         move_num = data['position']['move_num'];
1040         toplay = data['position']['toplay'];
1041         refutation_lines = data['refutation_lines'];
1042         update_refutation_lines();
1043
1044         // Update the sparkline last, since its size depends on how everything else reflowed.
1045         update_sparkline(data);
1046 }
1047
1048 var update_sparkline = function(data) {
1049         if (data && data['score_history']) {
1050                 var first_move_num = undefined;
1051                 for (var halfmove_num in data['score_history']) {
1052                         halfmove_num = parseInt(halfmove_num);
1053                         if (first_move_num === undefined || halfmove_num < first_move_num) {
1054                                 first_move_num = halfmove_num;
1055                         }
1056                 }
1057                 if (first_move_num !== undefined) {
1058                         var last_move_num = data['position']['move_num'] * 2 - 3;
1059                         if (data['position']['toplay'] === 'B') {
1060                                 ++last_move_num;
1061                         }
1062
1063                         // Possibly truncate some moves if we don't have enough width.
1064                         // FIXME: Sometimes width() for #scorecontainer (and by extent,
1065                         // #scoresparkcontainer) on Chrome for mobile seems to start off
1066                         // at something very small, and then suddenly snap back into place.
1067                         // Figure out why.
1068                         var max_moves = Math.floor($("#scoresparkcontainer").width() / 5) - 5;
1069                         if (last_move_num - first_move_num > max_moves) {
1070                                 first_move_num = last_move_num - max_moves;
1071                         }
1072
1073                         var min_score = -100;
1074                         var max_score = 100;
1075                         var last_score = null;
1076                         var scores = [];
1077                         for (var halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
1078                                 if (data['score_history'][halfmove_num]) {
1079                                         var score = data['score_history'][halfmove_num][0];
1080                                         if (score < min_score) min_score = score;
1081                                         if (score > max_score) max_score = score;
1082                                         last_score = data['score_history'][halfmove_num][0];
1083                                 }
1084                                 scores.push(last_score);
1085                         }
1086                         if (data['plot_score']) {
1087                                 scores.push(data['plot_score']);
1088                         }
1089                         // FIXME: at some widths, calling sparkline() seems to push
1090                         // #scorecontainer under the board.
1091                         $("#scorespark").sparkline(scores, {
1092                                 type: 'bar',
1093                                 zeroColor: 'gray',
1094                                 chartRangeMin: min_score,
1095                                 chartRangeMax: max_score,
1096                                 tooltipFormatter: function(sparkline, options, fields) {
1097                                         return format_tooltip(data, fields[0].offset + first_move_num);
1098                                 }
1099                         });
1100                 } else {
1101                         $("#scorespark").text("");
1102                 }
1103         } else {
1104                 $("#scorespark").text("");
1105         }
1106 }
1107
1108 /**
1109  * @param {number} num_viewers
1110  */
1111 var update_num_viewers = function(num_viewers) {
1112         if (num_viewers === null) {
1113                 $("#numviewers").text("");
1114         } else if (num_viewers == 1) {
1115                 $("#numviewers").text("You are the only current viewer");
1116         } else {
1117                 $("#numviewers").text(num_viewers + " current viewers");
1118         }
1119 }
1120
1121 var update_clock = function() {
1122         clearTimeout(clock_timer);
1123
1124         var data = displayed_analysis_data || current_analysis_data;
1125         if (data['position']) {
1126                 var result = data['position']['result'];
1127                 if (result === '1-0') {
1128                         $("#whiteclock").text("1");
1129                         $("#blackclock").text("0");
1130                         $("#whiteclock").removeClass("running-clock");
1131                         $("#blackclock").removeClass("running-clock");
1132                         return;
1133                 }
1134                 if (result === '1/2-1/2') {
1135                         $("#whiteclock").text("1/2");
1136                         $("#blackclock").text("1/2");
1137                         $("#whiteclock").removeClass("running-clock");
1138                         $("#blackclock").removeClass("running-clock");
1139                         return;
1140                 }
1141                 if (result === '0-1') {
1142                         $("#whiteclock").text("0");
1143                         $("#blackclock").text("1");
1144                         $("#whiteclock").removeClass("running-clock");
1145                         $("#blackclock").removeClass("running-clock");
1146                         return;
1147                 }
1148         }
1149
1150         var white_clock_ms = null;
1151         var black_clock_ms = null;
1152         var show_seconds = false;
1153
1154         // Static clocks.
1155         if (data['position'] &&
1156             data['position']['white_clock'] &&
1157             data['position']['black_clock']) {
1158                 white_clock_ms = data['position']['white_clock'] * 1000;
1159                 black_clock_ms = data['position']['black_clock'] * 1000;
1160         }
1161
1162         // Dynamic clock (only one, obviously).
1163         var color;
1164         if (data['position']['white_clock_target']) {
1165                 color = "white";
1166                 $("#whiteclock").addClass("running-clock");
1167                 $("#blackclock").removeClass("running-clock");
1168         } else if (data['position']['black_clock_target']) {
1169                 color = "black";
1170                 $("#whiteclock").removeClass("running-clock");
1171                 $("#blackclock").addClass("running-clock");
1172         } else {
1173                 $("#whiteclock").removeClass("running-clock");
1174                 $("#blackclock").removeClass("running-clock");
1175         }
1176         var remaining_ms;
1177         if (color) {
1178                 var now = new Date().getTime() + client_clock_offset_ms;
1179                 remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
1180                 if (color === "white") {
1181                         white_clock_ms = remaining_ms;
1182                 } else {
1183                         black_clock_ms = remaining_ms;
1184                 }
1185         }
1186
1187         if (white_clock_ms === null || black_clock_ms === null) {
1188                 $("#whiteclock").empty();
1189                 $("#blackclock").empty();
1190                 return;
1191         }
1192
1193         // If either player has ten minutes or less left, add the second counters.
1194         var show_seconds = (white_clock_ms < 60 * 10 * 1000 || black_clock_ms < 60 * 10 * 1000);
1195
1196         if (color) {
1197                 // See when the clock will change next, and update right after that.
1198                 var next_update_ms;
1199                 if (show_seconds) {
1200                         next_update_ms = remaining_ms % 1000 + 100;
1201                 } else {
1202                         next_update_ms = remaining_ms % 60000 + 100;
1203                 }
1204                 clock_timer = setTimeout(update_clock, next_update_ms);
1205         }
1206
1207         $("#whiteclock").text(format_clock(white_clock_ms, show_seconds));
1208         $("#blackclock").text(format_clock(black_clock_ms, show_seconds));
1209 }
1210
1211 /**
1212  * @param {Number} remaining_ms
1213  * @param {boolean} show_seconds
1214  */
1215 var format_clock = function(remaining_ms, show_seconds) {
1216         if (remaining_ms <= 0) {
1217                 if (show_seconds) {
1218                         return "00:00:00";
1219                 } else {
1220                         return "00:00";
1221                 }
1222         }
1223
1224         var remaining = Math.floor(remaining_ms / 1000);
1225         var seconds = remaining % 60;
1226         remaining = (remaining - seconds) / 60;
1227         var minutes = remaining % 60;
1228         remaining = (remaining - minutes) / 60;
1229         var hours = remaining;
1230         if (show_seconds) {
1231                 return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
1232         } else {
1233                 return format_2d(hours) + ":" + format_2d(minutes);
1234         }
1235 }
1236
1237 /**
1238  * @param {Number} x
1239  */
1240 var format_2d = function(x) {
1241         if (x >= 10) {
1242                 return x;
1243         } else {
1244                 return "0" + x;
1245         }
1246 }
1247
1248 /**
1249  * @param {string} move
1250  * @param {Number} move_num
1251  * @param {boolean} white_to_play
1252  */
1253 var format_move_with_number = function(move, move_num, white_to_play) {
1254         var ret;
1255         if (white_to_play) {
1256                 ret = (move_num - 1) + '… ';
1257         } else {
1258                 ret = move_num + '. ';
1259         }
1260         ret += move;
1261         return ret;
1262 }
1263
1264 /**
1265  * @param {string} move
1266  * @param {Number} halfmove_num
1267  */
1268 var format_halfmove_with_number = function(move, halfmove_num) {
1269         return format_move_with_number(
1270                 move,
1271                 Math.floor(halfmove_num / 2) + 1,
1272                 halfmove_num % 2 == 0);
1273 }
1274
1275 /**
1276  * @param {Object} data
1277  * @param {Number} halfmove_num
1278  */
1279 var format_tooltip = function(data, halfmove_num) {
1280         if (data['score_history'][halfmove_num] ||
1281             halfmove_num === data['position']['pretty_history'].length) {
1282                 var move;
1283                 var short_score;
1284                 if (halfmove_num === data['position']['pretty_history'].length) {
1285                         move = data['position']['last_move'];
1286                         short_score = data['short_score'];
1287                 } else {
1288                         move = data['position']['pretty_history'][halfmove_num];
1289                         short_score = data['score_history'][halfmove_num][1];
1290                 }
1291                 var move_with_number = format_halfmove_with_number(move, halfmove_num);
1292
1293                 return "After " + move_with_number + ": " + short_score;
1294         } else {
1295                 for (var i = halfmove_num; i --> 0; ) {
1296                         if (data['score_history'][i]) {
1297                                 var move = data['position']['pretty_history'][i];
1298                                 return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
1299                         }
1300                 }
1301         }
1302 }
1303
1304 /**
1305  * @param {boolean} sort_by_score
1306  */
1307 var resort_refutation_lines = function(sort_by_score) {
1308         sort_refutation_lines_by_score = sort_by_score;
1309         if (supports_html5_storage()) {
1310                 localStorage['sort_refutation_lines_by_score'] = sort_by_score ? 1 : 0;
1311         }
1312         update_refutation_lines();
1313 }
1314 window['resort_refutation_lines'] = resort_refutation_lines;
1315
1316 /**
1317  * @param {boolean} truncate_history
1318  */
1319 var set_truncate_history = function(truncate_history) {
1320         truncate_display_history = truncate_history;
1321         update_refutation_lines();
1322 }
1323 window['set_truncate_history'] = set_truncate_history;
1324
1325 /**
1326  * @param {number} line_num
1327  * @param {number} move_num
1328  */
1329 var show_line = function(line_num, move_num) {
1330         if (line_num == -1) {
1331                 current_display_line = null;
1332                 current_display_move = null;
1333                 if (displayed_analysis_data) {
1334                         // TODO: Support exiting to history position if we are in an
1335                         // analysis line of a history position.
1336                         displayed_analysis_data = null;
1337                         update_board(current_analysis_data, displayed_analysis_data);
1338                 }
1339         } else {
1340                 current_display_line = display_lines[line_num];
1341                 current_display_move = move_num;
1342         }
1343         current_display_line_is_history = (line_num == 0);
1344
1345         update_historic_analysis();
1346         update_displayed_line();
1347         update_board_highlight();
1348         redraw_arrows();
1349 }
1350 window['show_line'] = show_line;
1351
1352 var prev_move = function() {
1353         if (current_display_move > -1) {
1354                 --current_display_move;
1355         }
1356         update_historic_analysis();
1357         update_displayed_line();
1358         update_move_highlight();
1359 }
1360 window['prev_move'] = prev_move;
1361
1362 var next_move = function() {
1363         if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
1364                 ++current_display_move;
1365         }
1366         update_historic_analysis();
1367         update_displayed_line();
1368         update_move_highlight();
1369 }
1370 window['next_move'] = next_move;
1371
1372 var update_historic_analysis = function() {
1373         if (!current_display_line_is_history) {
1374                 return;
1375         }
1376         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1377                 displayed_analysis_data = null;
1378                 update_board(current_analysis_data, displayed_analysis_data);
1379         }
1380
1381         // Fetch old analysis for this line if it exists.
1382         var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
1383         var filename = "/history/move" + (current_display_move + 1) + "-" +
1384                 hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
1385
1386         current_historic_xhr = $.ajax({
1387                 url: filename
1388         }).done(function(data, textstatus, xhr) {
1389                 displayed_analysis_data = data;
1390                 update_board(current_analysis_data, displayed_analysis_data);
1391         }).fail(function(jqXHR, textStatus, errorThrown) {
1392                 if (textStatus === "abort") {
1393                         // Aborted because we are switching backends. Don't do anything;
1394                         // we will already have been cleared.
1395                 } else {
1396                         displayed_analysis_data = {'failed': true};
1397                         update_board(current_analysis_data, displayed_analysis_data);
1398                 }
1399         });
1400 }
1401
1402 /**
1403  * @param {string} fen
1404  */
1405 var update_imbalance = function(fen) {
1406         var hiddenboard = new Chess(fen);
1407         var imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
1408         for (var row = 0; row < 8; ++row) {
1409                 for (var col = 0; col < 8; ++col) {
1410                         var col_text = String.fromCharCode('a1'.charCodeAt(0) + col);
1411                         var row_text = String.fromCharCode('a1'.charCodeAt(1) + row);
1412                         var square = col_text + row_text;
1413                         var contents = hiddenboard.get(square);
1414                         if (contents !== null) {
1415                                 if (contents.color === 'w') {
1416                                         ++imbalance[contents.type];
1417                                 } else {
1418                                         --imbalance[contents.type];
1419                                 }
1420                         }
1421                 }
1422         }
1423         var white_imbalance = '';
1424         var black_imbalance = '';
1425         for (var piece in imbalance) {
1426                 for (var i = 0; i < imbalance[piece]; ++i) {
1427                         white_imbalance += '<img src="img/chesspieces/wikipedia/w' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1428                 }
1429                 for (var i = 0; i < -imbalance[piece]; ++i) {
1430                         black_imbalance += '<img src="img/chesspieces/wikipedia/b' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
1431                 }
1432         }
1433         $('#whiteimbalance').html(white_imbalance);
1434         $('#blackimbalance').html(black_imbalance);
1435 }
1436
1437 /** Mark the currently selected move in red.
1438  */
1439 var update_move_highlight = function() {
1440         if (highlighted_move !== null) {
1441                 highlighted_move.removeClass('highlight');
1442         }
1443         if (current_display_line !== null) {
1444                 highlighted_move = $("#automove" + current_display_line.line_number + "-" + current_display_move);
1445                 highlighted_move.addClass('highlight');
1446         }
1447 }
1448
1449 var update_displayed_line = function() {
1450         if (current_display_line === null) {
1451                 $("#linenav").hide();
1452                 $("#linemsg").show();
1453                 board.position(fen);
1454                 update_imbalance(fen);
1455                 return;
1456         }
1457
1458         $("#linenav").show();
1459         $("#linemsg").hide();
1460
1461         if (current_display_move <= 0) {
1462                 $("#prevmove").html("Previous");
1463         } else {
1464                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
1465         }
1466         if (current_display_move == current_display_line.pretty_pv.length - 1) {
1467                 $("#nextmove").html("Next");
1468         } else {
1469                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
1470         }
1471
1472         var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pretty_pv, current_display_move);
1473         board.position(hiddenboard.fen());
1474         update_imbalance(hiddenboard.fen());
1475 }
1476
1477 /**
1478  * @param {boolean} param_enable_sound
1479  */
1480 var set_sound = function(param_enable_sound) {
1481         enable_sound = param_enable_sound;
1482         if (enable_sound) {
1483                 $("#soundon").html("<strong>On</strong>");
1484                 $("#soundoff").html("<a href=\"javascript:set_sound(false)\">Off</a>");
1485
1486                 // Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
1487                 // and also preload the file since the user has selected audio.
1488                 var ding = document.getElementById('ding');
1489                 if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
1490                         ding.src = 'ding.opus';
1491                         ding.load();
1492                 }
1493         } else {
1494                 $("#soundon").html("<a href=\"javascript:set_sound(true)\">On</a>");
1495                 $("#soundoff").html("<strong>Off</strong>");
1496         }
1497         if (supports_html5_storage()) {
1498                 localStorage['enable_sound'] = enable_sound ? 1 : 0;
1499         }
1500 }
1501 window['set_sound'] = set_sound;
1502
1503 /**
1504  * @param {string} new_backend_url
1505  */
1506 var switch_backend = function(new_backend_url) {
1507         // Stop looking at historic data.
1508         current_display_line = null;
1509         current_display_move = null;
1510         displayed_analysis_data = null;
1511         if (current_historic_xhr) {
1512                 current_historic_xhr.abort();
1513         }
1514
1515         // If we already have a backend response going, abort it.
1516         if (current_analysis_xhr) {
1517                 current_analysis_xhr.abort();
1518         }
1519
1520         // Otherwise, we should have a timer going to start a new one.
1521         // Kill that, too.
1522         if (current_analysis_request_timer) {
1523                 clearTimeout(current_analysis_request_timer);
1524                 current_analysis_request_timer = null;
1525         }
1526
1527         // Request an immediate fetch with the new backend.
1528         backend_url = new_backend_url;
1529         current_analysis_data = null;
1530         ims = 0;
1531         request_update();
1532 }
1533 window['switch_backend'] = switch_backend;
1534
1535 var init = function() {
1536         unique = get_unique();
1537
1538         // Load settings from HTML5 local storage if available.
1539         if (supports_html5_storage() && localStorage['enable_sound']) {
1540                 set_sound(parseInt(localStorage['enable_sound']));
1541         } else {
1542                 set_sound(false);
1543         }
1544         if (supports_html5_storage() && localStorage['sort_refutation_lines_by_score']) {
1545                 sort_refutation_lines_by_score = parseInt(localStorage['sort_refutation_lines_by_score']);
1546         } else {
1547                 sort_refutation_lines_by_score = true;
1548         }
1549
1550         // Create board.
1551         board = new window.ChessBoard('board', 'start');
1552
1553         request_update();
1554         $(window).resize(function() {
1555                 board.resize();
1556                 update_sparkline(displayed_analysis_data || current_analysis_data);
1557                 update_board_highlight();
1558                 redraw_arrows();
1559         });
1560         $(window).keyup(function(event) {
1561                 if (event.which == 39) {
1562                         next_move();
1563                 } else if (event.which == 37) {
1564                         prev_move();
1565                 }
1566         });
1567         window.addEventListener('hashchange', possibly_switch_game_from_hash, false);
1568 };
1569 $(document).ready(init);
1570
1571 })();