git.sesse.net Git - remoteglot/blob - www/js/remoteglot.js

   1 (function() {
   2
   3 /** @type {window.ChessBoard} @private */
   4 var board = null;
   5
   6 /** @type {window.ChessBoard} @private */
   7 var hiddenboard = null;
   8
   9 /** @type {Array.<{
  10  *      from_col: number,
  11  *      from_row: number,
  12  *      to_col: number,
  13  *      to_row: number,
  14  *      line_width: number,
  15  *      arrow_size: number,
  16  *      fg_color: string
  17  * }>}
  18  * @private
  19  */
  20 var arrows = [];
  21
  22 /** @type {Array.<Array.<boolean>>} */
  23 var occupied_by_arrows = [];
  24
  25 var refutation_lines = [];
  26
  27 /** @type {!number} @private */
  28 var move_num = 1;
  29
  30 /** @type {!string} @private */
  31 var toplay = 'W';
  32
  33 /** @type {number} @private */
  34 var ims = 0;
  35
  36 /** @type {boolean} @private */
  37 var sort_refutation_lines_by_score = true;
  38
  39 /** @type {boolean} @private */
  40 var truncate_display_history = true;
  41
  42 /** @type {!string|undefined} @private */
  43 var highlight_from = undefined;
  44
  45 /** @type {!string|undefined} @private */
  46 var highlight_to = undefined;
  47
  48 /** @type {!number} @private */
  49 var unique = Math.random();
  50
  51 /** The current position on the board, represented as a FEN string.
  52  * @type {?string}
  53  * @private
  54  */
  55 var fen = null;
  56
  57 /** @typedef {{
  58  *    start_fen: string,
  59  *    uci_pv: Array.<string>,
  60  *    pretty_pv: Array.<string>
  61  * }} DisplayLine
  62  */
  63
  64 /** @type {Array.<DisplayLine>}
  65  * @private
  66  */
  67 var display_lines = [];
  68
  69 /** @type {?DisplayLine} @private */
  70 var current_display_line = null;
  71
  72 /** @type {?number} @private */
  73 var current_display_move = null;
  74
  75 var request_update = function() {
  76         $.ajax({
  77                 url: "http://analysis.sesse.net/analysis.pl?ims=" + ims + "&unique=" + unique
  78                 //url: "http://analysis.sesse.net:5000/analysis.pl?ims=" + ims + "&unique=" + unique
  79         }).done(function(data, textstatus, xhr) {
  80                 ims = xhr.getResponseHeader('X-Remoteglot-Last-Modified');
  81                 var num_viewers = xhr.getResponseHeader('X-Remoteglot-Num-Viewers');
  82                 update_board(data, num_viewers);
  83         }).fail(function() {
  84                 // Wait ten seconds, then try again.
  85                 setTimeout(function() { request_update(); }, 10000);
  86         });
  87 }
  88
  89 var clear_arrows = function() {
  90         for (var i = 0; i < arrows.length; ++i) {
  91                 if (arrows[i].svg) {
  92                         arrows[i].svg.parentElement.removeChild(arrows[i].svg);
  93                         delete arrows[i].svg;
  94                 }
  95         }
  96         arrows = [];
  97
  98         occupied_by_arrows = [];
  99         for (var y = 0; y < 8; ++y) {
 100                 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
 101         }
 102 }
 103
 104 var redraw_arrows = function() {
 105         for (var i = 0; i < arrows.length; ++i) {
 106                 position_arrow(arrows[i]);
 107         }
 108 }
 109
 110 /** @param {!number} x
 111  * @return {!number}
 112  */
 113 var sign = function(x) {
 114         if (x > 0) {
 115                 return 1;
 116         } else if (x < 0) {
 117                 return -1;
 118         } else {
 119                 return 0;
 120         }
 121 }
 122
 123 /** See if drawing this arrow on the board would cause unduly amount of confusion.
 124  * @param {!string} from The square the arrow is from (e.g. e4).
 125  * @param {!string} to The square the arrow is to (e.g. e4).
 126  * @return {boolean}
 127  */
 128 var interfering_arrow = function(from, to) {
 129         var from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
 130         var from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
 131         var to_col   = to.charCodeAt(0) - "a1".charCodeAt(0);
 132         var to_row   = to.charCodeAt(1) - "a1".charCodeAt(1);
 133
 134         occupied_by_arrows[from_row][from_col] = true;
 135
 136         // Knight move: Just check that we haven't been at the destination before.
 137         if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
 138             (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
 139                 return occupied_by_arrows[to_row][to_col];
 140         }
 141
 142         // Sliding piece: Check if anything except the from-square is seen before.
 143         var dx = sign(to_col - from_col);
 144         var dy = sign(to_row - from_row);
 145         var x = from_col;
 146         var y = from_row;
 147         do {
 148                 x += dx;
 149                 y += dy;
 150                 if (occupied_by_arrows[y][x]) {
 151                         return true;
 152                 }
 153                 occupied_by_arrows[y][x] = true;
 154         } while (x != to_col || y != to_row);
 155
 156         return false;
 157 }
 158
 159 /** Find a point along the coordinate system given by the given line,
 160  * <t> units forward from the start of the line, <u> units to the right of it.
 161  * @param {!number} x1
 162  * @param {!number} x2
 163  * @param {!number} y1
 164  * @param {!number} y2
 165  * @param {!number} t
 166  * @param {!number} u
 167  * @return {!string} The point in "x y" form, suitable for SVG paths.
 168  */
 169 var point_from_start = function(x1, y1, x2, y2, t, u) {
 170         var dx = x2 - x1;
 171         var dy = y2 - y1;
 172
 173         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
 174         dx *= norm;
 175         dy *= norm;
 176
 177         var x = x1 + dx * t + dy * u;
 178         var y = y1 + dy * t - dx * u;
 179         return x + " " + y;
 180 }
 181
 182 /** Find a point along the coordinate system given by the given line,
 183  * <t> units forward from the end of the line, <u> units to the right of it.
 184  * @param {!number} x1
 185  * @param {!number} x2
 186  * @param {!number} y1
 187  * @param {!number} y2
 188  * @param {!number} t
 189  * @param {!number} u
 190  * @return {!string} The point in "x y" form, suitable for SVG paths.
 191  */
 192 var point_from_end = function(x1, y1, x2, y2, t, u) {
 193         var dx = x2 - x1;
 194         var dy = y2 - y1;
 195
 196         var norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
 197         dx *= norm;
 198         dy *= norm;
 199
 200         var x = x2 + dx * t + dy * u;
 201         var y = y2 + dy * t - dx * u;
 202         return x + " " + y;
 203 }
 204
 205 var position_arrow = function(arrow) {
 206         if (arrow.svg) {
 207                 arrow.svg.parentElement.removeChild(arrow.svg);
 208                 delete arrow.svg;
 209         }
 210         if (current_display_line !== null) {
 211                 return;
 212         }
 213
 214         var pos = $(".square-a8").position();
 215
 216         var zoom_factor = $("#board").width() / 400.0;
 217         var line_width = arrow.line_width * zoom_factor;
 218         var arrow_size = arrow.arrow_size * zoom_factor;
 219
 220         var square_width = $(".square-a8").width();
 221         var from_y = (7 - arrow.from_row + 0.5)*square_width;
 222         var to_y = (7 - arrow.to_row + 0.5)*square_width;
 223         var from_x = (arrow.from_col + 0.5)*square_width;
 224         var to_x = (arrow.to_col + 0.5)*square_width;
 225
 226         var SVG_NS = "http://www.w3.org/2000/svg";
 227         var XHTML_NS = "http://www.w3.org/1999/xhtml";
 228         var svg = document.createElementNS(SVG_NS, "svg");
 229         svg.setAttribute("width", /** @type{number} */ ($("#board").width()));
 230         svg.setAttribute("height", /** @type{number} */ ($("#board").height()));
 231         svg.setAttribute("style", "position: absolute");
 232         svg.setAttribute("position", "absolute");
 233         svg.setAttribute("version", "1.1");
 234         svg.setAttribute("class", "c1");
 235         svg.setAttribute("xmlns", XHTML_NS);
 236
 237         var x1 = from_x;
 238         var y1 = from_y;
 239         var x2 = to_x;
 240         var y2 = to_y;
 241
 242         // Draw the line.
 243         var outline = document.createElementNS(SVG_NS, "path");
 244         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));
 245         outline.setAttribute("xmlns", XHTML_NS);
 246         outline.setAttribute("stroke", "#666");
 247         outline.setAttribute("stroke-width", line_width + 2);
 248         outline.setAttribute("fill", "none");
 249         svg.appendChild(outline);
 250
 251         var path = document.createElementNS(SVG_NS, "path");
 252         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));
 253         path.setAttribute("xmlns", XHTML_NS);
 254         path.setAttribute("stroke", arrow.fg_color);
 255         path.setAttribute("stroke-width", line_width);
 256         path.setAttribute("fill", "none");
 257         svg.appendChild(path);
 258
 259         // Then the arrow head.
 260         var head = document.createElementNS(SVG_NS, "path");
 261         head.setAttribute("d",
 262                 "M " +  point_from_end(x1, y1, x2, y2, 0, 0) +
 263                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
 264                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
 265                 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
 266                 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
 267         head.setAttribute("xmlns", XHTML_NS);
 268         head.setAttribute("stroke", "#000");
 269         head.setAttribute("stroke-width", "1");
 270         head.setAttribute("fill", arrow.fg_color);
 271         svg.appendChild(head);
 272
 273         $(svg).css({ top: pos.top, left: pos.left });
 274         document.body.appendChild(svg);
 275         arrow.svg = svg;
 276 }
 277
 278 /**
 279  * @param {!string} from_square
 280  * @param {!string} to_square
 281  * @param {!string} fg_color
 282  * @param {number} line_width
 283  * @param {number} arrow_size
 284  */
 285 var create_arrow = function(from_square, to_square, fg_color, line_width, arrow_size) {
 286         var from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
 287         var from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
 288         var to_col   = to_square.charCodeAt(0) - "a1".charCodeAt(0);
 289         var to_row   = to_square.charCodeAt(1) - "a1".charCodeAt(1);
 290
 291         // Create arrow.
 292         var arrow = {
 293                 from_col: from_col,
 294                 from_row: from_row,
 295                 to_col: to_col,
 296                 to_row: to_row,
 297                 line_width: line_width,
 298                 arrow_size: arrow_size,
 299                 fg_color: fg_color
 300         };
 301
 302         position_arrow(arrow);
 303         arrows.push(arrow);
 304 }
 305
 306 var compare_by_sort_key = function(refutation_lines, a, b) {
 307         var ska = refutation_lines[a]['sort_key'];
 308         var skb = refutation_lines[b]['sort_key'];
 309         if (ska < skb) return -1;
 310         if (ska > skb) return 1;
 311         return 0;
 312 };
 313
 314 var compare_by_score = function(refutation_lines, a, b) {
 315         var sa = parseInt(refutation_lines[b]['score_sort_key'], 10);
 316         var sb = parseInt(refutation_lines[a]['score_sort_key'], 10);
 317         return sa - sb;
 318 }
 319
 320 /**
 321  * Fake multi-PV using the refutation lines. Find all “relevant” moves,
 322  * sorted by quality, descending.
 323  *
 324  * @param {!Object} data
 325  * @param {number} margin The maximum number of centipawns worse than the
 326  *     best move can be and still be included.
 327  * @return {Array.<string>} The UCI representation (e.g. e1g1) of all
 328  *     moves, in score order.
 329  */
 330 var find_nonstupid_moves = function(data, margin) {
 331         // First of all, if there are any moves that are more than 0.5 ahead of
 332         // the primary move, the refutation lines are probably bunk, so just
 333         // kill them all.
 334         var best_score = undefined;
 335         var pv_score = undefined;
 336         for (var move in data['refutation_lines']) {
 337                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
 338                 if (move == data['pv_uci'][0]) {
 339                         pv_score = score;
 340                 }
 341                 if (best_score === undefined || score > best_score) {
 342                         best_score = score;
 343                 }
 344                 if (!(data['refutation_lines'][move]['depth'] >= 8)) {
 345                         return [];
 346                 }
 347         }
 348
 349         if (best_score - pv_score > 50) {
 350                 return [];
 351         }
 352
 353         // Now find all moves that are within “margin” of the best score.
 354         // The PV move will always be first.
 355         var moves = [];
 356         for (var move in data['refutation_lines']) {
 357                 var score = parseInt(data['refutation_lines'][move]['score_sort_key'], 10);
 358                 if (move != data['pv_uci'][0] && best_score - score <= margin) {
 359                         moves.push(move);
 360                 }
 361         }
 362         moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], a, b) });
 363         moves.unshift(data['pv_uci'][0]);
 364
 365         return moves;
 366 }
 367
 368 /**
 369  * @param {number} x
 370  * @return {!string}
 371  */
 372 var thousands = function(x) {
 373         return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
 374 }
 375
 376 /**
 377  * @param {!string} fen
 378  * @param {Array.<string>} uci_pv
 379  * @param {Array.<string>} pretty_pv
 380  * @param {number} move_num
 381  * @param {!string} toplay
 382  * @param {number=} opt_limit
 383  * @param {boolean=} opt_showlast
 384  */
 385 var add_pv = function(fen, uci_pv, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 386         display_lines.push({
 387                 start_fen: fen,
 388                 uci_pv: uci_pv,
 389                 pretty_pv: pretty_pv
 390         });
 391         return print_pv(display_lines.length - 1, pretty_pv, move_num, toplay, opt_limit, opt_showlast);
 392 }
 393
 394 /**
 395  * @param {number} line_num
 396  * @param {Array.<string>} pretty_pv
 397  * @param {number} move_num
 398  * @param {!string} toplay
 399  * @param {number=} opt_limit
 400  * @param {boolean=} opt_showlast
 401  */
 402 var print_pv = function(line_num, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 403         var pv = '';
 404         var i = 0;
 405         if (opt_limit && opt_showlast) {
 406                 // Truncate the PV at the beginning (instead of at the end).
 407                 // We assume here that toplay is 'W'. We also assume that if
 408                 // opt_showlast is set, then it is the history, and thus,
 409                 // the UI should be to expand the history.
 410                 pv = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
 411                 i = pretty_pv.length - opt_limit;
 412                 if (i % 2 == 1) {
 413                         ++i;
 414                 }
 415                 move_num += i / 2;
 416         } else if (toplay == 'B') {
 417                 var move = "<a class=\"move\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
 418                 pv = move_num + '. … ' + move;
 419                 toplay = 'W';
 420                 ++i;
 421                 ++move_num;
 422         }
 423         for ( ; i < pretty_pv.length; ++i) {
 424                 var move = "<a class=\"move\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pretty_pv[i] + "</a>";
 425
 426                 if (toplay == 'W') {
 427                         if (i > opt_limit && !opt_showlast) {
 428                                 return pv + ' (…)';
 429                         }
 430                         if (pv != '') {
 431                                 pv += ' ';
 432                         }
 433                         pv += move_num + '. ' + move;
 434                         ++move_num;
 435                         toplay = 'B';
 436                 } else {
 437                         pv += ' ' + move;
 438                         toplay = 'W';
 439                 }
 440         }
 441         return pv;
 442 }
 443
 444 var update_highlight = function() {
 445         $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
 446         if (current_display_line === null && highlight_from !== undefined && highlight_to !== undefined) {
 447                 $("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
 448                 $("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
 449         }
 450 }
 451
 452 var update_history = function() {
 453         if (display_lines[0] === null) {
 454                 $("#history").html("No history");
 455         } else if (truncate_display_history) {
 456                 $("#history").html(print_pv(0, display_lines[0].pretty_pv, 1, 'W', 8, true));
 457         } else {
 458                 $("#history").html(
 459                         '(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
 460                         print_pv(0, display_lines[0].pretty_pv, 1, 'W'));
 461         }
 462 }
 463
 464 /**
 465  * @param {!boolean} truncate_history
 466  */
 467 var collapse_history = function(truncate_history) {
 468         truncate_display_history = truncate_history;
 469         update_history();
 470 }
 471 window['collapse_history'] = collapse_history;
 472
 473 var update_refutation_lines = function() {
 474         if (fen === null) {
 475                 return;
 476         }
 477         if (display_lines.length > 1) {
 478                 display_lines = [ display_lines[0] ];
 479         }
 480
 481         var tbl = $("#refutationlines");
 482         tbl.empty();
 483
 484         var moves = [];
 485         for (var move in refutation_lines) {
 486                 moves.push(move);
 487         }
 488         var compare = sort_refutation_lines_by_score ? compare_by_score : compare_by_sort_key;
 489         moves = moves.sort(function(a, b) { return compare(refutation_lines, a, b) });
 490         for (var i = 0; i < moves.length; ++i) {
 491                 var line = refutation_lines[moves[i]];
 492
 493                 var tr = document.createElement("tr");
 494
 495                 var move_td = document.createElement("td");
 496                 tr.appendChild(move_td);
 497                 $(move_td).addClass("move");
 498                 if (line['pv_uci'].length == 0) {
 499                         $(move_td).text(line['pretty_move']);
 500                 } else {
 501                         var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['pretty_move'] + "</a>";
 502                         $(move_td).html(move);
 503                 }
 504
 505                 var score_td = document.createElement("td");
 506                 tr.appendChild(score_td);
 507                 $(score_td).addClass("score");
 508                 $(score_td).text(line['pretty_score']);
 509
 510                 var depth_td = document.createElement("td");
 511                 tr.appendChild(depth_td);
 512                 $(depth_td).addClass("depth");
 513                 $(depth_td).text("d" + line['depth']);
 514
 515                 var pv_td = document.createElement("td");
 516                 tr.appendChild(pv_td);
 517                 $(pv_td).addClass("pv");
 518                 $(pv_td).html(add_pv(fen, line['pv_uci'], line['pv_pretty'], move_num, toplay, 10));
 519
 520                 tbl.append(tr);
 521         }
 522
 523         // Make one of the links clickable and the other nonclickable.
 524         if (sort_refutation_lines_by_score) {
 525                 $("#sortbyscore0").html("<a href=\"javascript:resort_refutation_lines(false)\">Move</a>");
 526                 $("#sortbyscore1").html("<strong>Score</strong>");
 527         } else {
 528                 $("#sortbyscore0").html("<strong>Move</strong>");
 529                 $("#sortbyscore1").html("<a href=\"javascript:resort_refutation_lines(true)\">Score</a>");
 530         }
 531 }
 532
 533 /**
 534  * @param {Object} data
 535  * @param {number} num_viewers
 536  */
 537 var update_board = function(data, num_viewers) {
 538         display_lines = [];
 539
 540         // The headline.
 541         var headline;
 542         if (data['position']['player_w'] && data['position']['player_b']) {
 543                 headline = data['position']['player_w'] + '–' +
 544                         data['position']['player_b'] + ', analysis';
 545         } else {
 546                 headline = 'Analysis';
 547         }
 548         if (data['position']['last_move'] !== 'none') {
 549                 headline += ' after '
 550                 if (data['position']['toplay'] == 'W') {
 551                         headline += (data['position']['move_num']-1) + '… ';
 552                 } else {
 553                         headline += data['position']['move_num'] + '. ';
 554                 }
 555                 headline += data['position']['last_move'];
 556         }
 557
 558         $("#headline").text(headline);
 559
 560         if (num_viewers === null) {
 561                 $("#numviewers").text("");
 562         } else if (num_viewers == 1) {
 563                 $("#numviewers").text("You are the only current viewer");
 564         } else {
 565                 $("#numviewers").text(num_viewers + " current viewers");
 566         }
 567
 568         // The engine id.
 569         if (data['id'] && data['id']['name'] !== null) {
 570                 $("#engineid").text(data['id']['name']);
 571         }
 572
 573         // The score.
 574         if (data['score'] !== null) {
 575                 $("#score").text(data['score']);
 576         }
 577
 578         // The search stats.
 579         if (data['nodes'] && data['nps'] && data['depth']) {
 580                 var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
 581                 if (data['seldepth']) {
 582                         stats += ' (' + data['seldepth'] + ' selective)';
 583                 }
 584                 if (data['tbhits'] && data['tbhits'] > 0) {
 585                         if (data['tbhits'] == 1) {
 586                                 stats += ', one Syzygy hit';
 587                         } else {
 588                                 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
 589                         }
 590                 }
 591
 592                 $("#searchstats").text(stats);
 593         }
 594
 595         // Update the board itself.
 596         fen = data['position']['fen'];
 597         update_displayed_line();
 598
 599         if (data['position']['last_move_uci']) {
 600                 highlight_from = data['position']['last_move_uci'].substr(0, 2);
 601                 highlight_to = data['position']['last_move_uci'].substr(2, 4);
 602         } else {
 603                 highlight_from = highlight_to = undefined;
 604         }
 605         update_highlight();
 606
 607         // Print the history.
 608         if (data['position']['history']) {
 609                 add_pv('start', data['position']['history'], data['position']['pretty_history'], 1, 'W', 8, true);
 610         } else {
 611                 displayed_lines.push(null);
 612         }
 613         update_history();
 614
 615         // Print the PV.
 616         $("#pv").html(add_pv(data['position']['fen'], data['pv_uci'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
 617
 618         // Update the PV arrow.
 619         clear_arrows();
 620         if (data['pv_uci'].length >= 1) {
 621                 // draw a continuation arrow as long as it's the same piece
 622                 for (var i = 0; i < data['pv_uci'].length; i += 2) {
 623                         var from = data['pv_uci'][i].substr(0, 2);
 624                         var to = data['pv_uci'][i].substr(2,4);
 625                         if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 4)) ||
 626                              interfering_arrow(from, to)) {
 627                                 break;
 628                         }
 629                         create_arrow(from, to, '#f66', 6, 20);
 630                 }
 631
 632                 var alt_moves = find_nonstupid_moves(data, 30);
 633                 for (var i = 1; i < alt_moves.length && i < 3; ++i) {
 634                         create_arrow(alt_moves[i].substr(0, 2),
 635                                      alt_moves[i].substr(2, 4), '#f66', 1, 10);
 636                 }
 637         }
 638
 639         // See if all semi-reasonable moves have only one possible response.
 640         if (data['pv_uci'].length >= 2) {
 641                 var nonstupid_moves = find_nonstupid_moves(data, 300);
 642                 var response = data['pv_uci'][1];
 643                 for (var i = 0; i < nonstupid_moves.length; ++i) {
 644                         if (nonstupid_moves[i] == data['pv_uci'][0]) {
 645                                 // ignore the PV move for refutation lines.
 646                                 continue;
 647                         }
 648                         if (!data['refutation_lines'] ||
 649                             !data['refutation_lines'][nonstupid_moves[i]] ||
 650                             !data['refutation_lines'][nonstupid_moves[i]]['pv_uci'] ||
 651                             data['refutation_lines'][nonstupid_moves[i]]['pv_uci'].length < 1) {
 652                                 // Incomplete PV, abort.
 653                                 response = undefined;
 654                                 break;
 655                         }
 656                         var this_response = data['refutation_lines'][nonstupid_moves[i]]['pv_uci'][1];
 657                         if (response !== this_response) {
 658                                 // Different response depending on lines, abort.
 659                                 response = undefined;
 660                                 break;
 661                         }
 662                 }
 663
 664                 if (nonstupid_moves.length > 0 && response !== undefined) {
 665                         create_arrow(response.substr(0, 2),
 666                                      response.substr(2, 4), '#66f', 6, 20);
 667                 }
 668         }
 669
 670         // Update the refutation lines.
 671         fen = data['position']['fen'];
 672         move_num = data['position']['move_num'];
 673         toplay = data['position']['toplay'];
 674         refutation_lines = data['refutation_lines'];
 675         update_refutation_lines();
 676
 677         // Next update.
 678         setTimeout(function() { request_update(); }, 100);
 679 }
 680
 681 /**
 682  * @param {boolean} sort_by_score
 683  */
 684 var resort_refutation_lines = function(sort_by_score) {
 685         sort_refutation_lines_by_score = sort_by_score;
 686         update_refutation_lines();
 687 }
 688 window['resort_refutation_lines'] = resort_refutation_lines;
 689
 690 /**
 691  * @param {boolean} truncate_history
 692  */
 693 var set_truncate_history = function(truncate_history) {
 694         truncate_display_history = truncate_history;
 695         update_refutation_lines();
 696 }
 697 window['set_truncate_history'] = set_truncate_history;
 698
 699 /**
 700  * @param {number} line_num
 701  * @param {number} move_num
 702  */
 703 var show_line = function(line_num, move_num) {
 704         if (line_num == -1) {
 705                 current_display_line = null;
 706                 current_display_move = null;
 707         } else {
 708                 current_display_line = display_lines[line_num];
 709                 current_display_move = move_num;
 710         }
 711         update_displayed_line();
 712         update_highlight();
 713         redraw_arrows();
 714 }
 715 window['show_line'] = show_line;
 716
 717 var prev_move = function() {
 718         if (current_display_move > -1) {
 719                 --current_display_move;
 720         }
 721         update_displayed_line();
 722 }
 723 window['prev_move'] = prev_move;
 724
 725 var next_move = function() {
 726         if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
 727                 ++current_display_move;
 728         }
 729         update_displayed_line();
 730 }
 731 window['next_move'] = next_move;
 732
 733 var update_displayed_line = function() {
 734         if (current_display_line === null) {
 735                 $("#linenav").hide();
 736                 $("#linemsg").show();
 737                 board.position(fen);
 738                 return;
 739         }
 740
 741         $("#linenav").show();
 742         $("#linemsg").hide();
 743
 744         if (current_display_move == 0) {
 745                 $("#prevmove").html("Previous");
 746         } else {
 747                 $("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
 748         }
 749         if (current_display_move == current_display_line.uci_pv.length - 1) {
 750                 $("#nextmove").html("Next");
 751         } else {
 752                 $("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
 753         }
 754
 755         hiddenboard.position(current_display_line.start_fen, false);
 756         for (var i = 0; i <= current_display_move; ++i) {
 757                 var move = current_display_line.uci_pv[i];
 758                 move = move.substr(0, 2) + "-" + move.substr(2, 4);
 759                 hiddenboard.move(move, false);
 760
 761                 // chessboard.js does not automatically move the rook on castling
 762                 // (issue #51; marked as won't fix), so update it ourselves.
 763                 if (move == "e1-g1" && hiddenboard.position().g1 == "wK") {  // white O-O
 764                         hiddenboard.move("h1-f1", false);
 765                 } else if (move == "e1-c1" && hiddenboard.position().c1 == "wK") {  // white O-O-O
 766                         hiddenboard.move("a1-d1", false);
 767                 } else if (move == "e8-g8" && hiddenboard.position().g8 == "bK") {  // black O-O
 768                         hiddenboard.move("h8-f8", false);
 769                 } else if (move == "e8-c8" && hiddenboard.position().c8 == "bK") {  // black O-O-O
 770                         hiddenboard.move("a8-d8", false);
 771                 }
 772         }
 773         board.position(hiddenboard.position());
 774 }
 775
 776 var init = function() {
 777         // Create board.
 778         board = new window.ChessBoard('board', 'start');
 779         hiddenboard = new window.ChessBoard('hiddenboard', 'start');
 780
 781         request_update();
 782         $(window).resize(function() {
 783                 board.resize();
 784                 update_highlight();
 785                 redraw_arrows();
 786         });
 787         $(window).keyup(function(event) {
 788                 if (event.which == 39) {
 789                         next_move();
 790                 } else if (event.which == 37) {
 791                         prev_move();
 792                 }
 793         });
 794 };
 795 $(document).ready(init);
 796
 797 })();