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