X-Git-Url: https://git.sesse.net/?p=remoteglot;a=blobdiff_plain;f=www%2Fjs%2Fremoteglot.js;h=673fd12eacb0e3cf9a2e7b4b5c8b4f330d81a389;hp=e74187307250a5870b7d11a3ed71536796e1c2a1;hb=243c535dd2efc9d8126aa6c153292d8253239dd9;hpb=6404163f499105481e17d5221641523cb15d02f2

diff --git a/www/js/remoteglot.js b/www/js/remoteglot.js
index e741873..673fd12 100644
--- a/www/js/remoteglot.js
+++ b/www/js/remoteglot.js
@@ -1,10 +1,41 @@
 (function() {
 
+/**
+ * Version of this script. If the server returns a version larger than
+ * this, it is a sign we should reload to upgrade ourselves.
+ *
+ * @type {Number}
+ * @const
+ * @private */
+var SCRIPT_VERSION = 2015062104;
+
+/**
+ * The current backend URL.
+ *
+ * @type {!string}
+ * @private
+ */
+var backend_url = "/analysis.pl";
+
 /** @type {window.ChessBoard} @private */
 var board = null;
 
-/** @type {window.ChessBoard} @private */
-var hiddenboard = null;
+/**
+ * The most recent analysis data we have from the server
+ * (about the most recent position).
+ *
+ * @type {?Object}
+ * @private */
+var current_analysis_data = null;
+
+/**
+ * If we are displaying previous analysis, this is non-null,
+ * and will override most of current_analysis_data.
+ *
+ * @type {?Object}
+ * @private
+ */
+var displayed_analysis_data = null;
 
 /** @type {Array.<{
  *      from_col: number,
@@ -34,7 +65,10 @@ var toplay = 'W';
 var ims = 0;
 
 /** @type {boolean} @private */
-var sort_refutation_lines_by_score = false;
+var sort_refutation_lines_by_score = true;
+
+/** @type {boolean} @private */
+var truncate_display_history = true;
 
 /** @type {!string|undefined} @private */
 var highlight_from = undefined;
@@ -42,8 +76,26 @@ var highlight_from = undefined;
 /** @type {!string|undefined} @private */
 var highlight_to = undefined;
 
-/** @type {!number} @private */
-var unique = Math.random();
+/** @type {?jQuery} @private */
+var highlighted_move = null;
+
+/** @type {?number} @private */
+var unique = null;
+
+/** @type {boolean} @private */
+var enable_sound = false;
+
+/**
+ * Our best estimate of how many milliseconds we need to add to 
+ * new Date() to get the true UTC time. Calibrated against the
+ * server clock.
+ *
+ * @type {?number}
+ * @private
+ */
+var client_clock_offset_ms = null;
+
+var clock_timer = null;
 
 /** The current position on the board, represented as a FEN string.
  * @type {?string}
@@ -54,7 +106,8 @@ var fen = null;
 /** @typedef {{
  *    start_fen: string,
  *    uci_pv: Array.<string>,
- *    pretty_pv: Array.<string>
+ *    pretty_pv: Array.<string>,
+ *    line_num: number
  * }} DisplayLine
  */
 
@@ -66,27 +119,142 @@ var display_lines = [];
 /** @type {?DisplayLine} @private */
 var current_display_line = null;
 
+/** @type {boolean} @private */
+var current_display_line_is_history = false;
+
 /** @type {?number} @private */
 var current_display_move = null;
 
+/**
+ * The current backend request to get main analysis (not history), if any,
+ * so that we can abort it.
+ *
+ * @type {?jqXHR}
+ * @private
+ */
+var current_analysis_xhr = null;
+
+/**
+ * The current timer to fire off a request to get main analysis (not history),
+ * if any, so that we can abort it.
+ *
+ * @type {?Number}
+ * @private
+ */
+var current_analysis_request_timer = null;
+
+/**
+ * The current backend request to get historic data, if any.
+ *
+ * @type {?jqXHR}
+ * @private
+ */
+var current_historic_xhr = null;
+
+var supports_html5_storage = function() {
+	try {
+		return 'localStorage' in window && window['localStorage'] !== null;
+	} catch (e) {
+		return false;
+	}
+}
+
+// Make the unique token persistent so people refreshing the page won't count twice.
+// Of course, you can never fully protect against people deliberately wanting to spam.
+var get_unique = function() {
+	var use_local_storage = supports_html5_storage();
+	if (use_local_storage && localStorage['unique']) {
+		return localStorage['unique'];
+	}
+	var unique = Math.random();
+	if (use_local_storage) {
+		localStorage['unique'] = unique;
+	}
+	return unique;
+}
+
 var request_update = function() {
-	$.ajax({
-		url: "http://analysis.sesse.net/analysis.pl?ims=" + ims + "&unique=" + unique
-		//url: "http://analysis.sesse.net:5000/analysis.pl?ims=" + ims + "&unique=" + unique
+	current_analysis_request_timer = null;
+
+	current_analysis_xhr = $.ajax({
+		url: backend_url + "?ims=" + ims + "&unique=" + unique
 	}).done(function(data, textstatus, xhr) {
-		ims = xhr.getResponseHeader('X-Remoteglot-Last-Modified');
-		var num_viewers = xhr.getResponseHeader('X-Remoteglot-Num-Viewers');
-		update_board(data, num_viewers);
-	}).fail(function() {
-		// Wait ten seconds, then try again.
-		setTimeout(function() { request_update(); }, 10000);
+		sync_server_clock(xhr.getResponseHeader('Date'));
+		ims = xhr.getResponseHeader('X-RGLM');
+		var num_viewers = xhr.getResponseHeader('X-RGNV');
+		var new_data;
+		if (Array.isArray(data)) {
+			new_data = JSON.parse(JSON.stringify(current_analysis_data));
+			JSON_delta.patch(new_data, data);
+		} else {
+			new_data = data;
+		}
+
+		var minimum_version = xhr.getResponseHeader('X-RGMV');
+		if (minimum_version && minimum_version > SCRIPT_VERSION) {
+			// Upgrade to latest version with a force-reload.
+			location.reload(true);
+		}
+
+		possibly_play_sound(current_analysis_data, new_data);
+		current_analysis_data = new_data;
+		update_board(current_analysis_data, displayed_analysis_data);
+		update_num_viewers(num_viewers);
+
+		// Next update.
+		current_analysis_request_timer = setTimeout(function() { request_update(); }, 100);
+	}).fail(function(jqXHR, textStatus, errorThrown) {
+		if (textStatus === "abort") {
+			// Aborted because we are switching backends. Abandon and don't retry,
+			// because another one is already started for us.
+		} else {
+			// Backend error or similar. Wait ten seconds, then try again.
+			current_analysis_request_timer = setTimeout(function() { request_update(); }, 10000);
+		}
 	});
 }
 
+var possibly_play_sound = function(old_data, new_data) {
+	if (!enable_sound) {
+		return;
+	}
+	if (old_data === null) {
+		return;
+	}
+	var ding = document.getElementById('ding');
+	if (ding && ding.play) {
+		if (old_data['position'] && old_data['position']['fen'] &&
+		    new_data['position'] && new_data['position']['fen'] &&
+		    (old_data['position']['fen'] !== new_data['position']['fen'] ||
+		     old_data['position']['move_num'] !== new_data['position']['move_num'])) {
+			ding.play();
+		}
+	}
+}
+
+/**
+ * @type {!string} server_date_string
+ */
+var sync_server_clock = function(server_date_string) {
+	var server_time_ms = new Date(server_date_string).getTime();
+	var client_time_ms = new Date().getTime();
+	var estimated_offset_ms = server_time_ms - client_time_ms;
+
+	// In order not to let the noise move us too much back and forth
+	// (the server only has one-second resolution anyway), we only
+	// change an existing skew if we are at least five seconds off.
+	if (client_clock_offset_ms === null ||
+	    Math.abs(estimated_offset_ms - client_clock_offset_ms) > 5000) {
+		client_clock_offset_ms = estimated_offset_ms;
+	}
+}
+
 var clear_arrows = function() {
 	for (var i = 0; i < arrows.length; ++i) {
 		if (arrows[i].svg) {
-			arrows[i].svg.parentElement.removeChild(arrows[i].svg);
+			if (arrows[i].svg.parentElement) {
+				arrows[i].svg.parentElement.removeChild(arrows[i].svg);
+			}
 			delete arrows[i].svg;
 		}
 	}
@@ -201,10 +369,12 @@ var point_from_end = function(x1, y1, x2, y2, t, u) {
 
 var position_arrow = function(arrow) {
 	if (arrow.svg) {
-		arrow.svg.parentElement.removeChild(arrow.svg);
+		if (arrow.svg.parentElement) {
+			arrow.svg.parentElement.removeChild(arrow.svg);
+		}
 		delete arrow.svg;
 	}
-	if (current_display_line !== null) {
+	if (current_display_line !== null && !current_display_line_is_history) {
 		return;
 	}
 
@@ -372,33 +542,55 @@ var thousands = function(x) {
 
 /**
  * @param {!string} fen
- * @param {Array.<string>} uci_pv
  * @param {Array.<string>} pretty_pv
  * @param {number} move_num
  * @param {!string} toplay
  * @param {number=} opt_limit
+ * @param {boolean=} opt_showlast
  */
-var print_pv = function(fen, uci_pv, pretty_pv, move_num, toplay, opt_limit) {
+var add_pv = function(fen, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 	display_lines.push({
 		start_fen: fen,
-		uci_pv: uci_pv,
-		pretty_pv: pretty_pv 
+		pretty_pv: pretty_pv,
+		line_number: display_lines.length
 	});
+	return print_pv(display_lines.length - 1, pretty_pv, move_num, toplay, opt_limit, opt_showlast);
+}
 
+/**
+ * @param {number} line_num
+ * @param {Array.<string>} pretty_pv
+ * @param {number} move_num
+ * @param {!string} toplay
+ * @param {number=} opt_limit
+ * @param {boolean=} opt_showlast
+ */
+var print_pv = function(line_num, pretty_pv, move_num, toplay, opt_limit, opt_showlast) {
 	var pv = '';
 	var i = 0;
-	if (toplay == 'B') {
-		var move = "<a class=\"move\" href=\"javascript:show_line(" + (display_lines.length - 1) + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
+	if (opt_limit && opt_showlast && pretty_pv.length > opt_limit) {
+		// Truncate the PV at the beginning (instead of at the end).
+		// We assume here that toplay is 'W'. We also assume that if
+		// opt_showlast is set, then it is the history, and thus,
+		// the UI should be to expand the history.
+		pv = '(<a class="move" href="javascript:collapse_history(false)">…</a>) ';
+		i = pretty_pv.length - opt_limit;
+		if (i % 2 == 1) {
+			++i;
+		}
+		move_num += i / 2;
+	} else if (toplay == 'B' && pretty_pv.length > 0) {
+		var move = "<a class=\"move\" id=\"automove" + line_num + "-0\" href=\"javascript:show_line(" + line_num + ", " + 0 + ");\">" + pretty_pv[0] + "</a>";
 		pv = move_num + '. … ' + move;
 		toplay = 'W';
 		++i;
 		++move_num;
 	}
 	for ( ; i < pretty_pv.length; ++i) {
-		var move = "<a class=\"move\" href=\"javascript:show_line(" + (display_lines.length - 1) + ", " + i + ");\">" + pretty_pv[i] + "</a>";
+		var move = "<a class=\"move\" id=\"automove" + line_num + "-" + i + "\" href=\"javascript:show_line(" + line_num + ", " + i + ");\">" + pretty_pv[i] + "</a>";
 
 		if (toplay == 'W') {
-			if (i > opt_limit) {
+			if (i > opt_limit && !opt_showlast) {
 				return pv + ' (…)';
 			}
 			if (pv != '') {
@@ -417,18 +609,40 @@ var print_pv = function(fen, uci_pv, pretty_pv, move_num, toplay, opt_limit) {
 
 var update_highlight = function() {
 	$("#board").find('.square-55d63').removeClass('nonuglyhighlight');
-	if (current_display_line === null && highlight_from !== undefined && highlight_to !== undefined) {
+	if ((current_display_line === null || current_display_line_is_history) &&
+	    highlight_from !== undefined && highlight_to !== undefined) {
 		$("#board").find('.square-' + highlight_from).addClass('nonuglyhighlight');
 		$("#board").find('.square-' + highlight_to).addClass('nonuglyhighlight');
 	}
 }
 
+var update_history = function() {
+	if (display_lines[0] === null || display_lines[0].pretty_pv.length == 0) {
+		$("#history").html("No history");
+	} else if (truncate_display_history) {
+		$("#history").html(print_pv(0, display_lines[0].pretty_pv, 1, 'W', 8, true));
+	} else {
+		$("#history").html(
+			'(<a class="move" href="javascript:collapse_history(true)">collapse</a>) ' +
+			print_pv(0, display_lines[0].pretty_pv, 1, 'W'));
+	}
+}
+
+/**
+ * @param {!boolean} truncate_history
+ */
+var collapse_history = function(truncate_history) {
+	truncate_display_history = truncate_history;
+	update_history();
+}
+window['collapse_history'] = collapse_history;
+
 var update_refutation_lines = function() {
 	if (fen === null) {
 		return;
 	}
-	if (display_lines.length > 1) {
-		display_lines = [ display_lines[0] ];
+	if (display_lines.length > 2) {
+		display_lines = [ display_lines[0], display_lines[1] ];
 	}
 
 	var tbl = $("#refutationlines");
@@ -448,7 +662,7 @@ var update_refutation_lines = function() {
 		var move_td = document.createElement("td");
 		tr.appendChild(move_td);
 		$(move_td).addClass("move");
-		if (line['pv_uci'].length == 0) {
+		if (line['pv_pretty'].length == 0) {
 			$(move_td).text(line['pretty_move']);
 		} else {
 			var move = "<a class=\"move\" href=\"javascript:show_line(" + display_lines.length + ", " + 0 + ");\">" + line['pretty_move'] + "</a>";
@@ -468,7 +682,7 @@ var update_refutation_lines = function() {
 		var pv_td = document.createElement("td");
 		tr.appendChild(pv_td);
 		$(pv_td).addClass("pv");
-		$(pv_td).html(print_pv(fen, line['pv_uci'], line['pv_pretty'], move_num, toplay, 10));
+		$(pv_td).html(add_pv(fen, line['pv_pretty'], move_num, toplay, 10));
 
 		tbl.append(tr);
 	}
@@ -483,34 +697,191 @@ var update_refutation_lines = function() {
 	}
 }
 
+/**
+ * @param {?string} fen
+ * @param {Array.<string>} moves
+ * @param {number} last_move
+ */
+var chess_from = function(fen, moves, last_move) {
+	var hiddenboard = new Chess();
+	if (fen !== null) {
+		hiddenboard.load(fen);
+	}
+	for (var i = 0; i <= last_move; ++i) {
+		if (moves[i] === '0-0') {
+			hiddenboard.move('O-O');
+		} else if (moves[i] === '0-0-0') {
+			hiddenboard.move('O-O-O');
+		} else {
+			hiddenboard.move(moves[i]);
+		}
+	}
+	return hiddenboard;
+}
+
 /**
  * @param {Object} data
- * @param {number} num_viewers
+ * @param {?Object} display_data
  */
-var update_board = function(data, num_viewers) {
+var update_board = function(current_data, display_data) {
+	var data = display_data || current_data;
+
 	display_lines = [];
 
-	// The headline.
-	var headline = 'Analysis';
-	if (data['position']['last_move'] !== 'none') {
-		headline += ' after '
-		if (data['position']['toplay'] == 'W') {
-			headline += (data['position']['move_num']-1) + '… ';
-		} else {
-			headline += data['position']['move_num'] + '. ';
+	// Print the history. This is pretty much the only thing that's
+	// unconditionally taken from current_data (we're not interested in
+	// historic history).
+	if (current_data['position']['pretty_history']) {
+		add_pv('start', current_data['position']['pretty_history'], 1, 'W', 8, true);
+	} else {
+		display_lines.push(null);
+	}
+	update_history();
+
+	// Games currently in progress, if any.
+	$("#games").text("");
+	if (current_data['games']) {
+		var games_div = document.getElementById('games');
+		for (var game_num = 0; game_num < current_data['games'].length; ++game_num) {
+			var game = current_data['games'][game_num];
+			var game_span = document.createElement("span");
+			game_span.setAttribute("class", "game");
+
+			var game_name = document.createTextNode(game['name']);
+			if (game['url'] === backend_url) {
+				game_span.appendChild(game_name);
+			} else {
+				var game_a = document.createElement("a");
+				game_a.setAttribute("href", "javascript:switch_backend('" + game['url'] + "')");
+				game_a.appendChild(game_name);
+				game_span.appendChild(game_a);
+			}
+			games_div.appendChild(game_span);
 		}
-		headline += data['position']['last_move'];
 	}
 
+	// The headline. Names are always fetched from current_data;
+	// the rest can depend a bit.
+	var headline;
+	if (current_data &&
+	    current_data['position']['player_w'] && current_data['position']['player_b']) {
+		headline = current_data['position']['player_w'] + '–' +
+			current_data['position']['player_b'] + ', analysis';
+	} else {
+		headline = 'Analysis';
+	}
+
+	// Credits, where applicable. Note that we don't want the footer to change a lot
+	// when e.g. viewing history, so if any of these changed during the game,
+	// use the current one still.
+	if (current_data['using_lomonosov']) {
+		$("#lomonosov").show();
+	} else {
+		$("#lomonosov").hide();
+	}
+
+	// Credits: The engine name/version.
+	if (current_data['engine'] && current_data['engine']['name'] !== null) {
+		$("#engineid").text(current_data['engine']['name']);
+	}
+
+	// Credits: The engine URL.
+	if (current_data['engine'] && current_data['engine']['url']) {
+		$("#engineid").attr("href", current_data['engine']['url']);
+	} else {
+		$("#engineid").removeAttr("href");
+	}
+
+	// Credits: Engine details.
+	if (current_data['engine'] && current_data['engine']['details']) {
+		$("#enginedetails").text(" (" + current_data['engine']['details'] + ")");
+	} else {
+		$("#enginedetails").text("");
+	}
+
+	// Credits: Move source, possibly with URL.
+	if (current_data['move_source'] && current_data['move_source_url']) {
+		$("#movesource").text("Moves provided by ");
+		var movesource_a = document.createElement("a");
+		movesource_a.setAttribute("href", current_data['move_source_url']);
+		var movesource_text = document.createTextNode(current_data['move_source']);
+		movesource_a.appendChild(movesource_text);
+		var movesource_period = document.createTextNode(".");
+		document.getElementById("movesource").appendChild(movesource_a);
+		document.getElementById("movesource").appendChild(movesource_period);
+	} else if (current_data['move_source']) {
+		$("#movesource").text("Moves provided by " + current_data['move_source'] + ".");
+	} else {
+		$("#movesource").text("");
+	}
+
+	var last_move;
+	if (display_data) {
+		// Displaying some non-current position, pick out the last move
+		// from the history. This will work even if the fetch failed.
+		last_move = format_halfmove_with_number(
+			current_display_line.pretty_pv[current_display_move],
+			current_display_move + 1);
+		headline += ' after ' + last_move;
+	} else if (data['position']['last_move'] !== 'none') {
+		last_move = format_move_with_number(
+			data['position']['last_move'],
+			data['position']['move_num'],
+			data['position']['toplay'] == 'W');
+		headline += ' after ' + last_move;
+	} else {
+		last_move = null;
+	}
 	$("#headline").text(headline);
 
-	if (num_viewers === null) {
-		$("#numviewers").text("");
-	} else if (num_viewers == 1) {
-		$("#numviewers").text("You are the only current viewer");
+	// The <title> contains a very brief headline.
+	var title_elems = [];
+	if (data['short_score'] !== undefined && data['short_score'] !== null) {
+		title_elems.push(data['short_score'].replace(/^ /, ""));
+	}
+	if (last_move !== null) {
+		title_elems.push(last_move);
+	}
+
+	if (title_elems.length != 0) {
+		document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
 	} else {
-		$("#numviewers").text(num_viewers + " current viewers");
+		document.title = 'analysis.sesse.net';
+	}
+
+	// The last move (shown by highlighting the from and to squares).
+	if (data['position'] && data['position']['last_move_uci']) {
+		highlight_from = data['position']['last_move_uci'].substr(0, 2);
+		highlight_to = data['position']['last_move_uci'].substr(2, 2);
+	} else if (current_display_line_is_history && current_display_move >= 0) {
+		// We don't have historic analysis for this position, but we
+		// can reconstruct what the last move was by just replaying
+		// from the start.
+		var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
+		var moves = hiddenboard.history({ verbose: true });
+		var last_move = moves.pop();
+		highlight_from = last_move.from;
+		highlight_to = last_move.to;
+	} else {
+		highlight_from = highlight_to = undefined;
 	}
+	update_highlight();
+
+	if (data['failed']) {
+		$("#score").text("No analysis for this move");
+		$("#pv").empty();
+		$("#searchstats").html("&nbsp;");
+		$("#refutationlines").empty();
+		$("#whiteclock").empty();
+		$("#blackclock").empty();
+		refutation_lines = [];
+		update_refutation_lines();
+		clear_arrows();
+		update_displayed_line();
+		return;
+	}
+
+	update_clock();
 
 	// The score.
 	if (data['score'] !== null) {
@@ -518,7 +889,9 @@ var update_board = function(data, num_viewers) {
 	}
 
 	// The search stats.
-	if (data['nodes'] && data['nps'] && data['depth']) {
+	if (data['tablebase'] == 1) {
+		$("#searchstats").text("Tablebase result");
+	} else if (data['nodes'] && data['nps'] && data['depth']) {
 		var stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
 		if (data['seldepth']) {
 			stats += ' (' + data['seldepth'] + ' selective)';
@@ -532,22 +905,16 @@ var update_board = function(data, num_viewers) {
 		}
 
 		$("#searchstats").text(stats);
+	} else {
+		$("#searchstats").text("");
 	}
 
 	// Update the board itself.
 	fen = data['position']['fen'];
 	update_displayed_line();
 
-	if (data['position']['last_move_uci']) {
-		highlight_from = data['position']['last_move_uci'].substr(0, 2);
-		highlight_to = data['position']['last_move_uci'].substr(2, 4);
-	} else {
-		highlight_from = highlight_to = undefined;
-	}
-	update_highlight();
-
 	// Print the PV.
-	$("#pv").html(print_pv(data['position']['fen'], data['pv_uci'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
+	$("#pv").html(add_pv(data['position']['fen'], data['pv_pretty'], data['position']['move_num'], data['position']['toplay']));
 
 	// Update the PV arrow.
 	clear_arrows();
@@ -556,7 +923,7 @@ var update_board = function(data, num_viewers) {
 		for (var i = 0; i < data['pv_uci'].length; i += 2) {
 			var from = data['pv_uci'][i].substr(0, 2);
 			var to = data['pv_uci'][i].substr(2,4);
-			if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 4)) ||
+			if ((i >= 2 && from != data['pv_uci'][i - 2].substr(2, 2)) ||
 			     interfering_arrow(from, to)) {
 				break;
 			}
@@ -566,7 +933,7 @@ var update_board = function(data, num_viewers) {
 		var alt_moves = find_nonstupid_moves(data, 30);
 		for (var i = 1; i < alt_moves.length && i < 3; ++i) {
 			create_arrow(alt_moves[i].substr(0, 2),
-				     alt_moves[i].substr(2, 4), '#f66', 1, 10);
+				     alt_moves[i].substr(2, 2), '#f66', 1, 10);
 		}
 	}
 
@@ -597,7 +964,7 @@ var update_board = function(data, num_viewers) {
 
 		if (nonstupid_moves.length > 0 && response !== undefined) {
 			create_arrow(response.substr(0, 2),
-				     response.substr(2, 4), '#66f', 6, 20);
+				     response.substr(2, 2), '#66f', 6, 20);
 		}
 	}
 
@@ -608,8 +975,264 @@ var update_board = function(data, num_viewers) {
 	refutation_lines = data['refutation_lines'];
 	update_refutation_lines();
 
-	// Next update.
-	setTimeout(function() { request_update(); }, 100);
+	// Update the sparkline last, since its size depends on how everything else reflowed.
+	update_sparkline(data);
+}
+
+var update_sparkline = function(data) {
+	if (data && data['score_history']) {
+		var first_move_num = undefined;
+		for (var halfmove_num in data['score_history']) {
+			halfmove_num = parseInt(halfmove_num);
+			if (first_move_num === undefined || halfmove_num < first_move_num) {
+				first_move_num = halfmove_num;
+			}
+		}
+		if (first_move_num !== undefined) {
+			var last_move_num = data['position']['move_num'] * 2 - 3;
+			if (data['position']['toplay'] === 'B') {
+				++last_move_num;
+			}
+
+			// Possibly truncate some moves if we don't have enough width.
+			// FIXME: Sometimes width() for #scorecontainer (and by extent,
+			// #scoresparkcontainer) on Chrome for mobile seems to start off
+			// at something very small, and then suddenly snap back into place.
+			// Figure out why.
+			var max_moves = Math.floor($("#scoresparkcontainer").width() / 5) - 5;
+			if (last_move_num - first_move_num > max_moves) {
+				first_move_num = last_move_num - max_moves;
+			}
+
+			var min_score = -100;
+			var max_score = 100;
+			var last_score = null;
+			var scores = [];
+			for (var halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
+				if (data['score_history'][halfmove_num]) {
+					var score = data['score_history'][halfmove_num][0];
+					if (score < min_score) min_score = score;
+					if (score > max_score) max_score = score;
+					last_score = data['score_history'][halfmove_num][0];
+				}
+				scores.push(last_score);
+			}
+			if (data['plot_score']) {
+				scores.push(data['plot_score']);
+			}
+			// FIXME: at some widths, calling sparkline() seems to push
+			// #scorecontainer under the board.
+			$("#scorespark").sparkline(scores, {
+				type: 'bar',
+				zeroColor: 'gray',
+				chartRangeMin: min_score,
+				chartRangeMax: max_score,
+				tooltipFormatter: function(sparkline, options, fields) {
+					return format_tooltip(data, fields[0].offset + first_move_num);
+				}
+			});
+		} else {
+			$("#scorespark").text("");
+		}
+	} else {
+		$("#scorespark").text("");
+	}
+}
+
+/**
+ * @param {number} num_viewers
+ */
+var update_num_viewers = function(num_viewers) {
+	if (num_viewers === null) {
+		$("#numviewers").text("");
+	} else if (num_viewers == 1) {
+		$("#numviewers").text("You are the only current viewer");
+	} else {
+		$("#numviewers").text(num_viewers + " current viewers");
+	}
+}
+
+var update_clock = function() {
+	clearTimeout(clock_timer);
+
+	var data = displayed_analysis_data || current_analysis_data;
+	if (data['position']) {
+		var result = data['position']['result'];
+		if (result === '1-0') {
+			$("#whiteclock").text("1");
+			$("#blackclock").text("0");
+			$("#whiteclock").removeClass("running-clock");
+			$("#blackclock").removeClass("running-clock");
+			return;
+		}
+		if (result === '1/2-1/2') {
+			$("#whiteclock").text("1/2");
+			$("#blackclock").text("1/2");
+			$("#whiteclock").removeClass("running-clock");
+			$("#blackclock").removeClass("running-clock");
+			return;
+		}	
+		if (result === '0-1') {
+			$("#whiteclock").text("0");
+			$("#blackclock").text("1");
+			$("#whiteclock").removeClass("running-clock");
+			$("#blackclock").removeClass("running-clock");
+			return;
+		}
+	}
+
+	var white_clock_ms = null;
+	var black_clock_ms = null;
+	var show_seconds = false;
+
+	// Static clocks.
+	if (data['position'] &&
+	    data['position']['white_clock'] &&
+	    data['position']['black_clock']) {
+		white_clock_ms = data['position']['white_clock'] * 1000;
+		black_clock_ms = data['position']['black_clock'] * 1000;
+	}
+
+	// Dynamic clock (only one, obviously).
+	var color;
+	if (data['position']['white_clock_target']) {
+		color = "white";
+		$("#whiteclock").addClass("running-clock");
+		$("#blackclock").removeClass("running-clock");
+	} else if (data['position']['black_clock_target']) {
+		color = "black";
+		$("#whiteclock").removeClass("running-clock");
+		$("#blackclock").addClass("running-clock");
+	} else {
+		$("#whiteclock").removeClass("running-clock");
+		$("#blackclock").removeClass("running-clock");
+	}
+	var remaining_ms;
+	if (color) {
+		var now = new Date().getTime() + client_clock_offset_ms;
+		remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
+		if (color === "white") {
+			white_clock_ms = remaining_ms;
+		} else {
+			black_clock_ms = remaining_ms;
+		}
+	}
+
+	if (white_clock_ms === null || black_clock_ms === null) {
+		$("#whiteclock").empty();
+		$("#blackclock").empty();
+		return;
+	}
+
+	// If either player has ten minutes or less left, add the second counters.
+	var show_seconds = (white_clock_ms < 60 * 10 * 1000 || black_clock_ms < 60 * 10 * 1000);
+
+	if (color) {
+		// See when the clock will change next, and update right after that.
+		var next_update_ms;
+		if (show_seconds) {
+			next_update_ms = remaining_ms % 1000 + 100;
+		} else {
+			next_update_ms = remaining_ms % 60000 + 100;
+		}
+		clock_timer = setTimeout(update_clock, next_update_ms);
+	}
+
+	$("#whiteclock").text(format_clock(white_clock_ms, show_seconds));
+	$("#blackclock").text(format_clock(black_clock_ms, show_seconds));
+}
+
+/**
+ * @param {Number} remaining_ms
+ * @param {boolean} show_seconds
+ */
+var format_clock = function(remaining_ms, show_seconds) {
+	if (remaining_ms <= 0) {
+		if (show_seconds) {
+			return "00:00:00";
+		} else {
+			return "00:00";
+		}
+	}
+
+	var remaining = Math.floor(remaining_ms / 1000);
+	var seconds = remaining % 60;
+	remaining = (remaining - seconds) / 60;
+	var minutes = remaining % 60;
+	remaining = (remaining - minutes) / 60;
+	var hours = remaining;
+	if (show_seconds) {
+		return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
+	} else {
+		return format_2d(hours) + ":" + format_2d(minutes);
+	}
+}
+
+/**
+ * @param {Number} x
+ */
+var format_2d = function(x) {
+	if (x >= 10) {
+		return x;
+	} else {
+		return "0" + x;
+	}
+}
+
+/**
+ * @param {string} move
+ * @param {Number} move_num
+ * @param {boolean} white_to_play
+ */
+var format_move_with_number = function(move, move_num, white_to_play) {
+	var ret;
+	if (white_to_play) {
+		ret = (move_num - 1) + '… ';
+	} else {
+		ret = move_num + '. ';
+	}
+	ret += move;
+	return ret;
+}
+
+/**
+ * @param {string} move
+ * @param {Number} halfmove_num
+ */
+var format_halfmove_with_number = function(move, halfmove_num) {
+	return format_move_with_number(
+		move,
+		Math.floor(halfmove_num / 2) + 1,
+		halfmove_num % 2 == 0);
+}
+
+/**
+ * @param {Object} data
+ * @param {Number} halfmove_num
+ */
+var format_tooltip = function(data, halfmove_num) {
+	if (data['score_history'][halfmove_num] ||
+	    halfmove_num === data['position']['pretty_history'].length) {
+		var move;
+		var short_score;
+		if (halfmove_num === data['position']['pretty_history'].length) {
+			move = data['position']['last_move'];
+			short_score = data['short_score'];
+		} else {
+			move = data['position']['pretty_history'][halfmove_num];
+			short_score = data['score_history'][halfmove_num][1];
+		}
+		var move_with_number = format_halfmove_with_number(move, halfmove_num);
+
+		return "After " + move_with_number + ": " + short_score;
+	} else {
+		for (var i = halfmove_num; i --> 0; ) {
+			if (data['score_history'][i]) {
+				var move = data['position']['pretty_history'][i];
+				return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
+			}
+		}
+	}
 }
 
 /**
@@ -617,10 +1240,22 @@ var update_board = function(data, num_viewers) {
  */
 var resort_refutation_lines = function(sort_by_score) {
 	sort_refutation_lines_by_score = sort_by_score;
+	if (supports_html5_storage()) {
+		localStorage['sort_refutation_lines_by_score'] = sort_by_score ? 1 : 0;
+	}
 	update_refutation_lines();
 }
 window['resort_refutation_lines'] = resort_refutation_lines;
 
+/**
+ * @param {boolean} truncate_history
+ */
+var set_truncate_history = function(truncate_history) {
+	truncate_display_history = truncate_history;
+	update_refutation_lines();
+}
+window['set_truncate_history'] = set_truncate_history;
+
 /**
  * @param {number} line_num
  * @param {number} move_num
@@ -629,10 +1264,19 @@ var show_line = function(line_num, move_num) {
 	if (line_num == -1) {
 		current_display_line = null;
 		current_display_move = null;
+		if (displayed_analysis_data) {
+			// TODO: Support exiting to history position if we are in an
+			// analysis line of a history position.
+			displayed_analysis_data = null;
+			update_board(current_analysis_data, displayed_analysis_data);
+		}
 	} else {
 		current_display_line = display_lines[line_num];
 		current_display_move = move_num;
 	}
+	current_display_line_is_history = (line_num == 0);
+
+	update_historic_analysis();
 	update_displayed_line();
 	update_highlight();
 	redraw_arrows();
@@ -640,59 +1284,212 @@ var show_line = function(line_num, move_num) {
 window['show_line'] = show_line;
 
 var prev_move = function() {
-	--current_display_move;
+	if (current_display_move > -1) {
+		--current_display_move;
+	}
+	update_historic_analysis();
 	update_displayed_line();
 }
 window['prev_move'] = prev_move;
 
 var next_move = function() {
-	++current_display_move;
+	if (current_display_line && current_display_move < current_display_line.pretty_pv.length - 1) {
+		++current_display_move;
+	}
+	update_historic_analysis();
 	update_displayed_line();
 }
 window['next_move'] = next_move;
 
+var update_historic_analysis = function() {
+	if (!current_display_line_is_history) {
+		return;
+	}
+	if (current_display_move == current_display_line.pretty_pv.length - 1) {
+		displayed_analysis_data = null;
+		update_board(current_analysis_data, displayed_analysis_data);
+	}
+
+	// Fetch old analysis for this line if it exists.
+	var hiddenboard = chess_from(null, current_display_line.pretty_pv, current_display_move);
+	var filename = "/history/move" + (current_display_move + 1) + "-" +
+		hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
+
+	current_historic_xhr = $.ajax({
+		url: filename
+	}).done(function(data, textstatus, xhr) {
+		displayed_analysis_data = data;
+		update_board(current_analysis_data, displayed_analysis_data);
+	}).fail(function(jqXHR, textStatus, errorThrown) {
+		if (textStatus === "abort") {
+			// Aborted because we are switching backends. Don't do anything;
+			// we will already have been cleared.
+		} else {
+			displayed_analysis_data = {'failed': true};
+			update_board(current_analysis_data, displayed_analysis_data);
+		}
+	});
+}
+
+/**
+ * @param {string} fen
+ */
+var update_imbalance = function(fen) {
+	var hiddenboard = new Chess(fen);
+	var imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
+	for (var row = 0; row < 8; ++row) {
+		for (var col = 0; col < 8; ++col) {
+			var col_text = String.fromCharCode('a1'.charCodeAt(0) + col);
+			var row_text = String.fromCharCode('a1'.charCodeAt(1) + row);
+			var square = col_text + row_text;
+			var contents = hiddenboard.get(square);
+			if (contents !== null) {
+				if (contents.color === 'w') {
+					++imbalance[contents.type];
+				} else {
+					--imbalance[contents.type];
+				}
+			}
+		}
+	}
+	var white_imbalance = '';
+	var black_imbalance = '';
+	for (var piece in imbalance) {
+		for (var i = 0; i < imbalance[piece]; ++i) {
+			white_imbalance += '<img src="img/chesspieces/wikipedia/w' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
+		}
+		for (var i = 0; i < -imbalance[piece]; ++i) {
+			black_imbalance += '<img src="img/chesspieces/wikipedia/b' + piece.toUpperCase() + '.png" alt="" style="width: 15px;height: 15px;">';
+		}
+	}
+	$('#whiteimbalance').html(white_imbalance);
+	$('#blackimbalance').html(black_imbalance);
+}
+
 var update_displayed_line = function() {
+	if (highlighted_move !== null) {
+		highlighted_move.removeClass('highlight'); 
+	}
 	if (current_display_line === null) {
 		$("#linenav").hide();
 		$("#linemsg").show();
 		board.position(fen);
+		update_imbalance(fen);
 		return;
 	}
 
 	$("#linenav").show();
 	$("#linemsg").hide();
 
-	if (current_display_move == 0) {
+	if (current_display_move <= 0) {
 		$("#prevmove").html("Previous");
 	} else {
 		$("#prevmove").html("<a href=\"javascript:prev_move();\">Previous</a></span>");
 	}
-	if (current_display_move == current_display_line.uci_pv.length - 1) {
+	if (current_display_move == current_display_line.pretty_pv.length - 1) {
 		$("#nextmove").html("Next");
 	} else {
 		$("#nextmove").html("<a href=\"javascript:next_move();\">Next</a></span>");
 	}
 
-	hiddenboard.position(current_display_line.start_fen, false);
-	for (var i = 0; i <= current_display_move; ++i) {
-		var move = current_display_line.uci_pv[i];
-		move = move.substr(0, 2) + "-" + move.substr(2, 4);
-		hiddenboard.move(move, false);
+	highlighted_move = $("#automove" + current_display_line.line_number + "-" + current_display_move);
+	highlighted_move.addClass('highlight'); 
+
+	var hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pretty_pv, current_display_move);
+	board.position(hiddenboard.fen());
+	update_imbalance(hiddenboard.fen());
+}
+
+/**
+ * @param {boolean} param_enable_sound
+ */
+var set_sound = function(param_enable_sound) {
+	enable_sound = param_enable_sound;
+	if (enable_sound) {
+		$("#soundon").html("<strong>On</strong>");
+		$("#soundoff").html("<a href=\"javascript:set_sound(false)\">Off</a>");
+
+		// Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
+		// and also preload the file since the user has selected audio.
+		var ding = document.getElementById('ding');
+		if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
+			ding.src = 'ding.opus';
+			ding.load();
+		}
+	} else {
+		$("#soundon").html("<a href=\"javascript:set_sound(true)\">On</a>");
+		$("#soundoff").html("<strong>Off</strong>");
+	}
+	if (supports_html5_storage()) {
+		localStorage['enable_sound'] = enable_sound ? 1 : 0;
 	}
-	board.position(hiddenboard.position());
 }
+window['set_sound'] = set_sound;
+
+/**
+ * @param {string} new_backend_url
+ */
+var switch_backend = function(new_backend_url) {
+	// Stop looking at historic data.
+	current_display_line = null;
+	current_display_move = null;
+	displayed_analysis_data = null;
+	if (current_historic_xhr) {
+		current_historic_xhr.abort();
+	}
+
+	// If we already have a backend response going, abort it.
+	if (current_analysis_xhr) {
+		current_analysis_xhr.abort();
+	}
+
+	// Otherwise, we should have a timer going to start a new one.
+	// Kill that, too.
+	if (current_analysis_request_timer) {
+		clearTimeout(current_analysis_request_timer);
+		current_analysis_request_timer = null;
+	}
+
+	// Request an immediate fetch with the new backend.
+	backend_url = new_backend_url;
+	current_analysis_data = null;
+	ims = 0;
+	request_update();
+}
+window['switch_backend'] = switch_backend;
 
 var init = function() {
+	unique = get_unique();
+
+	// Load settings from HTML5 local storage if available.
+	if (supports_html5_storage() && localStorage['enable_sound']) {
+		set_sound(parseInt(localStorage['enable_sound']));
+	} else {
+		set_sound(false);
+	}
+	if (supports_html5_storage() && localStorage['sort_refutation_lines_by_score']) {
+		sort_refutation_lines_by_score = parseInt(localStorage['sort_refutation_lines_by_score']);
+	} else {
+		sort_refutation_lines_by_score = true;
+	}
+
 	// Create board.
 	board = new window.ChessBoard('board', 'start');
-	hiddenboard = new window.ChessBoard('hiddenboard', 'start');
 
 	request_update();
 	$(window).resize(function() {
 		board.resize();
+		update_sparkline(displayed_analysis_data || current_analysis_data);
 		update_highlight();
 		redraw_arrows();
 	});
+	$(window).keyup(function(event) {
+		if (event.which == 39) {
+			next_move();
+		} else if (event.which == 37) {
+			prev_move();
+		}
+	});
 };
 $(document).ready(init);