From b6effd41313938e70b383f9d6fa61ff53806cf56 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Fri, 3 Jun 2016 21:40:54 +0200
Subject: [PATCH] Allow switching computer moves with j/k.

---
 www/js/book.js | 47 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/www/js/book.js b/www/js/book.js
index e4c3ce1..aacd980 100644
--- a/www/js/book.js
+++ b/www/js/book.js
@@ -158,12 +158,15 @@ var find_last_move_score = function() {
 	});
 }
 
+var candidate_moves = [];
+var chosen_index = null;
+
 var find_computer_move = function() {
 	var fen = current_display_fen();
 	$.ajax({
 		url: "/opening-stats.pl?fen=" + encodeURIComponent(fen) + ";includetransp=0"
 	}).done(function(data, textstatus, xhr) {
-		var candidate_moves = [];
+		candidate_moves = [];
 
 		var moves = data['moves'];
 		var root_move = sort_move_by_frequency(moves, data);
@@ -185,19 +188,37 @@ var find_computer_move = function() {
 		}
 
 		// Pick one at random.
-		var chosen_index = Math.floor(Math.random() * candidate_moves.length);
-		var chosen = candidate_moves[chosen_index];
-		$("#compmove").text(chosen['move']);
-		$("#compfraction").text((100.0 * chosen['fraction']).toFixed(1) + "%");
-		if (candidate_moves.length == 1) {
-			$("#comprank").text("only candidate move");
-		} else {
-			$("#comprank").text(format_ordinal(chosen_index + 1) + " out of " + candidate_moves.length + " candidate moves");
-		}
-		make_move(chosen['move']);
+		choose_move(Math.floor(Math.random() * candidate_moves.length));
 	});
 }
 
+var choose_move = function(idx) {
+	chosen_index = idx;
+	var chosen = candidate_moves[chosen_index];
+	$("#compmove").text(chosen['move']);
+	$("#compfraction").text((100.0 * chosen['fraction']).toFixed(1) + "%");
+	if (candidate_moves.length == 1) {
+		$("#comprank").text("only candidate move");
+	} else {
+		$("#comprank").text(format_ordinal(chosen_index + 1) + " out of " + candidate_moves.length + " candidate moves, j/k to switch");
+	}
+	make_move(chosen['move']);
+}
+
+var prev_variant = function() {
+	if (chosen_index !== null) {
+		--move_override;
+		choose_move((chosen_index + candidate_moves.length - 1) % candidate_moves.length);
+	}
+}
+
+var next_variant = function() {
+	if (chosen_index !== null) {
+		--move_override;
+		choose_move((chosen_index + 1) % candidate_moves.length);
+	}
+}
+
 // Add deried data and then sort moves to get the most common ones (in-place).
 // Remove the root mode and return it. Currently usable for practice mode only!
 var sort_move_by_frequency = function(moves, data)
@@ -734,6 +755,10 @@ var init = function() {
 			next_move();
 		} else if (event.which == 37) {
 			prev_move();
+		} else if (event.which == 74) {  // j
+			if (practice_mode) next_variant();
+		} else if (event.which == 75) {  // k
+			if (practice_mode) prev_variant();
 		}
 	});
 
-- 
2.39.2