From 3c09dc498791ac478679bf2f42f441342c4fa22c Mon Sep 17 00:00:00 2001
From: Benjamin Auder <benjamin.auder@somewhere>
Date: Tue, 27 Nov 2018 10:15:28 +0100
Subject: [PATCH] Add a soft timer to avoid spending much more than 5 seconds
 on a move

---
 TODO                                      |  4 +---
 public/javascripts/base_rules.js          | 22 +++++++++++++++++++---
 public/javascripts/components/game.js     |  7 +++++++
 public/javascripts/variants/Grand.js      |  2 ++
 public/javascripts/variants/Wildebeest.js |  2 ++
 5 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/TODO b/TODO
index 372fb25b..23b3412c 100644
--- a/TODO
+++ b/TODO
@@ -1,4 +1,2 @@
 For animation, moves should contains "moving" and "fading" maybe...
-Depth 2 or 3 depending on variant and if we detect smartphone or not?
-(static get SEARCH_DEPTH() { return 2; })
-Sur page d'accueil lien "contact" avec mail + instrus en cas de bug
+(But it's really just for Magnetic chess)
diff --git a/public/javascripts/base_rules.js b/public/javascripts/base_rules.js
index d4315c73..26c74477 100644
--- a/public/javascripts/base_rules.js
+++ b/public/javascripts/base_rules.js
@@ -800,9 +800,14 @@ class ChessRules
 		return VariantRules.INFINITY;
 	}
 
+	static get SEARCH_DEPTH() {
+		return 3; //2 for high branching factor, 4 for small (Loser chess)
+	}
+
 	// Assumption: at least one legal move
 	getComputerMove(moves1) //moves1 might be precomputed (Magnetic chess)
 	{
+		this.shouldReturn = false;
 		const maxeval = VariantRules.INFINITY;
 		const color = this.turn;
 		if (!moves1)
@@ -834,21 +839,32 @@ class ChessRules
 		}
 		moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 
+		let candidates = [0]; //indices of candidates moves
+		for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
+			candidates.push(j);
+		let currentBest = moves1[_.sample(candidates, 1)];
+
 		// Skip depth 3 if we found a checkmate (or if we are checkmated in 1...)
-		if (Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
+		if (VariantRules.SEARCH_DEPTH >= 3
+			&& Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
 		{
 			// TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0])
 			for (let i=0; i<moves1.length; i++)
 			{
+				if (this.shouldReturn)
+					return currentBest; //depth-2, minimum
 				this.play(moves1[i]);
 				// 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
-				moves1[i].eval = 0.1*moves1[i].eval + this.alphabeta(2, -maxeval, maxeval);
+				moves1[i].eval = 0.1*moves1[i].eval +
+					this.alphabeta(VariantRules.SEARCH_DEPTH-1, -maxeval, maxeval);
 				this.undo(moves1[i]);
 			}
 			moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 		}
+		else
+			return currentBest;
 
-		let candidates = [0]; //indices of candidates moves
+		candidates = [0];
 		for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
 			candidates.push(j);
 //		console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
diff --git a/public/javascripts/components/game.js b/public/javascripts/components/game.js
index b0fde5eb..1b216efa 100644
--- a/public/javascripts/components/game.js
+++ b/public/javascripts/components/game.js
@@ -649,6 +649,13 @@ Vue.component('my-game', {
 		},
 		playComputerMove: function() {
 			const timeStart = Date.now();
+			const nbMoves = this.vr.moves.length; //using played moves to know if search finished
+			setTimeout(
+				() => {
+					const L = this.vr.moves.length;
+					if (nbMoves == L || !this.vr.moves[L-1].notation) //move search didn't finish
+						this.vr.shouldReturn = true;
+				}, 5000);
 			const compMove = this.vr.getComputerMove();
 			// (first move) HACK: avoid selecting elements before they appear on page:
 			const delay = Math.max(500-(Date.now()-timeStart), 0);
diff --git a/public/javascripts/variants/Grand.js b/public/javascripts/variants/Grand.js
index faf7f63f..f4e325dc 100644
--- a/public/javascripts/variants/Grand.js
+++ b/public/javascripts/variants/Grand.js
@@ -202,6 +202,8 @@ class GrandRules extends ChessRules
 		);
 	}
 
+	static get SEARCH_DEPTH() { return 2; }
+
 	// TODO: this function could be generalized and shared better
 	static GenRandInitFen()
 	{
diff --git a/public/javascripts/variants/Wildebeest.js b/public/javascripts/variants/Wildebeest.js
index 5f706cf1..330db3fb 100644
--- a/public/javascripts/variants/Wildebeest.js
+++ b/public/javascripts/variants/Wildebeest.js
@@ -155,6 +155,8 @@ class GrandRules extends ChessRules
 		);
 	}
 
+	static get SEARCH_DEPTH() { return 2; }
+
 	// TODO:
 	static GenRandInitFen()
 	{
-- 
2.44.0