From 88074f53274be62db16bad9666150ecdfdb4553d Mon Sep 17 00:00:00 2001
From: Peter Osterlund <peterosterlund2@gmail.com>
Date: Wed, 6 Jan 2016 22:04:11 +0100
Subject: [PATCH] DroidFish: Let the human player claim a draw that involves
 specifying but not playing a move that would lead to a 50move/3rep draw.

---
 .../gamelogic/DroidChessController.java       | 54 ++++++++++++-------
 .../org/petero/droidfish/gamelogic/Game.java  | 17 ++++--
 2 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
index 1a3231d..3e7a475 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
@@ -305,23 +305,37 @@ public class DroidChessController {
 
     /** Make a move for a human player. */
     public final synchronized void makeHumanMove(Move m) {
-        if (humansTurn()) {
-            Position oldPos = new Position(game.currPos());
-            if (doMove(m)) {
-                if (m.equals(ponderMove) && !gameMode.analysisMode() &&
-                    (computerPlayer.getSearchType() == SearchType.PONDER)) {
-                    computerPlayer.ponderHit(searchId);
-                    ponderMove = null;
-                } else {
-                    abortSearch();
-                    updateComputeThreads();
+        if (!humansTurn())
+            return;
+        Position oldPos = new Position(game.currPos());
+        if (game.pendingDrawOffer) {
+            ArrayList<Move> moves = new MoveGen().legalMoves(oldPos);
+            for (Move m2 : moves) {
+                if (m2.equals(m)) {
+                    if (findValidDrawClaim(TextIO.moveToUCIString(m))) {
+                        stopPonder();
+                        updateGUI();
+                        gui.setSelection(-1);
+                        return;
+                    }
+                    break;
                 }
-                setAnimMove(oldPos, m, true);
-                updateGUI();
-            } else {
-                gui.setSelection(-1);
             }
         }
+        if (doMove(m)) {
+            if (m.equals(ponderMove) && !gameMode.analysisMode() &&
+                    (computerPlayer.getSearchType() == SearchType.PONDER)) {
+                computerPlayer.ponderHit(searchId);
+                ponderMove = null;
+            } else {
+                abortSearch();
+                updateComputeThreads();
+            }
+            setAnimMove(oldPos, m, true);
+            updateGUI();
+        } else {
+            gui.setSelection(-1);
+        }
     }
 
     /** Report promotion choice for incomplete move.
@@ -365,7 +379,7 @@ public class DroidChessController {
 
     /** Help human to claim a draw by trying to find and execute a valid draw claim. */
     public final synchronized boolean claimDrawIfPossible() {
-        if (!findValidDrawClaim())
+        if (!findValidDrawClaim(""))
             return false;
         updateGUI();
         return true;
@@ -1158,13 +1172,15 @@ public class DroidChessController {
         gui.setAnimMove(sourcePos, move, forward);
     }
 
-    private final boolean findValidDrawClaim() {
+    private final boolean findValidDrawClaim(String ms) {
+        if (!ms.isEmpty())
+            ms = " " + ms;
         if (game.getGameState() != GameState.ALIVE) return true;
-        game.processString("draw accept");
+        game.tryClaimDraw("draw accept");
         if (game.getGameState() != GameState.ALIVE) return true;
-        game.processString("draw rep");
+        game.tryClaimDraw("draw rep" + ms);
         if (game.getGameState() != GameState.ALIVE) return true;
-        game.processString("draw 50");
+        game.tryClaimDraw("draw 50" + ms);
         if (game.getGameState() != GameState.ALIVE) return true;
         return false;
     }
diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/Game.java b/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
index 30572cc..d4d7fbf 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/Game.java
@@ -39,7 +39,7 @@ public class Game {
     /** If true, add new moves as mainline moves. */
     private AddMoveBehavior addMoveBehavior;
 
-    PgnToken.PgnTokenReceiver gameTextListener;
+    private PgnToken.PgnTokenReceiver gameTextListener;
 
     public Game(PgnToken.PgnTokenReceiver gameTextListener, TimeControlData tcData) {
         this.gameTextListener = gameTextListener;
@@ -140,7 +140,7 @@ public class Game {
             return false;
         if (str.startsWith("draw ")) {
             String drawCmd = str.substring(str.indexOf(" ") + 1);
-            handleDrawCmd(drawCmd);
+            handleDrawCmd(drawCmd, true);
             return true;
         } else if (str.equals("resign")) {
             addToGameTree(new Move(0, 0, 0), "resign");
@@ -160,6 +160,15 @@ public class Game {
         return true;
     }
 
+    /** Try claim a draw using a command string. Does not play the move involved
+     *  in the draw claim if the draw claim is invalid. */
+    public final void tryClaimDraw(String str) {
+        if (str.startsWith("draw ")) {
+            String drawCmd = str.substring(str.indexOf(" ") + 1);
+            handleDrawCmd(drawCmd, false);
+        }
+    }
+
     private final void addToGameTree(Move m, String playerAction) {
         if (m.equals(new Move(0, 0, 0))) { // Don't create more than one game-ending move at a node
             List<Move> varMoves = tree.variations();
@@ -446,7 +455,7 @@ public class Game {
         return new Pair<Position, ArrayList<Move>>(pos, mList);
     }
 
-    private final void handleDrawCmd(String drawCmd) {
+    private final void handleDrawCmd(String drawCmd, boolean playDrawMove) {
         Position pos = tree.currentPos;
         if (drawCmd.startsWith("rep") || drawCmd.startsWith("50")) {
             boolean rep = drawCmd.startsWith("rep");
@@ -499,7 +508,7 @@ public class Game {
                 addToGameTree(new Move(0, 0, 0), playerAction);
             } else {
                 pendingDrawOffer = true;
-                if (m != null) {
+                if (m != null && playDrawMove) {
                     processString(ms);
                 }
             }