From fa6f6c3f5f8f872a216ccdb593492775c0d265a1 Mon Sep 17 00:00:00 2001
From: eug-vs <eugene@eug-vs.xyz>
Date: Tue, 14 Feb 2023 17:45:10 +0300
Subject: feat: consider checks in quiscence

---
 src/board/engine.rs | 40 ++++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/board/engine.rs b/src/board/engine.rs
index 46cf8ed..1516784 100644
--- a/src/board/engine.rs
+++ b/src/board/engine.rs
@@ -472,26 +472,36 @@ impl Board {
         let mut moves = self.generate_pseudolegal_moves(color);
         moves = self.order_moves(moves, Vec::new());
 
-        let stand_pat = self.evaluate();
+        if !self.is_king_in_check(color) {
+            // If we are not in check, we can evaluate stand pat
+            let stand_pat = self.evaluate();
 
-        if stand_pat >= beta {
-            return beta;
-        }
-        if alpha < stand_pat {
-            alpha = stand_pat;
-        }
+            if stand_pat >= beta {
+                return beta;
+            }
+            if alpha < stand_pat {
+                alpha = stand_pat;
+            }
 
-        let tactical_moves = moves.iter().filter(|m| m.is_tactical());
+            // If we are not in check, we can only search tactical moves
+            moves = moves
+                .iter()
+                .filter(|m| m.is_tactical())
+                .map(|m| *m)
+                .collect()
+        }
 
-        for mov in tactical_moves {
+        let mut legal_move_found = false;
+        for mov in moves {
             let ep_target_before = self.ep_target.clone();
             let castling_rights_before = self.castling_rights.clone();
             let hash_before = self.hash.clone();
-            let captured_piece = self.make_move(*mov);
+            let captured_piece = self.make_move(mov);
 
             if !self.is_king_in_check(color) {
+                legal_move_found = true;
                 let evaluation = -self.quiscence(-beta, -alpha);
-                self.unmake_move(*mov, captured_piece, ep_target_before, castling_rights_before, hash_before);
+                self.unmake_move(mov, captured_piece, ep_target_before, castling_rights_before, hash_before);
 
                 if evaluation >= beta {
                     return beta; // Fail-hard beta-cutoff
@@ -500,7 +510,13 @@ impl Board {
                     alpha = evaluation;
                 }
             } else {
-                self.unmake_move(*mov, captured_piece, ep_target_before, castling_rights_before, hash_before);
+                self.unmake_move(mov, captured_piece, ep_target_before, castling_rights_before, hash_before);
+            }
+        }
+
+        if !legal_move_found {
+            if self.is_king_in_check(color) {
+                return -VALUE_WIN
             }
         }
 
-- 
cgit v1.2.3