From 1b6275b4fbc4ab7bcd876938f807aad9ce1900a6 Mon Sep 17 00:00:00 2001
From: nil <niljo@airmail.cc>
Date: Fri, 13 Dec 2024 20:00:50 +0100
Subject: add liberties

---
 src/engine/liberty.js | 63 +++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 54 insertions(+), 9 deletions(-)

(limited to 'src/engine/liberty.js')

diff --git a/src/engine/liberty.js b/src/engine/liberty.js
index a006c62..d5d4448 100644
--- a/src/engine/liberty.js
+++ b/src/engine/liberty.js
@@ -12,13 +12,58 @@ export function hasLiberties({
     position,
     team
 }) {
-    return Array.from(SURROUNDING)
-	.map(v => Vector2.sum(v, position))
-	.filter(z => 0 <= z.x && z.x < board.size &&
-	    0 <= z.y && z.y < board.size
-	)
-	.some(z => board.stones[z.y][z.x] == undefined ?
-	    true :
-	    board.stones[z.y][z.x].team == team
-	)
+    return checkLiberties({
+        position,
+        team
+    })
+}
+
+function checkLiberties({
+    position,
+    team,
+    checkedStones = [],
+    checkedLiberties = [],
+}) {
+    if (
+        Array.from(checkedStones)
+            .some(p => Vector2.equals(p, position))
+    ) {
+        return false
+    }
+
+    checkedStones.push(position)
+
+    let surroundingSquares = Array.from(SURROUNDING)
+        .map(v => Vector2.sum(v, position))
+        .filter(z => 0 <= z.x && z.x < board.size &&
+            0 <= z.y && z.y < board.size
+        )
+
+    surroundingSquares
+        .filter(z => board.stones[z.y][z.x] == undefined)
+        .forEach(z => {
+            if (!Array.from(checkedStones)
+                .some(p => Vector2.equals(p, z))
+            ) {
+                checkedLiberties.push(z)
+            }
+        })
+
+    surroundingSquares
+        .filter(z => board.stones[z.y][z.x] != undefined)
+        .filter(z => board.stones[z.y][z.x].team == team)
+        .forEach(z => {
+            checkLiberties({
+                position: z,
+                team: team,
+                checkedStones: checkedStones,
+                checkedLiberties: checkedLiberties,
+            })
+        })
+
+    if (checkedLiberties.length > 0) {
+        return true
+    }
+
+    return false
 }
-- 
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