From e7cd079a5d9c5415fc1d7374d2fb771bbcbabf77 Mon Sep 17 00:00:00 2001
From: airkjw <airkjw@gmail.com>
Date: Thu, 18 Jun 2026 12:05:14 +0900
Subject: [PATCH] feat(engine): line-bomb booster clears a row or column

---
 lib/game/engine/game_engine.dart   | 14 ++++++++++++
 test/game/engine/booster_test.dart | 35 ++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/lib/game/engine/game_engine.dart b/lib/game/engine/game_engine.dart
index 1427f92..bddb5e3 100644
--- a/lib/game/engine/game_engine.dart
+++ b/lib/game/engine/game_engine.dart
@@ -236,4 +236,18 @@ class GameEngine {
     _checkStuck();
     return true;
   }
+
+  /// Booster: empties one row or one column (exactly one of [row]/[col]).
+  /// No move/score/objective effect. Re-checks stuck.
+  bool useLineBomb({int? row, int? col}) {
+    if (_phase == GamePhase.won || _phase == GamePhase.lost) return false;
+    if ((row == null) == (col == null)) return false; // need exactly one
+    for (var i = 0; i < GridState.size; i++) {
+      final x = col ?? i;
+      final y = row ?? i;
+      _grid = _grid.withCell(x, y, const Cell(CellType.empty));
+    }
+    _checkStuck();
+    return true;
+  }
 }
diff --git a/test/game/engine/booster_test.dart b/test/game/engine/booster_test.dart
index a20c2b1..7dd7923 100644
--- a/test/game/engine/booster_test.dart
+++ b/test/game/engine/booster_test.dart
@@ -66,4 +66,39 @@ void main() {
     e.declineAndLose();
     expect(e.useShuffle(), isFalse);
   });
+
+  test('useLineBomb(row:) empties that row, no scoring or move', () {
+    final e = GameEngine(_stage()); // row 0 has cells at x=0,1
+    final score0 = e.score;
+    final moves0 = e.movesUsed;
+
+    final ok = e.useLineBomb(row: 0);
+
+    expect(ok, isTrue);
+    for (var x = 0; x < 8; x++) {
+      expect(e.grid.isOccupied(x, 0), isFalse, reason: 'col $x');
+    }
+    expect(e.score, score0);
+    expect(e.movesUsed, moves0);
+  });
+
+  test('useLineBomb(col:) empties that column', () {
+    final e = GameEngine(_stage()); // (0,0) filled
+    expect(e.useLineBomb(col: 0), isTrue);
+    for (var y = 0; y < 8; y++) {
+      expect(e.grid.isOccupied(0, y), isFalse, reason: 'row $y');
+    }
+  });
+
+  test('useLineBomb requires exactly one of row/col', () {
+    final e = GameEngine(_stage());
+    expect(e.useLineBomb(), isFalse);
+    expect(e.useLineBomb(row: 0, col: 0), isFalse);
+  });
+
+  test('useLineBomb is rejected after the attempt finishes', () {
+    final e = GameEngine(_stage());
+    e.declineAndLose();
+    expect(e.useLineBomb(row: 0), isFalse);
+  });
 }