import 'package:block_seasons/game/engine/placement.dart';
import 'package:block_seasons/game/models/cell.dart';
import 'package:block_seasons/game/models/grid.dart';
import 'package:block_seasons/game/models/piece.dart';
import 'package:flutter_test/flutter_test.dart';

const mono = Piece(id: 'mono', colorId: 0, offsets: [(0, 0)]);
const dominoH = Piece(id: 'domino_h', colorId: 1, offsets: [(0, 0), (1, 0)]);
const square2 = Piece(
  id: 'square2',
  colorId: 2,
  offsets: [(0, 0), (1, 0), (0, 1), (1, 1)],
);

void main() {
  group('canPlace', () {
    test('any piece fits anywhere legal on an empty grid', () {
      final grid = GridState.empty();
      expect(canPlace(grid, mono, 0, 0), isTrue);
      expect(canPlace(grid, mono, 7, 7), isTrue);
      expect(canPlace(grid, square2, 6, 6), isTrue);
    });

    test('rejects out-of-bounds placements', () {
      final grid = GridState.empty();
      expect(canPlace(grid, square2, 7, 7), isFalse);
      expect(canPlace(grid, dominoH, 7, 0), isFalse);
      expect(canPlace(grid, mono, -1, 0), isFalse);
      expect(canPlace(grid, mono, 0, 8), isFalse);
    });

    test('rejects overlap with occupied cells', () {
      final grid = GridState.empty()
          .withCell(1, 0, const Cell(CellType.filled, colorId: 0));
      expect(canPlace(grid, dominoH, 0, 0), isFalse);
      expect(canPlace(grid, dominoH, 2, 0), isTrue);
    });
  });

  group('place', () {
    test('fills cells with the piece color and keeps original grid', () {
      final grid = GridState.empty();
      final next = place(grid, square2, 3, 3);

      expect(grid.occupiedCount, 0);
      expect(next.occupiedCount, 4);
      for (final (dx, dy) in square2.offsets) {
        expect(next.cellAt(3 + dx, 3 + dy).type, CellType.filled);
        expect(next.cellAt(3 + dx, 3 + dy).colorId, square2.colorId);
      }
    });
  });

  group('anyPlacementExists', () {
    test('true on an empty grid', () {
      expect(anyPlacementExists(GridState.empty(), [square2]), isTrue);
    });

    test('detects when only a small piece fits', () {
      // Fill everything except (7, 7).
      var grid = GridState.empty();
      for (var y = 0; y < GridState.size; y++) {
        for (var x = 0; x < GridState.size; x++) {
          if (x == 7 && y == 7) continue;
          grid = grid.withCell(x, y, const Cell(CellType.filled, colorId: 0));
        }
      }
      expect(anyPlacementExists(grid, [mono]), isTrue);
      expect(anyPlacementExists(grid, [dominoH]), isFalse);
      expect(anyPlacementExists(grid, [dominoH, mono]), isTrue);
    });

    test('false when the grid is completely full', () {
      var grid = GridState.empty();
      for (var y = 0; y < GridState.size; y++) {
        for (var x = 0; x < GridState.size; x++) {
          grid = grid.withCell(x, y, const Cell(CellType.filled, colorId: 0));
        }
      }
      expect(anyPlacementExists(grid, [mono]), isFalse);
    });
  });
}