[Add] Playful interaction with cells

Assets/Minesweeper/Runtime/Core/BoardService.cs

@@ -23,6 +23,8 @@ namespace Minesweeper.Core
         public int Height { get; private set; }
         public int MinesCount { get; private set; }
         public bool IsGenerated { get; private set; }
+        public int OpenedSafeCellsCount { get; private set; }
+        public int SafeCellsCount => Width * Height - MinesCount;
 
         public void InitializeEmptyBoard()
         {
@@ -31,6 +33,7 @@ namespace Minesweeper.Core
             Width = width;
             Height = height;
             MinesCount = minesCount;
+            OpenedSafeCellsCount = 0;
             IsGenerated = false;
             cells = new CellData[Width, Height];
 
@@ -55,11 +58,62 @@ namespace Minesweeper.Core
             PlaceMines(safeX, safeY);
             CalculateNeighborMines();
 
-            cells[safeX, safeY].IsOpened = true;
             IsGenerated = true;
             return true;
         }
 
+        public BoardActionResult OpenCell(int x, int y)
+        {
+            EnsureInitialized();
+
+            if (!IsGenerated || !IsInside(x, y))
+            {
+                return BoardActionResult.InvalidAction;
+            }
+
+            var cell = cells[x, y];
+            if (cell.IsOpened || cell.IsFlagged)
+            {
+                return BoardActionResult.NoChange;
+            }
+
+            if (cell.IsMine)
+            {
+                cell.IsOpened = true;
+                return new BoardActionResult(true, true, false, false);
+            }
+
+            if (cell.NeighborMines == 0)
+            {
+                RevealEmptyArea(x, y);
+            }
+            else
+            {
+                OpenSafeCell(cell);
+            }
+
+            return new BoardActionResult(true, false, IsWin(), false);
+        }
+
+        public BoardActionResult ToggleFlag(int x, int y)
+        {
+            EnsureInitialized();
+
+            if (!IsInside(x, y))
+            {
+                return BoardActionResult.InvalidAction;
+            }
+
+            var cell = cells[x, y];
+            if (cell.IsOpened)
+            {
+                return BoardActionResult.NoChange;
+            }
+
+            cell.IsFlagged = !cell.IsFlagged;
+            return new BoardActionResult(true, false, false, false);
+        }
+
         public bool IsInside(int x, int y)
         {
             return cells != null && x >= 0 && y >= 0 && x < Width && y < Height;
@@ -190,6 +244,63 @@ namespace Minesweeper.Core
             return count;
         }
 
+        private void RevealEmptyArea(int startX, int startY)
+        {
+            var visited = new bool[Width, Height];
+            var queue = new Queue<CellData>();
+            queue.Enqueue(cells[startX, startY]);
+
+            while (queue.Count > 0)
+            {
+                var cell = queue.Dequeue();
+                if (visited[cell.X, cell.Y] || cell.IsMine || cell.IsFlagged)
+                {
+                    continue;
+                }
+
+                visited[cell.X, cell.Y] = true;
+                OpenSafeCell(cell);
+
+                if (cell.NeighborMines != 0)
+                {
+                    continue;
+                }
+
+                for (var x = cell.X - 1; x <= cell.X + 1; x++)
+                {
+                    for (var y = cell.Y - 1; y <= cell.Y + 1; y++)
+                    {
+                        if ((x == cell.X && y == cell.Y) || !IsInside(x, y))
+                        {
+                            continue;
+                        }
+
+                        var neighbor = cells[x, y];
+                        if (!visited[x, y] && !neighbor.IsMine && !neighbor.IsFlagged && !neighbor.IsOpened)
+                        {
+                            queue.Enqueue(neighbor);
+                        }
+                    }
+                }
+            }
+        }
+
+        private void OpenSafeCell(CellData cell)
+        {
+            if (cell.IsOpened || cell.IsMine)
+            {
+                return;
+            }
+
+            cell.IsOpened = true;
+            OpenedSafeCellsCount++;
+        }
+
+        private bool IsWin()
+        {
+            return OpenedSafeCellsCount >= SafeCellsCount;
+        }
+
         private int ToIndex(int x, int y)
         {
             return y * Width + x;