Use 7-bag for tetromino sequence generation

TetrisKit/GameController.swift

@@ -24,9 +24,11 @@ public class GameController: ObservableObject {
         }
     }
     @Published public var currentPieceAtDropPoint: GamePiece?
-    @Published public var nextTetrominoes: [Tetromino] = [.random(), .random(), .random()]
+    @Published public var nextTetrominoes: [Tetromino] = []
     @Published public var heldTetromino: Tetromino?
     
+    var currentBag: [Tetromino] = []
+
     @Published public var score = 0
     var previousPieceWasTetris = false
 
@@ -41,13 +43,26 @@ public class GameController: ObservableObject {
     
     public func start() {
         state = .playing(.normal)
+        generateBag()
         nextPiece()
     }
     
     func nextPiece() {
         let tetromino = nextTetrominoes.removeFirst()
         currentPiece = GamePiece(tetromino: tetromino, topLeft: ((width - tetromino.shape.count) / 2, 0))
-        nextTetrominoes.append(.random())
+        
+        if currentBag.isEmpty {
+            generateBag()
+        }
+        nextTetrominoes.append(currentBag.removeFirst())
+    }
+    
+    func generateBag() {
+        currentBag = Array(0..<Tetromino.allCases.count).shuffled().map { Tetromino.allCases[$0] }
+        if nextTetrominoes.isEmpty {
+            nextTetrominoes = Array(currentBag[0..<3])
+            currentBag.removeFirst(3)
+        }
     }
     
     func finalizePiece() {
@@ -77,10 +92,15 @@ public class GameController: ObservableObject {
             previousPieceWasTetris = true
         } else if cleared == 3 {
             score += 500
+            previousPieceWasTetris = false
         } else if cleared == 2 {
             score += 300
+            previousPieceWasTetris = false
         } else if cleared == 1 {
             score += 100
+            previousPieceWasTetris = false
+        } else {
+            previousPieceWasTetris = false
         }
     }