feat: implement gravity on current piece

Tetris.py

@@ -40,9 +40,11 @@ class Tetris:
     # gets called from the games main loop
     def update(self) -> None:
         # TODO write not initialized exception
+        elapsed_time = self.clock.tick(self.fps)
+
+        if self.current_piece:
+            self.current_piece.update(elapsed_time, self.well, self.stack)
 
-        self.clock.tick(self.fps)
-         
         # TODO create control utility class
         for event in pygame.event.get():
             if event.type == pygame.QUIT:

entity/Entity.py

@@ -8,9 +8,10 @@ class Entity:
         self.points = points
         self.color = color
         self.border_color = border_color
+        self.elapsed_time = 0
 
-    def update(self) -> None:
+    def update(self, elapsed_time) -> None:
-        pass
+        self.elapsed_time += elapsed_time
 
     def draw(self, surface: pygame.Surface) -> None:
         tile_size = ConfigurationManager.configuration["engine"]["tile-size"]
@@ -20,7 +21,7 @@ class Entity:
             if self.border_color:
                 pygame.draw.polygon(surface, pygame.Color(self.border_color), square, max(tile_size // 6, 1))
 
-    def collide(self, entity) -> bool:
+    def collide(self, entity) -> bool: # TODO figure out how to do type hint for entity param of type Entity
         for square_one in self.points:
             for square_two in entity.points:
                 for i in range(4): # 4 vertices

entity/Piece.py

@@ -9,7 +9,9 @@ from util.ConfigurationManager import ConfigurationManager
     https://tetris.fandom.com/wiki/Tetromino
 '''
 class Piece(Entity):
-        
+    
+    GRAVITY = 800 # A move down every 800 ms
+
     def __init__(self, shape: Tuple, position: Tuple, color: str, border_color: str):
         super().__init__(self.__get_points(shape, position), color, border_color)
         self.center = self.__get_center(shape, position)
@@ -17,7 +19,24 @@ class Piece(Entity):
         self.previous_points = None
         self.previous_center = None
 
+    def update(self, elapsed_time: int, well: Entity, stack: Entity):
+        super().update(elapsed_time)
+
+        tile_size =  ConfigurationManager.configuration["engine"]["tile-size"]
+        if self.elapsed_time >= Piece.GRAVITY:
+            self.elapsed_time -= Piece.GRAVITY
+
+            self.move((0, tile_size))
+            if well and self.collide(well):     
+                self.revert()
+            if stack and self.collide(stack):     
+                self.revert()
+
     def move(self, vector: Tuple) -> None:
+        # reset elapsed time if user moves down to stall gravity
+        if vector[1] > 0:
+            self.elapsed_time = 0
+
         self.previous_points = copy.deepcopy(self.points)
         self.previous_center = copy.deepcopy(self.center)