extends Node2D


var shapes = [
	preload("res://ShapeI.tscn"),
	preload("res://ShapeJ.tscn"),
	preload("res://ShapeL.tscn"),
	preload("res://ShapeZ.tscn"),
	preload("res://ShapeS.tscn"),
	preload("res://ShapeT.tscn"),
	preload("res://ShapeO.tscn")
]

var active_shape: TetrisShape

const RASTER_SIZE = 64
const BOTTOM = RASTER_SIZE * 10
const SPAWN = -RASTER_SIZE * 7
const LEFT = -RASTER_SIZE * 5
const RIGHT = RASTER_SIZE * 5


func _ready():
	# Swipe input
	$SwipeHandler.connect("swipe_up", self, "rotate_shape")
	$SwipeHandler.connect("swipe_left", self, "move_left")
	$SwipeHandler.connect("swipe_right", self, "move_right")
	$SwipeHandler.connect("swipe_down", self, "drop")
	
	$GravityTimer.connect("timeout", self, "update_board")
	
	active_shape = get_random_shape()


func get_random_shape():
	var new_shape = shapes[randi() % shapes.size()].instance()
	add_child(new_shape)
	new_shape.position.y = SPAWN
	return new_shape


func update_board():
	if can_active_move_down():
		move_active_down()
	else:
		turn_active_into_static()
		check_for_full_line()
		
		active_shape = get_random_shape()


func move_active_down():
	active_shape.position.y += RASTER_SIZE


func can_active_move_down():
	return _can_active_move_towards(Vector2(0.0, RASTER_SIZE))


func can_active_move_left():
	return _can_active_move_towards(Vector2(-RASTER_SIZE, 0.0))


func can_active_move_right():
	return _can_active_move_towards(Vector2(RASTER_SIZE, 0.0))


func _can_active_move_towards(diff: Vector2):
	for block in active_shape.get_blocks():
		var new_x = block.global_position.x + diff.x
		var new_y = block.global_position.y + diff.y
		
		var global_bottom = to_global(Vector2(0.0, BOTTOM)).y
		var global_left = to_global(Vector2(LEFT, 0.0)).x
		var global_right = to_global(Vector2(RIGHT, 0.0)).x
		
		if new_x <= global_left \
				or new_x >= global_right \
				or new_y >= global_bottom:
			return false
		
		if is_block_at_position(new_x, new_y):
			return false
	
	return true


func turn_active_into_static():
	for block in active_shape.get_blocks():
		var global_shape_position = block.global_position
		active_shape.remove_child(block)
		$StaticBlocks.add_child(block)
		block.global_position = global_shape_position
	
	active_shape.free()


func check_for_full_line():
	var line_counts = {} # Maps a y position to a count
	
	# Count how many blocks we have in each line (with at least 1 block)
	for block in $StaticBlocks.get_children():
		if not line_counts.has(block.position.y):
			line_counts[block.position.y] = 0
		line_counts[block.position.y] += 1
	
	# Remember which blocks we need to move down later (we can't apply this immediately because that
	# would mess with comparisons to the line_counts
	var pending_position_diffs = {}
	
	for line_count_y in line_counts.keys():
		if line_counts[line_count_y] == 10:
			# Free this line
			for line_block in $StaticBlocks.get_children():
				if line_block.position.y == line_count_y:
					line_block.free()
				elif line_block.position.y < line_count_y:
					# If this block is above the line currently being freed, remember to move down
					# by one raster cell
					if not pending_position_diffs.has(line_block):
						pending_position_diffs[line_block] = 0
					pending_position_diffs[line_block] += RASTER_SIZE
	
	# Apply the pending downward movements, but only if the block hasn't been freed (because that
	# line was above, but also full)
	for block in pending_position_diffs.keys():
		if is_instance_valid(block):
			block.position.y += pending_position_diffs[block]


func move_left():
	if can_active_move_left():
		active_shape.position.x -= RASTER_SIZE


func move_right():
	if can_active_move_right():
		active_shape.position.x += RASTER_SIZE


func rotate_shape():
	active_shape.rotation_degrees += 90


func drop():
	while can_active_move_down():
		move_active_down()
	
	# Restart the timer to give full time for sliding the piece
	$GravityTimer.start()


func is_block_at_position(pos_x, pos_y):
	for block in $StaticBlocks.get_children():
		if block.global_position.x == pos_x and block.global_position.y == pos_y:
			return true
	
	return false


func _input(event):
	if event.is_action_pressed("move_left"):
		move_left()
	elif event.is_action_pressed("move_right"):
		move_right()
	elif event.is_action_pressed("rotate"):
		rotate_shape()
	elif event.is_action_pressed("drop"):
		drop()