extends Node2D


const TETROMINO_POOL = [
	preload("res://tetromino_bar.tscn"),
	preload("res://tetromino_cube.tscn"),
	preload("res://tetromino_t.tscn"),
	preload("res://tetromino_s.tscn"),
	preload("res://tetromino_z.tscn"),
	preload("res://tetromino_j.tscn"),
	preload("res://tetromino_l.tscn"),
]

const INPUT_BUFFER_TRHESHOLD := 0.1
var INPUT_BUFFER_MAP: Dictionary[String, float] = {
	#"ui_up": INPUT_BUFFER_TRHESHOLD,
	"ui_left": INPUT_BUFFER_TRHESHOLD,
	"ui_right": INPUT_BUFFER_TRHESHOLD,
	"ui_down": INPUT_BUFFER_TRHESHOLD,
}


signal tetromino_reached_bottom
signal game_over


@export var score_threshold: int


var grid: Dictionary[Vector2i, TetrominoSegment]
var grid_bounds: Rect2i

var current_tetromino: Tetromino
var next_tetromino: Tetromino: set = set_next_tetromino

var score: int


func _ready() -> void:
	grid_bounds = get_grid_bounds()
	
	next_tetromino = TETROMINO_POOL.pick_random().instantiate()
	_on_tick_timer_timeout()
	
	game_over.connect(_on_game_over)


func _input(event: InputEvent) -> void:
	if event.is_action_pressed("ui_up"):
		rotate_current_tetromino(1.0)


func _process(delta: float) -> void:
	if Input.is_action_pressed("ui_left") and INPUT_BUFFER_MAP["ui_left"] > INPUT_BUFFER_TRHESHOLD:
		move_current_tetromino(Vector2i.LEFT)
		INPUT_BUFFER_MAP["ui_left"] = 0.0
	
	if Input.is_action_pressed("ui_right") and INPUT_BUFFER_MAP["ui_right"] > INPUT_BUFFER_TRHESHOLD:
		move_current_tetromino(Vector2i.RIGHT)
		INPUT_BUFFER_MAP["ui_right"] = 0.0
	
	if Input.is_action_pressed("ui_down") and INPUT_BUFFER_MAP["ui_down"] > INPUT_BUFFER_TRHESHOLD:
		move_current_tetromino(Vector2i.DOWN)
		INPUT_BUFFER_MAP["ui_down"] = 0.0
	
	for key in INPUT_BUFFER_MAP.keys():
		INPUT_BUFFER_MAP[key] += delta
	
	if OS.is_debug_build():
		if current_tetromino:
			%Debug.text = "P: %s" % current_tetromino.current_grid_position
			%Debug.text += "\nPS: %s" % " ".join(current_tetromino.get_grid_occupations())
		else:
			%Debug.text = ""


func set_next_tetromino(value: Tetromino) -> void:
	next_tetromino = value
	%NextTetromino.texture = load("%s.png" % next_tetromino.name)


func spawn_tetromino() -> Tetromino:
	var tetromino: Tetromino = next_tetromino
	tetromino.init($Grid, $Grid.local_to_map($SpawnPosition.global_position))
	
	return tetromino


func set_current_tetromino_to_grid() -> void:
	var grid_segments := current_tetromino.get_grid_segments()
	
	var mapped: Dictionary[int, Variant]
	for grid_position: Vector2i in grid_segments.keys():
		if grid.get(grid_position, null) != null:
			game_over.emit()
			break
		
		grid.set(grid_position, grid_segments.get(grid_position))
		mapped.set(grid_position.y, true)
	
	$ProjectionSegments.visible = false
	clear_rows(mapped.keys())
	
	current_tetromino = null


func clear_rows(rows_to_check: Array[int] = []) -> void:
	if rows_to_check.is_empty():
		rows_to_check.assign(range(grid_bounds.size.y))
	
	var filled_rows: Array[int]
	
	for y in rows_to_check:
		var row_is_filled := true
		for x in range(grid_bounds.size.x):
			row_is_filled = row_is_filled and grid.get(Vector2i(x, y), null)
			if not row_is_filled:
				break
		
		if row_is_filled:
			filled_rows.append(y)
	
	# no rows filled? return
	if filled_rows.size() == 0:
		return
	
	# sort rows
	filled_rows.sort()
	
	$TickTimer.paused = true
	
	# animate
	var tween = create_tween().set_parallel()
	for y in filled_rows:
		for x in range(grid_bounds.size.x):
			var segment: TetrominoSegment = grid.get(Vector2i(x, y))
			var previous_modulate := segment.modulate
			tween.tween_property(segment, "modulate", Color(10, 10, 10, 1), 0.3)
			tween.tween_property(segment, "modulate", previous_modulate, 0.3).set_delay(0.3)
			tween.tween_property(segment, "modulate", Color(10, 10, 10, 1), 0.3).set_delay(0.6)
			tween.tween_property(segment, "modulate", previous_modulate, 0.3).set_delay(0.9)
	await tween.finished
	
	# remove segments
	for y in filled_rows:
		for x in range(grid_bounds.size.x):
			grid.get(Vector2i(x, y)).queue_free()
			grid.set(Vector2i(x, y), null)
	
	# shift rows down
	for y in filled_rows:
		for n in range(y - 1, 0, -1):
			for x in range(grid_bounds.size.x):
				var segment: TetrominoSegment = grid.get(Vector2i(x, n), null)
				grid.set(Vector2i(x, n + 1), segment)
				grid.set(Vector2i(x, n), null)
				if is_instance_valid(segment):
					segment.global_position.y += $Grid.tile_set.tile_size.y
	
	# increase score and game speed
	score += int(100 * pow(filled_rows.size(), 2))
	%Score.text = str(score)
	$TickTimer.wait_time = 1.0 - (score / float(score_threshold))
	
	$TickTimer.paused = false


func rotate_current_tetromino(direction: float) -> void:
	if not current_tetromino:
		return
	
	for grid_position in current_tetromino.get_grid_occupations(Vector2.ZERO, direction):
		if grid.get(grid_position, null) or not grid_bounds.has_point(grid_position):
			return
	
	current_tetromino.do_rotation(direction)
	update_projection()


func move_current_tetromino(direction: Vector2i) -> void:
	if not current_tetromino:
		return
	
	for grid_position in current_tetromino.get_grid_occupations(direction):
		if direction == Vector2i.DOWN:
			if grid.get(grid_position, null) or grid_position.y >= grid_bounds.size.y:
				set_current_tetromino_to_grid()
				tetromino_reached_bottom.emit()
				return
		
		elif grid.get(grid_position, null) or not grid_bounds.has_point(grid_position):
			return
	
	current_tetromino.current_grid_position += direction
	update_projection()


func advance_current_tetromino() -> void:
	move_current_tetromino(Vector2i.DOWN)


func update_projection() -> void:
	var current_segments := current_tetromino.get_grid_occupations()
	current_segments.sort_custom(func (a: Vector2i, b: Vector2i):
		return a.y < b.y
	)
	
	var highest_segment: int = current_segments[0].y
	var lowest_segment: int = current_segments[3].y
	
	var colliding_segment: int = lowest_segment
	var colliding_row := grid_bounds.size.y
	var is_colliding := false
	
	for y in range(grid_bounds.size.y - highest_segment):
		for segment in current_segments:
			if grid.get(Vector2i(segment.x, segment.y + y), null):
				colliding_row = segment.y + y
				colliding_segment = segment.y
				is_colliding = true
				break
			elif segment.y + y >= grid_bounds.size.y:
				is_colliding = true
				break
		if is_colliding:
			break
	
	var projection_segments := $ProjectionSegments.get_children()
	for index in current_segments.size():
		var segment := current_segments[index]
		var difference := colliding_segment - segment.y
		projection_segments[index].global_position = Vector2(
			segment.x,
			colliding_row - 1 - difference
		) * Vector2($Grid.tile_set.tile_size) + $Grid.position
	
	$ProjectionSegments.visible = true


func get_grid_bounds() -> Rect2i:
	return Rect2i(
		#Vector2i($Area.global_position - ($Area.shape.size / 2.0)) / $Grid.tile_set.tile_size,
		Vector2.ZERO,
		Vector2i($Area.shape.size) / $Grid.tile_set.tile_size
	)


func _on_tick_timer_timeout() -> void:
	if current_tetromino:
		advance_current_tetromino()
	else:
		current_tetromino = spawn_tetromino()
		add_child(current_tetromino)
		update_projection()
		
		next_tetromino = TETROMINO_POOL.pick_random().instantiate()


func _on_game_over() -> void:
	get_tree().quit()