extends Node2D

const ATLAS := preload("res://assets/game/tilesets/kenney_tiles_atlas.png")
const TILE := 18

## 隐藏通道：下面这些格子在关卡开始时会被"挖空"，
## 原本是实心石壁的地方就变成能穿过去的暗道。
## 坐标是格坐标（格边长 18px），改这里就能挪位置。
@export var hidden_cells: Array = [
	# ① 主线走廊上的石柱（第 13 列第 6~7 行）
	Vector2i(13, 6), Vector2i(13, 7),

	# ② 低层暗道（第 11 行第 12~15 列）
	Vector2i(12, 11), Vector2i(13, 11), Vector2i(14, 11), Vector2i(15, 11),
]

## 伪装贴图所在层：要低于角色(z=10)、高于地形(z=0~2)
@export var cover_z_index: int = 3
## 是否给洞口盖上"假墙"（关掉的话洞口会明显地露出来）
@export var hide_with_cover: bool = true


func _ready() -> void:
	var layers := _tile_layers()
	if layers.is_empty():
		return
	var base: TileMapLayer = layers[0]

	# 先把盖子做好（此时参考的那块墙还在），再挖空
	var covers: Array = []
	for cell in hidden_cells:
		covers.append([cell, _make_cover(cell) if hide_with_cover else null])

	for cell in hidden_cells:
		for layer in layers:
			layer.erase_cell(cell)

	for pair in covers:
		var sprite: Sprite2D = pair[1]
		if sprite != null:
			add_child(sprite)
			sprite.global_position = base.to_global(base.map_to_local(pair[0]))


func _tile_layers() -> Array:
	var out: Array = []
	for child in get_children():
		if child is TileMapLayer:
			out.append(child)
	return out


## 借用正下方最近一块实心墙的贴图，做成一个完全没有碰撞的 Sprite2D
func _make_cover(cell: Vector2i) -> Sprite2D:
	var found := Vector2i(-1, -1)
	for dy in range(1, 6):
		for layer in _tile_layers():
			var probe: Vector2i = cell + Vector2i(0, dy)
			var source_id: int = layer.get_cell_source_id(probe)
			if source_id == -1:
				continue
			var coords: Vector2i = layer.get_cell_atlas_coords(probe)
			var source := layer.tile_set.get_source(source_id) as TileSetAtlasSource
			if source == null:
				continue
			var data: TileData = source.get_tile_data(coords, 0)
			if data != null and data.get_collision_polygons_count(0) > 0:
				found = coords
				break
		if found.x >= 0:
			break
	if found.x < 0:
		return null

	var atlas_texture := AtlasTexture.new()
	atlas_texture.atlas = ATLAS
	atlas_texture.region = Rect2(found.x * TILE, found.y * TILE, TILE, TILE)

	var sprite := Sprite2D.new()
	sprite.texture = atlas_texture
	sprite.texture_filter = CanvasItem.TEXTURE_FILTER_NEAREST
	sprite.z_index = cover_z_index
	return sprite