extends SceneTree

const TILESET_PATH: String = "res://assets/maps/work_zone/v13/tilesets/work_zone_road_tileset.tres"
const TEXTURE_DIR: String = "res://assets/maps/work_zone/v13/tilesets"

func _init() -> void:
	var tileset := load(TILESET_PATH) as TileSet
	if tileset == null:
		push_error("无法加载 TileSet: %s" % TILESET_PATH)
		quit(1)
		return
	var candidates := _load_candidates()
	var replaced := 0
	for source_index in tileset.get_source_count():
		var source_id := tileset.get_source_id(source_index)
		var atlas_source := tileset.get_source(source_id) as TileSetAtlasSource
		if atlas_source == null or atlas_source.texture == null:
			continue
		var source_hash := _texture_hash(atlas_source.texture)
		var replacement: Texture2D = candidates.get(source_hash)
		if replacement == null:
			_write_audit_image(source_id, atlas_source.texture)
			push_error("未找到匹配的外置纹理，source=%d hash=%s" % [source_id, source_hash])
			quit(2)
			return
		atlas_source.texture = replacement
		replaced += 1
	var error := ResourceSaver.save(tileset, TILESET_PATH)
	if error != OK:
		push_error("保存 TileSet 失败: %s" % error_string(error))
		quit(3)
		return
	print("已外置 %d 个 TileSet 纹理源" % replaced)
	quit()

func _load_candidates() -> Dictionary:
	var candidates: Dictionary = {}
	for file_name in DirAccess.get_files_at(TEXTURE_DIR):
		if not file_name.ends_with(".png"):
			continue
		var path := "%s/%s" % [TEXTURE_DIR, file_name]
		var texture := load(path) as Texture2D
		if texture != null:
			candidates[_bytes_hash(FileAccess.get_file_as_bytes(path))] = texture
	return candidates

func _texture_hash(texture: Texture2D) -> String:
	var image := texture.get_image()
	if image == null:
		return ""
	return _bytes_hash(image.save_png_to_buffer())

func _bytes_hash(bytes: PackedByteArray) -> String:
	var context := HashingContext.new()
	var start_error := context.start(HashingContext.HASH_SHA256)
	if start_error != OK:
		return ""
	var update_error := context.update(bytes)
	if update_error != OK:
		return ""
	return context.finish().hex_encode()

func _write_audit_image(source_id: int, texture: Texture2D) -> void:
	var directory := ProjectSettings.globalize_path("res://build/tileset-audit")
	DirAccess.make_dir_recursive_absolute(directory)
	var image := texture.get_image()
	if image == null:
		return
	var path := "%s/source_%d.png" % [directory, source_id]
	var error := image.save_png(path)
	if error == OK:
		print("已写出待核对纹理: %s (%dx%d)" % [path, image.get_width(), image.get_height()])