class_name TileLayer
extends RefCounted
## A single tile layer within a chunk.
##
## Holds the dense grid of tile IDs, the palette mapping tile IDs to tile
## definitions, and the layer metadata. This is the runtime representation of
## the `TileLayer` from the chunk data format (see docs/architecture/world.md
## §3.2).

## Layer name (e.g. "ground", "walls", "decor").
var name: String = ""

## Numeric layer id, unique within the chunk.
var layer_id: int = 0

## Grid dimensions in tiles.
var width: int = 0
var height: int = 0
var depth: int = 1

## Palette mapping tile IDs to tile definitions (shared per layer).
var palette: Array[TileDef] = []

## Dense, row-major tile IDs. Length = width * height * depth.
var tiles: PackedInt32Array = PackedInt32Array()


func _init(
	p_layer_name: String = "",
	p_layer_id: int = 0,
	p_width: int = 0,
	p_height: int = 0,
	p_depth: int = 1
) -> void:
	name = p_layer_name
	layer_id = p_layer_id
	width = p_width
	height = p_height
	depth = p_depth


## Total number of tiles in this layer.
func tile_count() -> int:
	return width * height * depth


## Get the tile ID at (x, y, z). Returns 0 (empty) for out-of-bounds.
func get_tile(x: int, y: int, z: int = 0) -> int:
	if x < 0 or x >= width or y < 0 or y >= height or z < 0 or z >= depth:
		return 0
	var idx := (z * height + y) * width + x
	if idx < tiles.size():
		return tiles[idx]
	return 0


## Set the tile ID at (x, y, z). No-op if out of bounds.
func set_tile(x: int, y: int, z: int, tile_id: int) -> void:
	if x < 0 or x >= width or y < 0 or y >= height or z < 0 or z >= depth:
		return
	var idx := (z * height + y) * width + x
	if idx < tiles.size():
		tiles[idx] = tile_id


## Get the tile definition for a tile ID, or null if not in the palette.
func get_tile_def(tile_id: int) -> TileDef:
	for def in palette:
		if def.id == tile_id:
			return def
	return null


## Whether the tile at (x, y, z) is solid (collision).
func is_solid(x: int, y: int, z: int = 0) -> bool:
	var def := get_tile_def(get_tile(x, y, z))
	return def != null and def.solid


## Whether the tile at (x, y, z) is walkable.
func is_walkable(x: int, y: int, z: int = 0) -> bool:
	var def := get_tile_def(get_tile(x, y, z))
	return def != null and def.is_walkable()