## AvatarSystem - Global avatar orchestrator (autoload singleton).
##
## Owns the AvatarCatalog, AvatarLoader, and the current player's AvatarLoadout.
## Provides a single entry point for the rest of the game to:
##   - Load the asset catalog.
##   - Load a player's avatar from a loadout.
##   - Equip / unequip items and persist the resulting loadout.
##
## Registered as an autoload singleton named "AvatarSystem" in project.godot.

extends Node


# ---------------------------------------------------------------------------
# Signals
# ---------------------------------------------------------------------------

## Emitted when the catalog has finished loading.
signal catalog_loaded

## Emitted when the catalog fails to load.
signal catalog_load_failed(error_message: String)

## Emitted when the avatar has been fully assembled and is ready to render.
signal avatar_ready(avatar_node: Node3D)

## Emitted when the loadout changes (after equip/unequip).
signal loadout_changed(loadout: AvatarLoadout)


# ---------------------------------------------------------------------------
# State
# ---------------------------------------------------------------------------

## The asset catalog (id -> metadata + path).
var catalog: AvatarCatalog = null

## The loader used to import GLB assets and assemble the avatar.
var loader: AvatarLoader = null

## The current player's loadout.
var current_loadout: AvatarLoadout = null

## The assembled avatar node (null until avatar_ready).
var avatar_node: Node3D = null

## Whether the catalog has been loaded.
var is_catalog_loaded: bool = false

## Whether an avatar is currently assembled.
var is_avatar_ready: bool = false

## Default catalog path.
const DEFAULT_CATALOG_PATH := "res://assets/avatars/catalog.json"


# ---------------------------------------------------------------------------
# Lifecycle
# ---------------------------------------------------------------------------

func _ready() -> void:
	catalog = AvatarCatalog.new()
	loader = AvatarLoader.new()
	loader.init_loader(catalog)
	add_child(loader)


## Load the asset catalog. Call this once at startup (or on demand).
func load_catalog(path: String = DEFAULT_CATALOG_PATH) -> Error:
	var err := catalog.load_catalog(path)
	if err == OK:
		is_catalog_loaded = true
		catalog_loaded.emit()
	else:
		catalog_load_failed.emit("Failed to load catalog: %s" % err)
	return err


# ---------------------------------------------------------------------------
# Avatar assembly
# ---------------------------------------------------------------------------

## Load and assemble an avatar from a loadout.
## Returns the assembled avatar Node3D on success, or null on failure.
func load_avatar(loadout: AvatarLoadout) -> Node3D:
	if not is_catalog_loaded:
		push_error("AvatarSystem: catalog not loaded; call load_catalog() first")
		return null

	if loadout == null:
		push_error("AvatarSystem: loadout is null")
		return null

	# Validate the loadout against the catalog.
	var validation := catalog.validate_loadout(loadout)
	if not validation.valid:
		push_error("AvatarSystem: invalid loadout: %s" % str(validation.errors))
		return null

	current_loadout = loadout

	# Reset any previous avatar.
	loader.reset()

	# Load the base body.
	var base_body_id := loadout.base_body
	var base_node := loader.load_base_body(base_body_id)
	if base_node == null:
		push_error("AvatarSystem: failed to load base body '%s'" % base_body_id)
		return null

	# Load each equipped attachment.
	for slot_id in AvatarSlotRegistry.SLOT_IDS:
		var slot_value = loadout.slots.get(slot_id)

		if slot_id == "accessory":
			# Accessory is an array of asset ids.
			if slot_value is Array:
				for asset_id in slot_value:
					if asset_id is String and not (asset_id as String).is_empty():
						loader.load_attachment(slot_id, asset_id)
		else:
			# Exclusive slot: single asset id or null.
			if slot_value is String and not (slot_value as String).is_empty():
				loader.load_attachment(slot_id, slot_value)

	# Hide base meshes for equipped body-part slots.
	for slot_id in AvatarSlotRegistry.BODY_PART_SLOTS:
		var slot_value = loadout.slots.get(slot_id)
		if slot_value is String and not (slot_value as String).is_empty():
			loader.set_base_mesh_visible(slot_id, false)

	avatar_node = loader.avatar_node
	is_avatar_ready = avatar_node != null
	if is_avatar_ready:
		avatar_ready.emit(avatar_node)

	return avatar_node


## Equip an item into a slot and rebuild the avatar.
## Returns true on success.
func equip(slot_id: String, asset_id: String) -> bool:
	if current_loadout == null:
		push_error("AvatarSystem: no loadout loaded")
		return false

	if not AvatarSlotRegistry.has_slot(slot_id):
		push_error("AvatarSystem: unknown slot '%s'" % slot_id)
		return false

	if not catalog.has_asset(asset_id):
		push_error("AvatarSystem: unknown asset '%s'" % asset_id)
		return false

	var asset := catalog.resolve(asset_id)
	if asset.get("slot") != slot_id:
		push_error("AvatarSystem: asset '%s' is for slot '%s', not '%s'" % [
			asset_id, asset.get("slot"), slot_id])
		return false

	if slot_id == "accessory":
		if not current_loadout.add_accessory(asset_id):
			push_error("AvatarSystem: could not add accessory '%s'" % asset_id)
			return false
	else:
		current_loadout.set_equipment(slot_id, asset_id)

	loadout_changed.emit(current_loadout)
	return true


## Unequip an item from a slot and rebuild the avatar.
## Returns true on success.
func unequip(slot_id: String, asset_id: String = "") -> bool:
	if current_loadout == null:
		push_error("AvatarSystem: no loadout loaded")
		return false

	if not AvatarSlotRegistry.has_slot(slot_id):
		push_error("AvatarSystem: unknown slot '%s'" % slot_id)
		return false

	if slot_id == "accessory":
		if asset_id.is_empty():
			push_error("AvatarSystem: accessory unequip requires an asset id")
			return false
		if not current_loadout.remove_accessory(asset_id):
			push_error("AvatarSystem: accessory '%s' not equipped" % asset_id)
			return false
	else:
		current_loadout.set_equipment(slot_id, "")

	loadout_changed.emit(current_loadout)
	return true


## Serialize the current loadout to JSON.
func save_loadout() -> String:
	if current_loadout == null:
		return ""
	return current_loadout.to_json()


## Load a loadout from a JSON string.
func load_loadout_from_json(json_string: String) -> AvatarLoadout:
	var loadout := AvatarLoadout.from_json(json_string)
	if not loadout.validate():
		push_error("AvatarSystem: invalid loadout JSON: %s" % str(loadout.validation_errors))
		return null
	return loadout


## Get the list of available assets for a given slot.
func get_assets_for_slot(slot_id: String) -> Array[String]:
	return catalog.get_assets_by_slot(slot_id)


## Get the display name for an asset id.
func get_asset_display_name(asset_id: String) -> String:
	var asset := catalog.resolve(asset_id)
	return asset.get("display_name", asset_id)