class_name FallbackLibrary
extends RefCounted
## Authored degraded-DM fallback text (charter §13). On ANY failure the client
## shows one of these lines in-voice — never an error. Missing/malformed content
## yields a hardcoded constant, so the fallback itself cannot fail.

const PATH := "res://content/fallback/narrator.json"
const NPC_PATH := "res://content/fallback/npc.json"
const LAST_RESORT := "The chamber is cold. Something waits in the dark."
const NPC_LAST_RESORT := "The figure regards you in silence, and the moment passes."

var _lines: Array = []
var _npc_lines: Array = []


func _init(path := PATH, npc_path := NPC_PATH) -> void:
	_lines = _load(path, "narrator")
	_npc_lines = _load(npc_path, "npc")


func narrator_line() -> String:
	return str(_lines[0]) if not _lines.is_empty() else LAST_RESORT


func npc_line() -> String:
	return str(_npc_lines[0]) if not _npc_lines.is_empty() else NPC_LAST_RESORT


static func _load(path: String, key: String) -> Array:
	if not FileAccess.file_exists(path):
		return []
	var text := FileAccess.get_file_as_string(path)
	# Instance parse() (not JSON.parse_string) so malformed input returns an
	# Error code instead of pushing an engine error the test config promotes.
	var json := JSON.new()
	if json.parse(text) != OK:
		return []
	var data = json.get_data()
	if typeof(data) != TYPE_DICTIONARY:
		return []
	var lines = data.get(key, [])
	return lines if typeof(lines) == TYPE_ARRAY else []