class_name FallbackLibrary
extends RefCounted
## Authored degraded-DM fallback text (charter §13). The client shows one of
## these lines on ANY failure, in the Narrator's voice — never an error. If the
## content file is missing or malformed the library returns a hardcoded
## constant, so the fallback itself cannot fail.

const PATH := "res://content/fallback/narrator.json"
const LAST_RESORT := "The chamber is cold. Something waits in the dark."

var _lines: Array = []


func _init(path := PATH) -> void:
	_lines = _load(path)


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


static func _load(path: String) -> Array:
	if not FileAccess.file_exists(path):
		return []
	var text := FileAccess.get_file_as_string(path)
	# Use the instance API, not JSON.parse_string(): the static convenience
	# method pushes an engine-level error on malformed input, which is noisy
	# and (in this project's test config) turns a handled failure into a
	# reported test error. The instance parse() just returns an Error code.
	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("narrator", [])
	return lines if typeof(lines) == TYPE_ARRAY else []