extends SceneTree

# Forgejo #225: the menu offers to resume a run, and only when there is one.
#
# Covers:
#   A. with no save on disk there is no Continue entry at all - a first-time
#      player must not meet a button that does nothing
#   B. with a save, Continue appears and is offered
#   C. pressing it loads the run and starts the game, rather than resetting
#      to a new one the way Play does
#   D. a save this build cannot open is still SHOWN, disabled, with the
#      reason - a run that silently vanishes reads as lost, not incompatible

var game_state: Node
var menu: Node
var elapsed: float = 0.0
var stage: int = 0


func _initialize() -> void:
	game_state = root.get_node("GameState")
	SaveGame.clear()


func _rebuild_menu() -> void:
	if menu != null and is_instance_valid(menu):
		menu.free()
	menu = load("res://ui/MainMenu.tscn").instantiate()
	root.add_child(menu)


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			if elapsed < 0.3:
				return false
			# --- A. nothing saved, nothing offered ----------------------
			_rebuild_menu()
			elapsed = 0.0
			stage = 1
			return false
		1:
			if elapsed < 0.3:
				return false
			if menu.continue_button.visible:
				return _fail("a Continue entry is offered with no save on disk")
			print("no save: no Continue entry")

			# --- B. a saved run is offered ------------------------------
			game_state.reset_progression()
			game_state.reset_new_game()
			game_state.research_points = 31
			game_state.intro_active = false
			if not SaveGame.save(game_state):
				return _fail("could not write a save to offer")
			_rebuild_menu()
			elapsed = 0.0
			stage = 2
			return false
		2:
			if elapsed < 0.3:
				return false
			if not menu.continue_button.visible:
				return _fail("a save exists but no Continue entry is offered")
			if not menu.continue_button.enabled:
				return _fail("Continue is offered but disabled: '%s'" % menu.status_label.text)
			print("a saved run is offered")

			# --- C. and pressing it resumes rather than resets -----------
			game_state.research_points = 0
			menu._on_continue_pressed()
			if game_state.research_points != 31:
				return _fail("Continue did not restore the run (research %d, expected 31)" \
					% game_state.research_points)
			if menu.loading_path == "":
				return _fail("Continue restored the run but never started the game")
			print("Continue restored the run and started the game")

			# --- D. an unopenable save is shown, not hidden --------------
			_corrupt_version()
			_rebuild_menu()
			elapsed = 0.0
			stage = 3
			return false
		3:
			if elapsed < 0.3:
				return false
			if not menu.continue_button.visible:
				return _fail("a save this build cannot open was hidden, so the run looks lost")
			if menu.continue_button.enabled:
				return _fail("a save this build cannot open is still offered as loadable")
			if menu.status_label.text.strip_edges() == "":
				return _fail("an unopenable save is disabled with no reason given")
			print("an unopenable save is shown, disabled: %s" % menu.status_label.text)

			SaveGame.clear()
			print("TEST_MAIN_MENU_CONTINUE: PASS")
			quit(0)
			return true
	return false


func _corrupt_version() -> void:
	var f: FileAccess = FileAccess.open("user://savegame.json", FileAccess.READ)
	var data: Dictionary = JSON.parse_string(f.get_as_text())
	f.close()
	data["version"] = 999
	f = FileAccess.open("user://savegame.json", FileAccess.WRITE)
	f.store_string(JSON.stringify(data))
	f.close()


func _fail(message: String) -> bool:
	print("TEST_MAIN_MENU_CONTINUE: FAIL (%s)" % message)
	quit(1)
	return true