extends SceneTree

const WorldSimulation = preload("res://src/simulation/world_simulation.gd")
const DemoSnapshot = preload("res://src/persistence/demo_snapshot.gd")
const TEST_PATH := "user://mana_foundry_snapshot_test.json"


func _initialize() -> void:
	DemoSnapshot.path_override = TEST_PATH
	if FileAccess.file_exists(TEST_PATH):
		DirAccess.remove_absolute(ProjectSettings.globalize_path(TEST_PATH))

	var failures: Array[String] = []
	var live := _make_two_stage()
	for _tick in range(400):
		live.step()
	var before := live.state_fingerprint()
	var charged_before := live.get_charged_count()
	var snapshot := live.to_snapshot()

	var restored := WorldSimulation.new()
	if not restored.apply_snapshot(snapshot):
		failures.append("apply_snapshot rejected a live two-stage snapshot.")
	elif restored.state_fingerprint() != before:
		failures.append("Restored simulation fingerprint did not match the live factory.")
	elif restored.get_charged_count() != charged_before:
		failures.append("Restored charged count did not match.")

	if failures.is_empty():
		for _tick in range(200):
			live.step()
			restored.step()
		if live.state_fingerprint() != restored.state_fingerprint():
			failures.append("Live and restored factories diverged after more ticks.")

	if not DemoSnapshot.save_payload({"schema": DemoSnapshot.SCHEMA, "simulation": snapshot}):
		failures.append("DemoSnapshot could not write the test slot.")
	else:
		var loaded := DemoSnapshot.load_payload()
		var from_disk := WorldSimulation.new()
		if not from_disk.apply_snapshot(loaded.get("simulation", {})):
			failures.append("Disk snapshot failed to apply.")
		elif from_disk.state_fingerprint() != before:
			failures.append("Disk snapshot fingerprint did not match the pre-save factory.")

	var empty := WorldSimulation.new()
	if empty.is_demo_complete():
		failures.append("Empty factory reported demo complete.")
	var first_item := _make_two_stage()
	var saw_item := false
	for _tick in range(2000):
		first_item.step()
		if first_item.get_charged_count() >= 1:
			saw_item = true
			break
	if not saw_item:
		failures.append("Two-stage factory never produced a charged crystal for the one-item check.")
	elif first_item.is_demo_complete():
		failures.append("Demo completed after a single charged crystal.")
	else:
		var mid := WorldSimulation.new()
		if not mid.apply_snapshot(first_item.to_snapshot()):
			failures.append("Could not restore the one-item factory.")
		elif mid.is_demo_complete():
			failures.append("Loaded one-item factory reported complete.")

	var packed := load("res://scenes/main.tscn") as PackedScene
	var demo := packed.instantiate()
	root.add_child.call_deferred(demo)
	await process_frame
	await process_frame
	demo.call("_start_new_game")
	var sim: WorldSimulation = demo.get("simulation")
	for x in range(-5, -1):
		sim.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
	sim.place_building(WorldSimulation.KIND_BELT, Vector2i(0, 0), 0)
	for x in range(2, 6):
		sim.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
	for z in range(1, 5):
		sim.place_building(WorldSimulation.KIND_MANA_PIPE, Vector2i(0, z), 1)
	sim.configure_machine_bridge(int(demo.get("anchor_machine_id")), Vector2i(-2, 0), Vector2i(0, 0))
	sim.configure_machine_bridge(int(demo.get("charger_machine_id")), Vector2i(0, 0), Vector2i(2, 0))
	for _tick in range(240):
		sim.step()
	var scene_before := sim.state_fingerprint()
	var payload: Dictionary = demo.call("collect_demo_snapshot")
	if not bool(demo.call("_save_demo_snapshot")):
		failures.append("Scene save helper failed.")
	demo.call("_reset_demo")
	if sim.state_fingerprint() == scene_before:
		failures.append("Reset after save did not change simulation state.")
	if not bool(demo.call("_load_demo_snapshot")):
		failures.append("Scene load helper failed.")
	elif sim.state_fingerprint() != scene_before:
		failures.append("Scene save/load did not restore the simulation fingerprint.")

	if FileAccess.file_exists(TEST_PATH):
		DirAccess.remove_absolute(ProjectSettings.globalize_path(TEST_PATH))
	DemoSnapshot.path_override = ""

	if failures.is_empty():
		print("SNAPSHOT_SMOKE_OK charged=%d fingerprint=%s" % [charged_before, before])
		quit(0)
	else:
		for failure in failures:
			push_error(failure)
		quit(1)


func _make_two_stage() -> WorldSimulation:
	var simulation := WorldSimulation.new()
	simulation.place_building(WorldSimulation.KIND_SOURCE, Vector2i(-6, 0), 0)
	for x in range(-5, -1):
		simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
	simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(0, 0), 0)
	for x in range(2, 6):
		simulation.place_building(WorldSimulation.KIND_BELT, Vector2i(x, 0), 0)
	simulation.place_building(WorldSimulation.KIND_SINK, Vector2i(6, 0), 0)
	var refine_id := simulation.place_building(WorldSimulation.KIND_MACHINE, Vector2i(-1, 1), 0)
	var charger_id := simulation.place_building(WorldSimulation.KIND_CHARGER, Vector2i(1, 1), 0)
	simulation.place_building(WorldSimulation.KIND_MANA_SOURCE, Vector2i(0, 5), 1)
	for z in range(1, 5):
		simulation.place_building(WorldSimulation.KIND_MANA_PIPE, Vector2i(0, z), 1)
	simulation.configure_machine_bridge(refine_id, Vector2i(-2, 0), Vector2i(0, 0))
	simulation.configure_machine_bridge(charger_id, Vector2i(0, 0), Vector2i(2, 0))
	return simulation