extends MainLoop

# Test to verify that existing save files with old checksum format can be migrated
# This ensures backward compatibility with the checksum fix

func _initialize():
	test_migration_compatibility()

func _finalize():
	pass

func test_migration_compatibility():
	print("=== MIGRATION COMPATIBILITY TEST ===")

	# Test 1: Simulate old save file format (with problematic checksums)
	print("\n--- Test 1: Old Save File Compatibility ---")
	var old_save_data = {
		"_version": 1,
		"high_score": 150,
		"current_score": 0,
		"games_played": 5,
		"total_score": 450,
		"grid_state": {
			"grid_size": {"x": 8, "y": 8},
			"tile_types_count": 5,
			"active_gem_types": [0, 1, 2, 3, 4],
			"grid_layout": []
		}
	}

	# Create old checksum (without normalization)
	var old_checksum = _calculate_old_checksum(old_save_data)
	old_save_data["_checksum"] = old_checksum

	print("Old checksum format: %s" % old_checksum)

	# Simulate JSON round-trip (causes the type conversion issue)
	var json_string = JSON.stringify(old_save_data)
	var json = JSON.new()
	json.parse(json_string)
	var loaded_data = json.data

	# Calculate new checksum with fixed algorithm
	var new_checksum = _calculate_new_checksum(loaded_data)
	print("New checksum format: %s" % new_checksum)

	# The checksums should be different (old system broken)
	if old_checksum != new_checksum:
		print("✅ Confirmed: Old and new checksum formats are different")
		print("   This is expected - old checksums were broken by JSON serialization")
	else:
		print("⚠️ Unexpected: Checksums are the same (might indicate test issue)")

	# Test 2: Verify new system is self-consistent
	print("\n--- Test 2: New System Self-Consistency ---")
	# Remove old checksum and recalculate
	loaded_data.erase("_checksum")
	var first_checksum = _calculate_new_checksum(loaded_data)
	loaded_data["_checksum"] = first_checksum

	# Simulate another save/load cycle
	json_string = JSON.stringify(loaded_data)
	json = JSON.new()
	json.parse(json_string)
	var reloaded_data = json.data

	var second_checksum = _calculate_new_checksum(reloaded_data)

	if first_checksum == second_checksum:
		print("✅ New system is self-consistent across save/load cycles")
		print("   Checksum: %s" % first_checksum)
	else:
		print("❌ CRITICAL: New system is still inconsistent!")
		print("   First: %s, Second: %s" % [first_checksum, second_checksum])

	# Test 3: Verify migration strategy
	print("\n--- Test 3: Migration Strategy ---")
	print("Recommendation: Use version-based checksum handling")
	print("- Files without _checksum: Allow (backward compatibility)")
	print("- Files with version < current: Recalculate checksum after migration")
	print("- Files with current version: Use new checksum validation")