extends Node

const SAVE_FILE_PATH = "user://savegame.save"
const SAVE_FORMAT_VERSION = 1
const MAX_GRID_SIZE = 15
const MAX_TILE_TYPES = 10
const MAX_SCORE = 999999999
const MAX_GAMES_PLAYED = 100000

var game_data = {
	"high_score": 0,
	"current_score": 0,
	"games_played": 0,
	"total_score": 0,
	"grid_state": {
		"grid_size": {"x": 8, "y": 8},
		"tile_types_count": 5,
		"active_gem_types": [0, 1, 2, 3, 4],
		"grid_layout": []  # 2D array of tile types
	}
}

func _ready():
	load_game()

func save_game():
	# Create backup before saving
	_create_backup()

	# Add version and validation data
	var save_data = game_data.duplicate(true)
	save_data["_version"] = SAVE_FORMAT_VERSION
	save_data["_checksum"] = _calculate_checksum(save_data)

	var save_file = FileAccess.open(SAVE_FILE_PATH, FileAccess.WRITE)
	if save_file == null:
		DebugManager.log_error("Failed to open save file for writing: %s" % SAVE_FILE_PATH, "SaveManager")
		return false

	var json_string = JSON.stringify(save_data)

	# Validate JSON was created successfully
	if json_string.is_empty():
		DebugManager.log_error("Failed to serialize save data to JSON", "SaveManager")
		save_file.close()
		return false

	save_file.store_var(json_string)
	save_file.close()

	DebugManager.log_info("Game saved successfully. High score: %d, Current score: %d" % [game_data.high_score, game_data.current_score], "SaveManager")
	return true

func load_game():
	if not FileAccess.file_exists(SAVE_FILE_PATH):
		DebugManager.log_info("No save file found, using defaults", "SaveManager")
		return

	var save_file = FileAccess.open(SAVE_FILE_PATH, FileAccess.READ)
	if save_file == null:
		DebugManager.log_error("Failed to open save file for reading: %s" % SAVE_FILE_PATH, "SaveManager")
		return

	# Check file size to prevent memory exhaustion
	var file_size = save_file.get_length()
	if file_size > 1048576:  # 1MB limit
		DebugManager.log_error("Save file too large: %d bytes (max 1MB)" % file_size, "SaveManager")
		save_file.close()
		return

	var json_string = save_file.get_var()
	save_file.close()

	if not json_string is String:
		DebugManager.log_error("Save file contains invalid data type", "SaveManager")
		return

	var json = JSON.new()
	var parse_result = json.parse(json_string)
	if parse_result != OK:
		DebugManager.log_error("Failed to parse save file JSON: %s" % json.error_string, "SaveManager")
		_restore_backup_if_exists()
		return

	var loaded_data = json.data
	if not loaded_data is Dictionary:
		DebugManager.log_error("Save file root is not a dictionary", "SaveManager")
		_restore_backup_if_exists()
		return

	# Validate and sanitize loaded data
	if not _validate_save_data(loaded_data):
		DebugManager.log_error("Save file failed validation, using defaults", "SaveManager")
		_restore_backup_if_exists()
		return

	# Safely merge validated data
	_merge_validated_data(loaded_data)

	DebugManager.log_info("Game loaded successfully. High score: %d, Games played: %d" % [game_data.high_score, game_data.games_played], "SaveManager")

func update_current_score(score: int):
	# Input validation
	if score < 0:
		DebugManager.log_warn("Negative score rejected: %d" % score, "SaveManager")
		return
	if score > MAX_SCORE:
		DebugManager.log_warn("Score too high, capping at maximum: %d -> %d" % [score, MAX_SCORE], "SaveManager")
		score = MAX_SCORE

	game_data.current_score = score
	if score > game_data.high_score:
		game_data.high_score = score
		DebugManager.log_info("New high score: %d" % score, "SaveManager")

func start_new_game():
	game_data.current_score = 0
	game_data.games_played += 1
	# Clear any saved grid state for fresh start
	game_data.grid_state.grid_layout = []
	DebugManager.log_info("Started new game #%d (cleared grid state)" % game_data.games_played, "SaveManager")

func finish_game(final_score: int):
	# Input validation
	if final_score < 0:
		DebugManager.log_warn("Negative final score rejected: %d" % final_score, "SaveManager")
		return
	if final_score > MAX_SCORE:
		DebugManager.log_warn("Final score too high, capping: %d -> %d" % [final_score, MAX_SCORE], "SaveManager")
		final_score = MAX_SCORE

	DebugManager.log_info("Finishing game with score: %d (previous: %d)" % [final_score, game_data.current_score], "SaveManager")
	game_data.current_score = final_score

	# Prevent total_score overflow
	var new_total = game_data.total_score + final_score
	if new_total < game_data.total_score:  # Overflow check
		DebugManager.log_warn("Total score overflow prevented", "SaveManager")
		game_data.total_score = MAX_SCORE
	else:
		game_data.total_score = new_total

	if final_score > game_data.high_score:
		game_data.high_score = final_score
		DebugManager.log_info("New high score achieved: %d" % final_score, "SaveManager")
	save_game()

func get_high_score() -> int:
	return game_data.high_score

func get_current_score() -> int:
	return game_data.current_score

func get_games_played() -> int:
	return game_data.games_played

func get_total_score() -> int:
	return game_data.total_score

func save_grid_state(grid_size: Vector2i, tile_types_count: int, active_gem_types: Array, grid_layout: Array):
	# Comprehensive input validation
	if not _validate_grid_parameters(grid_size, tile_types_count, active_gem_types, grid_layout):
		DebugManager.log_error("Grid state validation failed, not saving", "SaveManager")
		return

	DebugManager.log_info("Saving grid state: size(%d,%d), types=%d, layout_rows=%d" % [grid_size.x, grid_size.y, tile_types_count, grid_layout.size()], "SaveManager")

	game_data.grid_state.grid_size = {"x": grid_size.x, "y": grid_size.y}
	game_data.grid_state.tile_types_count = tile_types_count
	game_data.grid_state.active_gem_types = active_gem_types.duplicate()
	game_data.grid_state.grid_layout = grid_layout.duplicate(true)  # Deep copy

	# Debug: Print first few rows of saved layout
	for y in range(min(3, grid_layout.size())):
		var row_str = ""
		for x in range(min(8, grid_layout[y].size())):
			row_str += str(grid_layout[y][x]) + " "
		DebugManager.log_debug("Saved row %d: %s" % [y, row_str], "SaveManager")

	save_game()

func get_saved_grid_state() -> Dictionary:
	return game_data.grid_state

func has_saved_grid() -> bool:
	return game_data.grid_state.grid_layout.size() > 0

func clear_grid_state():
	DebugManager.log_info("Clearing saved grid state", "SaveManager")
	game_data.grid_state.grid_layout = []
	save_game()

func reset_all_progress():
	"""Reset all game progress and delete save files completely"""
	DebugManager.log_info("Starting complete progress reset", "SaveManager")

	# Reset all game data to initial values
	game_data = {
		"high_score": 0,
		"current_score": 0,
		"games_played": 0,
		"total_score": 0,
		"grid_state": {
			"grid_size": {"x": 8, "y": 8},
			"tile_types_count": 5,
			"active_gem_types": [0, 1, 2, 3, 4],
			"grid_layout": []  # 2D array of tile types
		}
	}

	# Delete main save file
	if FileAccess.file_exists(SAVE_FILE_PATH):
		var error = DirAccess.remove_absolute(SAVE_FILE_PATH)
		if error == OK:
			DebugManager.log_info("Main save file deleted successfully", "SaveManager")
		else:
			DebugManager.log_error("Failed to delete main save file: error %d" % error, "SaveManager")

	# Delete backup file
	var backup_path = SAVE_FILE_PATH + ".backup"
	if FileAccess.file_exists(backup_path):
		var error = DirAccess.remove_absolute(backup_path)
		if error == OK:
			DebugManager.log_info("Backup save file deleted successfully", "SaveManager")
		else:
			DebugManager.log_error("Failed to delete backup save file: error %d" % error, "SaveManager")

	DebugManager.log_info("Progress reset completed - all scores and save data cleared", "SaveManager")
	return true

# Security and validation helper functions
func _validate_save_data(data: Dictionary) -> bool:
	# Check required fields exist and have correct types
	var required_fields = ["high_score", "current_score", "games_played", "total_score", "grid_state"]
	for field in required_fields:
		if not data.has(field):
			DebugManager.log_error("Missing required field: %s" % field, "SaveManager")
			return false

	# Validate numeric fields
	if not _is_valid_score(data.get("high_score", 0)):
		return false
	if not _is_valid_score(data.get("current_score", 0)):
		return false
	if not _is_valid_score(data.get("total_score", 0)):
		return false

	var games_played = data.get("games_played", 0)
	# Accept both int and float for games_played, convert to int for validation
	if not (games_played is int or games_played is float):
		DebugManager.log_error("Invalid games_played type: %s (type: %s)" % [str(games_played), typeof(games_played)], "SaveManager")
		return false

	var games_played_int = int(games_played)
	if games_played_int < 0 or games_played_int > MAX_GAMES_PLAYED:
		DebugManager.log_error("Invalid games_played value: %d (range: 0-%d)" % [games_played_int, MAX_GAMES_PLAYED], "SaveManager")
		return false

	# Validate grid state
	var grid_state = data.get("grid_state", {})
	if not grid_state is Dictionary:
		DebugManager.log_error("Grid state is not a dictionary", "SaveManager")
		return false

	return _validate_grid_state(grid_state)

func _validate_grid_state(grid_state: Dictionary) -> bool:
	# Check grid size
	if not grid_state.has("grid_size") or not grid_state.grid_size is Dictionary:
		DebugManager.log_error("Invalid grid_size in save data", "SaveManager")
		return false

	var size = grid_state.grid_size
	if not size.has("x") or not size.has("y"):
		return false

	var width = size.x
	var height = size.y
	if not width is int or not height is int:
		return false
	if width < 3 or height < 3 or width > MAX_GRID_SIZE or height > MAX_GRID_SIZE:
		DebugManager.log_error("Grid size out of bounds: %dx%d" % [width, height], "SaveManager")
		return false

	# Check tile types
	var tile_types = grid_state.get("tile_types_count", 0)
	if not tile_types is int or tile_types < 3 or tile_types > MAX_TILE_TYPES:
		DebugManager.log_error("Invalid tile_types_count: %s" % str(tile_types), "SaveManager")
		return false

	# Validate grid layout if present
	var layout = grid_state.get("grid_layout", [])
	if layout.size() > 0:
		return _validate_grid_layout(layout, width, height, tile_types)

	return true

func _validate_grid_layout(layout: Array, expected_width: int, expected_height: int, max_tile_type: int) -> bool:
	if layout.size() != expected_height:
		DebugManager.log_error("Grid layout height mismatch: %d vs %d" % [layout.size(), expected_height], "SaveManager")
		return false

	for y in range(layout.size()):
		var row = layout[y]
		if not row is Array:
			DebugManager.log_error("Grid layout row %d is not an array" % y, "SaveManager")
			return false
		if row.size() != expected_width:
			DebugManager.log_error("Grid layout row %d width mismatch: %d vs %d" % [y, row.size(), expected_width], "SaveManager")
			return false

		for x in range(row.size()):
			var tile_type = row[x]
			if not tile_type is int:
				DebugManager.log_error("Grid tile [%d][%d] is not an integer: %s" % [y, x, str(tile_type)], "SaveManager")
				return false
			if tile_type < -1 or tile_type >= max_tile_type:
				DebugManager.log_error("Grid tile [%d][%d] type out of range: %d" % [y, x, tile_type], "SaveManager")
				return false

	return true

func _validate_grid_parameters(grid_size: Vector2i, tile_types_count: int, active_gem_types: Array, grid_layout: Array) -> bool:
	# Validate grid size
	if grid_size.x < 3 or grid_size.y < 3 or grid_size.x > MAX_GRID_SIZE or grid_size.y > MAX_GRID_SIZE:
		DebugManager.log_error("Invalid grid size: %dx%d (min 3x3, max %dx%d)" % [grid_size.x, grid_size.y, MAX_GRID_SIZE, MAX_GRID_SIZE], "SaveManager")
		return false

	# Validate tile types count
	if tile_types_count < 3 or tile_types_count > MAX_TILE_TYPES:
		DebugManager.log_error("Invalid tile types count: %d (min 3, max %d)" % [tile_types_count, MAX_TILE_TYPES], "SaveManager")
		return false

	# Validate active gem types
	if active_gem_types.size() != tile_types_count:
		DebugManager.log_error("Active gem types size mismatch: %d vs %d" % [active_gem_types.size(), tile_types_count], "SaveManager")
		return false

	# Validate grid layout
	return _validate_grid_layout(grid_layout, grid_size.x, grid_size.y, tile_types_count)

func _is_valid_score(score) -> bool:
	# Accept both int and float, but convert to int for validation
	if not (score is int or score is float):
		DebugManager.log_error("Score is not a number: %s (type: %s)" % [str(score), typeof(score)], "SaveManager")
		return false

	var score_int = int(score)
	if score_int < 0 or score_int > MAX_SCORE:
		DebugManager.log_error("Score out of bounds: %d" % score_int, "SaveManager")
		return false
	return true

func _merge_validated_data(loaded_data: Dictionary):
	# Safely merge only validated fields, converting floats to ints for scores
	for key in ["high_score", "current_score", "total_score"]:
		if loaded_data.has(key):
			var value = loaded_data[key]
			# Convert float scores to integers
			game_data[key] = int(value) if (value is float or value is int) else 0

	# Games played should always be an integer
	if loaded_data.has("games_played"):
		var games_played = loaded_data["games_played"]
		game_data["games_played"] = int(games_played) if (games_played is float or games_played is int) else 0

	# Merge grid state carefully
	var loaded_grid = loaded_data.get("grid_state", {})
	for grid_key in ["grid_size", "tile_types_count", "active_gem_types", "grid_layout"]:
		if loaded_grid.has(grid_key):
			game_data.grid_state[grid_key] = loaded_grid[grid_key]

func _calculate_checksum(data: Dictionary) -> String:
	# Simple checksum for save file integrity
	var json_string = JSON.stringify(data)
	return str(json_string.hash())

func _create_backup():
	# Create backup of current save file
	if FileAccess.file_exists(SAVE_FILE_PATH):
		var backup_path = SAVE_FILE_PATH + ".backup"
		var original = FileAccess.open(SAVE_FILE_PATH, FileAccess.READ)
		var backup = FileAccess.open(backup_path, FileAccess.WRITE)
		if original and backup:
			backup.store_var(original.get_var())
			backup.close()
		if original:
			original.close()

func _restore_backup_if_exists():
	var backup_path = SAVE_FILE_PATH + ".backup"
	if FileAccess.file_exists(backup_path):
		DebugManager.log_info("Attempting to restore from backup", "SaveManager")
		var backup = FileAccess.open(backup_path, FileAccess.READ)
		var original = FileAccess.open(SAVE_FILE_PATH, FileAccess.WRITE)
		if backup and original:
			original.store_var(backup.get_var())
			original.close()
			DebugManager.log_info("Backup restored successfully", "SaveManager")
			load_game()  # Try to load the restored backup
		if backup:
			backup.close()