extends Node
class_name UpdateApplier
## Handles applying downloaded updates: backup, replace, rollback

signal update_started
signal update_progress(step: String, percentage: float)
signal update_completed
signal update_failed(error: String)
signal rollback_completed

const BACKUP_COUNT := 2 # Keep this many backup versions

func apply_update(downloaded_pck_path: String, version: String) -> void:
	emit_signal("update_started")
	
	var game_dir := Config.GAME_DIRECTORY
	var pck_name := Config.get_game_pck()
	var target_pck := game_dir + pck_name
	var backup_dir := Config.BACKUP_DIRECTORY
	
	# Step 1: Ensure game directory exists
	emit_signal("update_progress", "Preparing directories...", 10.0)
	if not _ensure_directory(game_dir):
		emit_signal("update_failed", "Failed to create game directory")
		return
	
	if not _ensure_directory(backup_dir):
		emit_signal("update_failed", "Failed to create backup directory")
		return
	
	# Step 2: Backup existing PCK if it exists
	emit_signal("update_progress", "Backing up current version...", 30.0)
	if FileAccess.file_exists(target_pck):
		var backup_name := pck_name.get_basename() + "_backup_" + Time.get_datetime_string_from_system().replace(":", "-") + ".pck"
		var backup_path := backup_dir + backup_name
		
		if not _copy_file(target_pck, backup_path):
			emit_signal("update_failed", "Failed to backup current version")
			return
		
		# Clean up old backups
		_cleanup_old_backups(backup_dir, BACKUP_COUNT)
	
	# Step 3: Move downloaded file to game directory
	emit_signal("update_progress", "Installing update...", 60.0)
	
	# Delete old PCK first
	if FileAccess.file_exists(target_pck):
		var dir := DirAccess.open(game_dir)
		if dir:
			var err := dir.remove(pck_name)
			if err != OK:
				emit_signal("update_failed", "Failed to remove old game file")
				return
	
	# Copy new PCK
	if not _copy_file(downloaded_pck_path, target_pck):
		emit_signal("update_failed", "Failed to install update")
		return
	
	# Step 4: Copy executable if needed (first install)
	emit_signal("update_progress", "Finalizing...", 80.0)
	
	# Clean up temp file
	var temp_dir := DirAccess.open("user://temp/")
	if temp_dir:
		temp_dir.remove(downloaded_pck_path.get_file())
	
	emit_signal("update_progress", "Update complete!", 100.0)
	emit_signal("update_completed")

func _ensure_directory(path: String) -> bool:
	var dir := DirAccess.open("user://")
	if dir:
		var relative_path := path.replace("user://", "")
		if not dir.dir_exists(relative_path):
			return dir.make_dir_recursive(relative_path) == OK
		return true
	return false

func _copy_file(from: String, to: String) -> bool:
	var source := FileAccess.open(from, FileAccess.READ)
	if not source:
		push_error("[UpdateApplier] Cannot open source file: " + from)
		return false
	
	var dest := FileAccess.open(to, FileAccess.WRITE)
	if not dest:
		source.close()
		push_error("[UpdateApplier] Cannot open destination file: " + to)
		return false
	
	# Copy in chunks for large files
	const CHUNK_SIZE := 1024 * 1024 # 1MB chunks
	while source.get_position() < source.get_length():
		var chunk := source.get_buffer(CHUNK_SIZE)
		dest.store_buffer(chunk)
	
	source.close()
	dest.close()
	
	print("[UpdateApplier] Copied: ", from, " -> ", to)
	return true

func _cleanup_old_backups(backup_dir: String, keep_count: int) -> void:
	var dir := DirAccess.open(backup_dir)
	if not dir:
		return
	
	var backups: Array[String] = []
	dir.list_dir_begin()
	var file := dir.get_next()
	while file != "":
		if file.ends_with(".pck") and "backup" in file:
			backups.append(file)
		file = dir.get_next()
	dir.list_dir_end()
	
	# Sort by name (which includes timestamp)
	backups.sort()
	
	# Remove oldest backups if we have too many
	while backups.size() > keep_count:
		var old_backup = backups.pop_front()
		dir.remove(old_backup)
		print("[UpdateApplier] Removed old backup: ", old_backup)

func rollback_to_backup() -> bool:
	## Rollback to the most recent backup
	var backup_dir := Config.BACKUP_DIRECTORY
	var game_dir := Config.GAME_DIRECTORY
	var pck_name := Config.get_game_pck()
	
	var dir := DirAccess.open(backup_dir)
	if not dir:
		push_error("[UpdateApplier] Cannot access backup directory")
		return false
	
	# Find the most recent backup
	var backups: Array[String] = []
	dir.list_dir_begin()
	var file := dir.get_next()
	while file != "":
		if file.ends_with(".pck") and "backup" in file:
			backups.append(file)
		file = dir.get_next()
	dir.list_dir_end()
	
	if backups.is_empty():
		push_error("[UpdateApplier] No backups found")
		return false
	
	backups.sort()
	var latest_backup = backups.back()
	
	# Restore the backup
	if _copy_file(backup_dir + latest_backup, game_dir + pck_name):
		emit_signal("rollback_completed")
		print("[UpdateApplier] Rolled back to: ", latest_backup)
		return true
	
	return false