# file_service.py
import json
import os
from typing import List, Dict, Any
from calendar_entry import CalendarEntry
from config import EventConfig

class FileService:
    """Centralized file operations with error handling"""
    
    @staticmethod
    def save_calendar_to_file(entries: List[CalendarEntry], filename: str) -> bool:
        """Save calendar entries to a JSON file"""
        try:
            # Ensure directory exists
            os.makedirs(os.path.dirname(filename) if os.path.dirname(filename) else '.', exist_ok=True)
            
            # Convert entries to dictionaries
            data = [entry.to_dict() for entry in entries]
            
            # Write to file
            with open(filename, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=4, ensure_ascii=False)
            
            return True
        except Exception as e:
            print(f"Error saving calendar to file {filename}: {e}")
            return False
    
    @staticmethod
    def load_calendar_from_file(filename: str) -> List[CalendarEntry]:
        """Load calendar entries from a JSON file"""
        try:
            if not os.path.exists(filename):
                print(f"File {filename} does not exist")
                return []
            
            with open(filename, 'r', encoding='utf-8') as f:
                data = json.load(f)
            
            # Convert dictionaries to CalendarEntry objects
            entries = []
            for entry_data in data:
                try:
                    entry = CalendarEntry.from_dict(entry_data)
                    entries.append(entry)
                except Exception as e:
                    print(f"Error parsing entry: {e}")
                    continue
            
            return entries
        except (FileNotFoundError, json.JSONDecodeError) as e:
            print(f"Error loading calendar from file {filename}: {e}")
            return []
        except Exception as e:
            print(f"Unexpected error loading calendar from file {filename}: {e}")
            return []
    
    @staticmethod
    def validate_file_extension(filename: str) -> bool:
        """Validate that file has correct extension"""
        if not filename:
            return False
        
        # Add extension if missing
        if not filename.endswith(EventConfig.DEFAULT_FILE_EXTENSION):
            filename += EventConfig.DEFAULT_FILE_EXTENSION
        
        return True
    
    @staticmethod
    def ensure_json_extension(filename: str) -> str:
        """Ensure filename has .json extension"""
        if not filename.endswith(EventConfig.DEFAULT_FILE_EXTENSION):
            return filename + EventConfig.DEFAULT_FILE_EXTENSION
        return filename
    
    @staticmethod
    def file_exists(filename: str) -> bool:
        """Check if file exists"""
        return os.path.exists(filename)
    
    @staticmethod
    def get_file_size(filename: str) -> int:
        """Get file size in bytes"""
        try:
            return os.path.getsize(filename)
        except OSError:
            return 0
    
    @staticmethod
    def backup_file(filename: str) -> str:
        """Create a backup of the file"""
        if not os.path.exists(filename):
            return filename
        
        backup_filename = filename.replace('.json', '_backup.json')
        try:
            with open(filename, 'r', encoding='utf-8') as src:
                with open(backup_filename, 'w', encoding='utf-8') as dst:
                    dst.write(src.read())
            return backup_filename
        except Exception as e:
            print(f"Error creating backup: {e}")
            return filename