#!/usr/bin/env python3
"""
Configuration Management for Chat Server
Supports both environment variables and .env files
"""

import os
from typing import Optional, Any, cast
from pathlib import Path

try:
    from dotenv import load_dotenv # type: ignore
    load_dotenv(override=True)
    DOTENV_AVAILABLE = True
except ImportError:
    DOTENV_AVAILABLE = False


class Config:
    """Configuration class with environment variable support"""
    
    # Server Configuration
    HOST: str = os.getenv('HOST', '127.0.0.1')
    PORT: int = int(os.getenv('PORT', '8765'))
    MAX_HISTORY: int = int(os.getenv('MAX_HISTORY', '100'))
    
    # Admin Configuration
    ADMIN_PASSWORD: str = os.getenv('ADMIN_PASSWORD', '') # Should be set in environment
    
    # SSL Configuration
    USE_SSL: bool = os.getenv('USE_SSL', 'false').lower() == 'true'
    SSL_CERT_PATH: Optional[str] = os.getenv('SSL_CERT_PATH')
    SSL_KEY_PATH: Optional[str] = os.getenv('SSL_KEY_PATH')
    
    # Database Configuration
    DB_PATH: str = os.getenv('DB_PATH', 'data/chat.db')
    
    # Logging Configuration
    LOG_LEVEL: str = os.getenv('LOG_LEVEL', 'INFO')
    LOG_FILE: Optional[str] = os.getenv('LOG_FILE', 'logs/chat_server.log')
    
    # Security Configuration
    MAX_MESSAGE_LENGTH: int = int(os.getenv('MAX_MESSAGE_LENGTH', '4096'))
    MAX_NICKNAME_LENGTH: int = int(os.getenv('MAX_NICKNAME_LENGTH', '32'))
    RATE_LIMIT_MESSAGES: int = int(os.getenv('RATE_LIMIT_MESSAGES', '120'))
    RATE_LIMIT_WINDOW: int = int(os.getenv('RATE_LIMIT_WINDOW', '60'))
    
    # Session Configuration
    SESSION_TIMEOUT: int = int(os.getenv('SESSION_TIMEOUT', '3600'))
    KEEPALIVE_INTERVAL: int = int(os.getenv('KEEPALIVE_INTERVAL', '30'))
    RECONNECT_TIMEOUT: int = int(os.getenv('RECONNECT_TIMEOUT', '300'))
    
    # Backup Configuration
    BACKUP_DIR: str = os.getenv('BACKUP_DIR', './backups')
    AUTO_BACKUP_ENABLED: bool = os.getenv('AUTO_BACKUP_ENABLED', 'false').lower() == 'true'
    AUTO_BACKUP_INTERVAL: int = int(os.getenv('AUTO_BACKUP_INTERVAL', '86400'))  # 24 hours
    
    # Room Configuration
    ROOM_EXPIRATION_HOURS: int = int(os.getenv('ROOM_EXPIRATION_HOURS', '24'))
    AUTO_HISTORY_CLEAR: bool = os.getenv('AUTO_HISTORY_CLEAR', 'false').lower() == 'true'
    
    @classmethod
    def validate(cls) -> bool:
        """Validate configuration"""
        errors = []
        
        # Validate port range
        if not (1 <= cls.PORT <= 65535):
            errors.append(f"Invalid PORT: {cls.PORT}. Must be between 1-65535")
        
        # Validate SSL configuration
        if cls.USE_SSL:
            if not cls.SSL_CERT_PATH or not cls.SSL_KEY_PATH:
                errors.append("SSL enabled but SSL_CERT_PATH or SSL_KEY_PATH not set")
            elif not Path(cast(str, cls.SSL_CERT_PATH)).exists():
                errors.append(f"SSL certificate not found: {cls.SSL_CERT_PATH}")
            elif not Path(cast(str, cls.SSL_KEY_PATH)).exists():
                errors.append(f"SSL key not found: {cls.SSL_KEY_PATH}")
        
        # Validate positive integers
        if cls.MAX_HISTORY < 1:
            errors.append(f"MAX_HISTORY must be positive, got {cls.MAX_HISTORY}")
        if cls.MAX_MESSAGE_LENGTH < 1:
            errors.append(f"MAX_MESSAGE_LENGTH must be positive, got {cls.MAX_MESSAGE_LENGTH}")
        if cls.MAX_NICKNAME_LENGTH < 1:
            errors.append(f"MAX_NICKNAME_LENGTH must be positive, got {cls.MAX_NICKNAME_LENGTH}")
        
        # Print errors
        if errors:
            print("[ERROR] Configuration errors:")
            for error in errors:
                print(f"  - {error}")
            return False
        
        return True
    
    @classmethod
    def display(cls):
        """Display current configuration"""
        print("\n" + "=" * 70)
        print("CHAT SERVER CONFIGURATION")
        print("=" * 70)
        print(f"Server:        {cls.HOST}:{cls.PORT}")
        print(f"SSL:           {'Enabled' if cls.USE_SSL else 'Disabled'}")
        print(f"Database:      {cls.DB_PATH}")
        print(f"Log Level:     {cls.LOG_LEVEL}")
        print(f"Log File:      {cls.LOG_FILE or 'Console only'}")
        print(f"Max History:   {cls.MAX_HISTORY} messages")
        print(f"Rate Limit:    {cls.RATE_LIMIT_MESSAGES} msg/{cls.RATE_LIMIT_WINDOW}s")
        print(f"Auto Backup:   {'Enabled' if cls.AUTO_BACKUP_ENABLED else 'Disabled'}")
        print("=" * 70 + "\n")


# Validate configuration on import
if __name__ != "__main__":
    if not Config.validate():
        raise ValueError("Invalid configuration. Please check your environment variables or .env file")