"""
Configuration settings for Chatty application
Handles different environments (development, production, testing)
"""

import os
import secrets
from datetime import timedelta
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()

class Config:
    """Base configuration class"""
    
    # Security Configuration
    SECRET_KEY = os.environ.get('SECRET_KEY') or secrets.token_hex(32)
    
    # MongoDB Configuration
    MONGODB_URL = os.environ.get('MONGODB_URL') or os.environ.get('MONGODB_URI')
    MONGODB_DATABASE = os.environ.get('MONGODB_DATABASE', 'Atlas')
    
    # Session Configuration
    PERMANENT_SESSION_LIFETIME = timedelta(hours=int(os.environ.get('SESSION_LIFETIME_HOURS', 24)))
    SESSION_COOKIE_SECURE = os.environ.get('SESSION_COOKIE_SECURE', 'False').lower() == 'true'
    SESSION_COOKIE_HTTPONLY = True
    SESSION_COOKIE_SAMESITE = 'Lax'
    
    # CSRF Configuration
    WTF_CSRF_TIME_LIMIT = int(os.environ.get('CSRF_TIME_LIMIT', 3600))  # 1 hour
    WTF_CSRF_SSL_STRICT = os.environ.get('WTF_CSRF_SSL_STRICT', 'False').lower() == 'true'
    WTF_CSRF_ENABLED = os.environ.get('WTF_CSRF_ENABLED', 'True').lower() == 'true'
    
    # Additional CSRF settings for proxy environments (like Hugging Face Spaces)
    WTF_CSRF_CHECK_DEFAULT = os.environ.get('WTF_CSRF_CHECK_DEFAULT', 'True').lower() == 'true'
    
    # Rate Limiting Configuration
    MAX_LOGIN_ATTEMPTS = int(os.environ.get('MAX_LOGIN_ATTEMPTS', 5))
    RATE_LIMIT_WINDOW = int(os.environ.get('RATE_LIMIT_WINDOW', 900))  # 15 minutes
    
    # Anonymous User Configuration
    ANONYMOUS_ENABLED = os.environ.get('ANONYMOUS_ENABLED', 'True').lower() == 'true'
    ANONYMOUS_RATE_LIMIT = int(os.environ.get('ANONYMOUS_RATE_LIMIT', 20))  # messages per hour
    ANONYMOUS_RATE_LIMIT_WINDOW = int(os.environ.get('ANONYMOUS_RATE_LIMIT_WINDOW', 3600))  # 1 hour
    ANONYMOUS_SESSION_TIMEOUT = int(os.environ.get('ANONYMOUS_SESSION_TIMEOUT', 3600))  # 1 hour
    ANONYMOUS_MAX_MESSAGE_LENGTH = int(os.environ.get('ANONYMOUS_MAX_MESSAGE_LENGTH', 2000))  # characters
    
    # API Configuration
    API_URL = os.environ.get('API_URL', 'https://findEthics-Atlas.hf.space/chat')
    API_TIMEOUT = int(os.environ.get('API_TIMEOUT', 30))
    
    # Logging Configuration
    LOG_LEVEL = os.environ.get('LOG_LEVEL', 'INFO')
    LOG_FILE = os.environ.get('LOG_FILE')
    
    # Application Configuration
    DEBUG = False
    TESTING = False
    
    @staticmethod
    def validate_config():
        """Validate required configuration values"""
        errors = []
        
        if not Config.MONGODB_URL:
            errors.append("MONGODB_URL environment variable is required")
        
        if not Config.SECRET_KEY or Config.SECRET_KEY == 'dev-secret-key-change-in-production':
            errors.append("SECRET_KEY environment variable must be set to a secure random value")
        
        if len(Config.SECRET_KEY) < 32:
            errors.append("SECRET_KEY should be at least 32 characters long")
        
        return errors

class DevelopmentConfig(Config):
    """Development configuration"""
    DEBUG = True
    SESSION_COOKIE_SECURE = False
    WTF_CSRF_SSL_STRICT = False
    WTF_CSRF_ENABLED = False  # Disable CSRF for testing
    LOG_LEVEL = 'DEBUG'

class ProductionConfig(Config):
    """Production configuration"""
    DEBUG = False
    
    # Hugging Face Spaces compatibility
    # HF Spaces runs behind a proxy, so we need to be more flexible with CSRF/session settings
    SESSION_COOKIE_SECURE = os.environ.get('SESSION_COOKIE_SECURE', 'False').lower() == 'true'
    WTF_CSRF_SSL_STRICT = os.environ.get('WTF_CSRF_SSL_STRICT', 'False').lower() == 'true'
    
    # Override with production-specific values
    MAX_LOGIN_ATTEMPTS = int(os.environ.get('MAX_LOGIN_ATTEMPTS', 3))  # Stricter in production
    RATE_LIMIT_WINDOW = int(os.environ.get('RATE_LIMIT_WINDOW', 1800))  # 30 minutes
    
    @staticmethod
    def validate_config():
        """Additional production-specific validation"""
        errors = Config.validate_config()
        
        # Production-specific checks
        if not os.environ.get('SECRET_KEY'):
            errors.append("SECRET_KEY environment variable must be explicitly set in production")
        
        # Relaxed validation for Hugging Face Spaces compatibility
        # SESSION_COOKIE_SECURE and WTF_CSRF_SSL_STRICT are now optional in production
        
        if ProductionConfig.DEBUG:
            errors.append("DEBUG must be False in production")
        
        return errors

class HuggingFaceConfig(Config):
    """Hugging Face Spaces specific configuration
    
    Security Note:
    CSRF protection is disabled for Hugging Face Spaces due to:
    1. HF Spaces runs applications in iframes which breaks CSRF token validation
    2. Cross-origin restrictions prevent proper CSRF token exchange
    3. HF Spaces provides its own security layer at the platform level
    
    Trade-offs:
    - Reduced protection against CSRF attacks
    - Mitigated by: HF Spaces platform security, rate limiting, and authentication requirements
    """
    DEBUG = False
    
    # Hugging Face Spaces runs in iframes with complex proxy setup
    # Sessions and CSRF are problematic in this environment
    SESSION_COOKIE_SECURE = False
    WTF_CSRF_SSL_STRICT = False
    WTF_CSRF_ENABLED = False  # Disable CSRF for HF Spaces due to iframe issues
    
    # Very permissive session settings for iframe compatibility
    SESSION_COOKIE_SAMESITE = None  # Most permissive setting
    SESSION_COOKIE_HTTPONLY = False  # Allow JavaScript access
    SESSION_COOKIE_DOMAIN = None     # Don't restrict domain
    SESSION_COOKIE_PATH = '/'        # Ensure cookies work across all paths
    
    # Extend session lifetime to help with iframe issues
    PERMANENT_SESSION_LIFETIME = timedelta(hours=int(os.environ.get('SESSION_LIFETIME_HOURS', 48)))
    
    # Production-level security for other settings
    MAX_LOGIN_ATTEMPTS = int(os.environ.get('MAX_LOGIN_ATTEMPTS', 3))
    RATE_LIMIT_WINDOW = int(os.environ.get('RATE_LIMIT_WINDOW', 1800))
    
    @staticmethod
    def validate_config():
        """Validation for Hugging Face Spaces"""
        errors = Config.validate_config()
        
        if not os.environ.get('SECRET_KEY'):
            errors.append("SECRET_KEY environment variable must be explicitly set")
        
        return errors

class TestingConfig(Config):
    """Testing configuration"""
    TESTING = True
    DEBUG = True
    SESSION_COOKIE_SECURE = False
    WTF_CSRF_ENABLED = False  # Disable CSRF for testing
    MONGODB_DATABASE = os.environ.get('TEST_MONGODB_DATABASE', 'Atlas_test')

# Configuration mapping
config = {
    'development': DevelopmentConfig,
    'production': ProductionConfig,
    'huggingface': HuggingFaceConfig,
    'testing': TestingConfig,
    'default': DevelopmentConfig
}

def get_config(config_name=None):
    """Get configuration class based on environment"""
    if config_name is None:
        config_name = os.environ.get('FLASK_ENV', 'development')
    
    return config.get(config_name, config['default'])

def validate_environment():
    """Validate the current environment configuration"""
    config_name = os.environ.get('FLASK_ENV', 'development')
    config_class = get_config(config_name)
    
    errors = config_class.validate_config()
    
    if errors:
        print(f"Configuration errors for {config_name} environment:")
        for error in errors:
            print(f"  - {error}")
        return False
    
    print(f"✓ Configuration validation passed for {config_name} environment")
    return True

if __name__ == "__main__":
    # Validate configuration when run directly
    validate_environment()