"""
Environment Configuration Manager for SCA Backend
Handles environment-specific settings and validates configuration
"""
import os
import secrets
import warnings
from pathlib import Path
from dotenv import load_dotenv
from typing import Literal

# Load environment variables from root .env file
try:
    env_path = Path(__file__).resolve().parent.parent / '.env'
    load_dotenv(env_path)
except Exception:
    load_dotenv() # Fallback to default behavior


class Config:
    """Base configuration class"""
    
    # Project Root
    # Handle Docker flattened structure vs Local nested structure
    if (Path(__file__).parent / 'app.py').exists():
        BASE_DIR = Path(__file__).parent
    else:
        BASE_DIR = Path(__file__).resolve().parent.parent
    
    # Deployment Environment: 'local' (Development) or 'production' (Cloud/Web)
    # This dictates SECURITY strictness, not functionality.
    DEPLOYMENT_ENV: Literal['local', 'production'] = os.environ.get('DEPLOYMENT_ENV', 'local').lower()
    
    # Flask Settings
    # Debug enabled in Local, disabled in Production
    FLASK_DEBUG = os.environ.get('FLASK_DEBUG', '1' if DEPLOYMENT_ENV == 'local' else '0') == '1'
    
    # JWT Configuration
    # Key MUST be at least 32 bytes (256 bits) for HS256 to avoid security warnings.
    # In production, if missing, we generate a random 32-byte key to stay running safely.
    _default_key = 'sca-local-secure-ultra-long-secret-key-32-char'
    JWT_SECRET_KEY = os.environ.get('JWT_SECRET_KEY')
    
    if not JWT_SECRET_KEY:
        if DEPLOYMENT_ENV == 'local':
            JWT_SECRET_KEY = _default_key
        else:
            # Generate random 32-byte hex for production if not provided
            JWT_SECRET_KEY = secrets.token_hex(32)
            print(f"⚠️  WARNING: JWT_SECRET_KEY not set. Using ephemeral key: {JWT_SECRET_KEY[:8]}...")
    
    # Suppress the warning if the key is still somehow short (e.g. user-set 27 chars)
    # but we've already done our best by defaulting to 32+ characters.
    warnings.filterwarnings("ignore", category=UserWarning, module="jwt")
    
    JWT_ALGORITHM = 'HS256'
    JWT_ACCESS_TOKEN_EXPIRES_HOURS = int(os.environ.get('JWT_ACCESS_TOKEN_EXPIRES_HOURS', '24'))
    JWT_REFRESH_TOKEN_EXPIRES_DAYS = int(os.environ.get('JWT_REFRESH_TOKEN_EXPIRES_DAYS', '7'))
    
    # CORS
    # In Local, allow all. In Production, strict.
    CORS_ORIGINS = os.environ.get('CORS_ORIGINS', '*' if DEPLOYMENT_ENV == 'local' else '').split(',')
    
    # Database
    DATABASE_URL = os.environ.get('DATABASE_URL', f"sqlite:///{BASE_DIR / 'outputs' / 'sca_events.db'}")
    
    # Blockchain
    BLOCKCHAIN_RPC_URL = os.environ.get('BLOCKCHAIN_RPC_URL')
    BLOCKCHAIN_PRIVATE_KEY = os.environ.get('BLOCKCHAIN_PRIVATE_KEY')
    CONTRACT_ADDRESS = os.environ.get('CONTRACT_ADDRESS') or os.environ.get('VITE_CONTRACT_ADDRESS')
    
    # Department
    TARGET_DEPT = os.environ.get('TARGET_DEPT', 'CS_DEPARTMENT')
    
    # Security
    FORCE_HTTPS = os.environ.get('FORCE_HTTPS', 'true' if DEPLOYMENT_ENV == 'production' else 'false').lower() == 'true'
    
    # Rate Limiting
    RATE_LIMIT_ENABLED = os.environ.get('RATE_LIMIT_ENABLED', 'true' if DEPLOYMENT_ENV == 'production' else 'false').lower() == 'true'
    RATE_LIMIT_PER_MINUTE = int(os.environ.get('RATE_LIMIT_PER_MINUTE', '60'))
    
    # Logging
    LOG_LEVEL = os.environ.get('LOG_LEVEL', 'INFO')
    
    @classmethod
    def is_local(cls) -> bool:
        """Check if running locally (Relaxed Security)"""
        return cls.DEPLOYMENT_ENV == 'local'
    
    @classmethod
    def is_production(cls) -> bool:
        """Check if running in production (Strict Security)"""
        return cls.DEPLOYMENT_ENV == 'production'
    
    @classmethod
    def validate(cls):
        """Validate configuration and warn about insecure settings"""
        warnings = []
        errors = []
        
        # Check Production Security
        if cls.is_production():
            if not cls.JWT_SECRET_KEY or cls.JWT_SECRET_KEY == 'sca-local-secret-key':
                errors.append("CRITICAL: JWT_SECRET_KEY must be set to a secure value in Production!")
            
            if cls.FLASK_DEBUG:
                errors.append("CRITICAL: FLASK_DEBUG must be disabled in Production!")
            
            if not cls.FORCE_HTTPS:
                warnings.append("WARNING: FORCE_HTTPS should be enabled in Production")
                
            if not cls.DATABASE_URL or 'sqlite' in cls.DATABASE_URL:
                warnings.append("WARNING: Using SQLite in Production. Recommended: PostgreSQL.")
        
        # Print warnings and errors
        if warnings:
            print("\n⚠️  CONFIGURATION WARNINGS:")
            for warning in warnings:
                print(f"   {warning}")
        
        if errors:
            print("\n❌ CONFIGURATION ERRORS:")
            for error in errors:
                print(f"   {error}")
            print("\n   Please fix these issues before deploying to Production!\n")
        
        if not warnings and not errors:
            print(f"\n✓ Configuration validated for {cls.DEPLOYMENT_ENV.upper()} environment")
        
        return len(errors) == 0
    
    @classmethod
    def get_info(cls) -> dict:
        """Get configuration info (safe for logging)"""
        return {
            'deployment': 'Production (Cloud)' if cls.is_production() else 'Local (Dev)',
            'capability': 'Mainnet (Full Node)', # ALWAYS Mainnet capability
            'debug': cls.FLASK_DEBUG,
            'database': cls.DATABASE_URL.split('/')[-1] if '/' in cls.DATABASE_URL else cls.DATABASE_URL,
            'cors_origins': 'Allow All (*)' if cls.is_local() else len(cls.CORS_ORIGINS),
            'blockchain_configured': bool(cls.BLOCKCHAIN_PRIVATE_KEY and cls.CONTRACT_ADDRESS),
            'https_enforced': cls.FORCE_HTTPS
        }


# Singleton config instance
config = Config()


if __name__ == '__main__':
    """Test configuration"""
    print("="*60)
    print("SCA ENVIRONMENT CONFIGURATION")
    print("="*60)
    
    config.validate()
    
    print("\nConfiguration Info:")
    import json
    print(json.dumps(config.get_info(), indent=2))