import os
from pathlib import Path

class Config:
    # Use a default secret key for development, but warn about it
    SECRET_KEY = os.getenv('SECRET_KEY', 'dev-secret-key-change-in-production')
    if SECRET_KEY == 'dev-secret-key-change-in-production':
        print("WARNING: Using default SECRET_KEY. This is insecure and should be changed in production.")
    
    # Use SQLite for simplicity
    SQLALCHEMY_DATABASE_URI = os.getenv('DATABASE_URL', 'sqlite:///app.db')
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    
    # Use SQLite for Celery broker instead of Redis
    CELERY_BROKER_URL = os.getenv('CELERY_BROKER_URL', 'sqla+sqlite:///celery.db')
    CELERY_RESULT_BACKEND = os.getenv('CELERY_RESULT_BACKEND', 'db+sqlite:///celery-results.db')
    
    # Use a mock API key for development if not provided
    OPENAI_API_KEY = os.getenv('OPENAI_API_KEY', 'sk-mock-key-for-development')
    if OPENAI_API_KEY == 'sk-mock-key-for-development':
        print("WARNING: Using mock OPENAI_API_KEY. API calls will fail in production.")
    
    # Ensure instance path exists
    INSTANCE_PATH = os.getenv('INSTANCE_PATH', '/tmp/instance')
    Path(INSTANCE_PATH).mkdir(parents=True, exist_ok=True)

class DevelopmentConfig(Config):
    DEBUG = True
    TESTING = False

class ProductionConfig(Config):
    DEBUG = False
    TESTING = False
    
    # In production, we require real values for these settings
    def __init__(self):
        if self.SECRET_KEY == 'dev-secret-key-change-in-production':
            raise ValueError("Production requires a real SECRET_KEY")
        if self.OPENAI_API_KEY == 'sk-mock-key-for-development':
            raise ValueError("Production requires a real OPENAI_API_KEY")

class TestingConfig(Config):
    TESTING = True
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = 'sqlite:///:memory:'

# Function to determine which config to use
def get_config():
    env = os.getenv('FLASK_ENV', 'development')
    if env == 'production':
        return ProductionConfig()
    elif env == 'testing':
        return TestingConfig()
    else:
        return DevelopmentConfig()