"""
Application Configuration

This module contains configuration classes for different environments.
Each configuration class inherits from the base Config class and can override
specific settings as needed.
"""

import os
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()


class Config:
    """Base configuration class with common settings."""
    
    # Flask settings
    SECRET_KEY = os.environ.get('SECRET_KEY') or 'dev-secret-key-change-in-production'
    
    # Database settings
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL') or \
        'postgresql://localhost/personal_finance_dev'
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    SQLALCHEMY_ECHO = False
    
    # API settings
    JSON_SORT_KEYS = False
    JSONIFY_PRETTYPRINT_REGULAR = True


class DevelopmentConfig(Config):
    """Development environment configuration."""
    
    DEBUG = True
    SQLALCHEMY_ECHO = True  # Log SQL queries in development
    
    # Override database URL for development
    SQLALCHEMY_DATABASE_URI = os.environ.get('DEV_DATABASE_URL') or \
        'postgresql://localhost/personal_finance_dev'


class TestingConfig(Config):
    """Testing environment configuration."""
    
    TESTING = True
    WTF_CSRF_ENABLED = False
    
    # Use in-memory SQLite for testing
    SQLALCHEMY_DATABASE_URI = os.environ.get('TEST_DATABASE_URL') or \
        'sqlite:///:memory:'


class ProductionConfig(Config):
    """Production environment configuration."""
    
    # Ensure SECRET_KEY is set in production
    SECRET_KEY = os.environ.get('SECRET_KEY')
    if not SECRET_KEY:
        raise ValueError("SECRET_KEY environment variable must be set in production")
    
    # Production database URL is required
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL')
    if not SQLALCHEMY_DATABASE_URI:
        raise ValueError("DATABASE_URL environment variable must be set in production")
    
    # Production optimizations
    SQLALCHEMY_ENGINE_OPTIONS = {
        'pool_pre_ping': True,
        'pool_recycle': 300,
    }


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


def get_config(config_name=None):
    """
    Get configuration class for the specified environment.
    
    Args:
        config_name (str): Configuration name ('development', 'testing', 'production')
        
    Returns:
        Config: Configuration class instance
    """
    if config_name is None:
        config_name = 'default'
    
    return config_map.get(config_name, DevelopmentConfig)