import os

class Config:
    """Base config."""
    SECRET_KEY = os.environ.get('SECRET_KEY', 'dev-key-placeholder')
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    WTF_CSRF_ENABLED = True
    SESSION_COOKIE_SECURE = False  # Set to True in production with HTTPS

class DevelopmentConfig(Config):
    """Development config."""
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL', 'sqlite:///app.db')
    SQLALCHEMY_ECHO = True

class ProductionConfig(Config):
    """Production config."""
    DEBUG = False
    TESTING = False
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL', 'sqlite:///app.db')
    SESSION_COOKIE_SECURE = True
    REMEMBER_COOKIE_SECURE = True

class TestingConfig(Config):
    """Testing config."""
    TESTING = True
    SQLALCHEMY_DATABASE_URI = 'sqlite:///:memory:'
    WTF_CSRF_ENABLED = False