import os
from datetime import timedelta


class Config:
    """Base configuration"""
    SECRET_KEY = os.environ.get('SECRET_KEY') or 'dev-secret-key-change-in-production'
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    JWT_SECRET_KEY = os.environ.get('JWT_SECRET_KEY') or 'jwt-secret-key-change-in-production'
    JWT_ACCESS_TOKEN_EXPIRES = timedelta(hours=1)
    JWT_REFRESH_TOKEN_EXPIRES = timedelta(days=30)
    
    # Celery Configuration
    CELERY = {
        "broker_url": os.environ.get("CELERY_BROKER_URL", "redis://localhost:6379/0"),
        "result_backend": os.environ.get("CELERY_RESULT_BACKEND", "redis://localhost:6379/0"),
        "task_serializer": "json",
        "result_serializer": "json",
        "accept_content": ["json"],
        "timezone": "UTC",
        "enable_utc": True,
        "task_track_started": True,
        "task_time_limit": 30 * 60,  # 30 minutes
        "task_soft_time_limit": 25 * 60,  # 25 minutes
        "task_acks_late": True,  # Acknowledge after task completion
        "task_reject_on_worker_lost": True,  # Re-queue if worker dies
        "worker_prefetch_multiplier": 1,  # Process one task at a time
        "worker_max_tasks_per_child": 100,  # Restart worker after 100 tasks
        "broker_connection_retry_on_startup": True,
        "broker_connection_max_retries": 5,
        "result_expires": 3600,  # Results expire in 1 hour
        "task_default_queue": "default",
        "task_default_exchange": "default",
        "task_default_routing_key": "default",
    }


class DevelopmentConfig(Config):
    """Development configuration"""
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = os.environ.get('DEV_DATABASE_URL') or \
        'sqlite:///dev.db'


class TestingConfig(Config):
    """Testing configuration"""
    TESTING = True
    SQLALCHEMY_DATABASE_URI = os.environ.get('TEST_DATABASE_URL') or \
        'sqlite:///test.db'
    WTF_CSRF_ENABLED = False


class ProductionConfig(Config):
    """Production configuration"""
    DEBUG = False
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL') or \
        'postgresql://user:password@localhost/proddb'
    
    # Security headers
    SESSION_COOKIE_SECURE = True
    SESSION_COOKIE_HTTPONLY = True
    SESSION_COOKIE_SAMESITE = 'Lax'


config_by_name = {
    'dev': DevelopmentConfig,
    'test': TestingConfig,
    'prod': ProductionConfig
}