"""
Module for automatic Alembic migration application
"""
import asyncio
import logging
from pathlib import Path
from alembic import command
from alembic.config import Config
from shared.config import settings

logger = logging.getLogger(__name__)


def get_alembic_config() -> Config:
    """
    Get Alembic configuration.
    
    Returns:
        Config: Alembic configuration object
    """
    # Path to alembic.ini
    alembic_ini_path = Path(__file__).parent.parent.parent / "alembic.ini"
    
    # Create configuration
    alembic_cfg = Config(str(alembic_ini_path))
    
    # Set DATABASE_URL from settings
    alembic_cfg.set_main_option("sqlalchemy.url", settings.DATABASE_URL)
    
    return alembic_cfg


async def upgrade_database(revision: str = "head") -> None:
    """
    Apply migrations to database.
    
    Args:
        revision: Revision to upgrade database to (default "head" - latest)
    """
    try:
        logger.info(f"Applying migrations to database (revision: {revision})...")
        
        # Get configuration
        alembic_cfg = get_alembic_config()
        
        # Apply migrations in separate thread (since command.upgrade is synchronous)
        loop = asyncio.get_event_loop()
        await loop.run_in_executor(
            None,
            command.upgrade,
            alembic_cfg,
            revision
        )
        
        logger.info("Migrations successfully applied")
    except Exception as e:
        logger.error(f"Error applying migrations: {e}", exc_info=True)
        raise


async def check_migrations() -> bool:
    """
    Check for unapplied migrations.
    
    Returns:
        bool: True if there are unapplied migrations, False if all are applied
    """
    try:
        alembic_cfg = get_alembic_config()
        
        # Check for migrations to apply
        # This is a simplified check - in reality can use command.heads()
        # and command.current() to compare revisions
        return True
    except Exception as e:
        logger.warning(f"Failed to check migration status: {e}")
        # On error assume migrations are needed
        return True


async def init_db_with_migrations() -> None:
    """
    Initialize database with migrations applied.
    Replaces old init_db() method for Alembic usage.
    """
    try:
        # Determine database type from URL
        db_type = "SQLite" if "sqlite" in settings.DATABASE_URL.lower() else "PostgreSQL"
        logger.info(f"Initializing {db_type} database with migrations...")
        
        # Apply migrations (this will create tables if they don't exist)
        await upgrade_database("head")
        
        logger.info(f"{db_type} database successfully initialized")
    except Exception as e:
        logger.error(f"Error initializing database: {e}", exc_info=True)
        raise