from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.orm import sessionmaker, declarative_base
from config import settings

DATABASE_URL = settings.database_url

if not DATABASE_URL:
    raise ValueError(
        "DATABASE_URL not found in environment variables. "
        "Please set it in .env file. Example: "
        "postgresql+asyncpg://user:password@localhost:5432/kairo_db"
    )

# Create async engine
engine = create_async_engine(
    DATABASE_URL,
    echo=False,  # Set to True for SQL logging
    future=True,
    pool_pre_ping=True,  # Verify connections before using
    pool_size=10,
    max_overflow=20,
)

# Create async session factory
async_session = sessionmaker(
    engine, class_=AsyncSession, expire_on_commit=False, autoflush=False
)

# Base class for all models
Base = declarative_base()


async def get_db() -> AsyncSession:
    """Dependency for getting async database session"""
    async with async_session() as session:
        try:
            yield session
        finally:
            await session.close()


async def init_db():
    """Initialize database by creating all tables"""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
        
        # Safely migrate existing Postgres table to add the 'what' column
        try:
            from sqlalchemy import text
            await conn.execute(text("ALTER TABLE portfolio_items ADD COLUMN IF NOT EXISTS what TEXT;"))
            print("[Migration] 'what' column migration completed successfully")
        except Exception as e:
            print(f"[Migration Warning] SQL migration warning (might be SQLite or column already exists): {e}")

        # Safely migrate existing Postgres table to add the 'sort_order' column
        try:
            from sqlalchemy import text
            await conn.execute(text("ALTER TABLE portfolio_items ADD COLUMN IF NOT EXISTS sort_order INTEGER DEFAULT 0 NOT NULL;"))
            print("[Migration] 'sort_order' column migration completed successfully")
        except Exception as e:
            print(f"[Migration Warning] SQL migration warning for sort_order: {e}")

        # Safely migrate existing Postgres table to add visitor tracking columns
        try:
            from sqlalchemy import text
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS visitor_id VARCHAR(100);"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS session_id VARCHAR(100);"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS ip_address VARCHAR(50);"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS user_agent TEXT;"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS country VARCHAR(100);"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS city VARCHAR(100);"))
            await conn.execute(text("ALTER TABLE visitor_telemetry ADD COLUMN IF NOT EXISTS visit_count INTEGER DEFAULT 1;"))
            print("[Migration] VisitorTelemetry schema migrations completed successfully!")
        except Exception as e:
            print(f"[Migration Warning] SQL migration warning for visitor_telemetry: {e}")


async def close_db():
    """Close database connections"""
    await engine.dispose()