"""
Database engine and session management with pgvector support.
"""

from sqlalchemy import create_engine, text
from sqlalchemy.orm import DeclarativeBase, sessionmaker

from app.core.config import get_settings

settings = get_settings()

engine = create_engine(
    settings.database_url,
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
    echo=settings.debug,
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


class Base(DeclarativeBase):
    """SQLAlchemy declarative base for all ORM models."""
    pass


def get_db():
    """FastAPI dependency — yields a DB session and closes it after use."""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """
    Initialize the database:
    1. Enable pgvector extension.
    2. Create all tables from ORM metadata.
    """
    with engine.begin() as conn:
        conn.execute(text("CREATE EXTENSION IF NOT EXISTS vector"))

    Base.metadata.create_all(bind=engine)