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

from app.config import settings


engine = create_engine(
    settings.database_url,
    connect_args={"check_same_thread": False} if settings.database_url.startswith("sqlite") else {},
    future=True,
)

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


class Base(DeclarativeBase):
    pass


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    from app import models  # noqa: F401 — registers models on Base

    Base.metadata.create_all(bind=engine)
    _migrate_employees_portal_user_id()
    _migrate_competitor_listings_auto_fields()


def _migrate_employees_portal_user_id() -> None:
    inspector = inspect(engine)
    if "employees" not in inspector.get_table_names():
        return
    columns = {col["name"] for col in inspector.get_columns("employees")}
    with engine.begin() as conn:
        if "portal_user_id" not in columns:
            conn.execute(text("ALTER TABLE employees ADD COLUMN portal_user_id VARCHAR(100)"))
        conn.execute(
            text("CREATE UNIQUE INDEX IF NOT EXISTS ix_employees_portal_user_id ON employees (portal_user_id)")
        )


def _migrate_competitor_listings_auto_fields() -> None:
    inspector = inspect(engine)
    if "competitor_listings" not in inspector.get_table_names():
        return
    columns = {col["name"] for col in inspector.get_columns("competitor_listings")}
    with engine.begin() as conn:
        if "permit_number" not in columns:
            conn.execute(text("ALTER TABLE competitor_listings ADD COLUMN permit_number VARCHAR(100)"))
        if "auto_discovered" not in columns:
            conn.execute(text("ALTER TABLE competitor_listings ADD COLUMN auto_discovered BOOLEAN NOT NULL DEFAULT 0"))