from sqlalchemy import create_engine, text
from sqlalchemy.orm import sessionmaker, DeclarativeBase
from app.core.config import DATABASE_URL

engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


class Base(DeclarativeBase):
    pass


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


# 既存DBに後から追加されたカラム: (テーブル名, カラム名, 型)
_ADDED_COLUMNS = [
    ("note_pages", "section", "VARCHAR"),
    ("knowledge_entries", "headline", "VARCHAR"),
]


def _add_missing_columns() -> None:
    """マイグレーションフレームワークを使っていないため、既存DBに後から追加されたカラムを
    ここで簡易的に補う。create_all() は既存テーブルへのカラム追加は行わないので必要。"""
    with engine.connect() as conn:
        for table, column, column_type in _ADDED_COLUMNS:
            existing = {row[1] for row in conn.execute(text(f"PRAGMA table_info({table})"))}
            if existing and column not in existing:
                conn.execute(text(f"ALTER TABLE {table} ADD COLUMN {column} {column_type}"))
                conn.commit()


def init_db():
    from app.db import models  # noqa: F401
    Base.metadata.create_all(bind=engine)
    _add_missing_columns()