import os
from pathlib import Path

from sqlalchemy import text
from sqlmodel import SQLModel, Session, create_engine

# 数据目录：优先使用环境变量（Docker 中设为 /app/data），否则用 backend/data/
DATA_DIR = Path(os.environ.get("NOVAL_DATA_DIR", Path(__file__).resolve().parent.parent / "data"))
DATA_DIR.mkdir(exist_ok=True)

DATABASE_URL = f"sqlite:///{DATA_DIR / 'noval.db'}"

engine = create_engine(DATABASE_URL, echo=False)


def init_db() -> None:
    SQLModel.metadata.create_all(engine)
    _migrate_outline_parent_id()


def _migrate_outline_parent_id() -> None:
    """迁移：为 outline 表添加 parent_id 列（如果尚不存在）"""
    with Session(engine) as session:
        # 检查 outline 表是否存在 parent_id 列
        result = session.exec(text("PRAGMA table_info(outline)"))
        columns = [row[1] for row in result]
        if "parent_id" not in columns:
            session.exec(text("ALTER TABLE outline ADD COLUMN parent_id INTEGER REFERENCES outline(id)"))
            session.exec(text("CREATE INDEX IF NOT EXISTS ix_outline_parent_id ON outline(parent_id)"))
            session.commit()


def get_session():
    with Session(engine) as session:
        yield session