#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Migration of token => token_digest"""

import hashlib
import os
from warnings import filterwarnings as filter_warnings

from sqlalchemy import MetaData, Table, create_engine
from sqlalchemy.engine import Engine
from sqlalchemy.orm import Session as SessionType
from sqlalchemy.orm import sessionmaker
from sqlalchemy.sql import Select, text


def main() -> int:
    """entry / main function"""

    engine: Engine = create_engine(os.environ["DB"])
    Session: SessionType = sessionmaker(bind=engine)  # type: ignore
    metadata: MetaData = MetaData()

    print("Migrating token_digest...")

    with Session() as session:  # type: ignore
        session.execute(text("ALTER TABLE comment ADD COLUMN token_digest tinyblob"))  # type: ignore

    metadata.clear()
    comment_table = Table("comment", metadata, autoload_with=engine)

    with Session() as session:  # type: ignore
        with session.begin():  # type: ignore
            comments = session.execute(Select(comment_table)).all()  # type: ignore

            for comment in comments:  # type: ignore
                token_digest: bytes = hashlib.sha3_256(comment[-2].encode()).digest()  # type: ignore

                session.execute(  # type: ignore
                    comment_table.update().where(comment_table.c.id == comment.id).values(token_digest=token_digest)  # type: ignore
                )

    with Session() as session:  # type: ignore
        session.execute(text("ALTER TABLE comment DROP COLUMN token"))  # type: ignore
        session.execute(text("ALTER TABLE comment ADD COLUMN score INTEGER DEFAULT 0"))  # type: ignore

    print("token_digest has been migrated.")

    return 0


if __name__ == "__main__":
    assert main.__annotations__.get("return") is int, "main() should return an integer"

    filter_warnings("error", category=Warning)
    raise SystemExit(main())