import datetime

MIGRATIONS = []
migration = MIGRATIONS.append


def migrate(db):
    ensure_migrations_table(db)
    already_applied = {r["name"] for r in db["_llm_migrations"].rows}
    for fn in MIGRATIONS:
        name = fn.__name__
        if name not in already_applied:
            fn(db)
            db["_llm_migrations"].insert(
                {"name": name, "applied_at": str(datetime.datetime.utcnow())}
            )
            already_applied.add(name)


def ensure_migrations_table(db):
    if not db["_llm_migrations"].exists():
        db["_llm_migrations"].create(
            {
                "name": str,
                "applied_at": str,
            },
            pk="name",
        )


@migration
def m001_initial(db):
    # Ensure the original table design exists, so other migrations can run
    if db["log"].exists():
        # It needs to have the chat_id column
        if not "chat_id" in db["log"].columns_dict:
            db["log"].add_column("chat_id")
        return
    db["log"].create(
        {
            "provider": str,
            "system": str,
            "prompt": str,
            "chat_id": str,
            "response": str,
            "model": str,
            "timestamp": str,
        }
    )


@migration
def m002_id_primary_key(db):
    db["log"].transform(pk="id")


@migration
def m003_chat_id_foreign_key(db):
    db["log"].transform(types={"chat_id": int})
    db["log"].add_foreign_key("chat_id", "log", "id")


@migration
def m004_column_order(db):
    db["log"].transform(
        column_order=(
            "id",
            "model",
            "timestamp",
            "prompt",
            "system",
            "response",
            "chat_id",
        )
    )


@migration
def m004_drop_provider(db):
    db["log"].transform(drop=("provider",))


@migration
def m005_debug(db):
    db["log"].add_column("debug", str)
    db["log"].add_column("duration_ms", int)