import pytest

from app.db.session import _normalize_payment_order_provision_username_index


class _FakeResult:
    def __init__(self, rows):
        self._rows = rows

    def __iter__(self):
        return iter(self._rows)


class _FakeConnection:
    def __init__(self, *, dialect_name: str, responses: list[list[tuple[str]]]) -> None:
        self.dialect = type("Dialect", (), {"name": dialect_name})()
        self._responses = list(responses)
        self.executed: list[tuple[str, dict[str, object] | None]] = []

    async def execute(self, statement, params=None):
        self.executed.append((str(statement), params))
        rows = self._responses.pop(0) if self._responses else []
        return _FakeResult(rows)


@pytest.mark.asyncio
async def test_normalize_payment_order_index_drops_stale_unique_and_recreates_plain_index() -> None:
    connection = _FakeConnection(
        dialect_name="mysql",
        responses=[
            [("ix_payment_orders_provision_username",)],
            [],
            [],
            [],
        ],
    )

    await _normalize_payment_order_provision_username_index(connection)

    executed_sql = [sql for sql, _ in connection.executed]

    assert any(
        "DROP INDEX `ix_payment_orders_provision_username` ON `payment_orders`" in sql
        for sql in executed_sql
    )
    assert any(
        "CREATE INDEX `ix_payment_orders_provision_username` ON `payment_orders` (`provision_username`)"
        in sql
        for sql in executed_sql
    )


@pytest.mark.asyncio
async def test_normalize_payment_order_index_keeps_existing_non_unique_index() -> None:
    connection = _FakeConnection(
        dialect_name="mysql",
        responses=[
            [],
            [("custom_payment_orders_provision_username",)],
        ],
    )

    await _normalize_payment_order_provision_username_index(connection)

    executed_sql = [sql for sql, _ in connection.executed]

    assert not any("DROP INDEX" in sql for sql in executed_sql)
    assert not any("CREATE INDEX" in sql for sql in executed_sql)


@pytest.mark.asyncio
async def test_normalize_payment_order_index_skips_non_mysql_backends() -> None:
    connection = _FakeConnection(dialect_name="sqlite", responses=[])

    await _normalize_payment_order_provision_username_index(connection)

    assert connection.executed == []