from unittest.mock import AsyncMock

import pytest

from fastapi_oidc_op.models import User
from fastapi_oidc_op.userid import generate_unique_userid, generate_userid


def test_generate_userid_format() -> None:
    userid = generate_userid()
    # 32-bit proquint format: xxxxx-xxxxx
    parts = userid.split("-")
    assert len(parts) == 2
    for part in parts:
        assert len(part) == 5


def test_generate_userid_uniqueness() -> None:
    ids = {generate_userid() for _ in range(100)}
    assert len(ids) == 100  # All unique


def test_generate_userid_is_lowercase() -> None:
    userid = generate_userid()
    assert userid == userid.lower()


@pytest.mark.anyio
async def test_generate_unique_userid_no_collision() -> None:
    """Returns a userid when no collision occurs."""
    user_repo = AsyncMock()
    user_repo.get_by_userid.return_value = None

    result = await generate_unique_userid(user_repo)

    parts = result.split("-")
    assert len(parts) == 2
    user_repo.get_by_userid.assert_called_once_with(result)


@pytest.mark.anyio
async def test_generate_unique_userid_retries_on_collision() -> None:
    """Retries when a collision is detected and succeeds on second attempt."""
    existing_user = User(userid="taken-xxxxx", username="existing")
    user_repo = AsyncMock()
    user_repo.get_by_userid.side_effect = [existing_user, None]

    result = await generate_unique_userid(user_repo)

    assert user_repo.get_by_userid.call_count == 2
    parts = result.split("-")
    assert len(parts) == 2


@pytest.mark.anyio
async def test_generate_unique_userid_raises_after_max_retries() -> None:
    """Raises RuntimeError when max retries are exhausted."""
    existing_user = User(userid="taken-xxxxx", username="existing")
    user_repo = AsyncMock()
    user_repo.get_by_userid.return_value = existing_user

    with pytest.raises(RuntimeError, match="Failed to generate unique userid"):
        await generate_unique_userid(user_repo)