"""Test the generic fetch_all paginator."""

from types import SimpleNamespace
from typing import Any
from unittest.mock import call, Mock

from src.connectors.utils import fetch_all
from src.constants import BATCH_SIZE


def _page(items: list[Any], total_count: int) -> SimpleNamespace:
    """Build a fake paginated response with .items and .total_count."""
    return SimpleNamespace(items=items, total_count=total_count)


def test_fetch_all_single_page() -> None:
    """A single page (total_count == len(items)) yields all items in one call."""
    fetch_page = Mock(side_effect=[_page(['a', 'b'], total_count=2)])

    res = list(fetch_all(fetch_page))

    assert res == ['a', 'b']
    assert fetch_page.call_args_list == [call(limit=BATCH_SIZE, offset=0)]


def test_fetch_all_multiple_pages() -> None:
    """Items are aggregated across pages and offset advances by limit."""
    fetch_page = Mock(
        side_effect=[
            _page(['a'], total_count=2),
            _page(['b'], total_count=2),
        ]
    )

    res = list(fetch_all(fetch_page, limit=1))

    assert res == ['a', 'b']
    assert fetch_page.call_args_list == [
        call(limit=1, offset=0),
        call(limit=1, offset=1),
    ]


def test_fetch_all_stops_on_empty_first_page() -> None:
    """An empty page terminates the loop even when total_count claims more.

    Guards against an infinite loop when total_count overstates the number of
    items the endpoint actually returns.
    """
    fetch_page = Mock(side_effect=[_page([], total_count=5)])

    res = list(fetch_all(fetch_page, limit=1))

    assert res == []
    assert fetch_page.call_count == 1


def test_fetch_all_stops_on_empty_mid_page() -> None:
    """A short/empty page after some items stops paging despite a larger total_count."""
    fetch_page = Mock(
        side_effect=[
            _page(['a'], total_count=5),
            _page([], total_count=5),
        ]
    )

    res = list(fetch_all(fetch_page, limit=1))

    assert res == ['a']
    assert fetch_page.call_count == 2


def test_fetch_all_forwards_args_and_kwargs() -> None:
    """Positional args and extra kwargs are forwarded to fetch_page each call."""
    fetch_page = Mock(side_effect=[_page(['a'], total_count=1)])

    res = list(fetch_all(fetch_page, 'arg1', limit=10, extra='value'))

    assert res == ['a']
    assert fetch_page.call_args_list == [
        call('arg1', limit=10, offset=0, extra='value')
    ]