"""Unit tests for the hasLast/end cursor pagination helper in
:mod:`scripts.scrape_via_page` (WeChat msg/chats deep-history paging).

No network/browser — the fetch callable is faked; these verify the
cursor protocol: page N+1 uses ``data.end - 1`` as ``end`` until
``hasLast`` is falsy, with guards for malformed ``end`` and a page cap.
"""

from __future__ import annotations

from scripts.scrape_via_page import paginate_chats


def _page(messages, has_last, end=1000):
    return {"data": {"messages": messages, "hasLast": has_last, "end": end}}


async def _noop_sleep(_seconds: float) -> None:
    return None


async def test_multi_page_uses_end_minus_one_cursor():
    calls: list[int] = []

    async def fetch(end_ms: int):
        calls.append(end_ms)
        if len(calls) == 1:
            return _page([{"id": 1}], has_last=True, end=1000)
        return _page([{"id": 2}], has_last=False, end=500)

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, sleep=_noop_sleep)]

    assert [len(d["messages"]) for d in datas] == [1, 1]
    assert calls == [2000, 999]  # 下一页游标 = end - 1


async def test_stops_when_has_last_falsy():
    async def fetch(end_ms: int):
        return _page([{"id": 1}], has_last=False)

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, sleep=_noop_sleep)]

    assert len(datas) == 1


async def test_stops_on_non_dict_data():
    calls = []

    async def fetch(end_ms: int):
        calls.append(end_ms)
        return {"message": "调用成功", "data": None}

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, sleep=_noop_sleep)]

    assert datas == []
    assert len(calls) == 1


async def test_stops_when_end_not_numeric():
    async def fetch(end_ms: int):
        return _page([{"id": 1}], has_last=True, end=None)

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, sleep=_noop_sleep)]

    assert len(datas) == 1  # hasLast 真但游标缺失 → 不再无限请求


async def test_page_cap_prevents_infinite_loop():
    calls = []

    async def fetch(end_ms: int):
        calls.append(end_ms)
        return _page([{"id": len(calls)}], has_last=True, end=end_ms - 1)

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, max_pages=5, sleep=_noop_sleep)]

    assert len(datas) == 5
    assert len(calls) == 5


async def test_empty_messages_list_still_pages():
    async def fetch(end_ms: int):
        if end_ms > 1500:
            return _page(None, has_last=True, end=1500)
        return _page([{"id": 1}], has_last=False)

    datas = [d async for d in paginate_chats(fetch, end_ms=2000, sleep=_noop_sleep)]

    assert len(datas) == 2