"""FakeAdapter M4 tests — list_callback_tasks pagination."""
from __future__ import annotations

import pytest

from backend.app.services.c2.adapter import C2HistoricalTask
from backend.app.services.c2.fake import FakeAdapter


@pytest.fixture()
def adapter() -> FakeAdapter:
    return FakeAdapter()


class TestFakeAdapterListCallbackTasks:
    def test_callback_1_returns_12_total(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=1, page=1, page_size=25)
        assert page.total == 12

    def test_callback_2_returns_0_tasks(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=2, page=1, page_size=25)
        assert page.total == 0
        assert page.items == []

    def test_callback_3_returns_5_tasks(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=3, page=1, page_size=25)
        assert page.total == 5
        assert len(page.items) == 5

    def test_items_are_c2_historical_task_instances(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=1, page=1, page_size=5)
        for item in page.items:
            assert isinstance(item, C2HistoricalTask)

    def test_pagination_page1(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=1, page=1, page_size=5)
        assert len(page.items) == 5
        assert page.page == 1
        assert page.page_size == 5

    def test_pagination_page2(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=1, page=2, page_size=5)
        assert len(page.items) == 5
        assert page.page == 2

    def test_pagination_last_page_partial(self, adapter):
        # 12 tasks, page_size=5 → page 3 has 2 items.
        page = adapter.list_callback_tasks(callback_display_id=1, page=3, page_size=5)
        assert len(page.items) == 2
        assert page.total == 12

    def test_pagination_beyond_range_returns_empty(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=1, page=99, page_size=25)
        assert len(page.items) == 0
        assert page.total == 12

    def test_history_is_deterministic_across_instances(self):
        a1 = FakeAdapter()
        a2 = FakeAdapter()
        p1 = a1.list_callback_tasks(callback_display_id=1, page=1, page_size=25)
        p2 = a2.list_callback_tasks(callback_display_id=1, page=1, page_size=25)
        assert [t.display_id for t in p1.items] == [t.display_id for t in p2.items]

    def test_completed_and_submitted_mix(self, adapter):
        """Callback 1 has alternating completed/submitted tasks (even=completed)."""
        page = adapter.list_callback_tasks(callback_display_id=1, page=1, page_size=12)
        completed = [t for t in page.items if t.completed]
        submitted = [t for t in page.items if not t.completed]
        assert len(completed) == 6
        assert len(submitted) == 6

    def test_unknown_callback_returns_empty(self, adapter):
        page = adapter.list_callback_tasks(callback_display_id=999, page=1, page_size=25)
        assert page.total == 0
        assert page.items == []