"""Store-side support for incremental sync: the known-id boundary and the
watermark that survives a re-discovery."""
from __future__ import annotations

from yt_scraper.store import Store, VideoRef


def _store(tmp_path) -> Store:
    store = Store(tmp_path / "state.db")
    store.upsert_channel("UC1", "@alpha", "Alpha", 0)
    return store


def test_known_video_ids_is_scoped_to_the_channel(tmp_path):
    store = _store(tmp_path)
    store.upsert_channel("UC2", "@beta", "Beta", 0)
    store.upsert_videos([
        VideoRef("a", "UC1", "A", "https://y/watch?v=a"),
        VideoRef("b", "UC1", "B", "https://y/watch?v=b"),
        VideoRef("c", "UC2", "C", "https://y/watch?v=c"),
    ])

    assert store.known_video_ids("UC1") == {"a", "b"}
    assert store.known_video_ids("UC2") == {"c"}
    assert store.known_video_ids("nope") == set()


def test_rediscovery_does_not_wipe_a_known_upload_date(tmp_path):
    """Flat discovery reports upload_date=None; without COALESCE a routine sync
    would erase the dates learned during extraction — and with them the very
    watermark this feature is built on."""
    store = _store(tmp_path)
    store.upsert_videos([VideoRef("a", "UC1", "A", "https://y/watch?v=a", "20260715", 120)])

    store.upsert_videos([VideoRef("a", "UC1", "A (renamed)", "https://y/watch?v=a", None, None)])

    row = store.get_video("a")
    assert row.upload_date == "20260715"
    assert row.duration == 120
    assert row.title == "A (renamed)", "titles should still refresh"


def test_latest_upload_date_ignores_undated_rows(tmp_path):
    store = _store(tmp_path)
    store.upsert_videos([
        VideoRef("a", "UC1", "A", "https://y/watch?v=a", "20260101"),
        VideoRef("b", "UC1", "B", "https://y/watch?v=b", None),
        VideoRef("c", "UC1", "C", "https://y/watch?v=c", "20260720"),
    ])

    assert store.latest_upload_date("UC1") == "20260720"


def test_mark_channel_synced_recounts_instead_of_trusting_the_window(tmp_path):
    """An incremental pass only sees the newest slice, so video_count must come
    from the DB — otherwise an 848-video channel shrinks to the window size."""
    store = _store(tmp_path)
    store.upsert_videos([
        VideoRef(f"v{i}", "UC1", f"V{i}", f"https://y/watch?v=v{i}", "20260101")
        for i in range(40)
    ])

    marks = store.mark_channel_synced("UC1")

    assert marks["video_count"] == 40
    channel = store.get_channel("UC1")
    assert channel["video_count"] == 40
    assert channel["last_video_date"] == "20260101"
    assert channel["last_synced_at"]


def test_mark_channel_synced_keeps_the_last_date_when_nothing_is_dated(tmp_path):
    store = _store(tmp_path)
    store.upsert_videos([VideoRef("a", "UC1", "A", "https://y/watch?v=a", "20260101")])
    store.mark_channel_synced("UC1")

    store.upsert_videos([VideoRef("b", "UC1", "B", "https://y/watch?v=b", None)])
    store.mark_channel_synced("UC1")

    assert store.get_channel("UC1")["last_video_date"] == "20260101"