from datetime import UTC, datetime, timedelta

import pytest

from app.db.models import ChangeOp, User
from app.db.session import SessionMaker
from app.repo.drafts import MAX_CHANGES, DraftFull, DraftService

UID = 7
SHA = "a" * 40


class Clock:
    now = datetime(2026, 10, 15, tzinfo=UTC)

    def __call__(self) -> datetime:
        return self.now


@pytest.fixture
async def svc(sessions: SessionMaker) -> DraftService:
    async with sessions.begin() as s:
        s.add(User(tg_id=UID, full_name="u"))
    return DraftService(sessions, clock=Clock())


async def test_put_get_and_order(svc: DraftService) -> None:
    await svc.put(UID, SHA, "b.py", ChangeOp.ADD, b"b")
    await svc.put(UID, "other-sha", "a.py", ChangeOp.MODIFY, b"a")

    draft = await svc.get(UID)
    assert draft is not None and draft.base_sha == SHA  # base fixed when the draft started
    assert [(c.path, c.op) for c in draft.changes] == [("b.py", ChangeOp.ADD), ("a.py", ChangeOp.MODIFY)]


async def test_editing_a_new_file_keeps_it_added_and_deleting_it_drops_it(svc: DraftService) -> None:
    await svc.put(UID, SHA, "n.py", ChangeOp.ADD, b"1")
    await svc.put(UID, SHA, "n.py", ChangeOp.MODIFY, b"2")
    draft = await svc.get(UID)
    assert draft is not None and draft.changes[0].op is ChangeOp.ADD and draft.changes[0].content == b"2"

    await svc.put(UID, SHA, "n.py", ChangeOp.DELETE, None)
    draft = await svc.get(UID)
    assert draft is not None and draft.changes == []


async def test_drop_message_clear(svc: DraftService) -> None:
    await svc.put(UID, SHA, "a.py", ChangeOp.ADD, b"1")
    await svc.put(UID, SHA, "b.py", ChangeOp.DELETE, None)
    await svc.drop(UID, "a.py")
    await svc.set_message(UID, "feat: x")

    draft = await svc.get(UID)
    assert draft is not None and [c.path for c in draft.changes] == ["b.py"] and draft.message == "feat: x"
    await svc.clear(UID)
    assert await svc.get(UID) is None


async def test_expired_draft_is_gone(svc: DraftService) -> None:
    await svc.put(UID, SHA, "a.py", ChangeOp.ADD, b"1")
    Clock.now += timedelta(hours=25)
    try:
        assert await svc.get(UID) is None
    finally:
        Clock.now -= timedelta(hours=25)


async def test_draft_size_limit(svc: DraftService) -> None:
    for i in range(MAX_CHANGES):
        await svc.put(UID, SHA, f"f{i}.py", ChangeOp.ADD, b"")
    with pytest.raises(DraftFull):
        await svc.put(UID, SHA, "one-more.py", ChangeOp.ADD, b"")