"""A note's own check — verify_with / expires_when (milestone 317 step 2).

Three behaviours the rules path (#3096) had to get right and this one inherits:
empty means NULL, clearing is explicit, and rewriting the check drops the
stamp. Plus one this path adds: not every record may carry a check, and the
rule is an INVARIANT over the record rather than a filter on the write.
"""
from unittest.mock import AsyncMock, MagicMock, patch

import pytest
from tests.helpers import drive_update_note as _update
from tests.helpers import fake_note, make_mock_session


def _checkable(**over):
    """A plain note — no status, no snippet type, no check. `fake_note` is a
    MagicMock, so every one of these must be set explicitly: an unset
    attribute is a truthy mock, which would look like a check that is there."""
    base = dict(
        status=None, note_type="note",
        verify_with=None, expires_when=None, verified_at=None,
        project_id=None,
    )
    base.update(over)
    return fake_note(**base)


async def _create(**kwargs):
    session = make_mock_session()
    captured = {}
    session.add = MagicMock(side_effect=lambda obj: captured.update(
        verify_with=getattr(obj, "verify_with", "MISSING"),
        expires_when=getattr(obj, "expires_when", "MISSING"),
    ))
    with patch("scribe.services.notes.async_session") as cls, \
         patch("scribe.services.notes.embed_note", MagicMock()), \
         patch("scribe.services.notes._maybe_reactivate_project", AsyncMock()):
        cls.return_value = session
        from scribe.services.notes import create_note
        await create_note(user_id=1, title="t", **kwargs)
    return captured


# ── empty means empty ────────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_an_empty_check_is_stored_as_null_not_as_a_blank():
    """The sweep's whole signal is `verify_with IS NULL` = "this is a decision,
    there is nothing to check". A "" that is not NULL makes a norm look like a
    constraint nobody has verified — and never-checked sorts FIRST, so it would
    sit at the top of the sweep forever."""
    assert (await _create(verify_with="", expires_when=""))["verify_with"] is None

    note = _checkable(verify_with="curl the docs")
    await _update(note, verify_with="")
    assert note.verify_with is None


@pytest.mark.asyncio
async def test_a_check_is_stored_when_given():
    captured = await _create(verify_with="curl the AMO docs", expires_when="AMO allows re-signing")
    assert captured["verify_with"] == "curl the AMO docs"
    assert captured["expires_when"] == "AMO allows re-signing"


# ── clearing is explicit ─────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_clear_unsets_a_field_the_mcp_door_cannot_empty():
    """At the MCP door "" means "leave this alone", so an agent updating a body
    does not wipe a check it was never asked about. That leaves no value
    meaning "remove it" — hence naming the field, which cannot happen by
    accident."""
    note = _checkable(verify_with="a check", expires_when="a state")
    await _update(note, clear=["verify_with"])
    assert note.verify_with is None
    assert note.expires_when == "a state", "clearing one must not clear the other"


@pytest.mark.asyncio
async def test_clear_ignores_a_field_that_is_not_clearable():
    note = _checkable(title="keep me", verify_with="a check")
    await _update(note, clear=["title"])
    assert note.title == "keep me"


# ── the stamp certifies a check, not a record ────────────────────────────────

@pytest.mark.asyncio
async def test_rewriting_the_check_drops_the_stamp():
    note = _checkable(verify_with="the old check", verified_at="2026-01-01")
    await _update(note, verify_with="a different check")
    assert note.verified_at is None


@pytest.mark.asyncio
async def test_clearing_the_check_drops_the_stamp():
    note = _checkable(verify_with="the old check", verified_at="2026-01-01")
    await _update(note, clear=["verify_with"])
    assert note.verified_at is None


@pytest.mark.asyncio
async def test_an_unchanged_check_keeps_its_stamp():
    """Only a CHANGE invalidates it — otherwise every unrelated edit would
    re-enter the note into the sweep and the signal would mean nothing."""
    note = _checkable(verify_with="the same check", verified_at="2026-01-01")
    await _update(note, title="a new title", verify_with="the same check")
    assert note.verified_at == "2026-01-01"


@pytest.mark.asyncio
async def test_a_stamp_cannot_be_set_through_an_ordinary_edit():
    """A stamp says somebody performed THIS check. Minting one from a write
    that ran no check is the one thing that would make the sweep lie."""
    note = _checkable(verify_with="a check", verified_at=None)
    await _update(note, verified_at="2026-08-28")
    assert note.verified_at is None


# ── the invariant: which records may carry a check ───────────────────────────

@pytest.mark.asyncio
async def test_a_task_is_refused_a_check():
    with pytest.raises(ValueError, match="task"):
        await _create(status="todo", verify_with="a check")


@pytest.mark.asyncio
async def test_a_snippet_is_refused_and_told_where_to_go():
    """The message has to name the alternative, or the caller is left with a
    refusal and no route."""
    with pytest.raises(ValueError, match="verify_snippet"):
        await _create(note_type="snippet", verify_with="a check")


@pytest.mark.asyncio
async def test_turning_a_checked_note_into_a_task_is_refused():
    """THE reason this is an invariant over the resulting record and not a
    filter on which fields were passed. This write names no check at all, and
    would sail past any per-field gate."""
    note = _checkable(verify_with="a check")
    with pytest.raises(ValueError, match="task"):
        await _update(note, status="todo")


@pytest.mark.asyncio
async def test_an_unchecked_note_can_still_become_a_task():
    """The invariant must not make ordinary promotion impossible."""
    note = _checkable()
    await _update(note, status="todo")
    assert note.status == "todo"


@pytest.mark.asyncio
async def test_clearing_the_check_in_the_same_write_lets_it_become_a_task():
    """The error tells the caller to clear the check first; doing both at once
    has to actually work, or the advice is wrong."""
    note = _checkable(verify_with="a check")
    await _update(note, status="todo", clear=["verify_with"])
    assert note.status == "todo"
    assert note.verify_with is None


@pytest.mark.asyncio
async def test_an_ordinary_note_write_is_untouched_by_any_of_this():
    """The common case: no check, nothing to guard, nothing to reset."""
    note = _checkable(title="before")
    await _update(note, title="after")
    assert note.title == "after"
    assert note.verify_with is None
    assert note.verified_at is None
