"""A lesson is a row the database actually accepts (milestone 385 step 2).

WHY THIS IS THE REAL GUARD, AND WHY IT IS HERE

The step asked for "a guard that the CHECK actually accepts `lesson` and
rejects a typo", citing #3128 — a `spike` kind that could not be written on an
instance predating its migration. That failure mode belongs to `task_kind`,
which IS gated (`notes_task_kind_check`, migrations 0056 and 0065).
`note_type` is not gated at all: migration 0036 added it as plain Text with a
server default and nothing has constrained it since.

So there is no whitelist to expand and no rejection to assert. Writing the
guard as "the constraint admits lesson" would have pinned a constraint that
does not exist; writing it as "no constraint exists" would pin today's schema
rather than the behaviour that matters, and would go red on a change that is
perfectly fine.

Asserting the WRITE covers both worlds. It passes today, it keeps passing if a
CHECK is added that admits `lesson`, and it goes red the day one is added that
does not — which is the only outcome anyone needs to be told about.

The second test is the cell #3163 asks to be left empty on purpose: a lesson
must not be a task. `is_task` is a read-only property over `status`, so this
cannot be asserted by setting a flag — it has to be observed on a real row.
"""
import pytest
import pytest_asyncio
from sqlalchemy import select

from scribe.models import async_session
from scribe.models.note import Note
from scribe.services import lessons as lessons_svc
from scribe.services import notes as notes_svc
from tests.helpers import ensure_user

pytestmark = [pytest.mark.integration, pytest.mark.usefixtures("_dispose_engine")]

OWNER_USERNAME = "lesson_kind_owner"

TRIGGER = "the operator pasted a stack trace and said it is still broken"
SUBJECT = "Change one thing, then look"


@pytest_asyncio.fixture
async def owner_id():
    async with async_session() as s:
        owner = await ensure_user(s, OWNER_USERNAME)
        await s.commit()
        uid = owner.id
        # Cleaned at SETUP rather than teardown: create_note fires a detached
        # embedding refresh that opens its own connection and writes the row,
        # and a teardown delete would race it. A fresh loop has already
        # cancelled whatever the previous test left in flight.
        for note in (await s.execute(
            select(Note).where(
                Note.user_id == uid,
                Note.note_type == lessons_svc.LESSON_NOTE_TYPE,
            )
        )).scalars().all():
            await s.delete(note)
        await s.commit()
    return uid


async def test_a_lesson_is_a_row_the_database_accepts(owner_id):
    """The whole point. Goes red if `note_type` is ever gated without this
    value, and stays correct if it is gated with it."""
    lesson = await notes_svc.create_note(
        owner_id,
        title=lessons_svc.compose_title(SUBJECT, TRIGGER),
        body=f"**When to apply:** {TRIGGER}\n\nOne change at a time.",
        note_type=lessons_svc.LESSON_NOTE_TYPE,
        data={lessons_svc.TRIGGER_KEY: TRIGGER},
    )

    async with async_session() as s:
        stored = (await s.execute(
            select(Note).where(Note.id == lesson.id)
        )).scalars().one()

    assert stored.note_type == "lesson"
    # The trigger survives the round trip on both halves — the indexed mirror
    # and the readable body — because the vector is built from the text and
    # the queries are built from the mirror.
    assert lessons_svc.lesson_trigger(stored) == TRIGGER
    assert stored.title == f"{SUBJECT} — {TRIGGER}"
    assert "**When to apply:**" in (stored.body or "")


async def test_a_lesson_is_not_a_task(owner_id):
    """#3163's cell left empty on purpose.

    `is_task` is `status is not None` and is read-only, so this is only
    observable on a stored row. A lesson that arrived with a status would join
    the open-work listings — the one way an unfilled field changes what the
    record IS rather than what it says.
    """
    lesson = await notes_svc.create_note(
        owner_id,
        title=lessons_svc.compose_title(SUBJECT, TRIGGER),
        body="One change at a time.",
        note_type=lessons_svc.LESSON_NOTE_TYPE,
    )

    async with async_session() as s:
        stored = (await s.execute(
            select(Note).where(Note.id == lesson.id)
        )).scalars().one()

    assert stored.status is None
    assert stored.is_task is False
    assert stored.milestone_id is None