"""Real-Postgres tests for a rule's CHECK — the write half (milestone 312).

What mocks cannot prove, and what the staleness sweep depends on:

1. **Empty means NULL.** The sweep asks for rules where `verify_with` is set.
   A write that stored "" would leave a column that is neither null nor
   content, and every rule ever touched through the REST door would answer
   "yes, I have a check" — the sweep would list the whole rulebook and mean
   nothing. Only a real column can show the difference; `to_dict`'s `or ""`
   renders both the same.

2. **Clearing is possible at all.** "" means "leave unchanged" at the MCP
   door, so without an explicit clear there is no way to retire a check.

3. **A stamp does not outlive the check it certifies.** Reword the check and
   the old `verified_at` vouches for something that no longer exists.
"""
from datetime import datetime, timezone

import pytest
import pytest_asyncio

from scribe.models import async_session
from scribe.models.rulebook import Rule
from scribe.services import rulebooks as rulebooks_svc
from tests.helpers import ensure_user

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


@pytest_asyncio.fixture
async def constraint():
    """One rule carrying a check, already verified.

    Verified at creation time rather than left null, because every assertion
    here is about what happens to an EXISTING stamp — a fixture that started
    null could pass all of them by doing nothing.
    """
    async with async_session() as s:
        owner = await ensure_user(s, "verification_owner")
        uid = owner.id
        await s.commit()

    book = await rulebooks_svc.create_rulebook(uid, "Environment facts")
    topic = await rulebooks_svc.create_topic(book.id, uid, "ci")
    rule = await rulebooks_svc.create_rule(
        topic.id, uid, "The runner has no bash",
        "Write every `run:` step in POSIX sh.",
        verify_with="read the workflow's shell setting",
        expires_when="the runner can be given a bash shell",
    )
    async with async_session() as s:
        row = await s.get(Rule, rule.id)
        row.verified_at = datetime(2026, 8, 1, tzinfo=timezone.utc)
        await s.commit()
    return {"uid": uid, "rule": rule.id}


async def _row(rule_id: int) -> Rule:
    async with async_session() as s:
        return await s.get(Rule, rule_id)


async def test_the_check_and_its_expiry_persist(constraint):
    row = await _row(constraint["rule"])
    assert row.verify_with == "read the workflow's shell setting"
    assert row.expires_when == "the runner can be given a bash shell"
    assert row.verified_at is not None


async def test_an_empty_string_becomes_null_not_an_empty_column(constraint):
    """The REST door's idiom: a cleared form input arrives as "".

    NULL is asserted directly against the column rather than through to_dict,
    which renders `None` and `""` identically — the difference this test
    exists for would be invisible one layer up.
    """
    await rulebooks_svc.update_rule(
        constraint["rule"], constraint["uid"], verify_with="", expires_when="",
    )
    row = await _row(constraint["rule"])
    assert row.verify_with is None
    assert row.expires_when is None


async def test_naming_a_field_in_clear_empties_it(constraint):
    """The MCP door's idiom, where "" already means "leave this alone"."""
    await rulebooks_svc.update_rule(
        constraint["rule"], constraint["uid"], clear=["verify_with"],
    )
    row = await _row(constraint["rule"])
    assert row.verify_with is None
    # expires_when was NOT named, so it survives — clearing is per-field, and
    # a caller retiring one field must not lose the others.
    assert row.expires_when == "the runner can be given a bash shell"


async def test_rewording_the_check_drops_the_stamp(constraint):
    """A stamp certifies a check, not a rule.

    The safe direction, for the same reason _valid_tier falls back to
    always_on: a rule wrongly listed as due costs one look, a rule wrongly
    vouched for costs exactly what the sweep exists to catch.
    """
    await rulebooks_svc.update_rule(
        constraint["rule"], constraint["uid"],
        verify_with="read the runner's container shell, not the image's",
    )
    row = await _row(constraint["rule"])
    assert row.verified_at is None


async def test_clearing_the_check_drops_the_stamp(constraint):
    await rulebooks_svc.update_rule(
        constraint["rule"], constraint["uid"], clear=["verify_with"],
    )
    row = await _row(constraint["rule"])
    assert row.verified_at is None


async def test_editing_anything_else_leaves_the_stamp_alone(constraint):
    """The other half of the rule above, and the one that keeps it useful.

    If any edit reset the stamp, a rulebook tidy-up would put every constraint
    back at the top of the sweep and the ordering would carry no information.
    Only the check's own text invalidates its verification.
    """
    await rulebooks_svc.update_rule(
        constraint["rule"], constraint["uid"],
        why="act_runner picks the shell, and the image's SHELL directive "
            "applies to the build, not to `run:`.",
        expires_when="the runner grows a shell setting",
    )
    row = await _row(constraint["rule"])
    assert row.verified_at is not None
    assert row.why.startswith("act_runner picks the shell")