"""A lesson's surfaced-vs-opened counts reach a reader (#4196).

The lesson slot has recorded usage since it shipped, and until this nothing
showed it. `get_lesson`'s REST door attached it; the list did not, neither MCP
door did, and no view rendered it — so the one kind whose central question is
"is this trigger firing on the right situation" was the one kind whose answer
was unreadable.

WHY THE COUNTS MATTER MORE HERE THAN ON A SNIPPET. #4196 asks whether a lesson
repeatedly followed should become a rule, and names the trap: raw frequency
cannot tell "this should bind" from "this trigger is too broad", which is the
commoner reading. Surfaced-AND-opened can. Neither question is answerable by
anything that cannot see the numbers, which is why this is the first step and
not the threshold.

NO THRESHOLD IS ASSERTED ANYWHERE HERE, deliberately. At the time of writing
the corpus is 10 lessons with 7 recorded surfacings and 3 opens; a promotion
rule fitted to that would be fitting noise, and `UsageBadge` already declines
to render a verdict on fewer than three surfacings for the same reason.
"""
import inspect
from pathlib import Path
from unittest.mock import AsyncMock, MagicMock, patch

import pytest

from scribe.mcp.tools import lessons as lesson_tools
from scribe.services.note_usage import empty_usage


def _rows():
    return [
        {"id": 7, "title": "a", "tags": [], "snippet": "", "when_to_apply": "x"},
        {"id": 9, "title": "b", "tags": [], "snippet": "", "when_to_apply": "y"},
    ]


@pytest.mark.asyncio
async def test_the_mcp_listing_carries_usage_for_every_row():
    """Zero-filled, not omitted. A missing key would make the reader treat
    "never surfaced" and "not reported" as the same thing, which is the
    distinction the whole readout exists to keep."""
    used = {7: {**empty_usage(), "surfaced_count": 5, "pull_count": 2}}
    with (
        patch.object(lesson_tools, "current_user_id", return_value=1),
        patch.object(lesson_tools.knowledge_svc, "query_knowledge",
                     new=AsyncMock(return_value=(_rows(), 2))),
        patch.object(lesson_tools.access_svc, "label_shared_items",
                     new=AsyncMock(side_effect=lambda _uid, items: items)),
        patch.object(lesson_tools, "usage_for_notes",
                     new=AsyncMock(return_value=used)),
    ):
        out = await lesson_tools.list_lessons()

    by_id = {r["id"]: r for r in out["lessons"]}
    assert by_id[7]["usage"]["surfaced_count"] == 5
    assert by_id[7]["usage"]["pull_count"] == 2
    # The row nobody has surfaced still carries the key.
    assert by_id[9]["usage"] == empty_usage()


@pytest.mark.asyncio
async def test_the_listing_asks_for_usage_once_for_the_whole_page():
    """One aggregate, not one lookup per row — the snippet listing's own
    comment calls a per-row read N+1 by construction, and a lesson list is the
    same shape."""
    reader = AsyncMock(return_value={})
    with (
        patch.object(lesson_tools, "current_user_id", return_value=1),
        patch.object(lesson_tools.knowledge_svc, "query_knowledge",
                     new=AsyncMock(return_value=(_rows(), 2))),
        patch.object(lesson_tools.access_svc, "label_shared_items",
                     new=AsyncMock(side_effect=lambda _uid, items: items)),
        patch.object(lesson_tools, "usage_for_notes", new=reader),
    ):
        await lesson_tools.list_lessons()

    assert reader.await_count == 1
    assert sorted(reader.await_args.args[0]) == [7, 9]


@pytest.mark.asyncio
async def test_get_lesson_reads_the_count_before_recording_its_own_pull():
    """Otherwise the first read of a lesson reports a pull that is its own.

    `get_lesson` records a pull on every open — it has to, or the kind sits
    permanently at zero and reads as dead weight. That makes the ORDER load
    bearing in a way it is not for kinds that only count.
    """
    order: list[str] = []
    note = MagicMock(id=7, user_id=1)

    async def _usage_read(ids):
        order.append("read")
        return {7: {**empty_usage(), "surfaced_count": 4, "pull_count": 1}}

    with (
        patch.object(lesson_tools, "current_user_id", return_value=1),
        patch.object(lesson_tools.lessons_svc, "get_lesson",
                     new=AsyncMock(return_value=note)),
        patch.object(lesson_tools, "_to_dict", return_value={"id": 7}),
        patch.object(lesson_tools.access_svc, "describe_provenance",
                     new=AsyncMock(return_value={})),
        patch.object(lesson_tools, "usage_for_notes", new=_usage_read),
        patch.object(lesson_tools, "record_pulled",
                     side_effect=lambda **_kw: order.append("pull")),
    ):
        out = await lesson_tools.get_lesson(7)

    assert order == ["read", "pull"], (
        "the pull was recorded before the count was read, so the number the "
        "caller is shown includes the read that produced it"
    )
    assert out["usage"]["pull_count"] == 1


# ── the REST door, on structure (rule 167) ───────────────────────────────────
#
# Its siblings in test_lesson_rest_door.py are source guards for the same
# reason: the route is decorated and returns a Quart response, so driving it
# means standing up the app. What matters here is reachable from the source
# and falsifiable from it — an aggregate rather than a per-row read, and the
# same read-then-record order the MCP door is pinned to above.


def _route_source(name: str) -> str:
    from scribe.routes import lessons as routes

    src = inspect.getsource(routes)
    start = src.index(f"async def {name}(")
    nxt = src.find("\n@lessons_bp.route", start)
    return src[start:nxt if nxt > 0 else len(src)]


def test_the_rest_listing_reads_usage_once_for_the_page():
    """A per-row lookup would be N+1 by construction — the listing's own
    comment says so, and this is what makes that comment checkable."""
    src = _route_source("list_lessons_route")
    assert src.count("usage_for_notes(") == 1
    # The one call is not inside the loop that assigns the rows.
    call = src.index("usage_for_notes(")
    assign = src.index('["usage"]')
    assert call < assign


def test_every_rest_row_carries_the_key_even_at_zero():
    """"Never surfaced" is a state the UI renders; a missing field is not."""
    src = _route_source("list_lessons_route")
    assert "empty_usage()" in src, (
        "a row with no recorded usage would come back without the key, and a "
        "reader cannot tell that from a reporting failure"
    )


def test_the_rest_detail_door_also_reads_before_it_records():
    """Two doors that disagree about what the number counts are worse than
    one door that is wrong, because only one of them looks wrong."""
    src = _route_source("get_lesson_route")
    assert src.index("usage_for_notes(") < src.index("record_pulled(")


def test_these_guards_can_fail():
    """Rule 167: falsify the shape they assert against, so a guard that has
    quietly stopped describing anything cannot pass by describing nothing."""
    src = _route_source("list_lessons_route")
    assert "def list_lessons_route" in src
    assert "def get_lesson_route" not in src, "the slice ran past its route"


def test_the_detail_view_renders_the_badge_rather_than_respelling_it():
    """Snippet #3460: reach for UsageBadge and pass the kind's own advice; a
    view's scoped re-spelling of `.usage-tag` is what that component replaced.

    The advice is the kind-specific half. For a lesson it points at the
    trigger, not at deletion — a lesson nobody opens is usually keyed to a
    situation nobody is in, which is `update_lesson`'s own words and the
    reading #4196 calls the commoner one.
    """
    view = (Path(__file__).resolve().parents[1]
            / "frontend/src/views/LessonDetailView.vue").read_text()
    assert "UsageBadge" in view
    assert "usage-tag" not in view, "re-spelled the chip instead of reusing it"

    key = 'dead-weight-advice="'
    start = view.index(key) + len(key)
    advice = view[start:view.index('"', start)]
    assert "when_to_apply" in advice, (
        f"the dead-weight advice does not point at the trigger: {advice!r}"
    )