"""A snippet's notes — the explanation that had nowhere to go (#4378).

Before this field, a snippet had name, code, signature, locations and
`when_to_use`, and nothing for prose. What a session learned about a snippet
went into `when_to_use` — the trigger, joined onto the title of every chunk the
snippet is embedded as — so a multi-paragraph write-up there blurred the one
situation it is ranked on.

The rules pinned here, each with a way to rot silently:

  - Notes live in the BODY, after the code, under `## Notes`, and read back
    from it. A `## Notes` line inside the code is code, not the section.
  - A snippet with no notes composes the body it always did, byte for byte —
    no re-embed for the corpus that has none.
  - Every path that rebuilds the body CARRIES the notes. `update_snippet`,
    merge and un-merge all compose the body from scratch, so a field one of
    them forgets is erased by any edit to something else.
  - `trigger_advice` speaks for a write-up and stays quiet for a situation.
"""
import pytest
import pytest_asyncio

from tests.helpers import ensure_user

from scribe.services import snippets as s

CODE = "def helper():\n    return 1"
NOTES = "Shaped this way because the caller owns the session.\n\nSuperseded #12."


# --- unit: the body convention -----------------------------------------------

def test_notes_follow_the_code_under_their_heading():
    body = s.compose_body(code=CODE, language="python", when_to_use="a helper", notes=NOTES)
    code_at = body.index("```python")
    notes_at = body.index(s.NOTES_HEADING)
    assert code_at < notes_at
    assert body.rstrip().endswith("Superseded #12.")


def test_notes_round_trip_through_the_body():
    body = s.compose_body(code=CODE, language="python", notes=NOTES)
    got = s.parse_snippet_fields("helper", body, ["python", "snippet"])
    assert got["notes"] == NOTES
    assert got["code"] == CODE


def test_a_snippet_without_notes_composes_the_body_it_always_did():
    """No trailing section, no extra blank line: the corpus that has no notes
    must embed exactly as before."""
    body = s.compose_body(code=CODE, language="python", when_to_use="a helper")
    assert body == "**When to use:** a helper\n\n```python\n" + CODE + "\n```\n"
    assert s.parse_snippet_fields("helper", body)["notes"] == ""


def test_a_notes_heading_inside_the_code_is_code():
    md = "# Title\n\n## Notes\n\nthis is markdown being recorded"
    body = s.compose_body(code=md, language="markdown")
    got = s.parse_snippet_fields("md_template", body)
    assert got["notes"] == ""
    assert got["code"] == md


def test_notes_after_code_that_itself_contains_the_heading():
    md = "## Notes\ninside"
    body = s.compose_body(code=md, language="markdown", notes="the real notes")
    got = s.parse_snippet_fields("md_template", body)
    assert got["notes"] == "the real notes"
    assert got["code"] == md


def test_long_notes_are_chunked_apart_from_the_code():
    """The heading is the chunker's split point, so a long explanation gets
    vectors of its own instead of averaging into the code's."""
    from scribe.services.embeddings import chunk_document

    long_notes = "\n\n".join(["An explanatory paragraph about the history. " * 12] * 4)
    body = s.compose_body(code=CODE, language="python", when_to_use="a helper",
                          notes=long_notes)
    chunks = chunk_document("helper — a helper", body)
    assert len(chunks) > 1
    assert "```python" in chunks[0]
    assert "```python" not in chunks[-1]


# --- unit: the advice ---------------------------------------------------------

def test_a_situation_draws_no_advice():
    assert s.trigger_advice("Debouncing a reactive input before it fetches.") is None
    assert s.trigger_advice("") is None
    assert s.trigger_advice(None) is None


def test_a_long_trigger_is_advised_toward_notes():
    advice = s.trigger_advice("x" * (s.TRIGGER_ADVISE_CHARS + 1))
    assert advice and "notes" in advice
    assert f"{s.TRIGGER_ADVISE_CHARS + 1} characters" in advice


def test_a_headed_or_multi_paragraph_trigger_is_advised_even_when_short():
    assert "headings" in s.trigger_advice("When adding a record.\n\n## Why\nbecause")
    assert "paragraphs" in s.trigger_advice("When adding a record.\n\nAlso, history.")


# --- integration: every body rebuild carries the notes ------------------------


@pytest_asyncio.fixture
async def user_id(_dispose_engine):
    from scribe.models import async_session

    async with async_session() as session:
        uid = (await ensure_user(session, "snippet_notes_itest")).id
        await session.commit()
    return uid


async def _fields(uid, note_id):
    return s.snippet_fields(await s.get_snippet(uid, note_id))


@pytest.mark.integration
async def test_an_edit_to_another_field_keeps_the_notes(user_id):
    note = await s.create_snippet(
        user_id, name="notes_keep", code=CODE, language="python",
        when_to_use="a helper", notes=NOTES,
    )
    assert (await _fields(user_id, note.id))["notes"] == NOTES

    await s.update_snippet(user_id, note.id, when_to_use="a sharper situation")
    got = await _fields(user_id, note.id)
    assert got["notes"] == NOTES
    assert got["when_to_use"] == "a sharper situation"

    # And an empty string clears them, like every other field.
    await s.update_snippet(user_id, note.id, notes="")
    assert (await _fields(user_id, note.id))["notes"] == ""


@pytest.mark.integration
async def test_a_merge_keeps_the_survivors_notes(user_id):
    survivor = await s.create_snippet(
        user_id, name="notes_merge_a", code=CODE, language="python",
        repo="R", path="a.py", symbol="helper", notes=NOTES,
    )
    source = await s.create_snippet(
        user_id, name="notes_merge_b", code=CODE + "  # variant", language="python",
        repo="R", path="b.py", symbol="helper",
    )
    await s.merge_snippets(user_id, survivor.id, [source.id])
    assert (await _fields(user_id, survivor.id))["notes"] == NOTES

    await s.unmerge_snippet(user_id, survivor.id, source.id)
    assert (await _fields(user_id, survivor.id))["notes"] == NOTES