"""P18/A — a listing is a WINDOW, and a path the caller invented is refused by name.

P16 (the first stress round; the ledger is ``docs/invarianter.md``) measured the ladder S7a-3
built against a DELIVERED corpus for the first time, and found two things the fixture bases could
not show:

* **one level is not bounded by being one level.** ``okf.directory_listing`` on one requirements
  level was 69 250 characters over 445 documents, on another 169 974 over 1 132, and a process
  catalogue's own root 110 912 over 2 728 SUBDIRECTORIES — 27-113x the 1 500-character ceiling
  S7a-3 set, riding in every later prompt. Three of seven paid runs died on the token cap.
* **0 of 26 fasit concepts were opened** in 24 ``read_file`` calls, and 10 of those calls named a
  path the base does not hold. Each reached the model as MAF's opaque ``"Error: Function failed."``
  (``agent_framework/_tools.py:1410-1432``) while counting toward the three consecutive tool errors
  that end a request — so the one thing the caller could have acted on, the level that DOES hold
  documents, never reached it.

Three seams, each with its own arms below:

* **A1** ``offset``/``limit`` over the level's entries — directories first, then documents — with
  ``total`` as the denominator. Clamped, never refused.
* **A2** ``filter``: a case-insensitive substring over a document's title and reference number and
  over a directory's path, answering with ``total_matches``. A filter that matches nothing is an
  ANSWER, not a refusal.
* **A3** an absent path becomes ``BundlePathNotFound`` in the funn-99 returned form, naming the
  nearest directory that actually holds documents. Narrowness is arm (h) and lives in
  ``test_read_file_directory_refusal_loadbearing.py`` alongside the tripwire it replaced.

The bases this measures are the package's two example bases (``data/kunnskapsbaser/``, pinned
in ``frozen_bundles.json``), so the arms that need them run wherever the package does; they SKIP,
with the store named, only when a user's own store (``PORTFOLIO_FROZEN_BUNDLES``) lacks them. The
arms that do NOT need them (the window's own algebra, the filter's negative, the refusal) are
UNCONDITIONAL and run over a synthetic base, so this file can never be silently absent in full.
"""

from __future__ import annotations

import json
from pathlib import Path
from typing import Any

import pytest

from portfolio_optimiser import frozen_bundles, okf
from portfolio_optimiser.explore import navigator_tools
from portfolio_optimiser.mandate import load_mandate
from portfolio_optimiser.stress import read_bundle_declarations

#: S7a-3's ceiling, restated here rather than imported: a gate that imported the implementation's
#: own budget would move with it, and raising the budget is exactly the regression it guards.
_CEILING_CHARS = 1_500


def _delivered(name: str) -> Path:
    """The FROZEN copy this repository pins, resolved at call time.

    Absence SKIPS (a user's own store, named by ``PORTFOLIO_FROZEN_BUNDLES``, may not hold it),
    drift is allowed to propagate and FAIL — a measurement of the wrong corpus is not a missing one.
    """
    try:
        return frozen_bundles.bundle_dir(name)
    except frozen_bundles.FrozenBundleMissing as exc:
        pytest.skip(str(exc))


def _tools(bundle_dir: Path) -> dict[str, Any]:
    return {t.name: t for t in navigator_tools([bundle_dir])}


def _bid(bundle_dir: Path) -> str:
    """The id the tools answer to: the DECLARED one, with the mount as fallback (S7a-3 pkt. 1)."""
    return okf.reconcile_bundle_id(str(bundle_dir)).id


def _read_file(bundle_dir: Path, path: str) -> str:
    return str(_tools(bundle_dir)["read_file"].func(bundle_id=_bid(bundle_dir), path=path))


def _read_dir(bundle_dir: Path, path: str, **window: Any) -> dict[str, Any]:
    return _tools(bundle_dir)["read_dir"].func(bundle_id=_bid(bundle_dir), path=path, **window)


def _chars(payload: Any) -> int:
    return len(json.dumps(payload, ensure_ascii=False))


def _synthetic(tmp_path: Path, *, dirs: int, per_dir: int) -> Path:
    """A base wide enough that a window is visibly a window, and deterministic."""
    base = tmp_path / "syntetisk-korpus"
    (base).mkdir(parents=True)
    links = []
    for d in range(dirs):
        (base / f"seksjon-{d:02d}").mkdir()
        for n in range(per_dir):
            rel = f"seksjon-{d:02d}/dok-{n:02d}.md"
            (base / rel).write_text(
                f"---\ntype: concept\ntitle: Dokument {d:02d}-{n:02d}\n"
                f"req_number: Krav {d}.{n}\n---\n\nkort tekst.\n",
                encoding="utf-8",
            )
            links.append(f"- [{rel}]({rel})")
    (base / "index.md").write_text("# Korpus\n\n" + "\n".join(links) + "\n", encoding="utf-8")
    return base


# --- A1: the window ------------------------------------------------------------------------------


@pytest.mark.parametrize(
    ("name", "level", "before"),
    [
        ("driftskrav-2027", "krav/D200", 29_453),
        ("prosesskatalog-2027", "P900", 12_345),
    ],
)
def test_a_default_listing_of_a_delivered_level_is_bounded(
    name: str, level: str, before: int
) -> None:
    """(a) The two example levels that are far wider than one window: the requirements level
    ``krav/D200`` (220 documents) and the process catalogue's root ``P900``, whose 300 entries are
    DIRECTORIES — which is why the window covers both kinds and not only documents.

    ``before`` is what reading the WHOLE level costs through the window (every page at the maximum
    limit, summed), measured on the pinned base and carried so the arm cannot pass by the level
    having shrunk. The control below proves the fixture is the thing that did not fit."""
    base = _delivered(name)
    listing = _read_dir(base, level)

    assert _chars(listing) <= _CEILING_CHARS, (
        f"{name}/{level} default listing is {_chars(listing)} chars, over {_CEILING_CHARS}"
    )
    assert _chars(listing) * 20 < before, "the bound must be a fall, not a rounding"
    assert int(listing["total"]) > 10 * int(listing["limit"]), (
        "the CONTROL is inert: this level must hold far more than one window, or the bound above "
        "is measuring a small level rather than the window"
    )
    whole = 0
    for offset in range(0, int(listing["total"]), okf._DIRECTORY_PAGE_MAX):
        whole += _chars(_read_dir(base, level, offset=offset, limit=okf._DIRECTORY_PAGE_MAX))
    assert whole == before, f"{name}/{level}: the whole level now costs {whole}, pinned {before}"


def test_the_window_pages_the_whole_level_exactly_once(tmp_path: Path) -> None:
    """(b) The anti-vacuity arm for A1. ``{"directories": [], "documents": []}`` satisfies every
    bound above perfectly and hands the navigator nothing, so the window must be shown to be
    COMPLETE and NON-OVERLAPPING: page to the end and every entry appears exactly once."""
    base = _synthetic(tmp_path, dirs=7, per_dir=4)
    first = _read_dir(base, "")

    seen: list[str] = []
    offset = 0
    while offset < int(first["total"]):
        page = _read_dir(base, "", offset=offset)
        assert page["total"] == first["total"], "the denominator must not move between pages"
        assert page["offset"] == offset
        seen.extend(str(e["path"]) for e in page["directories"])
        seen.extend(str(e["name"]) for e in page["documents"])
        offset += int(page["limit"])

    assert len(seen) == len(set(seen)) == int(first["total"]) == 7
    assert set(seen) == {f"seksjon-{d:02d}" for d in range(7)}


def test_a_caller_cannot_ask_for_an_unbounded_window(tmp_path: Path) -> None:
    """(c) The bound is this rung's to keep, not the caller's to remember. A limit past the maximum
    is CLAMPED rather than refused: the caller asked for a listing, and refusing it would send a
    model that asked for too much away with nothing."""
    base = _synthetic(tmp_path, dirs=3, per_dir=60)
    everything = _read_dir(base, "seksjon-00", limit=10_000)

    assert int(everything["limit"]) == okf._DIRECTORY_PAGE_MAX < int(everything["total"])
    assert len(everything["documents"]) == okf._DIRECTORY_PAGE_MAX
    assert int(_read_dir(base, "seksjon-00", limit=3)["limit"]) == 3, "a small limit is honoured"


def test_an_offset_past_the_end_is_an_empty_window_over_an_honest_total(tmp_path: Path) -> None:
    """(d) ``total`` is what makes an empty answer readable: without the denominator, "nothing
    here" and "you asked past the end" are the same payload."""
    base = _synthetic(tmp_path, dirs=2, per_dir=3)
    page = _read_dir(base, "seksjon-00", offset=999)

    assert page["documents"] == [] and page["directories"] == []
    assert int(page["total"]) == 3


# --- A2: the filter ------------------------------------------------------------------------------


def test_the_known_positive_filter_finds_the_fasit_concepts_and_not_the_level() -> None:
    """(e) The known positive: ``filter="autonomitid"`` on ``krav/D200`` must answer with the
    two concepts serverrom/a2 must cite, and NOT with 220 rows."""
    base = _delivered("driftskrav-2027")
    fasit = json.loads(Path("contexts/serverrom-2027/fasit.json").read_text(encoding="utf-8"))
    wanted = {
        c["path"]
        for m in fasit["must_cite"]
        if m["approach_id"] == "a2-ups-autonomi"
        for c in m["concepts"]
    }
    assert wanted, "the fixture must name concepts, or this arm proves nothing"

    hits = _read_dir(base, "krav/D200", filter="autonomitid", limit=50)

    assert wanted <= {str(d["name"]) for d in hits["documents"]}
    assert int(hits["total_matches"]) < int(hits["total"]) / 50
    assert _chars(hits) <= _CEILING_CHARS


def test_a_filter_that_matches_nothing_is_an_answer_and_not_a_refusal(tmp_path: Path) -> None:
    """(f) The order's known NEGATIVE. "No document here is about X" is a finding; refusing it
    would make an honest negative indistinguishable from a path that does not exist — which is the
    very confusion ``BundlePathNotFound`` exists to prevent one line below."""
    base = _synthetic(tmp_path, dirs=2, per_dir=3)
    empty = _read_dir(base, "seksjon-00", filter="finnes-ikke-noe-sted")

    assert "refused" not in empty
    assert empty["documents"] == [] and int(empty["total_matches"]) == 0
    assert int(empty["total"]) == 3, "the denominator survives the filter"


def test_the_filter_reads_the_reference_number_and_not_only_the_title(tmp_path: Path) -> None:
    """(g) The second field is load-bearing: on a process catalogue the thing a navigator knows
    is the process number, which is not in the title. Written over a synthetic base so it is
    unconditional."""
    base = _synthetic(tmp_path, dirs=2, per_dir=3)
    by_ref = _read_dir(base, "seksjon-01", filter="krav 1.2")

    assert [str(d["name"]) for d in by_ref["documents"]] == ["seksjon-01/dok-02.md"]
    assert int(by_ref["total_matches"]) == 1


def test_a_filter_narrows_directories_too(tmp_path: Path) -> None:
    """(h) A process catalogue's root is all DIRECTORIES (P900's: 300; the largest ever measured
    here: 2 728): a filter that only narrowed documents would leave the biggest level
    unnarrowable."""
    base = _synthetic(tmp_path, dirs=12, per_dir=2)
    narrowed = _read_dir(base, "", filter="seksjon-0")

    assert int(narrowed["total_matches"]) == 10 < int(narrowed["total"]) == 12
    assert all(str(d["path"]).startswith("seksjon-0") for d in narrowed["directories"])


# --- A3: the invented path -----------------------------------------------------------------------


def test_an_invented_path_is_refused_by_name_over_a_delivered_base() -> None:
    """(i) The measured live shape: a one-character slip in a UUID. Before, this reached the model
    as ``"Error: Function failed."``; the refusal now names the path AND the level that holds
    documents, which is the only thing the caller can act on."""
    base = _delivered("driftskrav-2027")
    real = "krav/D200/id-b1e2ba25-9825-57b0-a358-569be457d2c8.md"
    slip = _slip(real)
    assert (base / real).is_file() and not (base / slip).exists(), "control: one real, one invented"
    answer = _read_file(base, slip)

    assert answer.startswith(f"REFUSED ({okf.BundlePathNotFound.__name__})")
    assert slip in answer and "krav/D200" in answer and "read_dir" in answer
    # The named level resolves, and it is the one the caller was already in.
    assert int(_read_dir(base, "krav/D200")["total"]) > 0


def _slip(path: str) -> str:
    """The measured live shape of an invented path: ONE character of the document id changed."""
    stem, suffix = path[:-3], path[-3:]
    return stem[:-1] + ("b" if stem[-1] == "a" else "a") + suffix


def test_every_invented_path_answers_by_name_and_every_real_one_is_served() -> None:
    """(j) The nevner arm (ansikt 4). P16 replayed its own population — 32 ``read_file`` calls from
    four paid runs, 10 of them naming a path the base does not hold — but those runs read corpora
    this repository no longer carries, so the population here is CONSTRUCTED from the three context
    sets' own fasit: every cited path (routed at the base its approach names), and the same path
    with one id character changed. The denominator is re-measured from the fasit, not quoted.

    Every invented path must come back as a NAMED refusal, and every real one must still return
    the document — a gate that refused everything would pass the first half on its own, which is
    the failure this file's own A2 negative arm is written against."""
    calls: list[tuple[str, str]] = []
    for fasit_path in sorted(Path("contexts").glob("*/fasit.json")):
        set_dir = fasit_path.parent
        names = {
            b["bundle_id"]: b["name"] for b in read_bundle_declarations(set_dir / "bundle.txt")
        }
        routed = {
            a.id: names[a.bundle_id] for a in load_mandate(set_dir / "mandate.json").approaches
        }
        for row in json.loads(fasit_path.read_text(encoding="utf-8"))["must_cite"]:
            for concept in row["concepts"]:
                calls.append((routed[row["approach_id"]], concept["path"]))
                calls.append((routed[row["approach_id"]], _slip(concept["path"])))
    refused = served = 0
    cache: dict[str, Any] = {}
    for name, path in calls:
        base = _delivered(name)
        if name not in cache:
            cache[name] = (_tools(base)["read_file"], _bid(base))
        tool, bundle_id = cache[name]
        answer = str(tool.func(bundle_id=bundle_id, path=path))
        if answer.startswith("REFUSED ("):
            refused += 1
            assert okf.BundlePathNotFound.__name__ in answer and "read_dir" in answer
        else:
            served += 1

    assert (refused, served) == (18, 18), f"population moved: {refused} refused, {served} served"