"""
The export route: what it serves, what it refuses, and what it will not truncate.

WHY THE CEILING IS TESTED AS HARD AS THE GEOMETRY
    ``/m/stl`` is reachable without authentication on a public name, and
    ``member_length_ft`` is an unbounded number. The response body grows with
    nothing but that parameter. The bound is the only thing standing between a
    short URL and a very large computation, so a bound that silently stopped
    applying would be worse than none -- it would be documented, believed, and
    absent.
"""

from __future__ import annotations

import struct

import pytest

app = pytest.importorskip("mechcomp.web.app")
stl = pytest.importorskip("mechcomp.stl")

CEILING = app.DEFAULT_MAX_EXPORT_MM


def export(ceiling=None, **overrides):
    return app.build_export("3x", "Y", dict(overrides), "", ceiling)


# ---------------------------------------------------------------------------
# It serves a file
# ---------------------------------------------------------------------------

def test_a_default_export_is_a_named_stl():
    filename, data = export()
    assert filename.endswith(".stl")
    assert len(data) == 84 + 50 * struct.unpack("<I", data[80:84])[0]


def test_the_filename_carries_the_design_id():
    from mechcomp.profiles import build
    filename, _ = export()
    assert build("3x", "Y").record.input_id in filename


def test_the_header_identifies_the_design():
    _, data = export()
    text = data[:80].rstrip(b"\0").decode("ascii")
    assert text.startswith("mechcomp")
    assert "input=" in text and "build=" in text


def test_the_export_is_the_part_the_view_shows():
    """
    Both go through ``typed_overrides``. If they coerced differently the file
    would not be the drawing, and neither would look wrong on its own -- which
    is why the coercion is shared rather than written twice.
    """
    params = {"preview_length_mm": "37.5", "bundle_count": "2"}
    payload = app.build_payload("3x", "Y", dict(params))
    _, data = export(**params)

    zs = []
    count = struct.unpack("<I", data[80:84])[0]
    for n in range(count):
        base = 84 + n * 50 + 12
        for v in range(3):
            zs.append(struct.unpack("<3f", data[base + v * 12:base + v * 12 + 12])[2])
    assert max(zs) == pytest.approx(payload["report"]["LENGTH_MM"], rel=1e-6)
    assert payload["values"]["bundle_count"] == 2


# ---------------------------------------------------------------------------
# The ceiling
# ---------------------------------------------------------------------------

def test_the_default_ceiling_is_one_ten_foot_member():
    assert CEILING == 3048.0


def test_a_member_at_the_ceiling_exports():
    """The boundary is inclusive, and this is the positive control for below."""
    filename, data = export(length_view="Full Length", member_length_ft=10)
    assert filename.endswith(".stl")
    assert len(data) > 84


def test_a_member_over_the_ceiling_is_refused():
    outcome = export(length_view="Full Length", member_length_ft=100)
    assert isinstance(outcome, app.ExportRefusal)
    assert outcome.status == 413


def test_the_refusal_names_the_limit_and_how_to_raise_it():
    """
    A refusal a person cannot act on is a wall. This one says the length, the
    limit, and the configuration key.
    """
    outcome = export(length_view="Full Length", member_length_ft=100)
    assert "30480" in outcome.message
    assert "3048" in outcome.message
    assert "MECHCOMP_MAX_EXPORT_MM" in outcome.message


def test_nothing_is_truncated_to_fit():
    """
    The failure this prevents: exporting a 3048 mm file for a 30480 mm request
    would ship a design record describing a different object -- the same class
    of silent wrongness the length_view control was added to stop, arriving by
    a different door.
    """
    outcome = export(length_view="Full Length", member_length_ft=100)
    assert isinstance(outcome, app.ExportRefusal)
    assert "truncated" in outcome.message.lower()


def test_the_ceiling_is_configurable():
    """Raising it lets the same member through, which proves the gate is the
    ceiling rather than something else about a long member."""
    assert isinstance(export(length_view="Full Length", member_length_ft=100),
                      app.ExportRefusal)
    filename, data = export(ceiling=1e9, length_view="Full Length",
                            member_length_ft=100)
    assert filename.endswith(".stl")


def test_a_broken_ceiling_setting_falls_back_to_the_default(monkeypatch, tmp_path):
    """
    A typo must not silently remove the bound. That is the failure where a
    limit exists in the documentation and nowhere else.
    """
    empty = tmp_path / "none.env"
    empty.write_text("")
    for bad in ("", "abc", "0", "-5", "   "):
        monkeypatch.setenv("MECHCOMP_MAX_EXPORT_MM", bad)
        assert app.max_export_mm(str(empty)) == CEILING
    monkeypatch.setenv("MECHCOMP_MAX_EXPORT_MM", "5000")
    assert app.max_export_mm(str(empty)) == 5000.0


# ---------------------------------------------------------------------------
# Refusals are readable, not stack traces
# ---------------------------------------------------------------------------

def test_an_unknown_family_is_a_404():
    outcome = app.build_export("9x", "Y", {}, "")
    assert isinstance(outcome, app.ExportRefusal)
    assert outcome.status == 404


def test_an_unknown_profile_is_not_a_500():
    outcome = app.build_export("3x", "Nonexistent", {}, "")
    assert isinstance(outcome, app.ExportRefusal)
    assert outcome.status < 500


def test_a_rejected_profile_is_a_422_carrying_the_reason():
    """
    A rejection is the compiler working. The message names the parameter and
    the limit, as the reference did, and must survive to the caller.
    """
    outcome = export(min_wall_mm=50)
    assert isinstance(outcome, app.ExportRefusal)
    assert outcome.status == 422
    assert outcome.message
    assert "Traceback" not in outcome.message


def test_a_buildable_member_is_not_refused():
    """Positive control: the refusals are not simply refusing everything."""
    assert not isinstance(export(), app.ExportRefusal)


# ---------------------------------------------------------------------------
# Authorship travels with the export
# ---------------------------------------------------------------------------

def test_an_author_reaches_the_record_without_moving_the_file_identity():
    plain = app.build_export("3x", "Y", {}, "")
    signed = app.build_export("3x", "Y", {}, "someone@example.org")
    assert plain[0] == signed[0], "input_id must not move with the author"
    assert plain[1][:80] == signed[1][:80], "neither id may move"