"""
Enumerated parameters, and the length control that motivated them.

WHAT THIS IS ACTUALLY GUARDING
    ``model_length_mm`` compares ``length_view`` against the literal
    "Full Length" and falls through to the preview length for anything else --
    no rejection, no error. The reference behaved the same way, so the port is
    right to keep it.

    That makes the composer the only place the mistake can be caught. Before
    this, ``length_view`` was not in COMMON_GROUPS at all, so the Full Length
    branch was unreachable and every model was a 100 mm preview whatever
    ``member_length_ft`` said. Exposing it as free text would have replaced an
    unreachable control with a silent one: "Full Length " with a trailing space
    builds a preview and says nothing.

    So the claims under test are: the branch is reachable, it moves the length
    it is supposed to move, and a value outside the declared set cannot reach
    the build.
"""

from __future__ import annotations

import pytest

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


def payload(**overrides):
    return app.build_payload("3x", "Y", dict(overrides))


def length_of(**overrides):
    p = payload(**overrides)
    assert p["ok"], p.get("message")
    return p["report"]["LENGTH_MM"]


# ---------------------------------------------------------------------------
# The declaration
# ---------------------------------------------------------------------------

def test_length_view_is_declared_with_exactly_its_two_values():
    assert app.ENUM_PARAMS["length_view"] == ["Preview", "Full Length"]


def test_every_enumerated_parameter_is_a_real_family_parameter():
    """
    A declared choice for a parameter no family has would render a control
    that does nothing -- the failure COMMON_GROUPS has a comment about.
    """
    for family in app.families().values():
        for key in app.ENUM_PARAMS:
            assert key in family.defaults, key


def test_every_declared_default_is_one_of_its_own_choices():
    """
    If a family's default were outside the list, the select would open showing
    a value it cannot represent and the first interaction would silently move
    the model.
    """
    for family in app.families().values():
        for key, allowed in app.ENUM_PARAMS.items():
            assert family.defaults[key] in allowed


# ---------------------------------------------------------------------------
# Reachability -- the defect that started this
# ---------------------------------------------------------------------------

def test_length_view_is_reachable_from_the_composer():
    for name, family in app.families().items():
        exposed = {k for _, keys in app.profile_params(family, "Y" if name == "3x" else "Cross")
                   for k in keys}
        assert "length_view" in exposed, name


def test_the_browser_is_told_the_choices():
    assert payload()["choices"]["length_view"] == ["Preview", "Full Length"]


# ---------------------------------------------------------------------------
# It moves the length it claims to move
# ---------------------------------------------------------------------------

def test_preview_is_the_preview_length():
    assert length_of(length_view="Preview", preview_length_mm=100) == 100


def test_full_length_is_feet_times_304_8():
    assert length_of(length_view="Full Length", member_length_ft=10) == 3048


def test_full_length_follows_member_length_ft():
    """
    The positive control for the pair above: a length that ignored its input
    would satisfy either test alone by returning a constant.
    """
    assert length_of(length_view="Full Length", member_length_ft=20) == 6096


def test_preview_ignores_member_length_ft():
    assert length_of(length_view="Preview", member_length_ft=40) == 100


# ---------------------------------------------------------------------------
# A value outside the set never reaches the build
# ---------------------------------------------------------------------------

@pytest.mark.parametrize("bad", ["Full Length ", "full length", "FULL LENGTH",
                                 "", "Fully Lengthed", "Preview\n"])
def test_an_unrecognised_value_falls_back_to_the_default(bad):
    """
    Not a rejection -- a fallback. The family default is a valid model, and
    the composer is a viewer rather than a validator. What must not happen is
    the string reaching ``model_length_mm`` and being silently ignored there,
    which is how a trailing space becomes a 100 mm export of a 10 ft member.
    """
    p = payload(length_view=bad, member_length_ft=10)
    assert p["ok"]
    assert p["values"]["length_view"] == "Preview"
    assert p["report"]["LENGTH_MM"] == 100


def test_the_unrecognised_value_is_not_merely_unused_but_absent():
    """
    Asserts the mechanism rather than its effect. If the string were passed
    through and happened to be ignored downstream, the test above would still
    pass and a later change to ``model_length_mm`` would turn it into a defect.
    """
    p = payload(length_view="Full Length ", member_length_ft=10)
    assert "Full Length " not in p["values"].values()


def test_a_recognised_value_does_reach_the_build():
    """The positive control: the fallback is not simply dropping everything."""
    p = payload(length_view="Full Length", member_length_ft=10)
    assert p["values"]["length_view"] == "Full Length"
    assert p["report"]["LENGTH_MM"] == 3048


# ---------------------------------------------------------------------------
# The length control does not disturb identity
# ---------------------------------------------------------------------------

def test_length_view_changes_the_design_id():
    """
    It is a build parameter, so it belongs in the hash -- unlike the author.
    Two members of different lengths are different designs.
    """
    preview = payload(length_view="Preview")["input_id"]
    full = payload(length_view="Full Length")["input_id"]
    assert preview != full


def test_an_unrecognised_value_yields_the_default_design_id():
    """Follows from the fallback, and is the property someone would rely on."""
    assert payload(length_view="Full Length ")["input_id"] == payload()["input_id"]