"""
The design record has to survive being the only thing left.

A part on the bench, a text file beside it, and five years. If the record cannot
regenerate the design from that, it is decoration. These tests are mostly about
exactness and about what must NOT change an identity.
"""

from __future__ import annotations

import pytest

from mechcomp.design_record import (
    FORMAT_VERSION,
    VERIFY_KEYS,
    DesignRecord,
    canonical_params,
    canonical_value,
    parse_value,
    record_for,
    resolve,
    toolchain_versions,
)
from mechcomp.profiles.three_x import FAMILY as THREE_X


def _record(**over):
    base = dict(
        family="3x", profile="Y",
        defaults=THREE_X.defaults,
        params={"fit_clearance_mm": 0.25},
        code_revision="abc1234",
        generator_revision="8.0.0",
    )
    base.update(over)
    return record_for(**base)


# ---------------------------------------------------------------------------
# Exactness -- the record is a recipe, not a description
# ---------------------------------------------------------------------------

def test_floats_round_trip_exactly():
    """
    Every float must survive render -> parse unchanged, bit for bit.

    This is the property the whole record rests on. ``%g`` at six significant
    figures -- what the report emits -- would lose bits here and turn the record
    into a description of the part rather than a means of rebuilding it.
    """
    hostile = [0.1, 0.2, 0.30000000000000004, 1 / 3, 15.875, 0.508, 13.4, 0.79,
               1e-9, 1.7976931348623157e308, 5e-324, 2.2250738585072014e-308,
               123456.789012345, 0.1 + 0.2]
    for value in hostile:
        assert float(canonical_value(value)) == value, value
        assert parse_value(canonical_value(value)) == value, value

    rec = _record(params={"fit_clearance_mm": 0.1 + 0.2, "strap_width_mm": 1 / 3})
    back = DesignRecord.parse(rec.render())
    assert back.params["fit_clearance_mm"] == 0.1 + 0.2
    assert back.params["strap_width_mm"] == 1 / 3


def test_render_parse_round_trip_preserves_identity():
    """A record written out and read back is the same design."""
    rec = _record()
    back = DesignRecord.parse(rec.render())
    assert back.family == rec.family
    assert back.profile == rec.profile
    assert back.params == rec.params
    assert back.input_id == rec.input_id
    assert back.code_revision == rec.code_revision
    assert back.generator_revision == rec.generator_revision
    assert back.toolchain == rec.toolchain
    assert back.build_id == rec.build_id


def test_resolve_matches_the_assemble_merge():
    """
    ``resolve`` reproduces ``_common.assemble``'s ``{**defaults, **params}``.

    Duplicated deliberately, to keep this module off the build path. Duplication
    is only safe while it is checked, so it is checked.
    """
    params = {"fit_clearance_mm": 0.4, "y_junction_web_mm": 2.0}
    got = resolve(THREE_X.defaults, params)
    want = {**THREE_X.defaults, **params}
    assert got == want
    assert got["fit_clearance_mm"] == 0.4
    assert got["strap_width_mm"] == THREE_X.defaults["strap_width_mm"]
    assert set(got) == set(THREE_X.defaults)


# ---------------------------------------------------------------------------
# Identity -- what must and must not change it
# ---------------------------------------------------------------------------

def test_identical_designs_have_identical_ids():
    assert _record().input_id == _record().input_id
    assert _record().build_id == _record().build_id


def test_parameter_order_does_not_change_identity():
    """Dict ordering is an accident of how a caller built the mapping."""
    a = record_for(family="3x", profile="Y", defaults={},
                   params={"a": 1.0, "b": 2.0, "c": 3.0})
    b = record_for(family="3x", profile="Y", defaults={},
                   params={"c": 3.0, "b": 2.0, "a": 1.0})
    assert a.input_id == b.input_id
    assert canonical_params(a.params) == canonical_params(b.params)


def test_any_parameter_change_changes_the_input_id():
    """The tuning loop must never silently reuse an identity."""
    base = _record()
    seen = {base.input_id}
    for clearance in (0.15, 0.2, 0.24, 0.2500001, 0.26, 0.0, -0.05):
        other = _record(params={"fit_clearance_mm": clearance})
        assert other.input_id != base.input_id, clearance
        assert other.input_id not in seen, "collision at %r" % clearance
        seen.add(other.input_id)

    assert _record(profile="T").input_id != base.input_id
    assert _record(family="4x").input_id != base.input_id


def test_code_revision_changes_build_id_but_not_input_id():
    """
    The distinction that makes the pair useful: same intent, different bytes
    possible. That is the moment to check whether the geometry moved, and the
    record is what tells you to look.
    """
    a = _record(code_revision="aaaaaaa")
    b = _record(code_revision="bbbbbbb")
    assert a.input_id == b.input_id
    assert a.build_id != b.build_id

    c = _record(generator_revision="8.0.1")
    assert c.input_id == a.input_id
    assert c.build_id != a.build_id


def test_timestamp_and_note_are_excluded_from_both_ids():
    """
    A design regenerated tomorrow is the same design. If the clock entered the
    identity, nothing would ever reproduce.
    """
    a = _record(generated="2026-08-23T10:00:00Z", note="first attempt")
    b = _record(generated="2027-01-01T00:00:00Z", note="reprint for Dave")
    assert a.input_id == b.input_id
    assert a.build_id == b.build_id
    assert "2026-08-23" in a.render()
    assert "first attempt" in a.render()


def test_verification_values_do_not_affect_identity():
    """
    Reported values are outputs. If they entered the hash, a part would be
    identified by what it turned out to be rather than by what was asked for --
    and two runs of the same design on different GEOS builds could then claim to
    be different designs.
    """
    report = {k: 1.0 for k in VERIFY_KEYS}
    other = {k: 2.0 for k in VERIFY_KEYS}
    a = _record(report=report)
    b = _record(report=other)
    c = _record()
    assert a.input_id == b.input_id == c.input_id
    assert a.build_id == b.build_id == c.build_id
    assert a.verification != b.verification


# ---------------------------------------------------------------------------
# The rendered artifact
# ---------------------------------------------------------------------------

def test_render_is_deterministic():
    assert _record().render() == _record().render()


def test_render_is_readable_without_this_software():
    """
    Plain text, one fact per line, no framing that needs a parser. A record that
    only this program can open is not a record.
    """
    rec = _record(report={k: 12.3456 for k in VERIFY_KEYS},
                  stock=["PET strap 15.875 x 0.508 -- unverified: supplied at design time"],
                  fit=["clearance 0.2500 mm per face"],
                  generated="2026-08-23T10:00:00Z")
    text = rec.render()

    assert text.startswith("MECHCOMP DESIGN RECORD %s" % FORMAT_VERSION)
    assert rec.input_id in text and rec.build_id in text
    assert "3x" in text and "Y" in text
    assert "PET strap" in text and "unverified" in text
    assert "clearance 0.2500 mm per face" in text
    assert "fit_clearance_mm=0.25" in text
    assert "code_revision=abc1234" in text
    assert "generator_revision=8.0.0" in text
    assert "ENVELOPE_X_MM" in text
    assert text.endswith("\n")

    # Every resolved parameter reaches the file. A record that carries only the
    # overrides cannot rebuild anything, because the defaults it silently relied
    # on will have moved by then.
    for key in THREE_X.defaults:
        assert key in text, "parameter %s missing from the record" % key


def test_record_carries_every_resolved_parameter_not_just_overrides():
    rec = _record(params={"fit_clearance_mm": 0.25})
    assert set(rec.params) == set(THREE_X.defaults)
    assert len(rec.params) > 20


def test_unrecorded_stock_and_fit_say_so_rather_than_being_blank():
    text = _record().render()
    assert "(none recorded)" in text


def test_toolchain_is_captured_and_reaches_the_build_id():
    """
    GEOS can change boolean results on near-degenerate geometry -- the F-034
    mechanism exactly. A record omitting it cannot explain why the same
    parameters produced a different part, so its absence must be a failure and
    not a quiet blank.
    """
    shapely = pytest.importorskip(
        "shapely",
        reason="the toolchain assertion is about capturing the real GEOS "
               "version; without shapely there is nothing to capture")

    tools = toolchain_versions()
    assert "shapely" in tools, "shapely version not captured"
    assert tools["shapely"] == shapely.__version__
    assert tools["shapely"] != "unavailable", "shapely version lookup failed"

    rec = _record()
    assert rec.toolchain == tools
    assert rec.toolchain.get("shapely")

    text = rec.render()
    assert "shapely=%s" % tools["shapely"] in text

    # A different toolchain is a different build, even at identical intent.
    same_intent = DesignRecord(
        family=rec.family, profile=rec.profile, params=dict(rec.params),
        code_revision=rec.code_revision,
        generator_revision=rec.generator_revision,
        toolchain={**tools, "shapely": "0.0.0-not-real"})
    assert same_intent.input_id == rec.input_id
    assert same_intent.build_id != rec.build_id

    empty = DesignRecord(family=rec.family, profile=rec.profile,
                         params=dict(rec.params),
                         code_revision=rec.code_revision,
                         generator_revision=rec.generator_revision,
                         toolchain={})
    assert empty.build_id != rec.build_id


def test_missing_report_keys_are_omitted_not_invented():
    rec = _record(report={"ENVELOPE_X_MM": 20.5})
    assert rec.verification == {"ENVELOPE_X_MM": 20.5}
    assert "MASS_G" not in rec.verification


def test_bools_survive_the_round_trip():
    """``length_view`` is a string and some profile extras are bools."""
    assert canonical_value(True) == "true"
    assert parse_value("true") is True
    assert parse_value("false") is False
    rec = record_for(family="3x", profile="Y", defaults={},
                     params={"flag": True, "off": False, "name": "Preview"})
    back = DesignRecord.parse(rec.render())
    assert back.params["flag"] is True
    assert back.params["off"] is False
    assert back.params["name"] == "Preview"