"""Phase A3 — assembler bridge proof (SPEC_OPTION_A.md §3.3, §10).

The crucial offline gate: each build-spec fixture, run through the real
generator + kernel + repair + assembler, produces output that passes BOTH the
existing frontend contract (`validate_shape`) AND the geometric metric gate.
Also proves model-free regeneration (new vane count -> valid contract).
"""
import importlib.util
import json
import sys
from pathlib import Path

import pytest

ROOT = Path(__file__).resolve().parent.parent
if str(ROOT) not in sys.path:
    sys.path.insert(0, str(ROOT))

from geometry import assembler, metrics  # noqa: E402

# Reuse the contract validator from the Phase 1 schema tests.
_spec = importlib.util.spec_from_file_location("schema_mod", ROOT / "tests" / "test_schema.py")
_schema = importlib.util.module_from_spec(_spec)
_spec.loader.exec_module(_schema)
validate_shape = _schema.validate_shape

FIX = ROOT / "tests" / "fixtures" / "codegen"
SPECS = {"octahedron": "spec_octahedron.json",
         "cube": "spec_cube.json",
         "cylindrical_vent": "spec_cylindrical_vent.json"}


def load_spec(name):
    return json.loads((FIX / SPECS[name]).read_text())


def _geom(contract):
    verts = contract["geometry"]["vertices"]
    faces = [f["indices"] for f in contract["geometry"]["faces"]]
    return verts, faces


@pytest.mark.parametrize("name", list(SPECS))
def test_assembled_passes_frontend_contract(name):
    spec = load_spec(name)
    contract, warnings = assembler.build(spec)
    errors = validate_shape(contract)
    assert errors == [], errors


@pytest.mark.parametrize("name", list(SPECS))
def test_assembled_passes_metric_gate(name):
    spec = load_spec(name)
    contract, _ = assembler.build(spec)
    verts, faces = _geom(contract)
    ok, fails = metrics.passes(verts, faces, spec["regularity"])
    assert ok, fails


def test_octahedron_decomposed_into_8_components():
    contract, _ = assembler.build(load_spec("octahedron"))
    assert contract["complexity"]["component_count"] == 8
    assert contract["complexity"]["face_count"] == 8


def test_cube_six_components_twelve_triangles():
    contract, _ = assembler.build(load_spec("cube"))
    assert contract["complexity"]["component_count"] == 6
    assert contract["complexity"]["face_count"] == 12


def test_complexity_counts_match_arrays():
    for name in SPECS:
        contract, _ = assembler.build(load_spec(name))
        assert contract["complexity"]["vertex_count"] == len(contract["geometry"]["vertices"])
        assert contract["complexity"]["face_count"] == len(contract["geometry"]["faces"])
        assert contract["complexity"]["component_count"] == len(contract["components"])


def test_regeneration_more_vanes_is_model_free_and_valid():
    # Re-running the cached generator with vanes=12 must yield a valid contract
    # with auto-reconciled vane components — no model call involved.
    spec = load_spec("cylindrical_vent")
    contract, warnings = assembler.build(spec, params={"vanes": 12, "height": 2.0})
    assert validate_shape(contract) == []
    vane_comps = [c for c in contract["components"] if c["id"].startswith("vane_")]
    assert len(vane_comps) == 12
    assert any("auto-reconciled" in w for w in warnings)  # vane_8..11 were undeclared


def test_regeneration_fewer_vanes_valid():
    spec = load_spec("cylindrical_vent")
    contract, _ = assembler.build(spec, params={"vanes": 5, "height": 2.0})
    assert validate_shape(contract) == []
    vane_comps = [c for c in contract["components"] if c["id"].startswith("vane_")]
    assert len(vane_comps) == 5


def test_sanitizes_invalid_transform_axis():
    # Model emits axis "xy" (only x|y|z is valid) — assembler must coerce so the
    # contract validates instead of the frontend rejecting it.
    spec = load_spec("octahedron")
    spec["params"][0]["transform"] = {"op": "scale_axis", "axis": "xy", "components": "all"}
    contract, _ = assembler.build(spec)
    assert validate_shape(contract) == []
    p = next(p for p in contract["params"] if p["id"] == "scale")
    assert p["transform"]["axis"] == "x"  # coerced to first valid axis char


def test_sanitizes_unfixable_axis_drops_transform():
    spec = load_spec("octahedron")
    spec["params"][0]["transform"] = {"op": "rotate", "axis": "diagonal"}
    contract, _ = assembler.build(spec)
    assert validate_shape(contract) == []
    p = next(p for p in contract["params"] if p["id"] == "scale")
    assert "transform" not in p  # no valid axis -> transform dropped


def test_sanitizes_out_of_range_valid_band_and_dropdown():
    spec = load_spec("octahedron")
    spec["params"][0]["valid_min"] = spec["params"][0]["min"] - 5  # below min
    spec["params"][0]["valid_max"] = spec["params"][0]["max"] + 5  # above max
    spec["params"].append({"id": "style", "label": "Style", "type": "dropdown",
                           "options": ["a", "b"], "default": "zzz"})  # bad default
    contract, _ = assembler.build(spec)
    assert validate_shape(contract) == []
    style = next(p for p in contract["params"] if p["id"] == "style")
    assert style["default"] == "a"


def test_constraint_referencing_dropped_param_removed():
    spec = load_spec("octahedron")
    spec["constraints"] = [{"id": "c1", "params": ["ghost_param"], "rule": "x"}]
    contract, _ = assembler.build(spec)
    assert validate_shape(contract) == []
    assert contract["constraints"] == []


def test_triangle_counts_sum_to_face_count():
    for name in SPECS:
        contract, _ = assembler.build(load_spec(name))
        total = sum(c["triangle_count"] for c in contract["components"])
        assert total == contract["complexity"]["face_count"]