"""Import a browser-produced OBJ in pinned Blender 5.2 and emit a semantic report."""

import hashlib
import json
import sys
from pathlib import Path

import bpy


def sha256_file(path):
    digest = hashlib.sha256()
    with open(path, "rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def report_scene():
    objects = []
    for obj in sorted((item for item in bpy.context.scene.objects if item.type == "MESH"), key=lambda item: item.name):
        mesh = obj.data
        mesh.calc_loop_triangles()
        uv_layers = sorted(layer.name for layer in mesh.uv_layers)
        objects.append({
            "name": obj.name,
            "vertexCount": len(mesh.vertices),
            "polygonCount": len(mesh.polygons),
            "triangleCount": len(mesh.loop_triangles),
            "normalCount": len(mesh.vertices),
            "uvLayers": uv_layers,
            "uvLoopCount": len(mesh.uv_layers.active.data) if mesh.uv_layers.active else 0,
            "materials": sorted(material.name for material in mesh.materials if material),
        })
    return {"objects": objects, "objectCount": len(objects), "meshCount": len(objects)}


def main(obj_path, report_path):
    obj_path = Path(obj_path).resolve()
    report_path = Path(report_path).resolve()
    bpy.ops.wm.read_factory_settings(use_empty=True)
    result = bpy.ops.wm.obj_import(
        filepath=str(obj_path),
        directory=str(obj_path.parent),
        forward_axis="NEGATIVE_Z",
        up_axis="Y",
        global_scale=1.0,
        use_split_objects=True,
        use_split_groups=True,
        validate_meshes=True,
        import_vertex_groups=False,
    )
    if "FINISHED" not in result:
        raise RuntimeError("Blender OBJ import did not finish: %s" % (result,))
    report = {
        "schemaVersion": 1,
        "operation": "DESKTOP_IMPORT_WEB_OBJ",
        "sourceObjSha256": sha256_file(obj_path),
        "sourceObjBytes": obj_path.stat().st_size,
        **report_scene(),
    }
    report_path.parent.mkdir(parents=True, exist_ok=True)
    report_path.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    print("obj-web-roundtrip-desktop-imported objects=%s triangles=%s" % (report["objectCount"], sum(item["triangleCount"] for item in report["objects"])))


if __name__ == "__main__":
    args = sys.argv[sys.argv.index("--") + 1 :] if "--" in sys.argv else []
    if len(args) != 2:
        raise SystemExit("usage: blender --background --python check-obj-web-roundtrip.py -- OBJ REPORT")
    main(args[0], args[1])