#!/usr/bin/env python3
import hashlib
import json
import os
import pathlib
import sys
import tempfile

import bpy


def report():
    scene = bpy.data.scenes.get("WebGapScene")
    if scene is None:
        raise RuntimeError("WebGapScene is missing")
    return {
        "id": "scene:" + scene.name,
        "name": scene.name,
        "frameCurrent": int(scene.frame_current),
        "frameStart": int(scene.frame_start),
        "frameEnd": int(scene.frame_end),
        "fps": round(float(scene.render.fps), 6),
        "fpsBase": round(float(scene.render.fps_base), 6),
        "unitSystem": {"NONE": 0, "METRIC": 1, "IMPERIAL": 2}.get(scene.unit_settings.system, -1),
        "unitScale": round(float(scene.unit_settings.scale_length), 6),
        "renderEngine": scene.render.engine,
    }


def main():
    arguments = sys.argv[sys.argv.index("--") + 1 :]
    if len(arguments) != 2:
        raise SystemExit("usage: blender -b --python check-scene-desktop.py -- FIXTURE REPORT")
    fixture, output = (pathlib.Path(value).resolve() for value in arguments)
    bpy.ops.wm.open_mainfile(filepath=str(fixture), load_ui=False)
    before = report()
    descriptor, temporary = tempfile.mkstemp(prefix="m16-scene-reopen-", suffix=".blend", dir=fixture.parent)
    os.close(descriptor)
    try:
        bpy.ops.wm.save_as_mainfile(filepath=temporary, check_existing=False, compress=True)
        bpy.ops.wm.open_mainfile(filepath=temporary, load_ui=False)
        after = report()
    finally:
        pathlib.Path(temporary).unlink(missing_ok=True)
    if before != after:
        raise RuntimeError(f"scene save/reopen drift: {before} != {after}")
    value = {"schemaVersion": 1, "task": "M16-GAP-00020", "operation": "SCENE_DATABLOCK_DESKTOP", "fixture": str(fixture), "fixtureSha256": hashlib.sha256(fixture.read_bytes()).hexdigest(), "scene": after, "saveReopen": "EXACT", "blenderVersion": bpy.app.version_string}
    output.parent.mkdir(parents=True, exist_ok=True)
    output.write_text(json.dumps(value, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    print(f"scene-desktop-ok id={after['id']} frames={after['frameStart']}-{after['frameEnd']} saveReopen=exact")


if __name__ == "__main__":
    main()