import json
import pathlib
import sys

import bpy


def main(blend_path: str, output_path: str) -> None:
    bpy.ops.wm.open_mainfile(filepath=str(pathlib.Path(blend_path).resolve()), load_ui=False)
    obj = bpy.data.objects.get("RiggedShapeObject")
    if obj is None:
        raise RuntimeError("RiggedShapeObject is missing")
    # This golden isolates Blender's shape-key plus armature deformation. The saved fixture still
    # keeps Decimate enabled so modifier undo/redo tests exercise its normal default state.
    if obj.modifiers.get("Preview Decimate") is not None:
        obj.modifiers["Preview Decimate"].show_viewport = False
    scene = bpy.context.scene
    scene.frame_set(scene.frame_current)
    depsgraph = bpy.context.evaluated_depsgraph_get()
    evaluated = obj.evaluated_get(depsgraph)
    mesh = evaluated.to_mesh(preserve_all_data_layers=True, depsgraph=depsgraph)
    try:
        positions = [coordinate for vertex in mesh.vertices for coordinate in vertex.co]
        result = {
            "schemaVersion": 1,
            "fixture": "rigged_shape_scene.blend",
            "evaluator": "Blender Depsgraph",
            "blenderVersion": bpy.app.version_string,
            "frame": scene.frame_current,
            "object": obj.name,
            "mesh": obj.data.name,
            "vertexCount": len(mesh.vertices),
            "polygonCount": len(mesh.polygons),
            "positions": positions,
            "tolerance": {"maxPositionError": 1e-5, "rmsPositionError": 1e-6},
            "modifierStack": [{"name": modifier.name, "type": modifier.type, "showViewport": modifier.show_viewport} for modifier in obj.modifiers],
        }
    finally:
        evaluated.to_mesh_clear()
    pathlib.Path(output_path).write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")


if __name__ == "__main__":
    if "--" not in sys.argv or len(sys.argv) <= sys.argv.index("--") + 2:
        raise SystemExit("usage: blender -b --python generate-blender-deformation-golden.py -- input.blend output.json")
    arguments = sys.argv[sys.argv.index("--") + 1:]
    main(arguments[0], arguments[1])