"""Prints a JSON summary of a .blend file (objects, meshes, materials, armatures, actions).
Usage: blender --background <file.blend> --python tools/blender/inspect_blend.py -- <out.json>"""
import bpy, json, sys
out = sys.argv[sys.argv.index('--') + 1] if '--' in sys.argv else None
scene = bpy.context.scene
info = {'file': bpy.data.filepath, 'unit_system': scene.unit_settings.system, 'scale_length': scene.unit_settings.scale_length,
        'fps': scene.render.fps, 'objects': [], 'actions': []}
for obj in bpy.data.objects:
    entry = {'name': obj.name, 'type': obj.type, 'parent': obj.parent.name if obj.parent else None,
             'location': [round(v, 4) for v in obj.location], 'rotation': [round(v, 4) for v in obj.rotation_euler],
             'scale': [round(v, 4) for v in obj.scale], 'in_scene': obj.name in scene.objects,
             'hide_render': obj.hide_render}
    if obj.type == 'MESH':
        me = obj.data
        entry.update({'mesh': me.name, 'verts': len(me.vertices), 'polys': len(me.polygons),
                      'ngons': sum(1 for p in me.polygons if len(p.vertices) > 4),
                      'materials': [m.name if m else None for m in me.materials], 'uv_layers': [uv.name for uv in me.uv_layers],
                      'color_attributes': [(c.name, c.domain, c.data_type) for c in me.color_attributes],
                      'custom_normals': me.has_custom_normals, 'shape_keys': [k.name for k in me.shape_keys.key_blocks] if me.shape_keys else [],
                      'modifiers': [(m.type, m.name) for m in obj.modifiers], 'vertex_groups': len(obj.vertex_groups)})
    if obj.type == 'ARMATURE':
        arm = obj.data
        entry.update({'bones': len(arm.bones), 'roots': [b.name for b in arm.bones if b.parent is None],
                      'bone_names': [b.name for b in arm.bones][:80], 'action': obj.animation_data.action.name if obj.animation_data and obj.animation_data.action else None,
                      'nla': [(t.name, [s.action.name for s in t.strips if s.action]) for t in obj.animation_data.nla_tracks] if obj.animation_data else []})
    info['objects'].append(entry)
for act in bpy.data.actions:
    info['actions'].append({'name': act.name, 'range': [round(v, 2) for v in act.frame_range], 'users': act.users, 'fake_user': act.use_fake_user})
text = json.dumps(info, indent=1)
if out:
    open(out, 'w').write(text)
else:
    print(text)