"""Load the Web Blender profile without touching the desktop user's config."""
from pathlib import Path
import bpy


def load_preferences(root):
    if (root / 'config' / 'userpref.blend').is_file():
        state = bpy.ops.wm.read_userpref('EXEC_DEFAULT')
        if 'FINISHED' not in state: raise RuntimeError('PREFERENCES_LOAD_FAILED')
    # Persistence is an explicit Web session command, not shutdown of a temporary job.
    bpy.context.preferences.use_preferences_save = False


def save_preferences(root, sequence):
    state = bpy.ops.wm.save_userpref('EXEC_DEFAULT')
    if 'FINISHED' not in state: raise RuntimeError('PREFERENCES_SAVE_FAILED')
    source = Path(bpy.utils.user_resource('CONFIG')) / 'userpref.blend'
    if not source.is_file() or source.stat().st_size > 16 * 1024 * 1024:
        raise RuntimeError('PREFERENCES_SAVE_OUTPUT_INVALID')
    destination = root / f'preferences-{sequence:08d}.blend'
    destination.write_bytes(source.read_bytes())
    return destination