import bpy

def popup_error(message: str):
    def _draw(self, context):
        self.layout.label(text=message)
    try:
        bpy.context.window_manager.popup_menu(_draw, title="HardHat", icon='ERROR')
    except Exception:
        print(f"ERROR: {message}")


def selected_hair_meshes():
    # Use stored scene targets if present (strict requirement per user preference)
    names = (bpy.context.scene.get('HH_HairTargets') or '').split(';')
    names = [n for n in names if n]
    if names:
        objs = [bpy.data.objects.get(n) for n in names]
        return [o for o in objs if o and o.type == 'MESH']
    popup_error("No HardHat hair targets set. Click 'Set HardHat Hair Targets' first.")
    return []


def ensure_empty_vertex_group(obj, name):
    vg = obj.vertex_groups.get(name)
    if vg:
        # Clear existing by removing and recreating to guarantee emptiness
        obj.vertex_groups.remove(vg)
    return obj.vertex_groups.new(name=name)


def ensure_full_vertex_group(obj, name):
    vg = obj.vertex_groups.get(name)
    if vg:
        obj.vertex_groups.remove(vg)
    vg = obj.vertex_groups.new(name=name)
    if obj.data.vertices:
        vg.add(range(len(obj.data.vertices)), 1.0, 'REPLACE')
    return vg


def set_mask_modifiers(obj, main_name, hh_name):
    # Remove existing
    for m in list(obj.modifiers):
        if m.type == 'MASK' and m.name in {main_name, hh_name}:
            obj.modifiers.remove(m)
    m1 = obj.modifiers.new(name=main_name, type='MASK')
    m1.vertex_group = main_name
    m2 = obj.modifiers.new(name=hh_name, type='MASK')
    m2.vertex_group = hh_name
    return m1, m2


def run():
    hair_objs = selected_hair_meshes()
    if not hair_objs:
        print("Error: Select hair mesh object(s) before running")
        return

    for obj in hair_objs:
        ensure_full_vertex_group(obj, 'MainMask')
        ensure_empty_vertex_group(obj, 'HHMask')
        set_mask_modifiers(obj, 'MainMask', 'HHMask')
        print(f"Prepared '{obj.name}': MainMask=all verts, HHMask=empty, mask modifiers created")

    print("hh_mask: Done. Assign weights to HHMask as needed.")


run()