"""Asset library helpers for Blender render scripts.

Provides functions to link materials and node groups from a .blend asset library
into the current scene, and apply them to mesh objects.

These functions are intended to be imported by still_render.py / turntable_render.py
when a RenderTemplate has an asset library associated.
"""
from __future__ import annotations

import logging

logger = logging.getLogger(__name__)


def apply_asset_library_materials(blend_path: str, material_map: dict) -> None:
    """Link materials from an asset library .blend and apply them to mesh slots.

    Args:
        blend_path: Absolute path to the .blend library file.
        material_map: Mapping of current slot material name -> library material name.
                      E.g. {"Steel--Stahl": "SCHAEFFLER_010101_Steel-Bare"}
    """
    import bpy  # type: ignore[import]

    if not material_map:
        return

    target_names = set(material_map.values())

    # Link materials from the library
    with bpy.data.libraries.load(blend_path, link=True, assets_only=True) as (src, dst):
        dst.materials = [name for name in src.materials if name in target_names]

    linked = {m.name for m in dst.materials if m is not None}
    logger.info("Linked %d materials from %s", len(linked), blend_path)

    # Apply to all mesh object material slots
    for obj in bpy.data.objects:
        if obj.type != "MESH":
            continue
        for slot in obj.material_slots:
            if slot.material is None:
                continue
            resolved = material_map.get(slot.material.name)
            if resolved and resolved in bpy.data.materials:
                slot.material = bpy.data.materials[resolved]


def apply_asset_library_node_groups(blend_path: str, modifier_map: dict) -> None:
    """Link geometry node groups from an asset library and apply as modifiers.

    Args:
        blend_path: Absolute path to the .blend library file.
        modifier_map: Mapping of object name substring -> node group name.
                      E.g. {"ring": "WearPattern_GeoNodes"}
    """
    import bpy  # type: ignore[import]

    if not modifier_map:
        return

    target_names = set(modifier_map.values())

    with bpy.data.libraries.load(blend_path, link=True, assets_only=True) as (src, dst):
        dst.node_groups = [name for name in src.node_groups if name in target_names]

    for obj in bpy.data.objects:
        if obj.type != "MESH":
            continue
        for part_substr, ng_name in modifier_map.items():
            if part_substr.lower() in obj.name.lower():
                ng = bpy.data.node_groups.get(ng_name)
                if ng:
                    mod = obj.modifiers.new(name=ng_name, type="NODES")
                    mod.node_group = ng
                    logger.info("Applied node group %s to %s", ng_name, obj.name)