Function resolveLayerGroups

modules/mapbox/src/resolve-layer-groups.ts:26–88

(map?: Map, oldLayers?: LayersList, newLayers?: LayersList)

 **/
// eslint-disable-next-line complexity, max-statements
export function resolveLayerGroups(map?: Map, oldLayers?: LayersList, newLayers?: LayersList) {
  // Wait until map style is loaded
  // @ts-ignore non-public map property
  if (!map || !map.style || !map.style._loaded) {
    return;
  }

  const layers = flatten(newLayers, Boolean) as Layer<LayerOverlayProps>[];

  if (oldLayers !== newLayers) {
    // Step 1: remove "group" layers that no longer exist
    const prevLayers = flatten(oldLayers, Boolean) as Layer<LayerOverlayProps>[];
    const prevLayerGroupIds = new Set<string>(prevLayers.map(l => getLayerGroupId(l)));
    const newLayerGroupIds = new Set<string>(layers.map(l => getLayerGroupId(l)));

    for (const groupId of prevLayerGroupIds) {
      if (!newLayerGroupIds.has(groupId)) {
        if (map.getLayer(groupId)) {
          map.removeLayer(groupId);
        }
      }
    }
  }

  // Step 2: add missing "group" layers
  const layerGroups: Record<string, MapboxLayerGroup> = {};
  for (const layer of layers) {
    const groupId = getLayerGroupId(layer);
    const mapboxGroup = map.getLayer(groupId) as MapboxLayerGroup;
    if (mapboxGroup) {
      // Mapbox's map.getLayer() had a breaking change in v3.6.0, see https://github.com/visgl/deck.gl/issues/9086
      // @ts-expect-error not typed
      const groupInstance = mapboxGroup.implementation || mapboxGroup;
      layerGroups[groupId] = groupInstance;
    } else {
      const newGroup = new MapboxLayerGroup({
        id: groupId,
        slot: layer.props.slot,
        beforeId: layer.props.beforeId
      });
      layerGroups[groupId] = newGroup;
      map.addLayer(newGroup, layer.props.beforeId);
    }
  }

  // Step 3: check the order of layers
  // If beforeId move "group" layers to proper position in the mapbox layer order
  // @ts-ignore non-public map property
  const mapLayers: string[] = map.style._order;

  for (const [groupId, group] of Object.entries(layerGroups)) {
    const beforeId = group.beforeId || UNDEFINED_BEFORE_ID;

    const expectedGroupIndex =
      beforeId === UNDEFINED_BEFORE_ID ? mapLayers.length : mapLayers.indexOf(beforeId);

    const currentGropupIndex = mapLayers.indexOf(groupId);
    if (currentGropupIndex !== expectedGroupIndex - 1) {