/**
   * Filters SchemaContext for yang modules
   *
   * @param delegate original SchemaContext
   * @param rootModules modules (yang schemas) to be available and all their dependencies (modules
   *     importing rootModule and whole chain of their imports)
   * @param additionalModuleIds (additional) modules (yang schemas) to be available and whole chain
   *     of their imports
   */
  public FilteringSchemaContextProxy(
      final SchemaContext delegate,
      final Collection<ModuleId> rootModules,
      final Set<ModuleId> additionalModuleIds) {

    Preconditions.checkArgument(rootModules != null, "Base modules cannot be null.");
    Preconditions.checkArgument(additionalModuleIds != null, "Additional modules cannot be null.");

    final Builder<Module> filteredModulesBuilder = new Builder<>();

    final SetMultimap<URI, Module> nsMap =
        Multimaps.newSetMultimap(new TreeMap<URI, Collection<Module>>(), MODULE_SET_SUPPLIER);
    final SetMultimap<String, Module> nameMap =
        Multimaps.newSetMultimap(new TreeMap<String, Collection<Module>>(), MODULE_SET_SUPPLIER);

    ImmutableMap.Builder<ModuleIdentifier, String> identifiersToSourcesBuilder =
        ImmutableMap.builder();

    // preparing map to get all modules with one name but difference in revision
    final TreeMultimap<String, Module> nameToModulesAll = getStringModuleTreeMultimap();

    nameToModulesAll.putAll(getStringModuleMap(delegate));

    // in case there is a particular dependancy to view filteredModules/yang models
    // dependancy is checked for module name and imports
    processForRootModules(delegate, rootModules, filteredModulesBuilder);

    // adding additional modules
    processForAdditionalModules(delegate, additionalModuleIds, filteredModulesBuilder);

    filteredModulesBuilder.addAll(
        getImportedModules(
            Maps.uniqueIndex(delegate.getModules(), ModuleId.MODULE_TO_MODULE_ID),
            filteredModulesBuilder.build(),
            nameToModulesAll));

    /**
     * Instead of doing this on each invocation of getModules(), pre-compute it once and keep it
     * around -- better than the set we got in.
     */
    this.filteredModules = filteredModulesBuilder.build();

    for (final Module module : filteredModules) {
      nameMap.put(module.getName(), module);
      nsMap.put(module.getNamespace(), module);
      identifiersToSourcesBuilder.put(module, module.getSource());
    }

    namespaceToModules = ImmutableSetMultimap.copyOf(nsMap);
    nameToModules = ImmutableSetMultimap.copyOf(nameMap);
    identifiersToSources = identifiersToSourcesBuilder.build();
  }