content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.content;
  
  import android.annotation.NonNull;
  import android.annotation.Nullable;
  
  import java.util.ArrayList;
  
  /**
   * Provides utility methods for matching MIME type filters used in ContentProvider.
   *
   * <p>Wildcards are allowed only instead of the entire type or subtype with a tree prefix.
   * Eg. image\/*, *\/* is a valid filter and will match image/jpeg, but image/j* is invalid and
   * it will not match image/jpeg. Suffixes and parameters are not supported, and they are treated
   * as part of the subtype during matching. Neither type nor subtype can be empty.
   *
   * <p><em>Note: MIME type matching in the Android framework is case-sensitive, unlike the formal
   * RFC definitions. As a result, you should always write these elements with lower case letters,
   * or use {@link android.content.Intent#normalizeMimeType} to ensure that they are converted to
   * lower case.</em>
   *
   * <p>MIME types can be null or ill-formatted. In such case they won't match anything.
   *
   * <p>MIME type filters must be correctly formatted, or an exception will be thrown.
   * Copied from support library.
   * {@hide}
   */
  public final class MimeTypeFilter {
  
      private MimeTypeFilter() {
      }
  
      private static boolean mimeTypeAgainstFilter(
              @NonNull String[] mimeTypeParts, @NonNull String[] filterParts) {
          if (filterParts.length != 2) {
              throw new IllegalArgumentException(
                      "Ill-formatted MIME type filter. Must be type/subtype.");
          }
          if (filterParts[0].isEmpty() || filterParts[1].isEmpty()) {
              throw new IllegalArgumentException(
                      "Ill-formatted MIME type filter. Type or subtype empty.");
          }
          if (mimeTypeParts.length != 2) {
              return false;
          }
          if (!"*".equals(filterParts[0])
                  && !filterParts[0].equals(mimeTypeParts[0])) {
              return false;
          }
          if (!"*".equals(filterParts[1])
                  && !filterParts[1].equals(mimeTypeParts[1])) {
              return false;
          }
  
          return true;
      }
  
      /**
       * Matches one nullable MIME type against one MIME type filter.
       * @return True if the {@code mimeType} matches the {@code filter}.
       */
      public static boolean matches(@Nullable String mimeType, @NonNull String filter) {
          if (mimeType == null) {
              return false;
          }
  
          final String[] mimeTypeParts = mimeType.split("/");
          final String[] filterParts = filter.split("/");
  
          return mimeTypeAgainstFilter(mimeTypeParts, filterParts);
      }
  
      /**
       * Matches one nullable MIME type against an array of MIME type filters.
       * @return The first matching filter, or null if nothing matches.
       */
      @Nullable
      public static String matches(
              @Nullable String mimeType, @NonNull String[] filters) {
          if (mimeType == null) {
              return null;
          }
  
          final String[] mimeTypeParts = mimeType.split("/");
          for (String filter : filters) {
              final String[] filterParts = filter.split("/");
              if (mimeTypeAgainstFilter(mimeTypeParts, filterParts)) {
                  return filter;
              }
          }
  
          return null;
      }
  
      /**
       * Matches multiple MIME types against an array of MIME type filters.
       * @return The first matching MIME type, or null if nothing matches.
       */
      @Nullable
      public static String matches(
              @Nullable String[] mimeTypes, @NonNull String filter) {
          if (mimeTypes == null) {
              return null;
          }
  
          final String[] filterParts = filter.split("/");
          for (String mimeType : mimeTypes) {
              final String[] mimeTypeParts = mimeType.split("/");
              if (mimeTypeAgainstFilter(mimeTypeParts, filterParts)) {
                  return mimeType;
              }
          }
  
          return null;
      }
  
      /**
       * Matches multiple MIME types against an array of MIME type filters.
       * @return The list of matching MIME types, or empty array if nothing matches.
       */
      @NonNull
      public static String[] matchesMany(
              @Nullable String[] mimeTypes, @NonNull String filter) {
          if (mimeTypes == null) {
              return new String[] {};
          }
  
          final ArrayList<String> list = new ArrayList<>();
          final String[] filterParts = filter.split("/");
          for (String mimeType : mimeTypes) {
              final String[] mimeTypeParts = mimeType.split("/");
              if (mimeTypeAgainstFilter(mimeTypeParts, filterParts)) {
                  list.add(mimeType);
              }
          }
  
          return list.toArray(new String[list.size()]);
      }
  }
  