content: /*******************************************************************************
   * Copyright 2011-2013 Sergey Tarasevich
   *
   * 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 com.nostra13.universalimageloader.core.download;
  
  import com.nostra13.universalimageloader.core.DisplayImageOptions;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.Locale;
  
  /**
   * Provides retrieving of {@link InputStream} of image by URI.<br />
   * Implementations have to be thread-safe.
   *
   * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
   * @since 1.4.0
   */
  public interface ImageDownloader {
  	/**
  	 * Retrieves {@link InputStream} of image by URI.
  	 *
  	 * @param imageUri Image URI
  	 * @param extra    Auxiliary object which was passed to {@link DisplayImageOptions.Builder#extraForDownloader(Object)
  	 *                 DisplayImageOptions.extraForDownloader(Object)}; can be null
  	 * @return {@link InputStream} of image
  	 * @throws IOException                   if some I/O error occurs during getting image stream
  	 * @throws UnsupportedOperationException if image URI has unsupported scheme(protocol)
  	 */
  	InputStream getStream(String imageUri, Object extra) throws IOException;
  
  	/** Represents supported schemes(protocols) of URI. Provides convenient methods for work with schemes and URIs. */
  	public enum Scheme {
  		HTTP("http"), HTTPS("https"), FILE("file"), CONTENT("content"), ASSETS("assets"), DRAWABLE("drawable"), UNKNOWN("");
  
  		private String scheme;
  		private String uriPrefix;
  
  		Scheme(String scheme) {
  			this.scheme = scheme;
  			uriPrefix = scheme + "://";
  		}
  
  		/**
  		 * Defines scheme of incoming URI
  		 *
  		 * @param uri URI for scheme detection
  		 * @return Scheme of incoming URI
  		 */
  		public static Scheme ofUri(String uri) {
  			if (uri != null) {
  				for (Scheme s : values()) {
  					if (s.belongsTo(uri)) {
  						return s;
  					}
  				}
  			}
  			return UNKNOWN;
  		}
  
  		private boolean belongsTo(String uri) {
  			return uri.toLowerCase(Locale.US).startsWith(uriPrefix);
  		}
  
  		/** Appends scheme to incoming path */
  		public String wrap(String path) {
  			return uriPrefix + path;
  		}
  
  		/** Removed scheme part ("scheme://") from incoming URI */
  		public String crop(String uri) {
  			if (!belongsTo(uri)) {
  				throw new IllegalArgumentException(String.format("URI [%1$s] doesn't have expected scheme [%2$s]", uri, scheme));
  			}
  			return uri.substring(uriPrefix.length());
  		}
  	}
  }
  