/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.wicket.resource;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Iterator;
import java.util.Map;
import java.util.ServiceLoader;

import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.request.resource.IResource;
import org.apache.wicket.request.resource.ResourceReference;

/**
 * This resource reference is used to provide a reference to a resource based on Java NIO FileSystem
 * API.<br>
 * <br>
 * To implement a mime type detection refer to the documentation of
 * {@link java.nio.file.Files#probeContentType(Path)} and provide an implementation for
 * java.nio.file.spi.FileTypeDetector in the META-INF/services folder for jars or in the
 * /WEB-INF/classes/META-INF/services folder for webapps<br>
 * <br>
 * You can optionally override {@link #getFileSystemResource()} to provide an inline mime type
 * detection, which is preferred to the default detection.<br>
 * <br>
 * Example:
 * 
 * <pre>
 * <code>
 * Path path = FileSystemResourceReference.getPath(URI.create("jar:file:///folder/file.zip!/folderInZip/video.mp4"));
 * add(new Video("video", new FileSystemResourceReference(path)));
 * </code>
 * </pre>
 * 
 * Example 2:
 * 
 * <pre>
 * <code>
 * mountResource("/filecontent/${name}", new FileSystemResourceReference("filesystem")
 * {
 *      private static final long serialVersionUID = 1L;
 * 
 *      {@literal @}Override
 *      public IResource getResource()
 *      {
 *              return new FileSystemResource()
 *              {
 *                      private static final long serialVersionUID = 1L;
 * 
 *                      protected ResourceResponse newResourceResponse(Attributes attributes)
 *                      {
 *                              try
 *                              {
 *                                      String name = attributes.getParameters().get("name").toString("");
 *                                      URI uri = URI.create(
 *                                              "jar:file:////folder/example.zip!/zipfolder/" + name);
 *                                      return createResourceResponse(attributes, 
 *                                              FileSystemResourceReference.getPath(uri));
 *                              }
 *                              catch (IOException | URISyntaxException e)
 *                              {
 *                                      throw new WicketRuntimeException("Error while reading the file.", e);
 *                              }
 *                      };
 *              };
 *      }
 * });
 * </code>
 * </pre>
 * 
 * @author Tobias Soloschenko
 */
public class FileSystemResourceReference extends ResourceReference
{
        private static final long serialVersionUID = 1L;

        private Path path;

        /**
         * Creates a file system resource reference based on the given path
         * 
         * @param name
         *            the name of the resource reference to expose data
         * @param path
         *            the path to create the resource reference
         */
        public FileSystemResourceReference(String name, Path path)
        {
                super(name);
                this.path = path;
        }

        /**
         * Creates a file system resource reference based on the given name
         * 
         * @param name
         *            the name of the resource reference
         * 
         */
        public FileSystemResourceReference(String name)
        {
                super(name);
        }

        /**
         * Creates a file system resource reference based on the given scope and name
         * 
         * @param scope
         *            the scope as class
         * @param name
         *            the name of the resource reference
         * 
         */
        public FileSystemResourceReference(Class<?> scope, String name)
        {
                super(scope, name);
        }

        /**
         * Creates a new {@link FileSystemResource} and applies the
         * path to it.
         */
        @Override
        public IResource getResource()
        {
                return getFileSystemResource();
        }

        /**
         * Gets the file system resource to be used for the resource reference
         * 
         * @return the file system resource to be used for the resource reference
         */
        protected FileSystemResource getFileSystemResource()
        {
                if (path == null)
                {
                        throw new WicketRuntimeException(
                                "Please override #getResource() and provide a path if using a constructor which doesn't take one as argument.");
                }
                return new FileSystemResource(path);
        }

        /**
         * Creates a path and a file system (if required) based on the given URI
         * 
         * @param uri
         *            the URI to create the file system and the path of
         * @param env
         *            the environment parameter to create the file system with
         * @return the path of the file in the file system
         */
        public static Path getPath(URI uri, Map<String, String> env)
        {
                Iterator<FileSystemPathService> pathServiceIterator = ServiceLoader
                        .load(FileSystemPathService.class).iterator();
                while (pathServiceIterator.hasNext())
                {
                        FileSystemPathService pathService = pathServiceIterator.next();
                        if (pathService.isResponsible(uri))
                        {
                                Path fileSystemPath = pathService.getPath(uri, env);
                                if (fileSystemPath != null)
                                {
                                        return fileSystemPath;
                                }
                        }
                }
                // fall back to just get the path from the URI
                return Paths.get(uri);
        }

        /**
         * Creates a path and a file system (if required) based on the given URI
         * 
         * @param uri
         *            the URI to create the file system and the path of
         * @return the path of the file in the file system
         * @throws IOException
         *             if the file system could'nt be created
         * @throws URISyntaxException
         *             if the URI has no valid syntax
         */
        public static Path getPath(URI uri) throws IOException, URISyntaxException
        {
                return getPath(uri, null);
        }
}