/*
    * Copyright (C) 2009-2010, Google Inc.
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
    *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.eclipse.jgit.http.server;
  
  import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;
  import static javax.servlet.http.HttpServletResponse.SC_NOT_MODIFIED;
  import static org.eclipse.jgit.http.server.ServletUtils.getRepository;
  import static org.eclipse.jgit.util.HttpSupport.HDR_ETAG;
  import static org.eclipse.jgit.util.HttpSupport.HDR_IF_MODIFIED_SINCE;
  import static org.eclipse.jgit.util.HttpSupport.HDR_IF_NONE_MATCH;
  import static org.eclipse.jgit.util.HttpSupport.HDR_LAST_MODIFIED;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jgit.internal.storage.file.ObjectDirectory;
  import org.eclipse.jgit.lib.Repository;
  
  /** Sends any object from {@code GIT_DIR/objects/??/0 38}, or any pack file. */
  abstract class ObjectFileServlet extends HttpServlet {
  	private static final long serialVersionUID = 1L;
  
  	static class Loose extends ObjectFileServlet {
  		private static final long serialVersionUID = 1L;
  
  		Loose() {
  			super("application/x-git-loose-object");
  		}
  
  		@Override
  		String etag(FileSender sender) throws IOException {
  			return Long.toHexString(sender.getLastModified());
  		}
  	}
  
  	private static abstract class PackData extends ObjectFileServlet {
  		private static final long serialVersionUID = 1L;
  
  		PackData(String contentType) {
  			super(contentType);
  		}
  
  		@Override
  		String etag(FileSender sender) throws IOException {
  			return sender.getTailChecksum();
  		}
  	}
  
  	static class Pack extends PackData {
  		private static final long serialVersionUID = 1L;
  
  		Pack() {
 			super("application/x-git-packed-objects");
 		}
 	}
 
 	static class PackIdx extends PackData {
 		private static final long serialVersionUID = 1L;
 
 		PackIdx() {
 			super("application/x-git-packed-objects-toc");
 		}
 	}
 
 	private final String contentType;
 
 	ObjectFileServlet(String contentType) {
 		this.contentType = contentType;
 	}
 
 	abstract String etag(FileSender sender) throws IOException;
 
 	/** {@inheritDoc} */
 	@Override
 	public void doGet(final HttpServletRequest req,
 			final HttpServletResponse rsp) throws IOException {
 		serve(req, rsp, true);
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	protected void doHead(final HttpServletRequest req,
 			final HttpServletResponse rsp) throws ServletException, IOException {
 		serve(req, rsp, false);
 	}
 
 	private void serve(final HttpServletRequest req,
 			final HttpServletResponse rsp, final boolean sendBody)
 			throws IOException {
 		final File obj = new File(objects(req), req.getPathInfo());
 		final FileSender sender;
 		try {
 			sender = new FileSender(obj);
 		} catch (FileNotFoundException e) {
 			rsp.sendError(SC_NOT_FOUND);
 			return;
 		}
 
 		try {
 			final String etag = etag(sender);
 			final long lastModified = (sender.getLastModified() / 1000) * 1000;
 
 			String ifNoneMatch = req.getHeader(HDR_IF_NONE_MATCH);
 			if (etag != null && etag.equals(ifNoneMatch)) {
 				rsp.sendError(SC_NOT_MODIFIED);
 				return;
 			}
 
 			long ifModifiedSince = req.getDateHeader(HDR_IF_MODIFIED_SINCE);
 			if (0 < lastModified && lastModified < ifModifiedSince) {
 				rsp.sendError(SC_NOT_MODIFIED);
 				return;
 			}
 
 			if (etag != null)
 				rsp.setHeader(HDR_ETAG, etag);
 			if (0 < lastModified)
 				rsp.setDateHeader(HDR_LAST_MODIFIED, lastModified);
 			rsp.setContentType(contentType);
 			sender.serve(req, rsp, sendBody);
 		} finally {
 			sender.close();
 		}
 	}
 
 	private static File objects(HttpServletRequest req) {
 		final Repository db = getRepository(req);
 		return ((ObjectDirectory) db.getObjectDatabase()).getDirectory();
 	}
 }