/*
    * Copyright (C) 2015, Sasa Zivkov <sasa.zivkov@sap.com>
    * 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,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * 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,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package org.eclipse.jgit.lfs.server;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.apache.http.HttpStatus.SC_FORBIDDEN;
  import static org.apache.http.HttpStatus.SC_INSUFFICIENT_STORAGE;
  import static org.apache.http.HttpStatus.SC_INTERNAL_SERVER_ERROR;
  import static org.apache.http.HttpStatus.SC_NOT_FOUND;
  import static org.apache.http.HttpStatus.SC_OK;
  import static org.apache.http.HttpStatus.SC_SERVICE_UNAVAILABLE;
  import static org.apache.http.HttpStatus.SC_UNAUTHORIZED;
  import static org.apache.http.HttpStatus.SC_UNPROCESSABLE_ENTITY;
  import static org.eclipse.jgit.lfs.lib.Constants.DOWNLOAD;
  import static org.eclipse.jgit.lfs.lib.Constants.UPLOAD;
  import static org.eclipse.jgit.lfs.lib.Constants.VERIFY;
  import static org.eclipse.jgit.util.HttpSupport.HDR_AUTHORIZATION;
  
  import java.io.BufferedReader;
  import java.io.BufferedWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.io.Reader;
  import java.io.Writer;
  import java.text.MessageFormat;
  import java.util.List;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jgit.lfs.errors.LfsBandwidthLimitExceeded;
  import org.eclipse.jgit.lfs.errors.LfsException;
  import org.eclipse.jgit.lfs.errors.LfsInsufficientStorage;
  import org.eclipse.jgit.lfs.errors.LfsRateLimitExceeded;
  import org.eclipse.jgit.lfs.errors.LfsRepositoryNotFound;
  import org.eclipse.jgit.lfs.errors.LfsRepositoryReadOnly;
  import org.eclipse.jgit.lfs.errors.LfsUnauthorized;
  import org.eclipse.jgit.lfs.errors.LfsUnavailable;
  import org.eclipse.jgit.lfs.errors.LfsValidationError;
  import org.eclipse.jgit.lfs.internal.LfsText;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.gson.FieldNamingPolicy;
  import com.google.gson.Gson;
  import com.google.gson.GsonBuilder;
  
  /**
   * LFS protocol handler implementing the LFS batch API [1]
   *
   * [1] https://github.com/github/git-lfs/blob/master/docs/api/v1/http-v1-batch.md
   *
   * @since 4.3
   */
  public abstract class LfsProtocolServlet extends HttpServlet {
  	private static Logger LOG = LoggerFactory
 			.getLogger(LfsProtocolServlet.class);
 
 	private static final long serialVersionUID = 1L;
 
 	private static final String CONTENTTYPE_VND_GIT_LFS_JSON =
 			"application/vnd.git-lfs+json; charset=utf-8"; //$NON-NLS-1$
 
 	private static final int SC_RATE_LIMIT_EXCEEDED = 429;
 
 	private static final int SC_BANDWIDTH_LIMIT_EXCEEDED = 509;
 
 	private Gson gson = createGson();
 
 	/**
 	 * Get the large file repository for the given request and path.
 	 *
 	 * @param request
 	 *            the request
 	 * @param path
 	 *            the path
 	 *
 	 * @return the large file repository storing large files.
 	 * @throws LfsException
 	 *             implementations should throw more specific exceptions to
 	 *             signal which type of error occurred:
 	 *             <dl>
 	 *             <dt>{@link LfsValidationError}</dt>
 	 *             <dd>when there is a validation error with one or more of the
 	 *             objects in the request</dd>
 	 *             <dt>{@link LfsRepositoryNotFound}</dt>
 	 *             <dd>when the repository does not exist for the user</dd>
 	 *             <dt>{@link LfsRepositoryReadOnly}</dt>
 	 *             <dd>when the user has read, but not write access. Only
 	 *             applicable when the operation in the request is "upload"</dd>
 	 *             <dt>{@link LfsRateLimitExceeded}</dt>
 	 *             <dd>when the user has hit a rate limit with the server</dd>
 	 *             <dt>{@link LfsBandwidthLimitExceeded}</dt>
 	 *             <dd>when the bandwidth limit for the user or repository has
 	 *             been exceeded</dd>
 	 *             <dt>{@link LfsInsufficientStorage}</dt>
 	 *             <dd>when there is insufficient storage on the server</dd>
 	 *             <dt>{@link LfsUnavailable}</dt>
 	 *             <dd>when LFS is not available</dd>
 	 *             <dt>{@link LfsException}</dt>
 	 *             <dd>when an unexpected internal server error occurred</dd>
 	 *             </dl>
 	 * @since 4.5
 	 * @deprecated use
 	 *             {@link #getLargeFileRepository(LfsRequest, String, String)}
 	 */
 	@Deprecated
 	protected LargeFileRepository getLargeFileRepository(LfsRequest request,
 			String path) throws LfsException {
 		return getLargeFileRepository(request, path, null);
 	}
 
 	/**
 	 * Get the large file repository for the given request and path.
 	 *
 	 * @param request
 	 *            the request
 	 * @param path
 	 *            the path
 	 * @param auth
 	 *            the Authorization HTTP header
 	 *
 	 * @return the large file repository storing large files.
 	 * @throws LfsException
 	 *             implementations should throw more specific exceptions to
 	 *             signal which type of error occurred:
 	 *             <dl>
 	 *             <dt>{@link LfsValidationError}</dt>
 	 *             <dd>when there is a validation error with one or more of the
 	 *             objects in the request</dd>
 	 *             <dt>{@link LfsRepositoryNotFound}</dt>
 	 *             <dd>when the repository does not exist for the user</dd>
 	 *             <dt>{@link LfsRepositoryReadOnly}</dt>
 	 *             <dd>when the user has read, but not write access. Only
 	 *             applicable when the operation in the request is "upload"</dd>
 	 *             <dt>{@link LfsRateLimitExceeded}</dt>
 	 *             <dd>when the user has hit a rate limit with the server</dd>
 	 *             <dt>{@link LfsBandwidthLimitExceeded}</dt>
 	 *             <dd>when the bandwidth limit for the user or repository has
 	 *             been exceeded</dd>
 	 *             <dt>{@link LfsInsufficientStorage}</dt>
 	 *             <dd>when there is insufficient storage on the server</dd>
 	 *             <dt>{@link LfsUnavailable}</dt>
 	 *             <dd>when LFS is not available</dd>
 	 *             <dt>{@link LfsException}</dt>
 	 *             <dd>when an unexpected internal server error occurred</dd>
 	 *             </dl>
 	 * @since 4.7
 	 */
 	protected abstract LargeFileRepository getLargeFileRepository(
 			LfsRequest request, String path, String auth) throws LfsException;
 
 	/**
 	 * LFS request.
 	 *
 	 * @since 4.5
 	 */
 	protected static class LfsRequest {
 		private String operation;
 
 		private List<LfsObject> objects;
 
 		/**
 		 * Get the LFS operation.
 		 *
 		 * @return the operation
 		 */
 		public String getOperation() {
 			return operation;
 		}
 
 		/**
 		 * Get the LFS objects.
 		 *
 		 * @return the objects
 		 */
 		public List<LfsObject> getObjects() {
 			return objects;
 		}
 
 		/**
 		 * @return true if the operation is upload.
 		 * @since 4.7
 		 */
 		public boolean isUpload() {
 			return operation.equals(UPLOAD);
 		}
 
 		/**
 		 * @return true if the operation is download.
 		 * @since 4.7
 		 */
 		public boolean isDownload() {
 			return operation.equals(DOWNLOAD);
 		}
 
 		/**
 		 * @return true if the operation is verify.
 		 * @since 4.7
 		 */
 		public boolean isVerify() {
 			return operation.equals(VERIFY);
 		}
 	}
 
 	@Override
 	protected void doPost(HttpServletRequest req, HttpServletResponse res)
 			throws ServletException, IOException {
 		Writer w = new BufferedWriter(
 				new OutputStreamWriter(res.getOutputStream(), UTF_8));
 
 		Reader r = new BufferedReader(
 				new InputStreamReader(req.getInputStream(), UTF_8));
 		LfsRequest request = gson.fromJson(r, LfsRequest.class);
 		String path = req.getPathInfo();
 
 		res.setContentType(CONTENTTYPE_VND_GIT_LFS_JSON);
 		LargeFileRepository repo = null;
 		try {
 			repo = getLargeFileRepository(request, path,
 					req.getHeader(HDR_AUTHORIZATION));
 			if (repo == null) {
 				String error = MessageFormat
 						.format(LfsText.get().lfsFailedToGetRepository, path);
 				LOG.error(error);
 				throw new LfsException(error);
 			}
 			res.setStatus(SC_OK);
 			TransferHandler handler = TransferHandler
 					.forOperation(request.operation, repo, request.objects);
 			gson.toJson(handler.process(), w);
 		} catch (LfsValidationError e) {
 			sendError(res, w, SC_UNPROCESSABLE_ENTITY, e.getMessage());
 		} catch (LfsRepositoryNotFound e) {
 			sendError(res, w, SC_NOT_FOUND, e.getMessage());
 		} catch (LfsRepositoryReadOnly e) {
 			sendError(res, w, SC_FORBIDDEN, e.getMessage());
 		} catch (LfsRateLimitExceeded e) {
 			sendError(res, w, SC_RATE_LIMIT_EXCEEDED, e.getMessage());
 		} catch (LfsBandwidthLimitExceeded e) {
 			sendError(res, w, SC_BANDWIDTH_LIMIT_EXCEEDED, e.getMessage());
 		} catch (LfsInsufficientStorage e) {
 			sendError(res, w, SC_INSUFFICIENT_STORAGE, e.getMessage());
 		} catch (LfsUnavailable e) {
 			sendError(res, w, SC_SERVICE_UNAVAILABLE, e.getMessage());
 		} catch (LfsUnauthorized e) {
 			sendError(res, w, SC_UNAUTHORIZED, e.getMessage());
 		} catch (LfsException e) {
 			sendError(res, w, SC_INTERNAL_SERVER_ERROR, e.getMessage());
 		} finally {
 			w.flush();
 		}
 	}
 
 	static class Error {
 		String message;
 
 		Error(String m) {
 			this.message = m;
 		}
 	}
 
 	private void sendError(HttpServletResponse rsp, Writer writer, int status,
 			String message) {
 		rsp.setStatus(status);
 		gson.toJson(new Error(message), writer);
 	}
 
 	private Gson createGson() {
 		return new GsonBuilder()
 				.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
 				.disableHtmlEscaping()
 				.create();
 	}
 }