/*
 * 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,
 * 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.http.server;

import static javax.servlet.http.HttpServletResponse.SC_FORBIDDEN;
import static javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR;
import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;
import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED;
import static org.eclipse.jgit.http.server.ServletUtils.ATTRIBUTE_REPOSITORY;
import static org.eclipse.jgit.util.HttpSupport.HDR_ACCEPT;

import java.io.IOException;
import java.text.MessageFormat;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jgit.errors.RepositoryNotFoundException;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.transport.PacketLineOut;
import org.eclipse.jgit.transport.resolver.RepositoryResolver;
import org.eclipse.jgit.transport.resolver.ServiceNotAuthorizedException;
import org.eclipse.jgit.transport.resolver.ServiceNotEnabledException;

/**
 * Opens a repository named by the path info through {@link RepositoryResolver}.
 * <p>
 * This filter assumes it is invoked by {@link GitServlet} and is likely to not
 * work as expected if called from any other class. This filter assumes the path
 * info of the current request is a repository name which can be used by the
 * configured {@link RepositoryResolver} to open a {@link Repository} and attach
 * it to the current request.
 * <p>
 * This filter sets request attribute {@link ServletUtils#ATTRIBUTE_REPOSITORY}
 * when it discovers the repository, and automatically closes and removes the
 * attribute when the request is complete.
 */
public class RepositoryFilter implements Filter {
	private final RepositoryResolver<HttpServletRequest> resolver;

	private ServletContext context;

	/**
	 * Create a new filter.
	 *
	 * @param resolver
	 *            the resolver which will be used to translate the URL name
	 *            component to the actual {@link Repository} instance for the
	 *            current web request.
	 */
	public RepositoryFilter(final RepositoryResolver<HttpServletRequest> resolver) {
		this.resolver = resolver;
	}

	public void init(final FilterConfig config) throws ServletException {
		context = config.getServletContext();
	}

	public void destroy() {
		context = null;
	}

	public void doFilter(final ServletRequest request,
			final ServletResponse rsp, final FilterChain chain)
			throws IOException, ServletException {
		if (request.getAttribute(ATTRIBUTE_REPOSITORY) != null) {
			context.log(MessageFormat.format(HttpServerText.get().internalServerErrorRequestAttributeWasAlreadySet
					, ATTRIBUTE_REPOSITORY
					, getClass().getName()));
			((HttpServletResponse) rsp).sendError(SC_INTERNAL_SERVER_ERROR);
			return;
		}

		final HttpServletRequest req = (HttpServletRequest) request;

		String name = req.getPathInfo();
		if (name == null || name.length() == 0) {
			((HttpServletResponse) rsp).sendError(SC_NOT_FOUND);
			return;
		}
		if (name.startsWith("/"))
			name = name.substring(1);

		final Repository db;
		try {
			db = resolver.open(req, name);
		} catch (RepositoryNotFoundException e) {
			sendError(SC_NOT_FOUND, req, (HttpServletResponse) rsp);
			return;
		} catch (ServiceNotEnabledException e) {
			sendError(SC_FORBIDDEN, req, (HttpServletResponse) rsp);
			return;
		} catch (ServiceNotAuthorizedException e) {
			((HttpServletResponse) rsp).sendError(SC_UNAUTHORIZED);
			return;
		}
		try {
			request.setAttribute(ATTRIBUTE_REPOSITORY, db);
			chain.doFilter(request, rsp);
		} finally {
			request.removeAttribute(ATTRIBUTE_REPOSITORY);
			db.close();
		}
	}

	static void sendError(int statusCode, HttpServletRequest req,
			HttpServletResponse rsp) throws IOException {
		String svc = req.getParameter("service");

		if (req.getRequestURI().endsWith("/info/refs") && isService(svc)) {
			// Smart HTTP service request, use an ERR response.
			rsp.setContentType("application/x-" + svc + "-advertisement");

			SmartOutputStream buf = new SmartOutputStream(req, rsp);
			PacketLineOut out = new PacketLineOut(buf);
			out.writeString("# service=" + svc + "\n");
			out.end();
			out.writeString("ERR " + translate(statusCode));
			buf.close();
			return;
		}

		String accept = req.getHeader(HDR_ACCEPT);
		if (accept != null && accept.contains(UploadPackServlet.RSP_TYPE)) {
			// An upload-pack wants ACK or NAK, return ERR
			// and the client will print this instead.
			rsp.setContentType(UploadPackServlet.RSP_TYPE);
			SmartOutputStream buf = new SmartOutputStream(req, rsp);
			PacketLineOut out = new PacketLineOut(buf);
			out.writeString("ERR " + translate(statusCode));
			buf.close();
			return;
		}

		// Otherwise fail with an HTTP error code instead of an
		// application level message. This may not be as pretty
		// of a result for the user, but its better than nothing.
		//
		rsp.sendError(statusCode);
	}

	private static boolean isService(String svc) {
		return "git-upload-pack".equals(svc) || "git-receive-pack".equals(svc);
	}

	private static String translate(int statusCode) {
		switch (statusCode) {
		case SC_NOT_FOUND:
			return HttpServerText.get().repositoryNotFound;

		case SC_FORBIDDEN:
			return HttpServerText.get().repositoryAccessForbidden;

		default:
			return String.valueOf(statusCode);
		}
	}
}