/*
    * 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.eclipse.aether.transport.http;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.net.URI;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import com.google.gson.Gson;
  import org.eclipse.aether.transport.http.RFC9457.RFC9457Payload;
  import org.eclipse.aether.util.ChecksumUtils;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.Response;
  import org.eclipse.jetty.server.Server;
  import org.eclipse.jetty.server.ServerConnector;
  import org.eclipse.jetty.server.handler.AbstractHandler;
  import org.eclipse.jetty.server.handler.HandlerList;
  import org.eclipse.jetty.util.B64Code;
  import org.eclipse.jetty.util.IO;
  import org.eclipse.jetty.util.StringUtil;
  import org.eclipse.jetty.util.URIUtil;
  import org.eclipse.jetty.util.ssl.SslContextFactory;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @SuppressWarnings("checkstyle:VisibilityModifier")
  public class HttpServer {
  
      public static class LogEntry {
  
          public final String method;
  
          public final String path;
  
          public final Map<String, String> headers;
  
          public LogEntry(String method, String path, Map<String, String> headers) {
              this.method = method;
              this.path = path;
              this.headers = headers;
          }
  
          @Override
          public String toString() {
              return method + " " + path;
          }
      }
  
      public enum ExpectContinue {
          FAIL,
          PROPER,
          BROKEN
      }
  
      public enum ChecksumHeader {
          NEXUS,
          XCHECKSUM
      }
  
      private static final Logger LOGGER = LoggerFactory.getLogger(HttpServer.class);
  
      private static final Pattern SIMPLE_RANGE = Pattern.compile("bytes=([0-9])+-");
  
      private File repoDir;
  
     private boolean rangeSupport = true;
 
     private boolean webDav;
 
     private ExpectContinue expectContinue = ExpectContinue.PROPER;
 
     private ChecksumHeader checksumHeader;
 
     private Server server;
 
     private ServerConnector httpConnector;
 
     private ServerConnector httpsConnector;
 
     private String username;
 
     private String password;
 
     private String proxyUsername;
 
     private String proxyPassword;
 
     private final AtomicInteger connectionsToClose = new AtomicInteger(0);
 
     private final List<LogEntry> logEntries = Collections.synchronizedList(new ArrayList<>());
 
     public String getHost() {
         return "localhost";
     }
 
     public int getHttpPort() {
         return httpConnector != null ? httpConnector.getLocalPort() : -1;
     }
 
     public int getHttpsPort() {
         return httpsConnector != null ? httpsConnector.getLocalPort() : -1;
     }
 
     public String getHttpUrl() {
         return "http://" + getHost() + ":" + getHttpPort();
     }
 
     public String getHttpsUrl() {
         return "https://" + getHost() + ":" + getHttpsPort();
     }
 
     public HttpServer addSslConnector() {
         return addSslConnector(true);
     }
 
     public HttpServer addSelfSignedSslConnector() {
         return addSslConnector(false);
     }
 
     private HttpServer addSslConnector(boolean needClientAuth) {
         if (httpsConnector == null) {
             SslContextFactory.Server ssl = new SslContextFactory.Server();
             if (needClientAuth) {
                 ssl.setNeedClientAuth(true);
                 ssl.setKeyStorePath(new File("src/test/resources/ssl/server-store").getAbsolutePath());
                 ssl.setKeyStorePassword("server-pwd");
                 ssl.setTrustStorePath(new File("src/test/resources/ssl/client-store").getAbsolutePath());
                 ssl.setTrustStorePassword("client-pwd");
             } else {
                 ssl.setNeedClientAuth(false);
                 ssl.setKeyStorePath(new File("src/test/resources/ssl/server-store-selfsigned").getAbsolutePath());
                 ssl.setKeyStorePassword("server-pwd");
             }
             httpsConnector = new ServerConnector(server, ssl);
             server.addConnector(httpsConnector);
             try {
                 httpsConnector.start();
             } catch (Exception e) {
                 throw new IllegalStateException(e);
             }
         }
         return this;
     }
 
     public List<LogEntry> getLogEntries() {
         return logEntries;
     }
 
     public HttpServer setRepoDir(File repoDir) {
         this.repoDir = repoDir;
         return this;
     }
 
     public HttpServer setRangeSupport(boolean rangeSupport) {
         this.rangeSupport = rangeSupport;
         return this;
     }
 
     public HttpServer setWebDav(boolean webDav) {
         this.webDav = webDav;
         return this;
     }
 
     public HttpServer setExpectSupport(ExpectContinue expectContinue) {
         this.expectContinue = expectContinue;
         return this;
     }
 
     public HttpServer setChecksumHeader(ChecksumHeader checksumHeader) {
         this.checksumHeader = checksumHeader;
         return this;
     }
 
     public HttpServer setAuthentication(String username, String password) {
         this.username = username;
         this.password = password;
         return this;
     }
 
     public HttpServer setProxyAuthentication(String username, String password) {
         proxyUsername = username;
         proxyPassword = password;
         return this;
     }
 
     public HttpServer setConnectionsToClose(int connectionsToClose) {
         this.connectionsToClose.set(connectionsToClose);
         return this;
     }
 
     public HttpServer start() throws Exception {
         if (server != null) {
             return this;
         }
 
         HandlerList handlers = new HandlerList();
         handlers.addHandler(new ConnectionClosingHandler());
         handlers.addHandler(new LogHandler());
         handlers.addHandler(new ProxyAuthHandler());
         handlers.addHandler(new AuthHandler());
         handlers.addHandler(new RedirectHandler());
         handlers.addHandler(new RepoHandler());
         handlers.addHandler(new RFC9457Handler());
 
         server = new Server();
         httpConnector = new ServerConnector(server);
         server.addConnector(httpConnector);
         server.setHandler(handlers);
         server.start();
 
         return this;
     }
 
     public void stop() throws Exception {
         if (server != null) {
             server.stop();
             server = null;
             httpConnector = null;
             httpsConnector = null;
         }
     }
 
     private class ConnectionClosingHandler extends AbstractHandler {
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response) {
             if (connectionsToClose.getAndDecrement() > 0) {
                 Response jettyResponse = (Response) response;
                 jettyResponse.getHttpChannel().getConnection().close();
             }
         }
     }
 
     private class LogHandler extends AbstractHandler {
 
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response) {
             LOGGER.info(
                     "{} {}{}",
                     req.getMethod(),
                     req.getRequestURL(),
                     req.getQueryString() != null ? "?" + req.getQueryString() : "");
 
             Map<String, String> headers = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
             for (Enumeration<String> en = req.getHeaderNames(); en.hasMoreElements(); ) {
                 String name = en.nextElement();
                 StringBuilder buffer = new StringBuilder(128);
                 for (Enumeration<String> ien = req.getHeaders(name); ien.hasMoreElements(); ) {
                     if (buffer.length() > 0) {
                         buffer.append(", ");
                     }
                     buffer.append(ien.nextElement());
                 }
                 headers.put(name, buffer.toString());
             }
             logEntries.add(new LogEntry(req.getMethod(), req.getOriginalURI(), Collections.unmodifiableMap(headers)));
         }
     }
 
     private class RepoHandler extends AbstractHandler {
 
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response)
                 throws IOException {
             String path = req.getPathInfo().substring(1);
 
             if (!path.startsWith("repo/")) {
                 return;
             }
             req.setHandled(true);
 
             if (ExpectContinue.FAIL.equals(expectContinue) && request.getHeader(HttpHeader.EXPECT.asString()) != null) {
                 response.setStatus(HttpServletResponse.SC_EXPECTATION_FAILED);
                 return;
             }
 
             File file = new File(repoDir, path.substring(5));
             if (HttpMethod.GET.is(req.getMethod()) || HttpMethod.HEAD.is(req.getMethod())) {
                 if (!file.isFile() || path.endsWith(URIUtil.SLASH)) {
                     response.setStatus(HttpServletResponse.SC_NOT_FOUND);
                     return;
                 }
                 long ifUnmodifiedSince = request.getDateHeader(HttpHeader.IF_UNMODIFIED_SINCE.asString());
                 if (ifUnmodifiedSince != -1L && file.lastModified() > ifUnmodifiedSince) {
                     response.setStatus(HttpServletResponse.SC_PRECONDITION_FAILED);
                     return;
                 }
                 long offset = 0L;
                 String range = request.getHeader(HttpHeader.RANGE.asString());
                 if (range != null && rangeSupport) {
                     Matcher m = SIMPLE_RANGE.matcher(range);
                     if (m.matches()) {
                         offset = Long.parseLong(m.group(1));
                         if (offset >= file.length()) {
                             response.setStatus(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                             return;
                         }
                     }
                     String encoding = request.getHeader(HttpHeader.ACCEPT_ENCODING.asString());
                     if ((encoding != null && !"identity".equals(encoding)) || ifUnmodifiedSince == -1L) {
                         response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
                         return;
                     }
                 }
                 response.setStatus((offset > 0L) ? HttpServletResponse.SC_PARTIAL_CONTENT : HttpServletResponse.SC_OK);
                 response.setDateHeader(HttpHeader.LAST_MODIFIED.asString(), file.lastModified());
                 response.setHeader(HttpHeader.CONTENT_LENGTH.asString(), Long.toString(file.length() - offset));
                 if (offset > 0L) {
                     response.setHeader(
                             HttpHeader.CONTENT_RANGE.asString(),
                             "bytes " + offset + "-" + (file.length() - 1L) + "/" + file.length());
                 }
                 if (checksumHeader != null) {
                     Map<String, Object> checksums = ChecksumUtils.calc(file, Collections.singleton("SHA-1"));
                     if (checksumHeader == ChecksumHeader.NEXUS) {
                         response.setHeader(HttpHeader.ETAG.asString(), "{SHA1{" + checksums.get("SHA-1") + "}}");
                     } else if (checksumHeader == ChecksumHeader.XCHECKSUM) {
                         response.setHeader(
                                 "x-checksum-sha1", checksums.get("SHA-1").toString());
                     }
                 }
                 if (HttpMethod.HEAD.is(req.getMethod())) {
                     return;
                 }
                 FileInputStream is = null;
                 try {
                     is = new FileInputStream(file);
                     if (offset > 0L) {
                         long skipped = is.skip(offset);
                         while (skipped < offset && is.read() >= 0) {
                             skipped++;
                         }
                     }
                     IO.copy(is, response.getOutputStream());
                     is.close();
                     is = null;
                 } finally {
                     try {
                         if (is != null) {
                             is.close();
                         }
                     } catch (final IOException e) {
                         // Suppressed due to an exception already thrown in the try block.
                     }
                 }
             } else if (HttpMethod.PUT.is(req.getMethod())) {
                 if (!webDav) {
                     file.getParentFile().mkdirs();
                 }
                 if (file.getParentFile().exists()) {
                     try {
                         FileOutputStream os = null;
                         try {
                             os = new FileOutputStream(file);
                             IO.copy(request.getInputStream(), os);
                             os.close();
                             os = null;
                         } finally {
                             try {
                                 if (os != null) {
                                     os.close();
                                 }
                             } catch (final IOException e) {
                                 // Suppressed due to an exception already thrown in the try block.
                             }
                         }
                     } catch (IOException e) {
                         file.delete();
                         throw e;
                     }
                     response.setStatus(HttpServletResponse.SC_NO_CONTENT);
                 } else {
                     response.setStatus(HttpServletResponse.SC_FORBIDDEN);
                 }
             } else if (HttpMethod.OPTIONS.is(req.getMethod())) {
                 if (webDav) {
                     response.setHeader("DAV", "1,2");
                 }
                 response.setHeader(HttpHeader.ALLOW.asString(), "GET, PUT, HEAD, OPTIONS");
                 response.setStatus(HttpServletResponse.SC_OK);
             } else if (webDav && "MKCOL".equals(req.getMethod())) {
                 if (file.exists()) {
                     response.setStatus(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
                 } else if (file.mkdir()) {
                     response.setStatus(HttpServletResponse.SC_CREATED);
                 } else {
                     response.setStatus(HttpServletResponse.SC_CONFLICT);
                 }
             } else {
                 response.setStatus(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
             }
         }
     }
 
     private class RedirectHandler extends AbstractHandler {
 
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response) {
             String path = req.getPathInfo();
             if (!path.startsWith("/redirect/")) {
                 return;
             }
             req.setHandled(true);
             StringBuilder location = new StringBuilder(128);
             String scheme = req.getParameter("scheme");
             location.append(scheme != null ? scheme : req.getScheme());
             location.append("://");
             location.append(req.getServerName());
             location.append(":");
             if ("http".equalsIgnoreCase(scheme)) {
                 location.append(getHttpPort());
             } else if ("https".equalsIgnoreCase(scheme)) {
                 location.append(getHttpsPort());
             } else {
                 location.append(req.getServerPort());
             }
             location.append("/repo").append(path.substring(9));
             response.setStatus(HttpServletResponse.SC_MOVED_PERMANENTLY);
             response.setHeader(HttpHeader.LOCATION.asString(), location.toString());
         }
     }
 
     private class AuthHandler extends AbstractHandler {
 
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response)
                 throws IOException {
             if (ExpectContinue.BROKEN.equals(expectContinue)
                     && "100-continue".equalsIgnoreCase(request.getHeader(HttpHeader.EXPECT.asString()))) {
                 request.getInputStream();
             }
 
             if (username != null && password != null) {
                 if (checkBasicAuth(request.getHeader(HttpHeader.AUTHORIZATION.asString()), username, password)) {
                     return;
                 }
                 req.setHandled(true);
                 response.setHeader(HttpHeader.WWW_AUTHENTICATE.asString(), "basic realm=\"Test-Realm\"");
                 response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
             }
         }
     }
 
     private class ProxyAuthHandler extends AbstractHandler {
 
         public void handle(String target, Request req, HttpServletRequest request, HttpServletResponse response) {
             if (proxyUsername != null && proxyPassword != null) {
                 if (checkBasicAuth(
                         request.getHeader(HttpHeader.PROXY_AUTHORIZATION.asString()), proxyUsername, proxyPassword)) {
                     return;
                 }
                 req.setHandled(true);
                 response.setHeader(HttpHeader.PROXY_AUTHENTICATE.asString(), "basic realm=\"Test-Realm\"");
                 response.setStatus(HttpServletResponse.SC_PROXY_AUTHENTICATION_REQUIRED);
             }
         }
     }
 
     private class RFC9457Handler extends AbstractHandler {
         @Override
         public void handle(
                 final String target,
                 final Request req,
                 final HttpServletRequest request,
                 final HttpServletResponse response)
                 throws IOException {
             String path = req.getPathInfo().substring(1);
 
             if (!path.startsWith("rfc9457/")) {
                 return;
             }
             req.setHandled(true);
 
             if (HttpMethod.GET.is(req.getMethod())) {
                 response.setStatus(HttpServletResponse.SC_FORBIDDEN);
                 response.setHeader(HttpHeader.CONTENT_TYPE.asString(), "application/problem+json");
                 RFC9457Payload rfc9457Payload;
                 if (path.endsWith("missing_fields.txt")) {
                     rfc9457Payload = new RFC9457Payload(null, null, null, null, null);
                 } else {
                     rfc9457Payload = new RFC9457Payload(
                             URI.create("https://example.com/probs/out-of-credit"),
                             HttpServletResponse.SC_FORBIDDEN,
                             "You do not have enough credit.",
                             "Your current balance is 30, but that costs 50.",
                             URI.create("/account/12345/msgs/abc"));
                 }
                 try (OutputStream outputStream = response.getOutputStream()) {
                     outputStream.write(buildRFC9457Message(rfc9457Payload).getBytes(StandardCharsets.UTF_8));
                 }
             }
         }
     }
 
     private String buildRFC9457Message(RFC9457Payload payload) {
         return new Gson().toJson(payload, RFC9457Payload.class);
     }
 
     static boolean checkBasicAuth(String credentials, String username, String password) {
         if (credentials != null) {
             int space = credentials.indexOf(' ');
             if (space > 0) {
                 String method = credentials.substring(0, space);
                 if ("basic".equalsIgnoreCase(method)) {
                     credentials = credentials.substring(space + 1);
                     credentials = B64Code.decode(credentials, StringUtil.__ISO_8859_1);
                     int i = credentials.indexOf(':');
                     if (i > 0) {
                         String user = credentials.substring(0, i);
                         String pass = credentials.substring(i + 1);
                         if (username.equals(user) && password.equals(pass)) {
                             return true;
                         }
                     }
                 }
             }
         }
         return false;
     }
 }