/**

  * Distribution License:

  * JSword is free software; you can redistribute it and/or modify it under

  * the terms of the GNU Lesser General Public License, version 2.1 or later

  * as published by the Free Software Foundation. This program is distributed

  * in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even

  * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

  * See the GNU Lesser General Public License for more details.

  *

  * The License is available on the internet at:

  *      http://www.gnu.org/copyleft/lgpl.html

  * or by writing to:

  *      Free Software Foundation, Inc.

  *      59 Temple Place - Suite 330

  *      Boston, MA 02111-1307, USA

  *

  * © CrossWire Bible Society, 2005 - 2016

  *

  */

 package org.crosswire.common.util;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStream;

 import java.net.URI;

 import java.util.Date;

 import org.apache.http.Header;

 import org.apache.http.HttpEntity;

 import org.apache.http.HttpHost;

 import org.apache.http.HttpResponse;

 import org.apache.http.HttpStatus;

 import org.apache.http.StatusLine;

 import org.apache.http.client.config.RequestConfig;

 import org.apache.http.client.methods.HttpGet;

 import org.apache.http.client.methods.HttpHead;

 import org.apache.http.client.methods.HttpRequestBase;

 import org.apache.http.client.utils.DateUtils;

 import org.apache.http.impl.client.CloseableHttpClient;

 import org.apache.http.impl.client.HttpClientBuilder;

 import org.crosswire.common.progress.Progress;

 import org.crosswire.jsword.JSMsg;

 /**

  * A WebResource is backed by an URL and potentially the proxy through which it

  * need go. It can get basic information about the resource and it can get the

  * resource. The requests are subject to a timeout, which can be set via the

  * constructor or previously by a call to set the default timeout. The initial

  * default timeout is 750 milliseconds.

  * 

  * 

  * @see gnu.lgpl.License The GNU Lesser General Public License for details.

  * @author DM Smith

  */

 public class WebResource {

     /**

      * Construct a WebResource for the given URL, while timing out if too much

      * time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      */

     public WebResource(URI theURI) {

         this(theURI, null, null, timeout);

     }

     /**

      * Construct a WebResource for the given URL, while timing out if too much

      * time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      * @param theTimeout

      *            the length of time in milliseconds to allow a connection to

      *            respond before timing out

      */

     public WebResource(URI theURI, int theTimeout) {

         this(theURI, null, null, theTimeout);

     }

     /**

      * Construct a WebResource for the given URL, going through the optional

      * proxy and default port, while timing out if too much time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      * @param theProxyHost

      *            the proxy host or null

      */

     public WebResource(URI theURI, String theProxyHost) {

         this(theURI, theProxyHost, null, timeout);

     }

     /**

      * Construct a WebResource for the given URL, going through the optional

      * proxy and default port, while timing out if too much time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      * @param theProxyHost

      *            the proxy host or null

      * @param theTimeout

      *            the length of time in milliseconds to allow a connection to

      *            respond before timing out

      */

     public WebResource(URI theURI, String theProxyHost, int theTimeout) {

         this(theURI, theProxyHost, null, theTimeout);

     }

     /**

      * Construct a WebResource for the given URL, going through the optional

      * proxy and port, while timing out if too much time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      * @param theProxyHost

      *            the proxy host or null

      * @param theProxyPort

      *            the proxy port or null, where null means use the standard port

      */

     public WebResource(URI theURI, String theProxyHost, Integer theProxyPort) {

         this(theURI, theProxyHost, theProxyPort, timeout);

     }

     /**

      * Construct a WebResource for the given URL, going through the optional

      * proxy and port, while timing out if too much time has passed.

      * 

      * @param theURI

      *            the Resource to get via HTTP

      * @param theProxyHost

      *            the proxy host or null

      * @param theProxyPort

      *            the proxy port or null, where null means use the standard port

      * @param theTimeout

      *            the length of time in milliseconds to allow a connection to

      *            respond before timing out

      */

     public WebResource(URI theURI, String theProxyHost, Integer theProxyPort, int theTimeout) {

         uri = theURI;

         HttpHost proxy = null;

         // Configure proxy info if necessary and defined

         if (theProxyHost != null && theProxyHost.length() > 0) {

             proxy = new HttpHost(theProxyHost, theProxyPort == null ? -1 : theProxyPort.intValue());

         }

         final RequestConfig.Builder builder = RequestConfig.custom();

         builder.setConnectTimeout(theTimeout).setConnectionRequestTimeout(theTimeout).setSocketTimeout(theTimeout).setProxy(proxy);

         client = HttpClientBuilder.create().setDefaultRequestConfig(builder.build()).build();

     }

     /**

      * When this WebResource is no longer needed it should be shutdown to return

      * underlying resources back to the OS.

      */

     public void shutdown() {

         IOUtil.close(client);

     }

     /**

      * @return the timeout in milliseconds

      */

     public static int getTimeout() {

         return timeout;

     }

     /**

      * @param timeout

      *            the timeout to set in milliseconds

      */

     public static void setTimeout(int timeout) {

         WebResource.timeout = timeout;

     }

     /**

      * Determine the size of this WebResource.

      * <p>

      * Note that the http client may read the entire file to determine this.

      * </p>

      * 

      * @return the size of the file

      */

     public int getSize() {

         HttpRequestBase method = new HttpHead(uri);

         HttpResponse response = null;

         try {

             // Execute the method.

             response = client.execute(method);

             StatusLine statusLine = response.getStatusLine();

             if (statusLine.getStatusCode() == HttpStatus.SC_OK) {

                 return getHeaderAsInt(response, "Content-Length");

             }

             String reason = response.getStatusLine().getReasonPhrase();

             // TRANSLATOR: Common error condition: {0} is a placeholder for the

             // URL of what could not be found.

             Reporter.informUser(this, JSMsg.gettext("Unable to find: {0}", reason + ':' + uri.getPath()));

         } catch (IOException e) {

             return 0;

         }

         return 0;

     }

     /**

      * Determine the last modified date of this WebResource.

      * <p>

      * Note that the http client may read the entire file.

      * </p>

      * 

      * @return the last mod date of the file

      */

     public long getLastModified() {

         HttpRequestBase method = new HttpHead(uri);

         HttpResponse response = null;

         try {

             // Execute the method.

             response = client.execute(method);

             StatusLine statusLine = response.getStatusLine();

             if (statusLine.getStatusCode() == HttpStatus.SC_OK) {

                 return getHeaderAsDate(response, "Last-Modified");

             }

             String reason = response.getStatusLine().getReasonPhrase();

             // TRANSLATOR: Common error condition: {0} is a placeholder for the

             // URL of what could not be found.

             Reporter.informUser(this, JSMsg.gettext("Unable to find: {0}", reason + ':' + uri.getPath()));

         } catch (IOException e) {

             return new Date().getTime();

         }

         return new Date().getTime();

     }

     /**

      * Copy this WebResource to the destination and report progress.

      * 

      * @param dest

      *            the URI of the destination, typically a file:///.

      * @param meter

      *            the job on which to report progress

      * @throws LucidException when an error is encountered

      */

     public void copy(URI dest, Progress meter) throws LucidException  {

         InputStream in = null;

         OutputStream out = null;

         HttpRequestBase method = new HttpGet(uri);

         HttpResponse response = null;

         HttpEntity entity = null;

         try {

             // Execute the method.

             response = client.execute(method);

             // Initialize the meter, if present

             if (meter != null) {

                 // Find out how big it is

                 int size = getHeaderAsInt(response, "Content-Length");

                 // Sometimes the Content-Length is not given and we have to grab it via HEAD method

                 if (size == 0) {

                     size = getSize();

                 }

                 meter.setTotalWork(size);

             }

             entity = response.getEntity();

             if (entity != null) {

                 in = entity.getContent();

                 // Download the index file

                 out = NetUtil.getOutputStream(dest);

                 byte[] buf = new byte[4096];

                 int count = in.read(buf);

                 while (-1 != count) {

                     if (meter != null) {

                         meter.incrementWorkDone(count);

                     }

                     out.write(buf, 0, count);

                     count = in.read(buf);

                 }

             } else {

                 String reason = response.getStatusLine().getReasonPhrase();

                 // TRANSLATOR: Common error condition: {0} is a placeholder for

                 // the URL of what could not be found.

                 Reporter.informUser(this, JSMsg.gettext("Unable to find: {0}", reason + ':' + uri.getPath()));

             }

         } catch (IOException e) {

             // TRANSLATOR: Common error condition: {0} is a placeholder for the

             // URL of what could not be found.

             throw new LucidException(JSMsg.gettext("Unable to find: {0}", uri.toString()), e);

         } finally {

             // Close the streams

             IOUtil.close(in);

             IOUtil.close(out);

         }

     }

     /**

      * Copy this WebResource to the destination.

      * 

      * @param dest the destination URI

      * @throws LucidException when an error is encountered

      */

     public void copy(URI dest) throws LucidException {

         copy(dest, null);

     }

     /**

      * Get the field as a long.

      * 

      * @param response The response from the request

      * @param field the header field to check

      * @return the int value for the field

      */

     private int getHeaderAsInt(HttpResponse response, String field) {

         Header header = response.getFirstHeader(field);

         // If there is no matching header in the message null is returned.

         if (header == null) {

             return 0;

         }

         String value = header.getValue();

         try {

             return Integer.parseInt(value);

         } catch (NumberFormatException ex) {

             return 0;

         }

     }

     /**

      * Get the number of seconds since start of epoch for the field in the response headers as a Date.

      * 

      * @param response The response from the request

      * @param field the header field to check

      * @return number of seconds since start of epoch

      */

     private long getHeaderAsDate(HttpResponse response, String field) {

         Header header = response.getFirstHeader(field);

         String value = header.getValue();

         // This date cannot be readily parsed with DateFormatter

         return DateUtils.parseDate(value).getTime();

     }

     /**

      * Define a 750 ms timeout to get a connection

      */

     private static int timeout = 750;

     private URI uri;

     private CloseableHttpClient client;

 }