//
   //  ========================================================================
   //  Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.server.handler;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.net.MalformedURLException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ReadableByteChannel;
  
  import javax.servlet.AsyncContext;
  import javax.servlet.RequestDispatcher;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.http.HttpFields;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.HttpStatus;
  import org.eclipse.jetty.http.MimeTypes;
  import org.eclipse.jetty.io.WriterOutputStream;
  import org.eclipse.jetty.server.HttpOutput;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.Response;
  import org.eclipse.jetty.server.handler.ContextHandler.Context;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.Callback;
  import org.eclipse.jetty.util.URIUtil;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.resource.PathResource;
  import org.eclipse.jetty.util.resource.Resource;
  
  
  /* ------------------------------------------------------------ */
  /** Resource Handler.
   *
   * This handle will serve static content and handle If-Modified-Since headers.
   * No caching is done.
   * Requests for resources that do not exist are let pass (Eg no 404's).
   *
   *
   */
  public class ResourceHandler extends HandlerWrapper
  {
      private static final Logger LOG = Log.getLogger(ResourceHandler.class);
  
      ContextHandler _context;
      Resource _baseResource;
      Resource _defaultStylesheet;
      Resource _stylesheet;
      String[] _welcomeFiles={"index.html"};
      MimeTypes _mimeTypes = new MimeTypes();
      String _cacheControl;
      boolean _directory;
      boolean _etags;
      int _minMemoryMappedContentLength=1024;
      int _minAsyncContentLength=0;
  
      /* ------------------------------------------------------------ */
      public ResourceHandler()
      {
  
      }
  
      /* ------------------------------------------------------------ */
      public MimeTypes getMimeTypes()
      {
          return _mimeTypes;
      }
  
      /* ------------------------------------------------------------ */
      public void setMimeTypes(MimeTypes mimeTypes)
      {
          _mimeTypes = mimeTypes;
      }
  
      /* ------------------------------------------------------------ */
      /** Get the directory option.
       * @return true if directories are listed.
       */
      public boolean isDirectoriesListed()
     {
         return _directory;
     }
 
     /* ------------------------------------------------------------ */
     /** Set the directory.
      * @param directory true if directories are listed.
      */
     public void setDirectoriesListed(boolean directory)
     {
         _directory = directory;
     }
 
     /* ------------------------------------------------------------ */
     /** Get minimum memory mapped file content length.
      * @return the minimum size in bytes of a file resource that will
      * be served using a memory mapped buffer, or -1 (default) for no memory mapped
      * buffers.
      */
     public int getMinMemoryMappedContentLength()
     {
         return _minMemoryMappedContentLength;
     }
 
     /* ------------------------------------------------------------ */
     /** Set minimum memory mapped file content length.
      * @param minMemoryMappedFileSize the minimum size in bytes of a file resource that will
      * be served using a memory mapped buffer, or -1 for no memory mapped
      * buffers.
      */
     public void setMinMemoryMappedContentLength(int minMemoryMappedFileSize)
     {
         _minMemoryMappedContentLength = minMemoryMappedFileSize;
     }
 
     /* ------------------------------------------------------------ */
     /** Get the minimum content length for async handling.
      * @return The minimum size in bytes of the content before asynchronous 
      * handling is used, or -1 for no async handling or 0 (default) for using
      * {@link HttpServletResponse#getBufferSize()} as the minimum length.
      */
     public int getMinAsyncContentLength()
     {
         return _minAsyncContentLength;
     }
 
     /* ------------------------------------------------------------ */
     /** Set the minimum content length for async handling.
      * @param minAsyncContentLength The minimum size in bytes of the content before asynchronous 
      * handling is used, or -1 for no async handling or 0 for using
      * {@link HttpServletResponse#getBufferSize()} as the minimum length.
      */
     public void setMinAsyncContentLength(int minAsyncContentLength)
     {
         _minAsyncContentLength = minAsyncContentLength;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return True if ETag processing is done
      */
     public boolean isEtags()
     {
         return _etags;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param etags True if ETag processing is done
      */
     public void setEtags(boolean etags)
     {
         _etags = etags;
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public void doStart()
     throws Exception
     {
         Context scontext = ContextHandler.getCurrentContext();
         _context = (scontext==null?null:scontext.getContextHandler());
 
         super.doStart();
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return Returns the resourceBase.
      */
     public Resource getBaseResource()
     {
         if (_baseResource==null)
             return null;
         return _baseResource;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return Returns the base resource as a string.
      */
     public String getResourceBase()
     {
         if (_baseResource==null)
             return null;
         return _baseResource.toString();
     }
 
 
     /* ------------------------------------------------------------ */
     /**
      * @param base The resourceBase to set.
      */
     public void setBaseResource(Resource base)
     {
         _baseResource=base;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param resourceBase The base resource as a string.
      */
     public void setResourceBase(String resourceBase)
     {
         try
         {
             setBaseResource(Resource.newResource(resourceBase));
         }
         catch (Exception e)
         {
             LOG.warn(e.toString());
             LOG.debug(e);
             throw new IllegalArgumentException(resourceBase);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return Returns the stylesheet as a Resource.
      */
     public Resource getStylesheet()
     {
         if(_stylesheet != null)
         {
             return _stylesheet;
         }
         else
         {
             if(_defaultStylesheet == null)
             {
                 _defaultStylesheet =  Resource.newResource(this.getClass().getResource("/jetty-dir.css"));
             }
             return _defaultStylesheet;
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param stylesheet The location of the stylesheet to be used as a String.
      */
     public void setStylesheet(String stylesheet)
     {
         try
         {
             _stylesheet = Resource.newResource(stylesheet);
             if(!_stylesheet.exists())
             {
                 LOG.warn("unable to find custom stylesheet: " + stylesheet);
                 _stylesheet = null;
             }
         }
         catch(Exception e)
         {
             LOG.warn(e.toString());
             LOG.debug(e);
             throw new IllegalArgumentException(stylesheet);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return the cacheControl header to set on all static content.
      */
     public String getCacheControl()
     {
         return _cacheControl;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param cacheControl the cacheControl header to set on all static content.
      */
     public void setCacheControl(String cacheControl)
     {
         _cacheControl=cacheControl;
     }
 
     /* ------------------------------------------------------------ */
     /*
      */
     public Resource getResource(String path) throws MalformedURLException
     {
         if (path==null || !path.startsWith("/"))
             throw new MalformedURLException(path);
 
         if (LOG.isDebugEnabled())
             LOG.debug("{} getResource({})",_context==null?_baseResource:_context,_baseResource,path);
         
         Resource base = _baseResource;
         if (base==null)
         {
             if (_context==null)
                 return null;
             return _context.getResource(path);
         }
 
         try
         {
             path=URIUtil.canonicalPath(path);
             Resource r = base.addPath(path);
             if (r!=null && r.isAlias() && (_context==null || !_context.checkAlias(path, r)))
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("resource={} alias={}",r,r.getAlias());
                 return null;
             }
             return r;
         }
         catch(Exception e)
         {
             LOG.ignore(e);
         }
 
         return null;
     }
 
     /* ------------------------------------------------------------ */
     protected Resource getResource(HttpServletRequest request) throws MalformedURLException
     {
         String servletPath;
         String pathInfo;
         Boolean included = request.getAttribute(RequestDispatcher.INCLUDE_REQUEST_URI) != null;
         if (included != null && included.booleanValue())
         {
             servletPath = (String)request.getAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH);
             pathInfo = (String)request.getAttribute(RequestDispatcher.INCLUDE_PATH_INFO);
 
             if (servletPath == null && pathInfo == null)
             {
                 servletPath = request.getServletPath();
                 pathInfo = request.getPathInfo();
             }
         }
         else
         {
             servletPath = request.getServletPath();
             pathInfo = request.getPathInfo();
         }
 
         String pathInContext=URIUtil.addPaths(servletPath,pathInfo);
         return getResource(pathInContext);
     }
 
 
     /* ------------------------------------------------------------ */
     public String[] getWelcomeFiles()
     {
         return _welcomeFiles;
     }
 
     /* ------------------------------------------------------------ */
     public void setWelcomeFiles(String[] welcomeFiles)
     {
         _welcomeFiles=welcomeFiles;
     }
 
     /* ------------------------------------------------------------ */
     protected Resource getWelcome(Resource directory) throws MalformedURLException, IOException
     {
         for (int i=0;i<_welcomeFiles.length;i++)
         {
             Resource welcome=directory.addPath(_welcomeFiles[i]);
             if (welcome.exists() && !welcome.isDirectory())
                 return welcome;
         }
 
         return null;
     }
 
     /* ------------------------------------------------------------ */
     /*
      * @see org.eclipse.jetty.server.Handler#handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, int)
      */
     @Override
     public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
     {
         if (baseRequest.isHandled())
             return;
 
         boolean skipContentBody = false;
 
         if(!HttpMethod.GET.is(request.getMethod()))
         {
             if(!HttpMethod.HEAD.is(request.getMethod()))
             {
                 //try another handler
                 super.handle(target, baseRequest, request, response);
                 return;
             }
             skipContentBody = true;
         }
 
         Resource resource = getResource(request);
         
         if (LOG.isDebugEnabled())
         { 
             if (resource==null)
                 LOG.debug("resource=null");
             else
                 LOG.debug("resource={} alias={} exists={}",resource,resource.getAlias(),resource.exists());
         }
         
         
         // If resource is not found
         if (resource==null || !resource.exists())
         {
             // inject the jetty-dir.css file if it matches
             if (target.endsWith("/jetty-dir.css"))
             {
                 resource = getStylesheet();
                 if (resource==null)
                     return;
                 response.setContentType("text/css");
             }
             else
             {
                 //no resource - try other handlers
                 super.handle(target, baseRequest, request, response);
                 return;
             }
         }
 
         // We are going to serve something
         baseRequest.setHandled(true);
 
         // handle directories
         if (resource.isDirectory())
         {
             String pathInfo = request.getPathInfo();
             boolean endsWithSlash=(pathInfo==null?request.getServletPath():pathInfo).endsWith(URIUtil.SLASH);
             if (!endsWithSlash)
             {
                 response.sendRedirect(response.encodeRedirectURL(URIUtil.addPaths(request.getRequestURI(),URIUtil.SLASH)));
                 return;
             }
 
             Resource welcome=getWelcome(resource);
             if (welcome!=null && welcome.exists())
                 resource=welcome;
             else
             {
                 doDirectory(request,response,resource);
                 baseRequest.setHandled(true);
                 return;
             }
         }
 
         // Handle ETAGS
         long last_modified=resource.lastModified();
         String etag=null;
         if (_etags)
         {
             // simple handling of only a single etag
             String ifnm = request.getHeader(HttpHeader.IF_NONE_MATCH.asString());
             etag=resource.getWeakETag();
             if (ifnm!=null && resource!=null && ifnm.equals(etag))
             {
                 response.setStatus(HttpStatus.NOT_MODIFIED_304);
                 baseRequest.getResponse().getHttpFields().put(HttpHeader.ETAG,etag);
                 return;
             }
         }
         
         // Handle if modified since 
         if (last_modified>0)
         {
             long if_modified=request.getDateHeader(HttpHeader.IF_MODIFIED_SINCE.asString());
             if (if_modified>0 && last_modified/1000<=if_modified/1000)
             {
                 response.setStatus(HttpStatus.NOT_MODIFIED_304);
                 return;
             }
         }
 
         // set the headers
         String mime=_mimeTypes.getMimeByExtension(resource.toString());
         if (mime==null)
             mime=_mimeTypes.getMimeByExtension(request.getPathInfo());
         doResponseHeaders(response,resource,mime);
         if (_etags)
             baseRequest.getResponse().getHttpFields().put(HttpHeader.ETAG,etag);
         
         if(skipContentBody)
             return;
         
         
         // Send the content
         OutputStream out =null;
         try {out = response.getOutputStream();}
         catch(IllegalStateException e) {out = new WriterOutputStream(response.getWriter());}
 
         // Has the output been wrapped
         if (!(out instanceof HttpOutput))
             // Write content via wrapped output
             resource.writeTo(out,0,resource.length());
         else
         {
             // select async by size
             int min_async_size=_minAsyncContentLength==0?response.getBufferSize():_minAsyncContentLength;
             
             if (request.isAsyncSupported() && 
                 min_async_size>0 &&
                 resource.length()>=min_async_size)
             {
                 final AsyncContext async = request.startAsync();
                 async.setTimeout(0);
                 Callback callback = new Callback()
                 {
                     @Override
                     public void succeeded()
                     {
                         async.complete();
                     }
 
                     @Override
                     public void failed(Throwable x)
                     {
                         LOG.warn(x.toString());
                         LOG.debug(x);
                         async.complete();
                     }   
                 };
 
                 // Can we use a memory mapped file?
                 if (_minMemoryMappedContentLength>0 && 
                     resource.length()>_minMemoryMappedContentLength &&
                     resource.length()<Integer.MAX_VALUE &&
                     resource instanceof PathResource)
                 {
                     ByteBuffer buffer = BufferUtil.toMappedBuffer(resource.getFile());
                     ((HttpOutput)out).sendContent(buffer,callback);
                 }
                 else  // Do a blocking write of a channel (if available) or input stream
                 {
                     // Close of the channel/inputstream is done by the async sendContent
                     ReadableByteChannel channel= resource.getReadableByteChannel();
                     if (channel!=null)
                         ((HttpOutput)out).sendContent(channel,callback);
                     else
                         ((HttpOutput)out).sendContent(resource.getInputStream(),callback);
                 }
             }
             else
             {
                 // Can we use a memory mapped file?
                 if (_minMemoryMappedContentLength>0 && 
                     resource.length()>_minMemoryMappedContentLength &&
                     resource instanceof PathResource)
                 {
                     ByteBuffer buffer = BufferUtil.toMappedBuffer(resource.getFile());
                     ((HttpOutput)out).sendContent(buffer);
                 }
                 else  // Do a blocking write of a channel (if available) or input stream
                 {
                     ReadableByteChannel channel= resource.getReadableByteChannel();
                     if (channel!=null)
                         ((HttpOutput)out).sendContent(channel);
                     else
                         ((HttpOutput)out).sendContent(resource.getInputStream());
                 }
             }
         }
     }
 
     /* ------------------------------------------------------------ */
     protected void doDirectory(HttpServletRequest request,HttpServletResponse response, Resource resource)
         throws IOException
     {
         if (_directory)
         {
             String listing = resource.getListHTML(request.getRequestURI(),request.getPathInfo().lastIndexOf("/") > 0);
             response.setContentType("text/html;charset=utf-8");
             response.getWriter().println(listing);
         }
         else
             response.sendError(HttpStatus.FORBIDDEN_403);
     }
 
     /* ------------------------------------------------------------ */
     /** Set the response headers.
      * This method is called to set the response headers such as content type and content length.
      * May be extended to add additional headers.
      * @param response the http response
      * @param resource the resource
      * @param mimeType the mime type
      */
     protected void doResponseHeaders(HttpServletResponse response, Resource resource, String mimeType)
     {
         if (mimeType!=null)
             response.setContentType(mimeType);
 
         long length=resource.length();
 
         if (response instanceof Response)
         {
             HttpFields fields = ((Response)response).getHttpFields();
 
             if (length>0)
                 ((Response)response).setLongContentLength(length);
 
             if (_cacheControl!=null)
                 fields.put(HttpHeader.CACHE_CONTROL,_cacheControl);
         }
         else
         {
             if (length>Integer.MAX_VALUE)
                 response.setHeader(HttpHeader.CONTENT_LENGTH.asString(),Long.toString(length));
             else if (length>0)
                 response.setContentLength((int)length);
 
             if (_cacheControl!=null)
                 response.setHeader(HttpHeader.CACHE_CONTROL.asString(),_cacheControl);
         }
     }
 }