/*
    * 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.apache.myfaces.application;
  
  import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
  import org.apache.myfaces.shared.resource.ResourceHandlerCache;
  import org.apache.myfaces.shared.resource.ResourceHandlerCache.ResourceValue;
  import org.apache.myfaces.shared.resource.ResourceHandlerSupport;
  import org.apache.myfaces.shared.resource.ResourceImpl;
  import org.apache.myfaces.shared.resource.ResourceLoader;
  import org.apache.myfaces.shared.resource.ResourceMeta;
  import org.apache.myfaces.shared.resource.ResourceValidationUtils;
  import org.apache.myfaces.shared.util.ClassUtils;
  import org.apache.myfaces.shared.util.ExternalContextUtils;
  import org.apache.myfaces.shared.util.StringUtils;
  import org.apache.myfaces.shared.util.WebConfigParamUtils;
  
  import javax.faces.application.Resource;
  import javax.faces.application.ResourceHandler;
  import javax.faces.application.ResourceWrapper;
  import javax.faces.context.ExternalContext;
  import javax.faces.context.FacesContext;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.URL;
  import java.util.Locale;
  import java.util.Map;
  import java.util.MissingResourceException;
  import java.util.ResourceBundle;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  /**
   * DOCUMENT ME!
   *
   * @author Simon Lessard (latest modification by $Author: lu4242 $)
   * 
   * @version $Revision: 1410540 $ $Date: 2012-11-16 13:59:39 -0500 (Fri, 16 Nov 2012) $
   */
  public class ResourceHandlerImpl extends ResourceHandler
  {
  
      private static final String IS_RESOURCE_REQUEST = "org.apache.myfaces.IS_RESOURCE_REQUEST";
  
      private ResourceHandlerSupport _resourceHandlerSupport;
  
      private ResourceHandlerCache _resourceHandlerCache;
  
      //private static final Log log = LogFactory.getLog(ResourceHandlerImpl.class);
      private static final Logger log = Logger.getLogger(ResourceHandlerImpl.class.getName());
  
      /**
       * Allow slash in the library name of a Resource. 
       */
      @JSFWebConfigParam(since="2.1.6, 2.0.12", defaultValue="false", 
              expectedValues="true, false", group="resources")
      public static final String INIT_PARAM_STRICT_JSF_2_ALLOW_SLASH_LIBRARY_NAME = 
              "org.apache.myfaces.STRICT_JSF_2_ALLOW_SLASH_LIBRARY_NAME";
      public static final boolean INIT_PARAM_STRICT_JSF_2_ALLOW_SLASH_LIBRARY_NAME_DEFAULT = false;
      
      /**
       * Define the default buffer size that is used between Resource.getInputStream() and 
       * httpServletResponse.getOutputStream() when rendering resources using the default
       * ResourceHandler.
       */
      @JSFWebConfigParam(since="2.1.10, 2.0.16", defaultValue="2048", group="resources")
      public static final String INIT_PARAM_RESOURCE_BUFFER_SIZE = "org.apache.myfaces.RESOURCE_BUFFER_SIZE";
      private static final int INIT_PARAM_RESOURCE_BUFFER_SIZE_DEFAULT = 2048;
      
      private Boolean _allowSlashLibraryName;
      private int _resourceBufferSize = -1;
  
      @Override
      public Resource createResource(String resourceName)
      {
          return createResource(resourceName, null);
      }
  
      @Override
      public Resource createResource(String resourceName, String libraryName)
      {
         return createResource(resourceName, libraryName, null);
     }
 
     @Override
     public Resource createResource(String resourceName, String libraryName,
             String contentType)
     {
         Resource resource = null;
         
         if (!ResourceValidationUtils.isValidResourceName(resourceName))
         {
             return null;
         }
         if (libraryName != null && !ResourceValidationUtils.isValidLibraryName(
                 libraryName, isAllowSlashesLibraryName()))
         {
             return null;
         }
         
         if (contentType == null)
         {
             //Resolve contentType using ExternalContext.getMimeType
             contentType = FacesContext.getCurrentInstance().getExternalContext().getMimeType(resourceName);
         }
 
         final String localePrefix = getLocalePrefixForLocateResource();
 
         // check cache
         if(getResourceLoaderCache().containsResource(resourceName, libraryName, contentType, localePrefix))
         {
             ResourceValue resourceValue = getResourceLoaderCache().getResource(
                     resourceName, libraryName, contentType, localePrefix);
             
             resource = new ResourceImpl(resourceValue.getResourceMeta(), resourceValue.getResourceLoader(),
                     getResourceHandlerSupport(), contentType);
         }
         else
         {
             for (ResourceLoader loader : getResourceHandlerSupport().getResourceLoaders())
             {
                 ResourceMeta resourceMeta = deriveResourceMeta(loader, resourceName, libraryName, localePrefix);
     
                 if (resourceMeta != null)
                 {
                     resource = new ResourceImpl(resourceMeta, loader, getResourceHandlerSupport(), contentType);
 
                     // cache it
                     getResourceLoaderCache().putResource(resourceName, libraryName, contentType,
                             localePrefix, resourceMeta, loader);
                     break;
                 }
             }
         }
         
         return resource;
     }
 
     /**
      * This method try to create a ResourceMeta for a specific resource
      * loader. If no library, or resource is found, just return null,
      * so the algorithm in createResource can continue checking with the 
      * next registered ResourceLoader. 
      */
     protected ResourceMeta deriveResourceMeta(ResourceLoader resourceLoader,
             String resourceName, String libraryName, String localePrefix)
     {
         String resourceVersion = null;
         String libraryVersion = null;
         ResourceMeta resourceId = null;
         
         //1. Try to locate resource in a localized path
         if (localePrefix != null)
         {
             if (null != libraryName)
             {
                 String pathToLib = localePrefix + '/' + libraryName;
                 libraryVersion = resourceLoader.getLibraryVersion(pathToLib);
 
                 if (null != libraryVersion)
                 {
                     String pathToResource = localePrefix + '/'
                             + libraryName + '/' + libraryVersion + '/'
                             + resourceName;
                     resourceVersion = resourceLoader
                             .getResourceVersion(pathToResource);
                 }
                 else
                 {
                     String pathToResource = localePrefix + '/'
                             + libraryName + '/' + resourceName;
                     resourceVersion = resourceLoader
                             .getResourceVersion(pathToResource);
                 }
 
                 if (!(resourceVersion != null && ResourceLoader.VERSION_INVALID.equals(resourceVersion)))
                 {
                     resourceId = resourceLoader.createResourceMeta(localePrefix, libraryName,
                             libraryVersion, resourceName, resourceVersion);
                 }
             }
             else
             {
                 resourceVersion = resourceLoader
                         .getResourceVersion(localePrefix + '/'+ resourceName);
                 if (!(resourceVersion != null && ResourceLoader.VERSION_INVALID.equals(resourceVersion)))
                 {               
                     resourceId = resourceLoader.createResourceMeta(localePrefix, null, null,
                             resourceName, resourceVersion);
                 }
             }
 
             if (resourceId != null)
             {
                 URL url = resourceLoader.getResourceURL(resourceId);
                 if (url == null)
                 {
                     resourceId = null;
                 }
             }            
         }
         
         //2. Try to localize resource in a non localized path
         if (resourceId == null)
         {
             if (null != libraryName)
             {
                 libraryVersion = resourceLoader.getLibraryVersion(libraryName);
 
                 if (null != libraryVersion)
                 {
                     String pathToResource = (libraryName + '/' + libraryVersion
                             + '/' + resourceName);
                     resourceVersion = resourceLoader
                             .getResourceVersion(pathToResource);
                 }
                 else
                 {
                     String pathToResource = (libraryName + '/'
                             + resourceName);
                     resourceVersion = resourceLoader
                             .getResourceVersion(pathToResource);
                 }
 
                 if (!(resourceVersion != null && ResourceLoader.VERSION_INVALID.equals(resourceVersion)))
                 {               
                     resourceId = resourceLoader.createResourceMeta(null, libraryName,
                             libraryVersion, resourceName, resourceVersion);
                 }
             }
             else
             {
                 resourceVersion = resourceLoader
                         .getResourceVersion(resourceName);
                 
                 if (!(resourceVersion != null && ResourceLoader.VERSION_INVALID.equals(resourceVersion)))
                 {               
                     resourceId = resourceLoader.createResourceMeta(null, null, null,
                             resourceName, resourceVersion);
                 }
             }
 
             if (resourceId != null)
             {
                 URL url = resourceLoader.getResourceURL(resourceId);
                 if (url == null)
                 {
                     resourceId = null;
                 }
             }            
         }
         
         return resourceId;
     }
 
     @Override
     public String getRendererTypeForResourceName(String resourceName)
     {
         if (resourceName.endsWith(".js"))
         {
             return "javax.faces.resource.Script";
         }
         else if (resourceName.endsWith(".css"))
         {
             return "javax.faces.resource.Stylesheet";
         }
         return null;
     }
 
     /**
      *  Handle the resource request, writing in the output. 
      *  
      *  This method implements an algorithm semantically identical to 
      *  the one described on the javadoc of ResourceHandler.handleResourceRequest 
      */
     @Override
     public void handleResourceRequest(FacesContext facesContext) throws IOException
     {
         //try
         //{
             String resourceBasePath = getResourceHandlerSupport()
                     .calculateResourceBasePath(facesContext);
     
             if (resourceBasePath == null)
             {
                 // No base name could be calculated, so no further
                 //advance could be done here. HttpServletResponse.SC_NOT_FOUND
                 //cannot be returned since we cannot extract the 
                 //resource base name
                 return;
             }
     
             // We neet to get an instance of HttpServletResponse, but sometimes
             // the response object is wrapped by several instances of 
             // ServletResponseWrapper (like ResponseSwitch).
             // Since we are handling a resource, we can expect to get an 
             // HttpServletResponse.
             ExternalContext extContext = facesContext.getExternalContext();
             Object response = extContext.getResponse();
             HttpServletResponse httpServletResponse = ExternalContextUtils.getHttpServletResponse(response);
             if (httpServletResponse == null)
             {
                 throw new IllegalStateException("Could not obtain an instance of HttpServletResponse.");
             }
     
             if (isResourceIdentifierExcluded(facesContext, resourceBasePath))
             {
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
                 return;
             }
     
             String resourceName = null;
             if (resourceBasePath.startsWith(ResourceHandler.RESOURCE_IDENTIFIER))
             {
                 resourceName = resourceBasePath
                         .substring(ResourceHandler.RESOURCE_IDENTIFIER.length() + 1);
                 
                 if (resourceBasePath != null && !ResourceValidationUtils.isValidResourceName(resourceName))
                 {
                     httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
                     return;
                 }
             }
             else
             {
                 //Does not have the conditions for be a resource call
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
                 return;
             }
     
             String libraryName = facesContext.getExternalContext()
                     .getRequestParameterMap().get("ln");
     
             if (libraryName != null && !ResourceValidationUtils.isValidLibraryName(
                     libraryName, isAllowSlashesLibraryName()))
             {
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
                 return;
             }
             
             Resource resource = null;
             if (libraryName != null)
             {
                 //log.info("libraryName=" + libraryName);
                 resource = facesContext.getApplication().getResourceHandler().createResource(resourceName, libraryName);
             }
             else
             {
                 resource = facesContext.getApplication().getResourceHandler().createResource(resourceName);
             }
     
             if (resource == null)
             {
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
                 return;
             }
     
             if (!resource.userAgentNeedsUpdate(facesContext))
             {
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                 return;
             }
     
             httpServletResponse.setContentType(_getContentType(resource, facesContext.getExternalContext()));
     
             Map<String, String> headers = resource.getResponseHeaders();
     
             for (Map.Entry<String, String> entry : headers.entrySet())
             {
                 httpServletResponse.setHeader(entry.getKey(), entry.getValue());
             }
     
             // Sets the preferred buffer size for the body of the response
             extContext.setResponseBufferSize(this.getResourceBufferSize());
             
             //serve up the bytes (taken from trinidad ResourceServlet)
             try
             {
                 InputStream in = resource.getInputStream();
                 OutputStream out = httpServletResponse.getOutputStream();
                 //byte[] buffer = new byte[_BUFFER_SIZE];
                 byte[] buffer = new byte[this.getResourceBufferSize()];
     
                 try
                 {
                     int count = pipeBytes(in, out, buffer);
                     //set the content lenght
                     httpServletResponse.setContentLength(count);
                 }
                 finally
                 {
                     try
                     {
                         in.close();
                     }
                     finally
                     {
                         out.close();
                     }
                 }
             }
             catch (IOException e)
             {
                 //TODO: Log using a localized message (which one?)
                 if (log.isLoggable(Level.SEVERE))
                 {
                     log.severe("Error trying to load resource " + resourceName
                             + " with library " + libraryName + " :"
                             + e.getMessage());
                 }
                 httpServletResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
             }
         //}
         //catch (Throwable ex)
         //{
             // handle the Throwable accordingly. Maybe generate an error page.
             // FIXME we are creating a html error page for a non html request here
             // shouln't we do something better? -=Jakob Korherr=-
             //ErrorPageWriter.handleThrowable(facesContext, ex);
         //}
     }
 
     /**
      * Reads the specified input stream into the provided byte array storage and
      * writes it to the output stream.
      */
     private static int pipeBytes(InputStream in, OutputStream out, byte[] buffer)
             throws IOException
     {
         int count = 0;
         int length;
 
         while ((length = (in.read(buffer))) >= 0)
         {
             out.write(buffer, 0, length);
             count += length;
         }
         return count;
     }
 
     @Override
     public boolean isResourceRequest(FacesContext facesContext)
     {
         // Since this method could be called many times we save it
         //on request map so the first time is calculated it remains
         //alive until the end of the request
         Boolean value = (Boolean) facesContext.getAttributes().get(IS_RESOURCE_REQUEST);
 
         if (value != null && value)
         {
             //return the saved value
             return value;
         }
         else
         {
             String resourceBasePath = getResourceHandlerSupport()
                     .calculateResourceBasePath(facesContext);
 
             if (resourceBasePath != null
                     && resourceBasePath.startsWith(ResourceHandler.RESOURCE_IDENTIFIER))
             {
                 facesContext.getAttributes().put(IS_RESOURCE_REQUEST, Boolean.TRUE);
                 return true;
             }
             else
             {
                 facesContext.getAttributes().put(IS_RESOURCE_REQUEST, Boolean.FALSE);
                 return false;
             }
         }
     }
 
     protected String getLocalePrefixForLocateResource()
     {
         String localePrefix = null;
         FacesContext context = FacesContext.getCurrentInstance();
         boolean isResourceRequest = context.getApplication().getResourceHandler().isResourceRequest(context);
 
         if (isResourceRequest)
         {
             localePrefix = context.getExternalContext().getRequestParameterMap().get("loc");
             
             if (localePrefix != null)
             {
                 if (!ResourceValidationUtils.isValidLocalePrefix(localePrefix))
                 {
                     return null;
                 }
                 return localePrefix;
             }
         }
         
         String bundleName = context.getApplication().getMessageBundle();
 
         if (null != bundleName)
         {
             Locale locale = null;
             
             if (isResourceRequest || context.getViewRoot() == null)
             {
                 locale = context.getApplication().getViewHandler()
                                 .calculateLocale(context);
             }
             else
             {
                 locale = context.getViewRoot().getLocale();
             }
 
             try
             {
                 ResourceBundle bundle = ResourceBundle
                         .getBundle(bundleName, locale, ClassUtils.getContextClassLoader());
 
                 if (bundle != null)
                 {
                     localePrefix = bundle.getString(ResourceHandler.LOCALE_PREFIX);
                 }
             }
             catch (MissingResourceException e)
             {
                 // Ignore it and return null
             }
         }
         return localePrefix;
     }
 
     protected boolean isResourceIdentifierExcluded(FacesContext context,
             String resourceIdentifier)
     {
         String value = context.getExternalContext().getInitParameter(
                 RESOURCE_EXCLUDES_PARAM_NAME);
         if (value == null)
         {
             value = RESOURCE_EXCLUDES_DEFAULT_VALUE;
         }
         //TODO: optimize this code
         String[] extensions = StringUtils.splitShortString(value, ' ');
         for (int i = 0; i < extensions.length; i++)
         {
             if (resourceIdentifier.endsWith(extensions[i]))
             {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Check if a library exists or not. This is done delegating
      * to each ResourceLoader used, because each one has a different
      * prefix and way to load resources.
      * 
      */
     @Override
     public boolean libraryExists(String libraryName)
     {
         String localePrefix = getLocalePrefixForLocateResource();
 
         String pathToLib = null;
         
         if (libraryName != null && !ResourceValidationUtils.isValidLibraryName(
                 libraryName, isAllowSlashesLibraryName()))
         {
             return false;
         }
         
         if (localePrefix != null)
         {
             //Check with locale
             pathToLib = localePrefix + '/' + libraryName;
             
             for (ResourceLoader loader : getResourceHandlerSupport()
                     .getResourceLoaders())
             {
                 if (loader.libraryExists(pathToLib))
                 {
                     return true;
                 }
             }            
         }
 
         //Check without locale
         for (ResourceLoader loader : getResourceHandlerSupport()
                 .getResourceLoaders())
         {
             if (loader.libraryExists(libraryName))
             {
                 return true;
             }
         }
 
         return false;
     }
 
     /**
      * @param resourceHandlerSupport
      *            the resourceHandlerSupport to set
      */
     public void setResourceHandlerSupport(
             ResourceHandlerSupport resourceHandlerSupport)
     {
         _resourceHandlerSupport = resourceHandlerSupport;
     }
 
     /**
      * @return the resourceHandlerSupport
      */
     protected ResourceHandlerSupport getResourceHandlerSupport()
     {
         if (_resourceHandlerSupport == null)
         {
             _resourceHandlerSupport = new DefaultResourceHandlerSupport();
         }
         return _resourceHandlerSupport;
     }
 
     private ResourceHandlerCache getResourceLoaderCache()
     {
         if (_resourceHandlerCache == null)
         {
             _resourceHandlerCache = new ResourceHandlerCache();
         }
         return _resourceHandlerCache;
     }
 
     private String _getContentType(Resource resource, ExternalContext externalContext)
     {
         String contentType = resource.getContentType();
 
         // the resource does not provide a content-type --> determine it via mime-type
         if (contentType == null || contentType.length() == 0)
         {
             String resourceName = getWrappedResourceName(resource);
 
             if (resourceName != null)
             {
                 contentType = externalContext.getMimeType(resourceName);
             }
         }
 
         return contentType;
     }
 
     /**
      * Recursively unwarp the resource until we find the real resourceName
      * This is needed because the JSF2 specced ResourceWrapper doesn't override
      * the getResourceName() method :(
      * @param resource
      * @return the first non-null resourceName or <code>null</code> if none set
      */
     private String getWrappedResourceName(Resource resource)
     {
         String resourceName = resource.getResourceName();
         if (resourceName != null)
         {
             return resourceName;
         }
 
         if (resource instanceof ResourceWrapper)
         {
             return getWrappedResourceName(((ResourceWrapper) resource).getWrapped());
         }
 
         return null;
     }
     
     protected boolean isAllowSlashesLibraryName()
     {
         if (_allowSlashLibraryName == null)
         {
             _allowSlashLibraryName = WebConfigParamUtils.getBooleanInitParameter(
                     FacesContext.getCurrentInstance().getExternalContext(), 
                     INIT_PARAM_STRICT_JSF_2_ALLOW_SLASH_LIBRARY_NAME,
                     INIT_PARAM_STRICT_JSF_2_ALLOW_SLASH_LIBRARY_NAME_DEFAULT);
         }
         return _allowSlashLibraryName;
     }
 
     protected int getResourceBufferSize()
     {
         if (_resourceBufferSize == -1)
         {
             _resourceBufferSize = WebConfigParamUtils.getIntegerInitParameter(
                 FacesContext.getCurrentInstance().getExternalContext(),
                 INIT_PARAM_RESOURCE_BUFFER_SIZE,
                 INIT_PARAM_RESOURCE_BUFFER_SIZE_DEFAULT);
         }
         return _resourceBufferSize;
     }
 
 }