/*
    * Copyright 2018 Jeremy Long.
    *
    * Licensed 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.owasp.maven.tools;
  
  import java.io.File;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import org.apache.commons.io.FilenameUtils;
  import org.apache.maven.shared.filtering.DefaultMavenFileFilter;
  import org.apache.maven.shared.filtering.MavenFileFilter;
  import org.apache.maven.shared.filtering.MavenFilteringException;
  import org.apache.maven.shared.utils.io.FileUtils;
  import org.codehaus.plexus.component.annotations.Component;
  
  /**
   * Simple resource filter that is used to remove excess whitespace from Velocity
   * Templates using standard Maven resource filtering. Leading whitespace is
   * removed from lines and a trailing Velocity comment (##) is appended to each
   * line to swallow the new line from the resulting output.
   *
   * @author Jeremy Long
   */
  @Component(role = MavenFileFilter.class, hint = "default")
  public class VelocityWhitespaceFilter extends DefaultMavenFileFilter {
  
      /**
       * The extensions that are supported.
       */
      private final List<String> extensions = Arrays.asList("vm", "vtl", "vsl");
  
      /**
       * Whether or not the given file should be filtered.
       *
       * @param from the file to test
       * @return true if this filter should transform the file, otherwise false
       */
      protected boolean shouldFilter(File from) {
          if (from == null) {
              return false;
          }
          final String ext = FilenameUtils.getExtension(from.getName());
          return extensions.contains(ext.toLowerCase());
      }
  
      /**
       * {@inheritDoc} Copies the given file using the
       * {@link org.owasp.maven.tools.VelocityWhitespaceFilteringReader} so that
       * the Velocity Template copied will output less whitespace.
       */
      @Override
      public void copyFile(File from, File to, boolean filtering, List<FileUtils.FilterWrapper> filterWrappers,
              String encoding, boolean overwrite) throws MavenFilteringException {
          List<FileUtils.FilterWrapper> wrappers = filterWrappers;
          if (filtering && shouldFilter(from)) {
              wrappers = new ArrayList<>(filterWrappers);
              wrappers.add(new VelocityWhitespaceFilterWrapper());
          }
          super.copyFile(from, to, filtering, wrappers, encoding, overwrite);
      }
  }