package com.atlassian.plugin.servlet.filter;
   
   import javax.servlet.Filter;
   import javax.servlet.FilterChain;
   import javax.servlet.ServletException;
   import javax.servlet.ServletRequest;
   import javax.servlet.ServletResponse;
   import java.io.IOException;
   import java.util.Iterator;
  
  /**
   * This FilterChain passes control from the first Filter in an iterator to the last. When the last iterator
   * calls the chain.doFilter(request, response) method, the supplied "parent" chain has control returned to it.
   *
   * @since 2.1.0
   */
  public final class IteratingFilterChain implements FilterChain {
      private final Iterator<Filter> iterator;
      private final FilterChain chain;
  
      /**
       * Create a new IteratingFilterChain which iterates over the Filters in the supplied Iterator and then returns
       * control to the main FilterChain.
       *
       * @param iterator Iterator over the Filters to apply
       * @param chain    FilterChain to return control to after the last Filter in the iterator has called the
       *                 chain.doFilter(request, response) method.
       */
      public IteratingFilterChain(Iterator<Filter> iterator, FilterChain chain) {
          this.iterator = iterator;
          this.chain = chain;
      }
  
      public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {
          if (iterator.hasNext()) {
              Filter filter = iterator.next();
              filter.doFilter(request, response, this);
          } else {
              chain.doFilter(request, response);
          }
      }
  }