package com.atlassian.plugin.webresource;
   
   import static com.atlassian.plugin.webresource.ContextBatchPluginResource.URL_PREFIX;
   
   import com.atlassian.plugin.servlet.DownloadableResource;
   
   import java.util.HashSet;
   import java.util.LinkedHashSet;
   import java.util.Map;
  import java.util.Set;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Provides a fallback to serve resources relative to a context batch resource
   * In practice, the resources url should be transformed via the
   * {{com.atlassian.plugin.webresource.RelativeURLTransformResource}}.
   * This builder is in place in case this does not happen
   * @since 2.9.0
   */
  public class ContextBatchSubResourceBuilder implements DownloadableResourceBuilder
  {
      public static final Pattern CONTEXT_BATCH_PATTERN = Pattern.compile(URL_PREFIX + "\\w*/([^/]*)/(?!batch\\.js)(.*)$");
  
      private final ResourceDependencyResolver dependencyResolver;
      private final DownloadableResourceFinder resourceFinder;
  
      public ContextBatchSubResourceBuilder(final ResourceDependencyResolver dependencyResolver, final DownloadableResourceFinder resourceFinder)
      {
          this.dependencyResolver = dependencyResolver;
          this.resourceFinder = resourceFinder;
      }
  
      public boolean matches(final String path)
      {
          return CONTEXT_BATCH_PATTERN.matcher(path).find();
      }
  
      public DownloadableResource parse(final String path, final Map<String, String> params) throws UrlParseException
      {
          final Matcher m = CONTEXT_BATCH_PATTERN.matcher(path);
          if (!m.find())
          {
              throw new UrlParseException("Context batch url could not be parsed.");
          }
  
          final String key = m.group(1);
          final String resourceName = m.group(2);
  
          final LinkedHashSet<String> includedContexts = new LinkedHashSet<String>();
          final Set<String> excludedContexts = new HashSet<String>();
  
          ContextBatchOperations.parseContexts(key, includedContexts, excludedContexts);
          
          for (final String context : includedContexts)
          {
              for (final WebResourceModuleDescriptor moduleDescriptor : dependencyResolver.getDependenciesInContext(context))
              {
                  final DownloadableResource resource = resourceFinder.find(moduleDescriptor.getCompleteKey(), resourceName);
                  if (resource != null)
                  {
                      return resource;
                  }
              }
          }
          return null; // 404 not found
      }
  }