package com.atlassian.plugin.validation;
   
   import com.google.common.collect.ImmutableMap;
   import org.dom4j.Document;
   import org.dom4j.Element;
   import org.dom4j.Node;
   
   import java.util.Collections;
   import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.stream.Collectors;
  
  import static com.atlassian.plugin.parsers.XmlDescriptorParserUtils.removeAllNamespaces;
  import static com.google.common.base.Preconditions.checkNotNull;
  import static java.util.stream.Collectors.collectingAndThen;
  import static java.util.stream.Collectors.toSet;
  
  /**
   * Reads information from the schema of plugin descriptors (dynamic per instance)
   *
   * @since 3.0.0
   */
  public final class SchemaReader {
      private Document schema;
  
      public SchemaReader(Document schema) {
          this.schema = removeAllNamespaces(checkNotNull(schema));
      }
  
      public Set<String> getAllowedPermissions() {
          return Collections.unmodifiableSet(getPermissionElements().stream()
                  .map(permission -> permission.attributeValue("value"))
                  .collect(Collectors.toSet()));
      }
  
      public Map<String, Set<String>> getModulesRequiredPermissions() {
          final List<Element> modulesDefinitions = selectNodes("//complexType[@name='AtlassianPluginType']/sequence/choice/element");
          ImmutableMap.Builder<String, Set<String>> permissions = ImmutableMap.builder();
          for (Element modulesDefinition : modulesDefinitions) {
              permissions.put(modulesDefinition.attributeValue("name"), getModuleRequiredPermissions(modulesDefinition));
          }
          return permissions.build();
      }
  
      private Set<String> getModuleRequiredPermissions(Element modulesDefinition) {
          return selectNodes(modulesDefinition, "annotation//required-permissions/permission").stream()
                  .map(Element::getTextTrim)
                  .collect(collectingAndThen(toSet(), Collections::unmodifiableSet));
      }
  
      private List<Element> getPermissionElements() {
          return selectNodes("//simpleType[@name='PermissionValueType']//enumeration");
      }
  
      private List<Element> selectNodes(String xpathExpression) {
          return selectNodes(schema, xpathExpression);
      }
  
      @SuppressWarnings("unchecked")
      private static List<Element> selectNodes(Node node, String xpathExpression) {
          return node.selectNodes(xpathExpression);
      }
  }