/*
    * 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.rat.config.parameters;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Method;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.rat.ConfigurationException;
  import org.apache.rat.ImplementationException;
  import org.apache.rat.analysis.IHeaderMatcher;
  import org.apache.rat.license.ILicense;
  
  /**
   * Builds Description objects for the various Component instances.
   */
  public class DescriptionBuilder {
      /* do not instantiate */
      private DescriptionBuilder() {}
  
      /**
       * Create the description for the object.
       * The object must have a ConfigComponent annotation or null will be returned.
       * @param obj the object to process.
       * @return the Description of the object.
       */
      public static Description build(Object obj) {
          if (obj instanceof ILicense) {
              ILicense license = (ILicense)obj;
              Class<?> clazz = obj.getClass();
              ConfigComponent configComponent = clazz.getAnnotation(ConfigComponent.class);
              if (configComponent == null || configComponent.type() != ComponentType.LICENSE) {
                  throw new ConfigurationException(String.format("Licenses must have License type specified in ConfigComponent annotation.  Annotation missing or incorrect in %s", clazz));
              }
              List<Description> children = getConfigComponents(obj.getClass());
              return new Description(ComponentType.LICENSE, license.getId(), license.getName(), false, null, children, false);
          }
          return buildMap(obj.getClass());
      }
  
      private static String fixupMethodName(Method method) {
          String name = method.getName();
          if (name.startsWith("get") || name.startsWith("set") || name.startsWith("add")) {
              if (name.length() > 3) {
                  String retval = name.substring(3,4).toLowerCase();
                  if (name.length() > 4) {
                      retval+=name.substring(4);
                  }
                  return retval;
              }
          } 
          throw new ImplementationException(String.format("'%s' is not a recognized method name", name));
      }
      /**
       * Build the list of descriptions for children of the class.
       * @param clazz
       * @return the Descriptions. of the child elements.
       */
      private static List<Description> getConfigComponents(Class<?> clazz) {
          if (clazz == null || clazz == String.class || clazz == Object.class) {
              return Collections.emptyList();
          }
          List<Description> result = new ArrayList<>();
          for (Field field : clazz.getDeclaredFields()) {
              ConfigComponent configComponent = field.getAnnotation(ConfigComponent.class);
              if (configComponent != null) {
                  String name = StringUtils.isBlank(configComponent.name()) ? field.getName() : configComponent.name();
                  Class<?> childClazz = configComponent.parameterType() == void.class ? field.getType()
                          : configComponent.parameterType();
                  boolean isCollection = Iterable.class.isAssignableFrom(field.getType());
  
                  Description desc = new Description(configComponent.type(), name, configComponent.desc(), isCollection,
                          childClazz, getConfigComponents(childClazz), configComponent.required());
                  result.add(desc);
              }
          }
          for (Method method : clazz.getDeclaredMethods()) {
              ConfigComponent configComponent = method.getAnnotation(ConfigComponent.class);
             if (configComponent != null) {
                 String name = StringUtils.isBlank(configComponent.name()) ? fixupMethodName(method) : configComponent.name();
                 Class<?> childClazz = configComponent.parameterType() == void.class ? method.getReturnType()
                         : configComponent.parameterType();
                 boolean isCollection = Iterable.class.isAssignableFrom(method.getReturnType());
 
                 Description desc = new Description(configComponent.type(), name, configComponent.desc(), isCollection,
                         childClazz, getConfigComponents(childClazz), configComponent.required());
                 result.add(desc);
             }
         }
         result.addAll(getConfigComponents(clazz.getSuperclass()));
         Arrays.stream(clazz.getInterfaces()).forEach(c -> result.addAll(getConfigComponents(c)));
         return result;
     }
 
     private static ConfigComponent findConfigComponent(Class<?> clazz) {
         if (clazz == null || clazz == String.class || clazz == Object.class) {
             return null;
         }
         ConfigComponent configComponent = clazz.getAnnotation(ConfigComponent.class);
         return configComponent == null ? findConfigComponent(clazz.getSuperclass()) : configComponent;
     }
     /**
      * Create a description for a class.
      * @param clazz the class to build the description for.
      * @return the Description of the class or null if no ConfigComponent annotation was found on the class.
      */
     public static Description buildMap(Class<?> clazz) {
         if (clazz == IHeaderMatcher.class) {
             throw new ImplementationException("'clazz' parameter must not be IHeaderMatcher.class but may be a child of it"); 
         }
         ConfigComponent configComponent = findConfigComponent(clazz);
         if (configComponent == null) {
             return null;
         }
         List<Description> children = getConfigComponents(clazz);
 
         return new Description(configComponent, false, null, children);
     }
 }