/*
    * 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.configuration;
  
  import java.lang.reflect.InvocationTargetException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Objects;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.commons.text.WordUtils;
  import org.apache.rat.ConfigurationException;
  import org.apache.rat.Defaults;
  import org.apache.rat.configuration.builders.AbstractBuilder;
  
  /**
   * A class to track the Matcher Builders as they are defined.  Matchers may be defined in multiple configuration files
   * this method tracks them so that they can be referenced across the configuration files.
   */
  public final class MatcherBuilderTracker {
  
      /** The instance of the BuildTracker. */
      public static MatcherBuilderTracker INSTANCE;
  
      private final Map<String, Class<? extends AbstractBuilder>> matcherBuilders;
  
      private static synchronized MatcherBuilderTracker instance() {
          if (INSTANCE == null) {
              INSTANCE = new MatcherBuilderTracker();
              Defaults.init();
          }
          return INSTANCE;
      }
  
      /**
       * Adds a builder to the tracker.
       * If the {@code name} is null then the builder class name simple is used with the "Builder" suffix removed.
       * @param className the Class name for the builder.
       * @param name the short name for the builder. 
       */
      public static void addBuilder(final String className, final String name) {
          instance().addBuilderImpl(className, name);
      }
  
      /**
       * Get the matching builder for the name.
       * @param name The name of the builder.
       * @return the builder for that name. (not null)
       */
      public static AbstractBuilder getMatcherBuilder(final String name) {
          Class<? extends AbstractBuilder> clazz = instance().matcherBuilders.get(name);
          if (clazz == null) {
              StringBuilder sb = new StringBuilder(System.lineSeparator()).append("Valid builders").append(System.lineSeparator());
              instance().matcherBuilders.keySet().forEach(x -> sb.append(x).append(System.lineSeparator()));
              sb.append("ERROR MSG").append(System.lineSeparator());
              throw new ConfigurationException(sb.append("No matcher builder named ").append(name).toString());
          }
          try {
              return clazz.getConstructor().newInstance();
          } catch (NoSuchMethodException | SecurityException | InstantiationException | IllegalAccessException
                  | IllegalArgumentException | InvocationTargetException e) {
              throw new ConfigurationException(
                      String.format("Can not instantiate matcher builder named %s (%s)", name, clazz.getName()), e);
          }
      }
  
      private MatcherBuilderTracker() {
          matcherBuilders = new HashMap<>();
      }
      
  
      /**
       * Gets a collection of classes that are recognized as builders.
       * @return the collection of builder classes
       */
      public Collection<Class<? extends AbstractBuilder>> getClasses() {
          return Collections.unmodifiableCollection(matcherBuilders.values());
      }
  
      private void addBuilderImpl(final String className, final String name) {
          Objects.requireNonNull(className, "className may not be null");
         Class<?> clazz;
         try {
             clazz = getClass().getClassLoader().loadClass(className);
         } catch (ClassNotFoundException e) {
             throw new ConfigurationException(e);
         }
         if (AbstractBuilder.class.isAssignableFrom(clazz)) {
             @SuppressWarnings("unchecked")
             Class<? extends AbstractBuilder> candidate = (Class<? extends AbstractBuilder>) clazz;
             String workingName = name;
             if (StringUtils.isBlank(workingName)) {
                 workingName = candidate.getSimpleName();
                 if (!workingName.endsWith("Builder")) {
                     throw new ConfigurationException(
                             "name is required, or " + candidate.getName() + " must end with 'Builder'");
                 }
                 workingName = workingName.substring(0, workingName.lastIndexOf("Builder"));
                 if (StringUtils.isBlank(workingName)) {
                     throw new ConfigurationException("Last segment of " + candidate.getName()
                             + " may not be 'Builder', but must end in 'Builder'");
                 }
                 workingName = WordUtils.uncapitalize(workingName);
             }
             matcherBuilders.put(workingName, candidate);
         } else {
             throw new ConfigurationException("Class " + clazz.getName() + " does not extend " + AbstractBuilder.class);
         }
     }
 }