/*
    * 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.syncope.client.enduser.init;
  
  import java.io.Serializable;
  import java.lang.reflect.Modifier;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  import org.apache.commons.lang3.ArrayUtils;
  import org.apache.syncope.client.enduser.pages.BaseExtPage;
  import org.apache.syncope.client.enduser.pages.BasePage;
  import org.apache.syncope.client.ui.commons.annotations.BinaryPreview;
  import org.apache.syncope.client.ui.commons.annotations.ExtPage;
  import org.apache.syncope.client.ui.commons.markup.html.form.preview.BinaryPreviewer;
  import org.apache.syncope.client.ui.commons.panels.BaseSSOLoginFormPanel;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.config.BeanDefinition;
  import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
  import org.springframework.core.type.filter.AssignableTypeFilter;
  import org.springframework.util.ClassUtils;
  
  public class ClassPathScanImplementationLookup implements Serializable {
  
      private static final long serialVersionUID = -4944986595429290116L;
  
      private static final Logger LOG = LoggerFactory.getLogger(ClassPathScanImplementationLookup.class);
  
      private static final String DEFAULT_BASE_PACKAGE = "org.apache.syncope";
  
      private List<Class<? extends BaseSSOLoginFormPanel>> ssoLoginFormPanels;
  
      private List<Class<? extends BasePage>> extPages;
  
      private List<Class<? extends BinaryPreviewer>> previewers;
  
      /**
       * This method can be overridden by subclasses to customize classpath scan.
       *
       * @return basePackage for classpath scanning
       */
      protected static String getBasePackage() {
          return DEFAULT_BASE_PACKAGE;
      }
  
      @SuppressWarnings("unchecked")
      public void load() {
          extPages = new ArrayList<>();
          ssoLoginFormPanels = new ArrayList<>();
          previewers = new ArrayList<>();
  
          ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
          scanner.addIncludeFilter(new AssignableTypeFilter(BasePage.class));
          scanner.addIncludeFilter(new AssignableTypeFilter(BaseSSOLoginFormPanel.class));
          scanner.addIncludeFilter(new AssignableTypeFilter(BinaryPreviewer.class));
  
          for (BeanDefinition bd : scanner.findCandidateComponents(getBasePackage())) {
              try {
                  Class<?> clazz = ClassUtils.resolveClassName(Objects.requireNonNull(bd.getBeanClassName()),
                          ClassUtils.getDefaultClassLoader());
                  if (Modifier.isAbstract(clazz.getModifiers())) {
                      continue;
                  }
  
                  if (BaseExtPage.class.isAssignableFrom(clazz)) {
                      if (clazz.isAnnotationPresent(ExtPage.class)) {
                          extPages.add((Class<? extends BasePage>) clazz);
                      } else {
                          LOG.error("Could not find annotation {} in {}, ignoring",
                                  ExtPage.class.getName(), clazz.getName());
                      }
                  } else if (BaseSSOLoginFormPanel.class.isAssignableFrom(clazz)) {
                      ssoLoginFormPanels.add((Class<? extends BaseSSOLoginFormPanel>) clazz);
                  } else if (BinaryPreviewer.class.isAssignableFrom(clazz)) {
                      previewers.add((Class<? extends BinaryPreviewer>) clazz);
                  }
              } catch (Throwable t) {
                  LOG.warn("Could not inspect class {}", bd.getBeanClassName(), t);
              }
          }
  
         ssoLoginFormPanels = Collections.unmodifiableList(ssoLoginFormPanels);
 
         LOG.debug("Extension pages found: {}", extPages);
         LOG.debug("SSO Login pages found: {}", ssoLoginFormPanels);
         LOG.debug("Binary previewers found: {}", previewers);
     }
 
     public List<Class<? extends BaseSSOLoginFormPanel>> getSSOLoginFormPanels() {
         return this.ssoLoginFormPanels;
     }
 
     public List<Class<? extends BasePage>> getExtPageClasses() {
         return extPages;
     }
 
     public Class<? extends BinaryPreviewer> getPreviewerClass(final String mimeType) {
         LOG.debug("Searching for previewer class for MIME type: {}", mimeType);
         Class<? extends BinaryPreviewer> previewer = null;
         for (Class<? extends BinaryPreviewer> candidate : previewers) {
             LOG.debug("Evaluating previewer class {} for MIME type {}", candidate.getName(), mimeType);
             if (candidate.isAnnotationPresent(BinaryPreview.class)
                     && ArrayUtils.contains(candidate.getAnnotation(BinaryPreview.class).mimeTypes(), mimeType)) {
                 LOG.debug("Found existing previewer for MIME type {}: {}", mimeType, candidate.getName());
                 previewer = candidate;
             }
         }
         return previewer;
     }
 }