/*
    * 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.maven.graph;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  import org.apache.maven.execution.ProjectDependencyGraph;
  import org.apache.maven.project.DuplicateProjectException;
  import org.apache.maven.project.MavenProject;
  import org.apache.maven.project.ProjectSorter;
  import org.codehaus.plexus.util.dag.CycleDetectedException;
  
  /**
   * Describes the inter-dependencies between projects in the reactor.
   *
   * @author Benjamin Bentmann
   */
  public class DefaultProjectDependencyGraph implements ProjectDependencyGraph {
  
      private final ProjectSorter sorter;
  
      private final List<MavenProject> allProjects;
  
      private final Map<MavenProject, Integer> order;
  
      private final Map<String, MavenProject> projects;
  
      /**
       * Creates a new project dependency graph based on the specified projects.
       *
       * @param projects The projects to create the dependency graph with
       * @throws DuplicateProjectException
       * @throws CycleDetectedException
       */
      public DefaultProjectDependencyGraph(Collection<MavenProject> projects)
              throws CycleDetectedException, DuplicateProjectException {
          super();
          this.allProjects = Collections.unmodifiableList(new ArrayList<>(projects));
          this.sorter = new ProjectSorter(projects);
          List<MavenProject> sorted = this.sorter.getSortedProjects();
          this.order = new HashMap<>(sorted.size());
          this.projects = new HashMap<>(sorted.size());
          int index = 0;
          for (MavenProject project : sorted) {
              String id = ProjectSorter.getId(project);
              this.projects.put(id, project);
              this.order.put(project, index++);
          }
      }
  
      /**
       * Creates a new project dependency graph based on the specified projects.
       *
       * @param allProjects All collected projects.
       * @param projects The projects to create the dependency graph with.
       *
       * @throws DuplicateProjectException
       * @throws CycleDetectedException
       * @since 3.5.0
       */
      public DefaultProjectDependencyGraph(final List<MavenProject> allProjects, final Collection<MavenProject> projects)
              throws CycleDetectedException, DuplicateProjectException {
          super();
          this.allProjects = Collections.unmodifiableList(new ArrayList<>(allProjects));
          this.sorter = new ProjectSorter(projects);
          List<MavenProject> sorted = this.sorter.getSortedProjects();
          this.order = new HashMap<>(sorted.size());
          this.projects = new HashMap<>(sorted.size());
          int index = 0;
          for (MavenProject project : sorted) {
              String id = ProjectSorter.getId(project);
              this.projects.put(id, project);
              this.order.put(project, index++);
          }
     }
 
     /**
      * @since 3.5.0
      */
     public List<MavenProject> getAllProjects() {
         return this.allProjects;
     }
 
     public List<MavenProject> getSortedProjects() {
         return new ArrayList<>(sorter.getSortedProjects());
     }
 
     public List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive) {
         Objects.requireNonNull(project, "project cannot be null");
 
         Set<String> projectIds = new HashSet<>();
 
         getDownstreamProjects(ProjectSorter.getId(project), projectIds, transitive);
 
         return getSortedProjects(projectIds);
     }
 
     private void getDownstreamProjects(String projectId, Set<String> projectIds, boolean transitive) {
         for (String id : sorter.getDependents(projectId)) {
             if (projectIds.add(id) && transitive) {
                 getDownstreamProjects(id, projectIds, transitive);
             }
         }
     }
 
     public List<MavenProject> getUpstreamProjects(MavenProject project, boolean transitive) {
         Objects.requireNonNull(project, "project cannot be null");
 
         Set<String> projectIds = new HashSet<>();
 
         getUpstreamProjects(ProjectSorter.getId(project), projectIds, transitive);
 
         return getSortedProjects(projectIds);
     }
 
     private void getUpstreamProjects(String projectId, Collection<String> projectIds, boolean transitive) {
         for (String id : sorter.getDependencies(projectId)) {
             if (projectIds.add(id) && transitive) {
                 getUpstreamProjects(id, projectIds, transitive);
             }
         }
     }
 
     private List<MavenProject> getSortedProjects(Set<String> projectIds) {
         List<MavenProject> result = new ArrayList<>(projectIds.size());
         for (String projectId : projectIds) {
             result.add(projects.get(projectId));
         }
 
         Collections.sort(result, new MavenProjectComparator());
 
         return result;
     }
 
     @Override
     public String toString() {
         return sorter.getSortedProjects().toString();
     }
 
     private class MavenProjectComparator implements Comparator<MavenProject> {
         @Override
         public int compare(MavenProject o1, MavenProject o2) {
             return order.get(o1) - order.get(o2);
         }
     }
 }