/*
    * 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.lifecycle.internal.concurrent;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.NoSuchElementException;
  import java.util.Optional;
  import java.util.Set;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import org.apache.maven.plugin.MojoExecution;
  import org.apache.maven.project.MavenProject;
  
  public class BuildPlan {
  
      private final Map<MavenProject, Map<String, BuildStep>> plan = new LinkedHashMap<>();
      private final Map<MavenProject, List<MavenProject>> projects;
      private final Map<String, String> aliases = new HashMap<>();
      private volatile Set<String> duplicateIds;
      private volatile List<BuildStep> sortedNodes;
  
      BuildPlan() {
          this.projects = null;
      }
  
      public BuildPlan(Map<MavenProject, List<MavenProject>> projects) {
          this.projects = projects;
      }
  
      public Map<MavenProject, List<MavenProject>> getAllProjects() {
          return projects;
      }
  
      public Map<String, String> aliases() {
          return aliases;
      }
  
      public Stream<MavenProject> projects() {
          return plan.keySet().stream();
      }
  
      public void addProject(MavenProject project, Map<String, BuildStep> steps) {
          plan.put(project, steps);
      }
  
      public void addStep(MavenProject project, String name, BuildStep step) {
          plan.get(project).put(name, step);
      }
  
      public Stream<BuildStep> allSteps() {
          return plan.values().stream().flatMap(m -> m.values().stream());
      }
  
      public Stream<BuildStep> steps(MavenProject project) {
          return Optional.ofNullable(plan.get(project))
                  .map(m -> m.values().stream())
                  .orElse(Stream.empty());
      }
  
      public Optional<BuildStep> step(MavenProject project, String name) {
          return Optional.ofNullable(plan.get(project)).map(m -> m.get(name));
      }
  
      public BuildStep requiredStep(MavenProject project, String name) {
          return step(project, name).orElseThrow(() -> new NoSuchElementException("Step " + name + " not found"));
      }
  
      // add a follow-up plan to this one
      public void then(BuildPlan step) {
          step.plan.forEach((k, v) -> plan.merge(k, v, this::merge));
          aliases.putAll(step.aliases);
      }
  
      private Map<String, BuildStep> merge(Map<String, BuildStep> org, Map<String, BuildStep> add) {
          // all new phases should be added after the existing ones
         List<BuildStep> lasts =
                 org.values().stream().filter(b -> b.successors.isEmpty()).collect(Collectors.toList());
         List<BuildStep> firsts =
                 add.values().stream().filter(b -> b.predecessors.isEmpty()).collect(Collectors.toList());
         firsts.stream()
                 .filter(addNode -> !org.containsKey(addNode.name))
                 .forEach(addNode -> lasts.forEach(orgNode -> addNode.executeAfter(orgNode)));
         add.forEach((name, node) -> org.merge(name, node, this::merge));
         return org;
     }
 
     private BuildStep merge(BuildStep node1, BuildStep node2) {
         node1.predecessors.addAll(node2.predecessors);
         node1.successors.addAll(node2.successors);
         node2.mojos.forEach((k, v) -> node1.mojos.merge(k, v, this::mergeMojos));
         return node1;
     }
 
     private Map<String, MojoExecution> mergeMojos(Map<String, MojoExecution> l1, Map<String, MojoExecution> l2) {
         l2.forEach(l1::putIfAbsent);
         return l1;
     }
 
     // gather artifactIds which are not unique so that the respective thread names can be extended with the groupId
     public Set<String> duplicateIds() {
         if (duplicateIds == null) {
             synchronized (this) {
                 if (duplicateIds == null) {
                     duplicateIds = projects()
                             .map(MavenProject::getArtifactId)
                             .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
                             .entrySet()
                             .stream()
                             .filter(p -> p.getValue() > 1)
                             .map(Map.Entry::getKey)
                             .collect(Collectors.toSet());
                 }
             }
         }
         return duplicateIds;
     }
 
     public List<BuildStep> sortedNodes() {
         if (sortedNodes == null) {
             synchronized (this) {
                 if (sortedNodes == null) {
                     List<BuildStep> sortedNodes = new ArrayList<>();
                     Set<BuildStep> visited = new HashSet<>();
                     // Visit each unvisited node
                     allSteps().forEach(node -> visitNode(node, visited, sortedNodes));
                     // Reverse the sorted nodes to get the correct order
                     Collections.reverse(sortedNodes);
                     this.sortedNodes = sortedNodes;
                 }
             }
         }
         return sortedNodes;
     }
 
     // Helper method to visit a node
     private static void visitNode(BuildStep node, Set<BuildStep> visited, List<BuildStep> sortedNodes) {
         if (visited.add(node)) {
             // For each successor of the current node, visit unvisited successors
             node.successors.forEach(successor -> visitNode(successor, visited, sortedNodes));
             sortedNodes.add(node);
         }
     }
 }