/*
    * 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.internal.impl;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import org.apache.maven.api.Artifact;
  import org.apache.maven.api.ArtifactCoordinate;
  import org.apache.maven.api.Dependency;
  import org.apache.maven.api.Node;
  import org.apache.maven.api.Project;
  import org.apache.maven.api.ResolutionScope;
  import org.apache.maven.api.Scope;
  import org.apache.maven.api.Session;
  import org.apache.maven.api.services.*;
  import org.apache.maven.lifecycle.LifecycleExecutionException;
  import org.apache.maven.lifecycle.internal.LifecycleDependencyResolver;
  import org.apache.maven.project.DependencyResolutionResult;
  import org.apache.maven.project.MavenProject;
  import org.eclipse.aether.graph.DependencyFilter;
  import org.eclipse.aether.graph.DependencyNode;
  
  import static org.apache.maven.internal.impl.Utils.cast;
  import static org.apache.maven.internal.impl.Utils.map;
  import static org.apache.maven.internal.impl.Utils.nonNull;
  
  @Named
  @Singleton
  public class DefaultDependencyResolver implements DependencyResolver {
  
      @Override
      public List<Node> flatten(Session s, Node node, ResolutionScope scope) throws DependencyResolverException {
          InternalSession session = InternalSession.from(s);
          DependencyNode root = cast(AbstractNode.class, node, "node").getDependencyNode();
          List<DependencyNode> dependencies = session.getRepositorySystem()
                  .flattenDependencyNodes(session.getSession(), root, getScopeDependencyFilter(scope));
          dependencies.remove(root);
          return map(dependencies, session::getNode);
      }
  
      private static DependencyFilter getScopeDependencyFilter(ResolutionScope scope) {
          Set<String> scopes = scope.scopes().stream().map(Scope::id).collect(Collectors.toSet());
          return (n, p) -> {
              org.eclipse.aether.graph.Dependency d = n.getDependency();
              return d == null || scopes.contains(d.getScope());
          };
      }
  
      @Override
      public DependencyResolverResult resolve(DependencyResolverRequest request)
              throws DependencyCollectorException, DependencyResolverException, ArtifactResolverException {
          nonNull(request, "request can not be null");
          InternalSession session = InternalSession.from(request.getSession());
  
          if (request.getProject().isPresent()) {
              DependencyResolutionResult result = resolveDependencies(
                      request.getSession(), request.getProject().get(), request.getResolutionScope());
  
              Map<org.eclipse.aether.graph.Dependency, org.eclipse.aether.graph.DependencyNode> nodes = stream(
                              result.getDependencyGraph())
                      .filter(n -> n.getDependency() != null)
                      .collect(Collectors.toMap(DependencyNode::getDependency, n -> n));
  
              Node root = session.getNode(result.getDependencyGraph());
              List<Node> dependencies = new ArrayList<>();
              Map<Dependency, Path> artifacts = new LinkedHashMap<>();
              List<Path> paths = new ArrayList<>();
              for (org.eclipse.aether.graph.Dependency dep : result.getResolvedDependencies()) {
                  dependencies.add(session.getNode(nodes.get(dep)));
                  Path path = dep.getArtifact().getFile().toPath();
                 artifacts.put(session.getDependency(dep), path);
                 paths.add(path);
             }
             return new DefaultDependencyResolverResult(
                     result.getCollectionErrors(), root, dependencies, paths, artifacts);
         }
 
         DependencyCollectorResult collectorResult =
                 session.getService(DependencyCollector.class).collect(request);
         List<Node> nodes = flatten(session, collectorResult.getRoot(), request.getResolutionScope());
         List<Dependency> deps =
                 nodes.stream().map(Node::getDependency).filter(Objects::nonNull).collect(Collectors.toList());
         List<ArtifactCoordinate> coordinates =
                 deps.stream().map(Artifact::toCoordinate).collect(Collectors.toList());
         Map<Artifact, Path> artifacts = session.resolveArtifacts(coordinates);
         Map<Dependency, Path> dependencies = deps.stream().collect(Collectors.toMap(d -> d, artifacts::get));
         List<Path> paths = new ArrayList<>(dependencies.values());
 
         return new DefaultDependencyResolverResult(
                 collectorResult.getExceptions(), collectorResult.getRoot(), nodes, paths, dependencies);
     }
 
     private Stream<DependencyNode> stream(DependencyNode node) {
         return Stream.concat(Stream.of(node), node.getChildren().stream().flatMap(this::stream));
     }
 
     private DependencyResolutionResult resolveDependencies(Session session, Project project, ResolutionScope scope) {
         Collection<String> toResolve = toScopes(scope);
         try {
             LifecycleDependencyResolver lifecycleDependencyResolver =
                     session.getService(Lookup.class).lookup(LifecycleDependencyResolver.class);
             return lifecycleDependencyResolver.getProjectDependencyResolutionResult(
                     getMavenProject(project),
                     toResolve,
                     toResolve,
                     InternalSession.from(session).getMavenSession(),
                     false,
                     Collections.emptySet());
         } catch (LifecycleExecutionException e) {
             throw new DependencyResolverException("Unable to resolve project dependencies", e);
         }
     }
 
     private MavenProject getMavenProject(Project project) {
         return ((DefaultProject) project).getProject();
     }
 
     private Collection<String> toScopes(ResolutionScope scope) {
         return map(scope.scopes(), Scope::id);
     }
 
     static class DefaultDependencyResolverResult implements DependencyResolverResult {
         private final List<Exception> exceptions;
         private final Node root;
         private final List<Node> nodes;
         private final List<Path> paths;
         private final Map<Dependency, Path> dependencies;
 
         DefaultDependencyResolverResult(
                 List<Exception> exceptions,
                 Node root,
                 List<Node> nodes,
                 List<Path> paths,
                 Map<Dependency, Path> dependencies) {
             this.exceptions = exceptions;
             this.root = root;
             this.nodes = nodes;
             this.paths = paths;
             this.dependencies = dependencies;
         }
 
         @Override
         public List<Exception> getExceptions() {
             return exceptions;
         }
 
         @Override
         public Node getRoot() {
             return root;
         }
 
         @Override
         public List<Node> getNodes() {
             return nodes;
         }
 
         @Override
         public List<Path> getPaths() {
             return paths;
         }
 
         @Override
         public Map<Dependency, Path> getDependencies() {
             return dependencies;
         }
     }
 }