/*
    * 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.Inject;
  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.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.stream.Collectors;
  
  import org.apache.maven.RepositoryUtils;
  import org.apache.maven.api.Artifact;
  import org.apache.maven.api.ArtifactCoordinate;
  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.MavenProject;
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.graph.DependencyFilter;
  import org.eclipse.aether.graph.DependencyNode;
  import org.eclipse.aether.graph.DependencyVisitor;
  import org.eclipse.aether.util.graph.visitor.FilteringDependencyVisitor;
  import org.eclipse.aether.util.graph.visitor.PreorderDependencyNodeConsumerVisitor;
  
  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 {
  
      @Inject
      public DefaultDependencyResolver() {}
  
      @Override
      public List<Node> flatten(Session s, Node node, ResolutionScope scope) throws DependencyResolverException {
          InternalSession session = InternalSession.from(s);
  
          // TODO: v4: refactor with RepositorySystem#flattenDependencyNodes with resolver alpha-3
          DependencyNode root = cast(AbstractNode.class, node, "node").getDependencyNode();
          List<DependencyNode> dependencies = new ArrayList<>();
          DependencyVisitor builder = new PreorderDependencyNodeConsumerVisitor(dependencies::add);
          DependencyFilter filter = getScopeDependencyFilter(scope);
          DependencyVisitor visitor = new FilteringDependencyVisitor(builder, filter);
          root.accept(visitor);
          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) -> {
              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()) {
              List<Artifact> artifacts = resolveDependencies(
                      request.getSession(), request.getProject().get(), request.getResolutionScope());
              List<Path> paths = artifacts.stream()
                      .map(a -> request.getSession()
                             .getService(ArtifactManager.class)
                             .getPath(a)
                             .get())
                     .collect(Collectors.toList());
             return new DefaultDependencyResolverResult(Collections.emptyList(), null, Collections.emptyList(), paths);
         }
 
         DependencyCollectorResult collectorResult =
                 session.getService(DependencyCollector.class).collect(request);
         List<Node> dependencies = flatten(session, collectorResult.getRoot(), request.getResolutionScope());
 
         List<ArtifactCoordinate> coordinates = dependencies.stream()
                 .map(Node::getDependency)
                 .filter(Objects::nonNull)
                 .map(Artifact::toCoordinate)
                 .collect(Collectors.toList());
         Map<Artifact, Path> artifacts = session.resolveArtifacts(coordinates);
         List<Path> paths = dependencies.stream()
                 .map(Node::getDependency)
                 .filter(Objects::nonNull)
                 .map(artifacts::get)
                 .filter(Objects::nonNull)
                 .collect(Collectors.toList());
 
         return new DefaultDependencyResolverResult(
                 collectorResult.getExceptions(), collectorResult.getRoot(), dependencies, paths);
     }
 
     private List<Artifact> resolveDependencies(Session session, Project project, ResolutionScope scope) {
         Collection<String> toResolve = toScopes(scope);
         try {
             LifecycleDependencyResolver lifecycleDependencyResolver =
                     session.getService(Lookup.class).lookup(LifecycleDependencyResolver.class);
             Set<org.apache.maven.artifact.Artifact> artifacts = lifecycleDependencyResolver.resolveProjectArtifacts(
                     getMavenProject(project),
                     toResolve,
                     toResolve,
                     InternalSession.from(session).getMavenSession(),
                     false,
                     Collections.emptySet());
             return map(artifacts, a -> InternalSession.from(session).getArtifact(RepositoryUtils.toArtifact(a)));
         } 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> dependencies;
         private final List<Path> paths;
 
         DefaultDependencyResolverResult(
                 List<Exception> exceptions, Node root, List<Node> dependencies, List<Path> paths) {
             this.exceptions = exceptions;
             this.root = root;
             this.dependencies = dependencies;
             this.paths = paths;
         }
 
         @Override
         public List<Exception> getExceptions() {
             return exceptions;
         }
 
         @Override
         public Node getRoot() {
             return root;
         }
 
         @Override
         public List<Node> getDependencies() {
             return dependencies;
         }
 
         @Override
         public List<Path> getPaths() {
             return paths;
         }
     }
 }