/*
    * 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 java.io.IOException;
  import java.nio.file.Path;
  import java.util.Collection;
  import java.util.List;
  import java.util.Objects;
  import java.util.Set;
  import java.util.function.Predicate;
  import java.util.stream.Collectors;
  
  import org.apache.maven.api.Artifact;
  import org.apache.maven.api.ArtifactCoordinates;
  import org.apache.maven.api.Dependency;
  import org.apache.maven.api.DependencyCoordinates;
  import org.apache.maven.api.DependencyScope;
  import org.apache.maven.api.Node;
  import org.apache.maven.api.PathScope;
  import org.apache.maven.api.PathType;
  import org.apache.maven.api.Project;
  import org.apache.maven.api.RemoteRepository;
  import org.apache.maven.api.Session;
  import org.apache.maven.api.annotations.Nonnull;
  import org.apache.maven.api.annotations.Nullable;
  import org.apache.maven.api.di.Named;
  import org.apache.maven.api.di.Singleton;
  import org.apache.maven.api.services.ArtifactResolver;
  import org.apache.maven.api.services.ArtifactResolverException;
  import org.apache.maven.api.services.ArtifactResolverResult;
  import org.apache.maven.api.services.DependencyResolver;
  import org.apache.maven.api.services.DependencyResolverException;
  import org.apache.maven.api.services.DependencyResolverRequest;
  import org.apache.maven.api.services.DependencyResolverResult;
  import org.apache.maven.api.services.ProjectManager;
  import org.eclipse.aether.DefaultRepositorySystemSession;
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.collection.CollectRequest;
  import org.eclipse.aether.collection.CollectResult;
  import org.eclipse.aether.collection.DependencyCollectionException;
  import org.eclipse.aether.graph.DependencyFilter;
  import org.eclipse.aether.graph.DependencyNode;
  import org.eclipse.aether.scope.ResolutionScope;
  import org.eclipse.aether.util.graph.manager.DependencyManagerUtils;
  import org.eclipse.aether.util.graph.transformer.ConflictResolver;
  
  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 {
  
      @Nonnull
      @Override
      public DependencyResolverResult collect(@Nonnull DependencyResolverRequest request)
              throws DependencyResolverException, IllegalArgumentException {
          nonNull(request, "request");
          InternalSession session = InternalSession.from(request.getSession());
  
          Artifact rootArtifact;
          DependencyCoordinates root;
          Collection<DependencyCoordinates> dependencies;
          Collection<DependencyCoordinates> managedDependencies;
          List<RemoteRepository> remoteRepositories;
          if (request.getProject().isPresent()) {
              Project project = request.getProject().get();
              rootArtifact = project.getPomArtifact();
              root = null;
              dependencies = project.getDependencies();
              managedDependencies = project.getManagedDependencies();
              remoteRepositories = request.getRepositories() != null
                      ? request.getRepositories()
                      : session.getService(ProjectManager.class).getRemoteProjectRepositories(project);
          } else {
              rootArtifact = request.getRootArtifact().orElse(null);
              root = request.getRoot().orElse(null);
              dependencies = request.getDependencies();
              managedDependencies = request.getManagedDependencies();
              remoteRepositories =
                      request.getRepositories() != null ? request.getRepositories() : session.getRemoteRepositories();
         }
         ResolutionScope resolutionScope = null;
         if (request.getPathScope() != null) {
             resolutionScope = session.getSession()
                     .getScopeManager()
                     .getResolutionScope(request.getPathScope().id())
                     .orElseThrow();
         }
         CollectRequest collectRequest = new CollectRequest()
                 .setRootArtifact(rootArtifact != null ? session.toArtifact(rootArtifact) : null)
                 .setRoot(root != null ? session.toDependency(root, false) : null)
                 .setDependencies(session.toDependencies(dependencies, false))
                 .setManagedDependencies(session.toDependencies(managedDependencies, true))
                 .setRepositories(session.toRepositories(remoteRepositories));
         collectRequest.setResolutionScope(resolutionScope);
 
         RepositorySystemSession systemSession = session.getSession();
         if (request.getVerbose()) {
             systemSession = new DefaultRepositorySystemSession(systemSession)
                     .setConfigProperty(ConflictResolver.CONFIG_PROP_VERBOSE, true)
                     .setConfigProperty(DependencyManagerUtils.CONFIG_PROP_VERBOSE, true);
         }
 
         try {
             final CollectResult result =
                     session.getRepositorySystem().collectDependencies(systemSession, collectRequest);
             return new DefaultDependencyResolverResult(
                     null, result.getExceptions(), session.getNode(result.getRoot(), request.getVerbose()), 0);
         } catch (DependencyCollectionException e) {
             throw new DependencyResolverException("Unable to collect dependencies", e);
         }
     }
 
     @Nonnull
     @Override
     public List<Node> flatten(@Nonnull Session s, @Nonnull Node node, @Nullable PathScope 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(PathScope scope) {
         if (scope == null) {
             return null;
         }
         Set<String> scopes =
                 scope.dependencyScopes().stream().map(DependencyScope::id).collect(Collectors.toSet());
         return (n, p) -> {
             org.eclipse.aether.graph.Dependency d = n.getDependency();
             return d == null || scopes.contains(d.getScope());
         };
     }
 
     /**
      * Collects, flattens and resolves the dependencies.
      *
      * @param request the request to resolve
      * @return the result of the resolution
      */
     @Override
     public DependencyResolverResult resolve(DependencyResolverRequest request)
             throws DependencyResolverException, DependencyResolverException, ArtifactResolverException {
         InternalSession session =
                 InternalSession.from(nonNull(request, "request").getSession());
         DependencyResolverResult result;
         DependencyResolverResult collectorResult = collect(request);
         List<RemoteRepository> repositories =
                 request.getRepositories() != null ? request.getRepositories() : session.getRemoteRepositories();
         if (request.getRequestType() == DependencyResolverRequest.RequestType.COLLECT) {
             result = collectorResult;
         } else {
             List<Node> nodes = flatten(session, collectorResult.getRoot(), request.getPathScope());
             List<ArtifactCoordinates> coordinates = nodes.stream()
                     .map(Node::getDependency)
                     .filter(Objects::nonNull)
                     .map(Artifact::toCoordinates)
                     .collect(Collectors.toList());
             Predicate<PathType> filter = request.getPathTypeFilter();
             if (request.getRequestType() == DependencyResolverRequest.RequestType.FLATTEN) {
                 DefaultDependencyResolverResult flattenResult = new DefaultDependencyResolverResult(
                         null, collectorResult.getExceptions(), collectorResult.getRoot(), nodes.size());
                 for (Node node : nodes) {
                     flattenResult.addNode(node);
                 }
                 result = flattenResult;
             } else {
                 PathModularizationCache cache = new PathModularizationCache(); // TODO: should be project-wide cache.
                 DefaultDependencyResolverResult resolverResult = new DefaultDependencyResolverResult(
                         cache, collectorResult.getExceptions(), collectorResult.getRoot(), nodes.size());
                 ArtifactResolverResult artifactResolverResult =
                         session.getService(ArtifactResolver.class).resolve(session, coordinates, repositories);
                 for (Node node : nodes) {
                     Dependency d = node.getDependency();
                     Path path = (d != null) ? artifactResolverResult.getPath(d) : null;
                     try {
                         resolverResult.addDependency(node, d, filter, path);
                     } catch (IOException e) {
                         throw cannotReadModuleInfo(path, e);
                     }
                 }
                 result = resolverResult;
             }
         }
         return result;
     }
 
     private static DependencyResolverException cannotReadModuleInfo(final Path path, final IOException cause) {
         return new DependencyResolverException("Cannot read module information of " + path, cause);
     }
 }