/*
    * 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.eclipse.aether.util.repository;
  
  import java.io.File;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.List;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.repository.LocalArtifactRegistration;
  import org.eclipse.aether.repository.LocalArtifactRequest;
  import org.eclipse.aether.repository.LocalArtifactResult;
  import org.eclipse.aether.repository.LocalMetadataRegistration;
  import org.eclipse.aether.repository.LocalMetadataRequest;
  import org.eclipse.aether.repository.LocalMetadataResult;
  import org.eclipse.aether.repository.LocalRepository;
  import org.eclipse.aether.repository.LocalRepositoryManager;
  import org.eclipse.aether.repository.RemoteRepository;
  
  import static java.util.Objects.requireNonNull;
  import static java.util.stream.Collectors.toList;
  
  /**
   * A local repository manager that chains multiple local repository managers: it directs all the write operations
   * to chain head, while uses tail for {@link #find(RepositorySystemSession, LocalArtifactRequest)} and
   * {@link #find(RepositorySystemSession, LocalMetadataRequest)} methods only. Hence, tail is used in resolving
   * metadata and artifacts with or without (configurable) artifact availability tracking.
   * <p>
   * Implementation represents itself using the head local repository manager.
   *
   * @since 1.9.2
   */
  public final class ChainedLocalRepositoryManager implements LocalRepositoryManager {
      private final LocalRepositoryManager head;
  
      private final List<LocalRepositoryManager> tail;
  
      private final boolean ignoreTailAvailability;
  
      public ChainedLocalRepositoryManager(
              LocalRepositoryManager head, List<LocalRepositoryManager> tail, boolean ignoreTailAvailability) {
          this.head = requireNonNull(head, "head cannot be null");
          this.tail = requireNonNull(tail, "tail cannot be null");
          this.ignoreTailAvailability = ignoreTailAvailability;
      }
  
      @Override
      public LocalRepository getRepository() {
          return head.getRepository();
      }
  
      @Override
      public String getPathForLocalArtifact(Artifact artifact) {
          return head.getPathForLocalArtifact(artifact);
      }
  
      @Override
      public String getPathForRemoteArtifact(Artifact artifact, RemoteRepository repository, String context) {
          return head.getPathForRemoteArtifact(artifact, repository, context);
      }
  
      @Override
      public String getPathForLocalMetadata(Metadata metadata) {
          return head.getPathForLocalMetadata(metadata);
      }
  
      @Override
      public String getPathForRemoteMetadata(Metadata metadata, RemoteRepository repository, String context) {
          return head.getPathForRemoteMetadata(metadata, repository, context);
      }
  
      @Override
      public LocalArtifactResult find(RepositorySystemSession session, LocalArtifactRequest request) {
          LocalArtifactResult result = head.find(session, request);
          if (result.isAvailable()) {
              return result;
          }
  
          for (LocalRepositoryManager lrm : tail) {
              result = lrm.find(session, request);
             if (result.getFile() != null) {
                 if (ignoreTailAvailability) {
                     result.setAvailable(true);
                     return result;
                 } else if (result.isAvailable()) {
                     return result;
                 }
             }
         }
         return new LocalArtifactResult(request);
     }
 
     @Override
     public void add(RepositorySystemSession session, LocalArtifactRegistration request) {
         String artifactPath;
         if (request.getRepository() != null) {
             artifactPath = getPathForRemoteArtifact(request.getArtifact(), request.getRepository(), "check");
         } else {
             artifactPath = getPathForLocalArtifact(request.getArtifact());
         }
 
         Path file = new File(head.getRepository().getBasedir(), artifactPath).toPath();
         if (Files.isRegularFile(file)) {
             head.add(session, request);
         }
     }
 
     @Override
     public LocalMetadataResult find(RepositorySystemSession session, LocalMetadataRequest request) {
         LocalMetadataResult result = head.find(session, request);
         if (result.getFile() != null) {
             return result;
         }
 
         for (LocalRepositoryManager lrm : tail) {
             result = lrm.find(session, request);
             if (result.getFile() != null) {
                 return result;
             }
         }
         return new LocalMetadataResult(request);
     }
 
     @Override
     public void add(RepositorySystemSession session, LocalMetadataRegistration request) {
         String metadataPath;
         if (request.getRepository() != null) {
             metadataPath = getPathForRemoteMetadata(request.getMetadata(), request.getRepository(), "check");
         } else {
             metadataPath = getPathForLocalMetadata(request.getMetadata());
         }
 
         Path file = new File(head.getRepository().getBasedir(), metadataPath).toPath();
         if (Files.isRegularFile(file)) {
             head.add(session, request);
         }
     }
 
     @Override
     public String toString() {
         return head.getRepository().toString()
                 + tail.stream().map(LocalRepositoryManager::getRepository).collect(toList());
     }
 }