/*
    * 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.nio.file.Files;
  import java.nio.file.Path;
  import java.util.List;
  
  import org.eclipse.aether.ConfigurationProperties;
  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 org.eclipse.aether.util.ConfigUtils;
  
  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 static final String CONFIG_PROPS_PREFIX = ConfigurationProperties.PREFIX_AETHER + "chainedLocalRepository.";
  
      /**
       * When using chained local repository, should be the artifact availability ignored in tail.
       *
       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
       * @configurationType {@link java.lang.Boolean}
       * @configurationDefaultValue {@link #DEFAULT_IGNORE_TAIL_AVAILABILITY}
       */
      public static final String CONFIG_PROP_IGNORE_TAIL_AVAILABILITY = CONFIG_PROPS_PREFIX + "ignoreTailAvailability";
  
      public static final boolean DEFAULT_IGNORE_TAIL_AVAILABILITY = true;
  
      private final LocalRepositoryManager head;
  
      private final List<LocalRepositoryManager> tail;
  
      private final boolean ignoreTailAvailability;
  
      private final int installTarget;
  
      private final int cacheTarget;
  
      public ChainedLocalRepositoryManager(
              LocalRepositoryManager head, List<LocalRepositoryManager> tail, boolean ignoreTailAvailability) {
          this(head, tail, ignoreTailAvailability, 0, 0);
      }
  
      public ChainedLocalRepositoryManager(
              LocalRepositoryManager head, List<LocalRepositoryManager> tail, RepositorySystemSession session) {
          this(
                  head,
                  tail,
                  ConfigUtils.getBoolean(session, DEFAULT_IGNORE_TAIL_AVAILABILITY, CONFIG_PROP_IGNORE_TAIL_AVAILABILITY),
                  0,
                  0);
      }
  
      /**
       * Warning: this is experimental feature of chained, is not recommended to be used/integrated into plain Maven.
       *
       * @param head The head LRM
       * @param tail The tail LRMs
       * @param ignoreTailAvailability Whether tail availability should be ignored (usually you do want this)
       * @param installTarget The installation LRM index, integer from 0 to size of tail.
       * @param cacheTarget The cache LRM index, integer from 0 to size of tail.
      * @since 2.0.5
      */
     public ChainedLocalRepositoryManager(
             LocalRepositoryManager head,
             List<LocalRepositoryManager> tail,
             boolean ignoreTailAvailability,
             int installTarget,
             int cacheTarget) {
         this.head = requireNonNull(head, "head cannot be null");
         this.tail = requireNonNull(tail, "tail cannot be null");
         this.ignoreTailAvailability = ignoreTailAvailability;
         if (installTarget < 0 || installTarget > tail.size()) {
             throw new IllegalArgumentException("Illegal installTarget value");
         }
         this.installTarget = installTarget;
         if (cacheTarget < 0 || cacheTarget > tail.size()) {
             throw new IllegalArgumentException("Illegal cacheTarget value");
         }
         this.cacheTarget = cacheTarget;
     }
 
     @Override
     public LocalRepository getRepository() {
         return head.getRepository();
     }
 
     private LocalRepositoryManager getInstallTarget() {
         if (installTarget == 0) {
             return head;
         } else {
             return tail.get(installTarget - 1);
         }
     }
 
     private LocalRepositoryManager getCacheTarget() {
         if (cacheTarget == 0) {
             return head;
         } else {
             return tail.get(cacheTarget - 1);
         }
     }
 
     @Override
     public Path getAbsolutePathForLocalArtifact(Artifact artifact) {
         return getInstallTarget().getAbsolutePathForLocalArtifact(artifact);
     }
 
     @Override
     public Path getAbsolutePathForRemoteArtifact(Artifact artifact, RemoteRepository repository, String context) {
         return getCacheTarget().getAbsolutePathForRemoteArtifact(artifact, repository, context);
     }
 
     @Override
     public Path getAbsolutePathForLocalMetadata(Metadata metadata) {
         return getInstallTarget().getAbsolutePathForLocalMetadata(metadata);
     }
 
     @Override
     public Path getAbsolutePathForRemoteMetadata(Metadata metadata, RemoteRepository repository, String context) {
         return getCacheTarget().getAbsolutePathForRemoteMetadata(metadata, repository, context);
     }
 
     @Override
     public String getPathForLocalArtifact(Artifact artifact) {
         return getInstallTarget().getPathForLocalArtifact(artifact);
     }
 
     @Override
     public String getPathForRemoteArtifact(Artifact artifact, RemoteRepository repository, String context) {
         return getCacheTarget().getPathForRemoteArtifact(artifact, repository, context);
     }
 
     @Override
     public String getPathForLocalMetadata(Metadata metadata) {
         return getInstallTarget().getPathForLocalMetadata(metadata);
     }
 
     @Override
     public String getPathForRemoteMetadata(Metadata metadata, RemoteRepository repository, String context) {
         return getCacheTarget().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.getPath() != 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;
         LocalRepositoryManager target;
         if (request.getRepository() != null) {
             artifactPath = getPathForRemoteArtifact(request.getArtifact(), request.getRepository(), "check");
             target = getCacheTarget();
         } else {
             artifactPath = getPathForLocalArtifact(request.getArtifact());
             target = getInstallTarget();
         }
         Path file = target.getRepository().getBasePath().resolve(artifactPath);
         if (Files.isRegularFile(file)) {
             target.add(session, request);
         }
     }
 
     @Override
     public LocalMetadataResult find(RepositorySystemSession session, LocalMetadataRequest request) {
         LocalMetadataResult result = head.find(session, request);
         if (result.getPath() != null) {
             return result;
         }
 
         for (LocalRepositoryManager lrm : tail) {
             result = lrm.find(session, request);
             if (result.getPath() != null) {
                 return result;
             }
         }
         return new LocalMetadataResult(request);
     }
 
     @Override
     public void add(RepositorySystemSession session, LocalMetadataRegistration request) {
         String metadataPath;
         LocalRepositoryManager target;
         if (request.getRepository() != null) {
             metadataPath = getPathForRemoteMetadata(request.getMetadata(), request.getRepository(), "check");
             target = getCacheTarget();
         } else {
             metadataPath = getPathForLocalMetadata(request.getMetadata());
             target = getInstallTarget();
         }
 
         Path file = target.getRepository().getBasePath().resolve(metadataPath);
         if (Files.isRegularFile(file)) {
             target.add(session, request);
         }
     }
 
     @Override
     public String toString() {
         return head.getRepository().toString()
                 + tail.stream().map(LocalRepositoryManager::getRepository).collect(toList());
     }
 }