/*
    * 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.project;
  
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import org.apache.maven.model.Model;
  
  /**
   * Holds all Models that are known to the reactor. This allows the project builder to resolve imported Models from the
   * reactor when building another project's effective model.
   *
   * @author Benjamin Bentmann
   * @author Robert Scholte
   */
  class ReactorModelPool {
      private final Map<GAKey, Set<Model>> modelsByGa = new HashMap<>();
  
      private final Map<Path, Model> modelsByPath = new HashMap<>();
  
      /**
       * Get the model by its GAV or (since 4.0.0) by its GA if there is only one.
       *
       * @param groupId never {@code null}
       * @param artifactId never {@code null}
       * @param version can be {@code null}
       * @return the matching model or {@code null}
       * @throws IllegalStateException if version was null and multiple modules share the same groupId + artifactId
       */
      public Model get(String groupId, String artifactId, String version) {
          return modelsByGa.getOrDefault(new GAKey(groupId, artifactId), Collections.emptySet()).stream()
                  .filter(m -> version == null || version.equals(getVersion(m)))
                  .reduce((a, b) -> {
                      throw new IllegalStateException(
                              "Multiple modules with key " + a.getGroupId() + ':' + a.getArtifactId());
                  })
                  .orElse(null);
      }
  
      /**
       * Find model by path, useful when location the parent by relativePath
       *
       * @param path
       * @return the matching model or {@code null}
       * @since 4.0.0
       */
      public Model get(Path path) {
          final Path pomFile;
          if (Files.isDirectory(path)) {
              pomFile = path.resolve("pom.xml");
          } else {
              pomFile = path;
          }
          return modelsByPath.get(pomFile);
      }
  
      private String getVersion(Model model) {
          String version = model.getVersion();
          if (version == null && model.getParent() != null) {
              version = model.getParent().getVersion();
          }
          return version;
      }
  
      static class Builder {
          private ReactorModelPool pool = new ReactorModelPool();
  
          Builder put(Path pomFile, Model model) {
              pool.modelsByPath.put(pomFile, model);
              pool.modelsByGa
                      .computeIfAbsent(new GAKey(getGroupId(model), model.getArtifactId()), k -> new HashSet<Model>())
                      .add(model);
              return this;
          }
  
          ReactorModelPool build() {
              return pool;
         }
 
         private static String getGroupId(Model model) {
             String groupId = model.getGroupId();
             if (groupId == null && model.getParent() != null) {
                 groupId = model.getParent().getGroupId();
             }
             return groupId;
         }
     }
 
     private static final class GAKey {
 
         private final String groupId;
 
         private final String artifactId;
 
         private final int hashCode;
 
         GAKey(String groupId, String artifactId) {
             this.groupId = (groupId != null) ? groupId : "";
             this.artifactId = (artifactId != null) ? artifactId : "";
 
             hashCode = Objects.hash(this.groupId, this.artifactId);
         }
 
         @Override
         public boolean equals(Object obj) {
             if (this == obj) {
                 return true;
             }
 
             GAKey that = (GAKey) obj;
 
             return artifactId.equals(that.artifactId) && groupId.equals(that.groupId);
         }
 
         @Override
         public int hashCode() {
             return hashCode;
         }
 
         @Override
         public String toString() {
             StringBuilder buffer = new StringBuilder(128);
             buffer.append(groupId).append(':').append(artifactId);
             return buffer.toString();
         }
     }
 }