/*
    * 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.collection;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashSet;
  import java.util.List;
  
  import org.eclipse.aether.RepositoryException;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.graph.DependencyNode;
  import org.eclipse.aether.version.VersionConstraint;
  
  /**
   * Thrown in case of an unsolvable conflict between different version constraints for a dependency.
   */
  public class UnsolvableVersionConflictException extends RepositoryException {
  
      private final transient Collection<String> versions;
  
      private final transient Collection<? extends List<? extends DependencyNode>> paths;
  
      /**
       * Creates a new exception with the specified paths to conflicting nodes in the dependency graph.
       *
       * @param paths The paths to the dependency nodes that participate in the version conflict, may be {@code null}.
       */
      public UnsolvableVersionConflictException(Collection<? extends List<? extends DependencyNode>> paths) {
          super("Could not resolve version conflict among " + toPaths(paths));
          if (paths == null) {
              this.paths = Collections.emptyList();
              this.versions = Collections.emptyList();
          } else {
              this.paths = paths;
              this.versions = new LinkedHashSet<>();
              for (List<? extends DependencyNode> path : paths) {
                  VersionConstraint constraint = path.get(path.size() - 1).getVersionConstraint();
                  if (constraint != null && constraint.getRange() != null) {
                      versions.add(constraint.toString());
                  }
              }
          }
      }
  
      private static String toPaths(Collection<? extends List<? extends DependencyNode>> paths) {
          String result = "";
  
          if (paths != null) {
              Collection<String> strings = new LinkedHashSet<>();
  
              for (List<? extends DependencyNode> path : paths) {
                  strings.add(toPath(path));
              }
  
              result = strings.toString();
          }
  
          return result;
      }
  
      private static String toPath(List<? extends DependencyNode> path) {
          StringBuilder buffer = new StringBuilder(256);
  
          for (Iterator<? extends DependencyNode> it = path.iterator(); it.hasNext(); ) {
              DependencyNode node = it.next();
              if (node.getDependency() == null) {
                  continue;
              }
  
              Artifact artifact = node.getDependency().getArtifact();
              buffer.append(artifact.getGroupId());
              buffer.append(':').append(artifact.getArtifactId());
              buffer.append(':').append(artifact.getExtension());
              if (!artifact.getClassifier().isEmpty()) {
                  buffer.append(':').append(artifact.getClassifier());
              }
              buffer.append(':').append(node.getVersionConstraint());
  
              if (it.hasNext()) {
                  buffer.append(" -> ");
              }
         }
 
         return buffer.toString();
     }
 
     /**
      * Gets the paths leading to the conflicting dependencies.
      *
      * @return The (read-only) paths leading to the conflicting dependencies, never {@code null}.
      */
     public Collection<? extends List<? extends DependencyNode>> getPaths() {
         return paths;
     }
 
     /**
      * Gets the conflicting version constraints of the dependency.
      *
      * @return The (read-only) conflicting version constraints, never {@code null}.
      */
     public Collection<String> getVersions() {
         return versions;
     }
 }