src/main/java/org/apache/maven/plugins/dependency/tree/AbstractVerboseGraphSerializer.java

package org.apache.maven.plugins.dependency.tree;

/*
 * 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.
 */

import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.graph.DependencyNode;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;

/**
 * Base class for verbose Serializers
 */
abstract class AbstractVerboseGraphSerializer
{
    protected static final String LINE_START_LAST_CHILD = "\\- ", LINE_START_CHILD = "+- ";
    protected static final String PRE_MANAGED_SCOPE = "preManagedScope", PRE_MANAGED_VERSION = "preManagedVersion",
            MANAGED_SCOPE = "managedScope";

    public abstract String serialize( DependencyNode root );

    protected static String getDependencyCoordinate( DependencyNode node )
    {
        Artifact artifact = node.getArtifact();

        if ( node.getDependency() == null )
        {
            // should only get here if node is root
            return artifact.getGroupId() + ":" + artifact.getArtifactId() + ":" + artifact.getExtension() + ":"
                    + artifact.getVersion();
        }

        String scope;
        if ( artifact.getProperties().containsKey( MANAGED_SCOPE ) )
        {
            scope = artifact.getProperties().get( MANAGED_SCOPE );
        }
        else
        {
            scope = node.getDependency().getScope();
        }

        String coords = artifact.getGroupId() + ":" + artifact.getArtifactId() + ":" + artifact.getExtension() + ":"
                + artifact.getVersion();

        if ( scope != null && !scope.isEmpty() )
        {
            coords = coords.concat( ":" + scope );
        }
        return coords;
    }

    private static String getVersionlessScopelessCoordinate( DependencyNode node )
    {
        Artifact artifact = node.getArtifact();
        // scope not included because we check for scope conflicts separately
        return artifact.getGroupId() + ":" + artifact.getArtifactId() + ":" + artifact.getExtension();
    }

    private static boolean isDuplicateDependencyCoordinate( DependencyNode node, Set<String> coordinateStrings )
    {
        return coordinateStrings.contains( getDependencyCoordinate( node ) );
    }

    private static String versionConflict( DependencyNode node, Map<String, String> coordinateVersionMap )
    {
        if ( coordinateVersionMap.containsKey( getVersionlessScopelessCoordinate( node ) ) )
        {
            return coordinateVersionMap.get( getVersionlessScopelessCoordinate( node ) );
        }
        return null;
    }

    private static String scopeConflict( DependencyNode node, Set<String> coordinateStrings )
    {
        Artifact artifact = node.getArtifact();
        List<String> scopes = Arrays.asList( "compile", "provided", "runtime", "test", "system" );

        for ( String scope : scopes )
        {
            String coordinate = artifact.getGroupId() + ":" + artifact.getArtifactId() + ":" + artifact.getExtension()
                    + ":" + artifact.getVersion() + ":" + scope;
            if ( coordinateStrings.contains( coordinate ) )
            {
                return scope;
            }
        }
        return null;
    }

    protected Map<DependencyNode, String> getNodeConflictMessagesBfs( DependencyNode root, Set<String> coordinateStrings
            , Map<String, String> coordinateVersionMap )
    {
        Map<DependencyNode, String> nodeErrors = new HashMap<>();
        Set<DependencyNode> visitedNodes = new HashSet<>( 512 );
        Queue<DependencyNode> queue = new LinkedList<>();
        visitedNodes.add( root );
        queue.add( root );

        while ( !queue.isEmpty() )
        {
            DependencyNode node = queue.poll();

            if ( node == null || node.getArtifact() == null )
            {
                // Should never reach hit this condition with a proper graph sent in
                nodeErrors.put( node, "Null Artifact Node" );
                break;
            }

            if ( isDuplicateDependencyCoordinate( node, coordinateStrings ) )
            {
                nodeErrors.put( node, "omitted for duplicate" );
            }
            else if ( scopeConflict( node, coordinateStrings ) != null )
            {
                nodeErrors.put( node, "omitted for conflict with " + scopeConflict( node, coordinateStrings ) );
            }
            else if ( versionConflict( node, coordinateVersionMap ) != null )
            {
                nodeErrors.put( node, "omitted for conflict with " + versionConflict( node, coordinateVersionMap ) );
            }
            else if ( versionConflict( node, coordinateVersionMap ) != null )
            {
                nodeErrors.put( node, "omitted for conflict with "
                        + versionConflict( node, coordinateVersionMap ) );
            }
            else if ( node.getDependency() != null && node.getDependency().isOptional() )
            {
                nodeErrors.put( node, "omitted due to optional dependency" );
            }
            else
            {
                boolean ignoreNode = false;
                nodeErrors.put( node, null );

                if ( node.getArtifact() != null )
                {
                    coordinateVersionMap.put( getVersionlessScopelessCoordinate( node ),
                            node.getArtifact().getVersion() );
                }

                for ( DependencyNode child : node.getChildren() )
                {
                    if ( visitedNodes.contains( child ) )
                    {
                        ignoreNode = true;
                        nodeErrors.put( node, "omitted for introducing a cycle with "
                                + getDependencyCoordinate( child ) );
                        node.setChildren( new ArrayList<DependencyNode>() );
                        break;
                    }
                }

                if ( !ignoreNode )
                {
                    for ( int i = 0; i < node.getChildren().size(); ++i )
                    {
                        DependencyNode child = node.getChildren().get( i );

                        if ( !visitedNodes.contains( child ) )
                        {
                            visitedNodes.add( child );
                            queue.add( child );
                        }
                    }
                }
            }
            coordinateStrings.add( getDependencyCoordinate( node ) );
        }
        return nodeErrors;
    }
}