package org.eclipse.aether.util.graph.visitor;

/*
 * 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.Dependency;
import org.eclipse.aether.graph.DependencyNode;
import org.eclipse.aether.graph.DependencyVisitor;

import java.io.File;
import java.util.ArrayList;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

Abstract base class for depth first dependency tree traversers. Subclasses of this visitor will visit each node
exactly once regardless how many paths within the dependency graph lead to the node such that the resulting node
sequence is free of duplicates.
 Actual vertex ordering (preorder, inorder, postorder) needs to be defined by subclasses through appropriate implementations for visitEnter(DependencyNode) and visitLeave(DependencyNode) /**
 * Abstract base class for depth first dependency tree traversers. Subclasses of this visitor will visit each node
 * exactly once regardless how many paths within the dependency graph lead to the node such that the resulting node
 * sequence is free of duplicates.
 * <p>
 * Actual vertex ordering (preorder, inorder, postorder) needs to be defined by subclasses through appropriate
 * implementations for {@link #visitEnter(org.eclipse.aether.graph.DependencyNode)} and
 * {@link #visitLeave(org.eclipse.aether.graph.DependencyNode)}
 */
abstract class AbstractDepthFirstNodeListGenerator
    implements DependencyVisitor
{

    private final Map<DependencyNode, Object> visitedNodes;

    protected final List<DependencyNode> nodes;

    AbstractDepthFirstNodeListGenerator()
    {
        nodes = new ArrayList<>( 128 );
        visitedNodes = new IdentityHashMap<>( 512 );
    }

    
Gets the list of dependency nodes that was generated during the graph traversal.
Returns:
The list of dependency nodes, never null./**
     * Gets the list of dependency nodes that was generated during the graph traversal.
     * 
     * @return The list of dependency nodes, never {@code null}.
     */
    public List<DependencyNode> getNodes()
    {
        return nodes;
    }

    
Gets the dependencies seen during the graph traversal.
Params:
includeUnresolved – Whether unresolved dependencies shall be included in the result or not.
Returns:
The list of dependencies, never null./**
     * Gets the dependencies seen during the graph traversal.
     * 
     * @param includeUnresolved Whether unresolved dependencies shall be included in the result or not.
     * @return The list of dependencies, never {@code null}.
     */
    public List<Dependency> getDependencies( boolean includeUnresolved )
    {
        List<Dependency> dependencies = new ArrayList<>( getNodes().size() );

        for ( DependencyNode node : getNodes() )
        {
            Dependency dependency = node.getDependency();
            if ( dependency != null )
            {
                if ( includeUnresolved || dependency.getArtifact().getFile() != null )
                {
                    dependencies.add( dependency );
                }
            }
        }

        return dependencies;
    }

    
Gets the artifacts associated with the list of dependency nodes generated during the graph traversal.
Params:
includeUnresolved – Whether unresolved artifacts shall be included in the result or not.
Returns:
The list of artifacts, never null./**
     * Gets the artifacts associated with the list of dependency nodes generated during the graph traversal.
     * 
     * @param includeUnresolved Whether unresolved artifacts shall be included in the result or not.
     * @return The list of artifacts, never {@code null}.
     */
    public List<Artifact> getArtifacts( boolean includeUnresolved )
    {
        List<Artifact> artifacts = new ArrayList<>( getNodes().size() );

        for ( DependencyNode node : getNodes() )
        {
            if ( node.getDependency() != null )
            {
                Artifact artifact = node.getDependency().getArtifact();
                if ( includeUnresolved || artifact.getFile() != null )
                {
                    artifacts.add( artifact );
                }
            }
        }

        return artifacts;
    }

    
Gets the files of resolved artifacts seen during the graph traversal.
Returns:
The list of artifact files, never null./**
     * Gets the files of resolved artifacts seen during the graph traversal.
     * 
     * @return The list of artifact files, never {@code null}.
     */
    public List<File> getFiles()
    {
        List<File> files = new ArrayList<>( getNodes().size() );

        for ( DependencyNode node : getNodes() )
        {
            if ( node.getDependency() != null )
            {
                File file = node.getDependency().getArtifact().getFile();
                if ( file != null )
                {
                    files.add( file );
                }
            }
        }

        return files;
    }

    
Gets a class path by concatenating the artifact files of the visited dependency nodes. Nodes with unresolved
artifacts are automatically skipped.
Returns:
The class path, using the platform-specific path separator, never null./**
     * Gets a class path by concatenating the artifact files of the visited dependency nodes. Nodes with unresolved
     * artifacts are automatically skipped.
     * 
     * @return The class path, using the platform-specific path separator, never {@code null}.
     */
    public String getClassPath()
    {
        StringBuilder buffer = new StringBuilder( 1024 );

        for ( Iterator<DependencyNode> it = getNodes().iterator(); it.hasNext(); )
        {
            DependencyNode node = it.next();
            if ( node.getDependency() != null )
            {
                Artifact artifact = node.getDependency().getArtifact();
                if ( artifact.getFile() != null )
                {
                    buffer.append( artifact.getFile().getAbsolutePath() );
                    if ( it.hasNext() )
                    {
                        buffer.append( File.pathSeparatorChar );
                    }
                }
            }
        }

        return buffer.toString();
    }

    
Marks the specified node as being visited and determines whether the node has been visited before.
Params:
node – The node being visited, must not be null.
Returns:
true if the node has not been visited before, false if the node was already visited./**
     * Marks the specified node as being visited and determines whether the node has been visited before.
     * 
     * @param node The node being visited, must not be {@code null}.
     * @return {@code true} if the node has not been visited before, {@code false} if the node was already visited.
     */
    protected boolean setVisited( DependencyNode node )
    {
        return visitedNodes.put( node, Boolean.TRUE ) == null;
    }

    public abstract boolean visitEnter( DependencyNode node );

    public abstract boolean visitLeave( DependencyNode node );

}