package org.eclipse.aether.graph;

/*
 * 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 java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static java.util.Objects.requireNonNull;

import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.repository.RemoteRepository;
import org.eclipse.aether.version.Version;
import org.eclipse.aether.version.VersionConstraint;

/**
 * A node within a dependency graph.
 */
public final class DefaultDependencyNode
    implements DependencyNode
{

    private List<DependencyNode> children;

    private Dependency dependency;

    private Artifact artifact;

    private List<? extends Artifact> relocations;

    private Collection<? extends Artifact> aliases;

    private VersionConstraint versionConstraint;

    private Version version;

    private byte managedBits;

    private List<RemoteRepository> repositories;

    private String context;

    private Map<Object, Object> data;

    /**
     * Creates a new node with the specified dependency.
     * 
     * @param dependency The dependency associated with this node, may be {@code null} for a root node.
     */
    public DefaultDependencyNode( Dependency dependency )
    {
        this.dependency = dependency;
        artifact = ( dependency != null ) ? dependency.getArtifact() : null;
        children = new ArrayList<>( 0 );
        aliases = Collections.emptyList();
        relocations = Collections.emptyList();
        repositories = Collections.emptyList();
        context = "";
        data = Collections.emptyMap();
    }

    /**
     * Creates a new root node with the specified artifact as its label. Note that the new node has no dependency, i.e.
     * {@link #getDependency()} will return {@code null}. Put differently, the specified artifact will not be subject to
     * dependency collection/resolution.
     * 
     * @param artifact The artifact to use as label for this node, may be {@code null}.
     */
    public DefaultDependencyNode( Artifact artifact )
    {
        this.artifact = artifact;
        children = new ArrayList<>( 0 );
        aliases = Collections.emptyList();
        relocations = Collections.emptyList();
        repositories = Collections.emptyList();
        context = "";
        data = Collections.emptyMap();
    }

    /**
     * Creates a mostly shallow clone of the specified node. The new node has its own copy of any custom data and
     * initially no children.
     * 
     * @param node The node to copy, must not be {@code null}.
     */
    public DefaultDependencyNode( DependencyNode node )
    {
        dependency = node.getDependency();
        artifact = node.getArtifact();
        children = new ArrayList<>( 0 );
        setAliases( node.getAliases() );
        setRequestContext( node.getRequestContext() );
        setManagedBits( node.getManagedBits() );
        setRelocations( node.getRelocations() );
        setRepositories( node.getRepositories() );
        setVersion( node.getVersion() );
        setVersionConstraint( node.getVersionConstraint() );
        Map<?, ?> data = node.getData();
        setData( data.isEmpty() ? null : new HashMap<>( data ) );
    }

    public List<DependencyNode> getChildren()
    {
        return children;
    }

    public void setChildren( List<DependencyNode> children )
    {
        if ( children == null )
        {
            this.children = new ArrayList<>( 0 );
        }
        else
        {
            this.children = children;
        }
    }

    public Dependency getDependency()
    {
        return dependency;
    }

    public Artifact getArtifact()
    {
        return artifact;
    }

    public void setArtifact( Artifact artifact )
    {
        if ( dependency == null )
        {
            throw new IllegalStateException( "node does not have a dependency" );
        }
        dependency = dependency.setArtifact( artifact );
        this.artifact = dependency.getArtifact();
    }

    public List<? extends Artifact> getRelocations()
    {
        return relocations;
    }

    /**
     * Sets the sequence of relocations that was followed to resolve this dependency's artifact.
     * 
     * @param relocations The sequence of relocations, may be {@code null}.
     */
    public void setRelocations( List<? extends Artifact> relocations )
    {
        if ( relocations == null || relocations.isEmpty() )
        {
            this.relocations = Collections.emptyList();
        }
        else
        {
            this.relocations = relocations;
        }
    }

    public Collection<? extends Artifact> getAliases()
    {
        return aliases;
    }

    /**
     * Sets the known aliases for this dependency's artifact.
     * 
     * @param aliases The known aliases, may be {@code null}.
     */
    public void setAliases( Collection<? extends Artifact> aliases )
    {
        if ( aliases == null || aliases.isEmpty() )
        {
            this.aliases = Collections.emptyList();
        }
        else
        {
            this.aliases = aliases;
        }
    }

    public VersionConstraint getVersionConstraint()
    {
        return versionConstraint;
    }

    /**
     * Sets the version constraint that was parsed from the dependency's version declaration.
     * 
     * @param versionConstraint The version constraint for this node, may be {@code null}.
     */
    public void setVersionConstraint( VersionConstraint versionConstraint )
    {
        this.versionConstraint = versionConstraint;
    }

    public Version getVersion()
    {
        return version;
    }

    /**
     * Sets the version that was selected for the dependency's target artifact.
     * 
     * @param version The parsed version, may be {@code null}.
     */
    public void setVersion( Version version )
    {
        this.version = version;
    }

    public void setScope( String scope )
    {
        if ( dependency == null )
        {
            throw new IllegalStateException( "node does not have a dependency" );
        }
        dependency = dependency.setScope( scope );
    }

    public void setOptional( Boolean optional )
    {
        if ( dependency == null )
        {
            throw new IllegalStateException( "node does not have a dependency" );
        }
        dependency = dependency.setOptional( optional );
    }

    public int getManagedBits()
    {
        return managedBits;
    }

    /**
     * Sets a bit field indicating which attributes of this node were subject to dependency management.
     * 
     * @param managedBits The bit field indicating the managed attributes or {@code 0} if dependency management wasn't
     *            applied.
     */
    public void setManagedBits( int managedBits )
    {
        this.managedBits = (byte) ( managedBits & 0x1F );
    }

    public List<RemoteRepository> getRepositories()
    {
        return repositories;
    }

    /**
     * Sets the remote repositories from which this node's artifact shall be resolved.
     * 
     * @param repositories The remote repositories to use for artifact resolution, may be {@code null}.
     */
    public void setRepositories( List<RemoteRepository> repositories )
    {
        if ( repositories == null || repositories.isEmpty() )
        {
            this.repositories = Collections.emptyList();
        }
        else
        {
            this.repositories = repositories;
        }
    }

    public String getRequestContext()
    {
        return context;
    }

    public void setRequestContext( String context )
    {
        this.context = ( context != null ) ? context : "";
    }

    public Map<Object, Object> getData()
    {
        return data;
    }

    public void setData( Map<Object, Object> data )
    {
        if ( data == null )
        {
            this.data = Collections.emptyMap();
        }
        else
        {
            this.data = data;
        }
    }

    public void setData( Object key, Object value )
    {
        requireNonNull( key, "key cannot be null" );

        if ( value == null )
        {
            if ( !data.isEmpty() )
            {
                data.remove( key );

                if ( data.isEmpty() )
                {
                    data = Collections.emptyMap();
                }
            }
        }
        else
        {
            if ( data.isEmpty() )
            {
                data = new HashMap<>( 1, 2 ); // nodes can be numerous so let's be space conservative
            }
            data.put( key, value );
        }
    }

    public boolean accept( DependencyVisitor visitor )
    {
        if ( visitor.visitEnter( this ) )
        {
            for ( DependencyNode child : children )
            {
                if ( !child.accept( visitor ) )
                {
                    break;
                }
            }
        }

        return visitor.visitLeave( this );
    }

    @Override
    public String toString()
    {
        Dependency dep = getDependency();
        if ( dep == null )
        {
            return String.valueOf( getArtifact() );
        }
        return dep.toString();
    }

}