package org.eclipse.aether.resolution;

/*
 * 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.Collections;
import java.util.List;

import org.eclipse.aether.RepositoryException;
import org.eclipse.aether.transfer.ArtifactNotFoundException;
import org.eclipse.aether.transfer.RepositoryOfflineException;

Thrown in case of a unresolvable artifacts.
/**
 * Thrown in case of a unresolvable artifacts.
 */
public class ArtifactResolutionException
    extends RepositoryException
{

    private final transient List<ArtifactResult> results;

    
Creates a new exception with the specified results.
Params:
results – The resolution results at the point the exception occurred, may be null./**
     * Creates a new exception with the specified results.
     * 
     * @param results The resolution results at the point the exception occurred, may be {@code null}.
     */
    public ArtifactResolutionException( List<ArtifactResult> results )
    {
        super( getMessage( results ), getCause( results ) );
        this.results = ( results != null ) ? results : Collections.<ArtifactResult>emptyList();
    }

    
Creates a new exception with the specified results and detail message.
Params:
results – The resolution results at the point the exception occurred, may be null.
message – The detail message, may be null./**
     * Creates a new exception with the specified results and detail message.
     * 
     * @param results The resolution results at the point the exception occurred, may be {@code null}.
     * @param message The detail message, may be {@code null}.
     */
    public ArtifactResolutionException( List<ArtifactResult> results, String message )
    {
        super( message, getCause( results ) );
        this.results = ( results != null ) ? results : Collections.<ArtifactResult>emptyList();
    }

    
Creates a new exception with the specified results, detail message and cause.
Params:
results – The resolution results at the point the exception occurred, may be null.
message – The detail message, may be null.
cause – The exception that caused this one, may be null./**
     * Creates a new exception with the specified results, detail message and cause.
     * 
     * @param results The resolution results at the point the exception occurred, may be {@code null}.
     * @param message The detail message, may be {@code null}.
     * @param cause The exception that caused this one, may be {@code null}.
     */
    public ArtifactResolutionException( List<ArtifactResult> results, String message, Throwable cause )
    {
        super( message, cause );
        this.results = ( results != null ) ? results : Collections.<ArtifactResult>emptyList();
    }

    
Gets the resolution results at the point the exception occurred. Despite being incomplete, callers might want to
use these results to fail gracefully and continue their operation with whatever interim data has been gathered.
Returns:
The resolution results or null if unknown./**
     * Gets the resolution results at the point the exception occurred. Despite being incomplete, callers might want to
     * use these results to fail gracefully and continue their operation with whatever interim data has been gathered.
     * 
     * @return The resolution results or {@code null} if unknown.
     */
    public List<ArtifactResult> getResults()
    {
        return results;
    }

    
Gets the first result from getResults(). This is a convenience method for cases where callers know only a single result/request is involved. 
Returns:
The (first) resolution result or null if none./**
     * Gets the first result from {@link #getResults()}. This is a convenience method for cases where callers know only
     * a single result/request is involved.
     * 
     * @return The (first) resolution result or {@code null} if none.
     */
    public ArtifactResult getResult()
    {
        return ( results != null && !results.isEmpty() ) ? results.get( 0 ) : null;
    }

    private static String getMessage( List<? extends ArtifactResult> results )
    {
        StringBuilder buffer = new StringBuilder( 256 );

        buffer.append( "The following artifacts could not be resolved: " );

        int unresolved = 0;

        String sep = "";
        for ( ArtifactResult result : results )
        {
            if ( !result.isResolved() )
            {
                unresolved++;

                buffer.append( sep );
                buffer.append( result.getRequest().getArtifact() );
                sep = ", ";
            }
        }

        Throwable cause = getCause( results );
        if ( cause != null )
        {
            if ( unresolved == 1 )
            {
                buffer.setLength( 0 );
                buffer.append( cause.getMessage() );
            }
            else
            {
                buffer.append( ": " ).append( cause.getMessage() );
            }
        }

        return buffer.toString();
    }

    private static Throwable getCause( List<? extends ArtifactResult> results )
    {
        for ( ArtifactResult result : results )
        {
            if ( !result.isResolved() )
            {
                Throwable notFound = null, offline = null;
                for ( Throwable t : result.getExceptions() )
                {
                    if ( t instanceof ArtifactNotFoundException )
                    {
                        if ( notFound == null )
                        {
                            notFound = t;
                        }
                        if ( offline == null && t.getCause() instanceof RepositoryOfflineException )
                        {
                            offline = t;
                        }
                    }
                    else
                    {
                        return t;
                    }

                }
                if ( offline != null )
                {
                    return offline;
                }
                if ( notFound != null )
                {
                    return notFound;
                }
            }
        }
        return null;
    }

}