maven-error-diagnostics/src/main/java/org/apache/maven/usability/diagnostics/ErrorDiagnostics.java

package org.apache.maven.usability.diagnostics;

/*
 * 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.codehaus.plexus.PlexusConstants;
import org.codehaus.plexus.PlexusContainer;
import org.codehaus.plexus.component.repository.exception.ComponentLifecycleException;
import org.codehaus.plexus.component.repository.exception.ComponentLookupException;
import org.codehaus.plexus.context.Context;
import org.codehaus.plexus.context.ContextException;
import org.codehaus.plexus.logging.AbstractLogEnabled;
import org.codehaus.plexus.personality.plexus.lifecycle.phase.Contextualizable;

import java.util.Iterator;
import java.util.List;

public class ErrorDiagnostics
    extends AbstractLogEnabled
    implements Contextualizable
{
    public static final String ROLE = ErrorDiagnostics.class.getName();

    private PlexusContainer container;

    private List errorDiagnosers;

    public void setErrorDiagnosers( List errorDiagnosers )
    {
        this.errorDiagnosers = errorDiagnosers;
    }

    public String diagnose( Throwable error )
    {
        List diags = errorDiagnosers;

        boolean releaseDiags = false;
        boolean errorProcessed = false;

        String message = null;

        try
        {
            if ( diags == null )
            {
                releaseDiags = true;

                try
                {
                    diags = container.lookupList( ErrorDiagnoser.ROLE );
                }
                catch ( ComponentLookupException e )
                {
                    getLogger().error( "Failed to lookup the list of error diagnosers.", e );
                }
            }

            if ( diags != null )
            {
                for ( Iterator it = diags.iterator(); it.hasNext(); )
                {
                    ErrorDiagnoser diagnoser = (ErrorDiagnoser) it.next();

                    if ( diagnoser.canDiagnose( error ) )
                    {
                        errorProcessed = true;

                        message = diagnoser.diagnose( error );

                        break;
                    }
                }
            }
        }
        finally
        {
            if ( releaseDiags && diags != null )
            {
                try
                {
                    container.releaseAll( diags );
                }
                catch ( ComponentLifecycleException e )
                {
                    getLogger().debug( "Failed to release error diagnoser list.", e );
                }
            }

            if ( !errorProcessed )
            {
                message = new PuntErrorDiagnoser().diagnose( error );
            }
        }

        return message;
    }

    public void contextualize( Context context )
        throws ContextException
    {
        this.container = (PlexusContainer) context.get( PlexusConstants.PLEXUS_KEY );
    }

    private static class PuntErrorDiagnoser
        implements ErrorDiagnoser
    {

        public boolean canDiagnose( Throwable error )
        {
            return true;
        }

        public String diagnose( Throwable error )
        {
            StringBuffer message = new StringBuffer();

            message.append( error.getMessage() );

            DiagnosisUtils.appendRootCauseIfPresentAndUnique( error, message, false );

            return message.toString();
        }

    }
}