package org.apache.maven;

/*
 * 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.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;

import org.apache.maven.artifact.ArtifactUtils;
import org.apache.maven.execution.DefaultMavenExecutionResult;
import org.apache.maven.execution.ExecutionEvent;
import org.apache.maven.execution.MavenExecutionRequest;
import org.apache.maven.execution.MavenExecutionResult;
import org.apache.maven.execution.MavenSession;
import org.apache.maven.execution.ProjectDependencyGraph;
import org.apache.maven.graph.GraphBuilder;
import org.apache.maven.internal.aether.DefaultRepositorySystemSessionFactory;
import org.apache.maven.lifecycle.internal.ExecutionEventCatapult;
import org.apache.maven.lifecycle.internal.LifecycleStarter;
import org.apache.maven.model.building.ModelProblem;
import org.apache.maven.model.building.Result;
import org.apache.maven.plugin.LegacySupport;
import org.apache.maven.project.MavenProject;
import org.apache.maven.project.ProjectBuilder;
import org.apache.maven.repository.LocalRepositoryNotAccessibleException;
import org.apache.maven.session.scope.internal.SessionScope;
import org.codehaus.plexus.PlexusContainer;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.component.annotations.Requirement;
import org.codehaus.plexus.component.repository.exception.ComponentLookupException;
import org.codehaus.plexus.logging.Logger;
import org.eclipse.aether.DefaultRepositorySystemSession;
import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.repository.WorkspaceReader;
import org.eclipse.aether.util.repository.ChainedWorkspaceReader;

import com.google.common.collect.Iterables;

/**
 * @author Jason van Zyl
 */
@Component( role = Maven.class )
public class DefaultMaven
    implements Maven
{

    @Requirement
    private Logger logger;

    @Requirement
    protected ProjectBuilder projectBuilder;

    @Requirement
    private LifecycleStarter lifecycleStarter;

    @Requirement
    protected PlexusContainer container;

    @Requirement
    private ExecutionEventCatapult eventCatapult;

    @Requirement
    private LegacySupport legacySupport;

    @Requirement
    private SessionScope sessionScope;

    @Requirement
    private DefaultRepositorySystemSessionFactory repositorySessionFactory;

    @Requirement( hint = GraphBuilder.HINT )
    private GraphBuilder graphBuilder;

    @Override
    public MavenExecutionResult execute( MavenExecutionRequest request )
    {
        MavenExecutionResult result;

        try
        {
            result = doExecute( request );
        }
        catch ( OutOfMemoryError e )
        {
            result = addExceptionToResult( new DefaultMavenExecutionResult(), e );
        }
        catch ( RuntimeException e )
        {
            //TODO Hack to make the cycle detection the same for the new graph builder
            if ( e.getCause() instanceof ProjectCycleException )
            {
                result = addExceptionToResult( new DefaultMavenExecutionResult(), e.getCause() );
            }
            else
            {
                result = addExceptionToResult( new DefaultMavenExecutionResult(),
                                               new InternalErrorException( "Internal error: " + e, e ) );
            }
        }
        finally
        {
            legacySupport.setSession( null );
        }

        return result;
    }

    //
    // 1) Setup initial properties.
    //
    // 2) Validate local repository directory is accessible.
    //
    // 3) Create RepositorySystemSession.
    //
    // 4) Create MavenSession.
    //
    // 5) Execute AbstractLifecycleParticipant.afterSessionStart(session)
    //
    // 6) Get reactor projects looking for general POM errors
    //
    // 7) Create ProjectDependencyGraph using trimming which takes into account --projects and reactor mode.
    // This ensures that the projects passed into the ReactorReader are only those specified.
    //
    // 8) Create ReactorReader with the getProjectMap( projects ). NOTE that getProjectMap(projects) is the code that
    // checks for duplicate projects definitions in the build. Ideally this type of duplicate checking should be
    // part of getting the reactor projects in 6). The duplicate checking is conflated with getProjectMap(projects).
    //
    // 9) Execute AbstractLifecycleParticipant.afterProjectsRead(session)
    //
    // 10) Create ProjectDependencyGraph without trimming (as trimming was done in 7). A new topological sort is
    // required after the execution of 9) as the AbstractLifecycleParticipants are free to mutate the MavenProject
    // instances, which may change dependencies which can, in turn, affect the build order.
    //
    // 11) Execute LifecycleStarter.start()
    //
    @SuppressWarnings( "checkstyle:methodlength" )
    private MavenExecutionResult doExecute( MavenExecutionRequest request )
    {        
        request.setStartTime( new Date() );

        MavenExecutionResult result = new DefaultMavenExecutionResult();

        try
        {
            validateLocalRepository( request );
        }
        catch ( LocalRepositoryNotAccessibleException e )
        {
            return addExceptionToResult( result, e );
        }

        //
        // We enter the session scope right after the MavenSession creation and before any of the
        // AbstractLifecycleParticipant lookups
        // so that @SessionScoped components can be @Injected into AbstractLifecycleParticipants.
        //
        sessionScope.enter();
        try
        {
            DefaultRepositorySystemSession repoSession =
                (DefaultRepositorySystemSession) newRepositorySession( request );
            MavenSession session = new MavenSession( container, repoSession, request, result );

            sessionScope.seed( MavenSession.class, session );

            legacySupport.setSession( session );

            return doExecute( request, session, result, repoSession );
        }
        finally
        {
            sessionScope.exit();
        }
    }

    private MavenExecutionResult doExecute( MavenExecutionRequest request, MavenSession session,
                                            MavenExecutionResult result, DefaultRepositorySystemSession repoSession )
    {
        try
        {
            for ( AbstractMavenLifecycleParticipant listener : getLifecycleParticipants( Collections
                .<MavenProject>emptyList() ) )
            {
                listener.afterSessionStart( session );
            }
        }
        catch ( MavenExecutionException e )
        {
            return addExceptionToResult( result, e );
        }

        eventCatapult.fire( ExecutionEvent.Type.ProjectDiscoveryStarted, session, null );

        Result<? extends ProjectDependencyGraph> graphResult = buildGraph( session, result );
        
        if ( graphResult.hasErrors() )
        {
            return addExceptionToResult( result,
                                         Iterables.toArray( graphResult.getProblems(), ModelProblem.class )[0]
                                             .getException() );
        }

        try
        {
            session.setProjectMap( getProjectMap( session.getProjects() ) );
        }
        catch ( DuplicateProjectException e )
        {
            return addExceptionToResult( result, e );
        }

        WorkspaceReader reactorWorkspace;
        try
        {
            reactorWorkspace = container.lookup( WorkspaceReader.class, ReactorReader.HINT );
        }
        catch ( ComponentLookupException e )
        {
            return addExceptionToResult( result, e );
        }

        //
        // Desired order of precedence for local artifact repositories
        //
        // Reactor
        // Workspace
        // User Local Repository
        //
        repoSession.setWorkspaceReader( ChainedWorkspaceReader.newInstance( reactorWorkspace,
                                                                            repoSession.getWorkspaceReader() ) );

        repoSession.setReadOnly();

        ClassLoader originalClassLoader = Thread.currentThread().getContextClassLoader();
        try
        {
            for ( AbstractMavenLifecycleParticipant listener : getLifecycleParticipants( session.getProjects() ) )
            {
                Thread.currentThread().setContextClassLoader( listener.getClass().getClassLoader() );

                listener.afterProjectsRead( session );
            }
        }
        catch ( MavenExecutionException e )
        {
            return addExceptionToResult( result, e );
        }
        finally
        {
            Thread.currentThread().setContextClassLoader( originalClassLoader );
        }

        //
        // The projects need to be topologically after the participants have run their afterProjectsRead(session)
        // because the participant is free to change the dependencies of a project which can potentially change the
        // topological order of the projects, and therefore can potentially change the build order.
        //
        // Note that participants may affect the topological order of the projects but it is
        // not expected that a participant will add or remove projects from the session.
        //
        
        graphResult = buildGraph( session, result );
        
        if ( graphResult.hasErrors() )
        {
            return addExceptionToResult( result,
                                         Iterables.toArray( graphResult.getProblems(), ModelProblem.class )[0]
                                             .getException() );
        }

        try
        {
            if ( result.hasExceptions() )
            {
                return result;
            }

            result.setTopologicallySortedProjects( session.getProjects() );

            result.setProject( session.getTopLevelProject() );

            lifecycleStarter.execute( session );

            validateActivatedProfiles( session.getProjects(), request.getActiveProfiles() );

            if ( session.getResult().hasExceptions() )
            {
                return addExceptionToResult( result, session.getResult().getExceptions().get( 0 ) );
            }
        }
        finally
        {
            try
            {
                afterSessionEnd( session.getProjects(), session );
            }
            catch ( MavenExecutionException e )
            {
                return addExceptionToResult( result, e );
            }
        }

        return result;
    }

    private void afterSessionEnd( Collection<MavenProject> projects, MavenSession session )
        throws MavenExecutionException
    {
        ClassLoader originalClassLoader = Thread.currentThread().getContextClassLoader();
        try
        {
            for ( AbstractMavenLifecycleParticipant listener : getLifecycleParticipants( projects ) )
            {
                Thread.currentThread().setContextClassLoader( listener.getClass().getClassLoader() );

                listener.afterSessionEnd( session );
            }
        }
        finally
        {
            Thread.currentThread().setContextClassLoader( originalClassLoader );
        }
    }
    
    public RepositorySystemSession newRepositorySession( MavenExecutionRequest request )
    {
        return repositorySessionFactory.newRepositorySession( request );
    }

    private void validateLocalRepository( MavenExecutionRequest request )
        throws LocalRepositoryNotAccessibleException
    {
        File localRepoDir = request.getLocalRepositoryPath();

        logger.debug( "Using local repository at " + localRepoDir );

        localRepoDir.mkdirs();

        if ( !localRepoDir.isDirectory() )
        {
            throw new LocalRepositoryNotAccessibleException( "Could not create local repository at " + localRepoDir );
        }
    }

    private Collection<AbstractMavenLifecycleParticipant> getLifecycleParticipants( Collection<MavenProject> projects )
    {
        Collection<AbstractMavenLifecycleParticipant> lifecycleListeners =
            new LinkedHashSet<AbstractMavenLifecycleParticipant>();

        ClassLoader originalClassLoader = Thread.currentThread().getContextClassLoader();
        try
        {
            try
            {
                lifecycleListeners.addAll( container.lookupList( AbstractMavenLifecycleParticipant.class ) );
            }
            catch ( ComponentLookupException e )
            {
                // this is just silly, lookupList should return an empty list!
                logger.warn( "Failed to lookup lifecycle participants: " + e.getMessage() );
            }

            Collection<ClassLoader> scannedRealms = new HashSet<ClassLoader>();

            for ( MavenProject project : projects )
            {
                ClassLoader projectRealm = project.getClassRealm();

                if ( projectRealm != null && scannedRealms.add( projectRealm ) )
                {
                    Thread.currentThread().setContextClassLoader( projectRealm );

                    try
                    {
                        lifecycleListeners.addAll( container.lookupList( AbstractMavenLifecycleParticipant.class ) );
                    }
                    catch ( ComponentLookupException e )
                    {
                        // this is just silly, lookupList should return an empty list!
                        logger.warn( "Failed to lookup lifecycle participants: " + e.getMessage() );
                    }
                }
            }
        }
        finally
        {
            Thread.currentThread().setContextClassLoader( originalClassLoader );
        }

        return lifecycleListeners;
    }

    private MavenExecutionResult addExceptionToResult( MavenExecutionResult result, Throwable e )
    {
        if ( !result.getExceptions().contains( e ) )
        {
            result.addException( e );
        }

        return result;
    }

    private void validateActivatedProfiles( List<MavenProject> projects, List<String> activeProfileIds )
    {
        Collection<String> notActivatedProfileIds = new LinkedHashSet<String>( activeProfileIds );

        for ( MavenProject project : projects )
        {
            for ( List<String> profileIds : project.getInjectedProfileIds().values() )
            {
                notActivatedProfileIds.removeAll( profileIds );
            }
        }

        for ( String notActivatedProfileId : notActivatedProfileIds )
        {
            logger.warn( "The requested profile \"" + notActivatedProfileId
                + "\" could not be activated because it does not exist." );
        }
    }

    private Map<String, MavenProject> getProjectMap( Collection<MavenProject> projects )
        throws DuplicateProjectException
    {
        Map<String, MavenProject> index = new LinkedHashMap<String, MavenProject>();
        Map<String, List<File>> collisions = new LinkedHashMap<String, List<File>>();

        for ( MavenProject project : projects )
        {
            String projectId = ArtifactUtils.key( project.getGroupId(), project.getArtifactId(), project.getVersion() );

            MavenProject collision = index.get( projectId );

            if ( collision == null )
            {
                index.put( projectId, project );
            }
            else
            {
                List<File> pomFiles = collisions.get( projectId );

                if ( pomFiles == null )
                {
                    pomFiles = new ArrayList<File>( Arrays.asList( collision.getFile(), project.getFile() ) );
                    collisions.put( projectId, pomFiles );
                }
                else
                {
                    pomFiles.add( project.getFile() );
                }
            }
        }

        if ( !collisions.isEmpty() )
        {
            throw new DuplicateProjectException( "Two or more projects in the reactor"
                + " have the same identifier, please make sure that <groupId>:<artifactId>:<version>"
                + " is unique for each project: " + collisions, collisions );
        }

        return index;
    }

    private Result<? extends ProjectDependencyGraph> buildGraph( MavenSession session, MavenExecutionResult result ) 
    {
        Result<? extends ProjectDependencyGraph> graphResult = graphBuilder.build( session );
        for ( ModelProblem problem : graphResult.getProblems() )
        {
            if ( problem.getSeverity() == ModelProblem.Severity.WARNING )
            {
                logger.warn( problem.toString() );
            }
            else
            {
                logger.error( problem.toString() );
            }
        }

        if ( !graphResult.hasErrors() )
        {
            ProjectDependencyGraph projectDependencyGraph = graphResult.get();
            session.setProjects( projectDependencyGraph.getSortedProjects() );
            session.setAllProjects( projectDependencyGraph.getSortedProjects() );
            session.setProjectDependencyGraph( projectDependencyGraph );                
        }
        
        return graphResult;        
    }
    
    @Deprecated
    // 5 January 2014
    protected Logger getLogger()
    {
        return logger;
    }
}