package org.eclipse.aether.internal.impl.synccontext.named;

/*
 * 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 javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.aether.MultiRuntimeException;
import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.impl.RepositorySystemLifecycle;
import org.eclipse.aether.named.NamedLockFactory;
import org.eclipse.aether.named.providers.FileLockNamedLockFactory;
import org.eclipse.aether.named.providers.LocalReadWriteLockNamedLockFactory;
import org.eclipse.aether.named.providers.LocalSemaphoreNamedLockFactory;
import org.eclipse.aether.named.providers.NoopNamedLockFactory;
import org.eclipse.aether.spi.locator.Service;
import org.eclipse.aether.spi.locator.ServiceLocator;
import org.eclipse.aether.util.ConfigUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static java.util.Objects.requireNonNull;

/**
 * Default implementation of {@link NamedLockFactoryAdapterFactory}. This implementation creates new instances of the
 * adapter on every call. In turn, on shutdown, it will shut down all existing named lock factories. This is merely for
 * simplicity, to not have to track "used" named lock factories, while it exposes all available named lock factories to
 * callers.
 * <p>
 * Most members and methods of this class are protected. It is meant to be extended in case of need to customize its
 * behavior. An exception from this are private static methods, mostly meant to provide out of the box
 * defaults and to be used when no Eclipse Sisu component container is used.
 *
 * @since 1.9.1
 */
@Singleton
@Named
public class NamedLockFactoryAdapterFactoryImpl implements NamedLockFactoryAdapterFactory, Service
{
    private static final String DEFAULT_FACTORY_NAME = LocalReadWriteLockNamedLockFactory.NAME;

    private static final String DEFAULT_NAME_MAPPER_NAME = NameMappers.GAV_NAME;

    private static Map<String, NamedLockFactory> getManuallyCreatedFactories()
    {
        HashMap<String, NamedLockFactory> factories = new HashMap<>();
        factories.put( NoopNamedLockFactory.NAME, new NoopNamedLockFactory() );
        factories.put( LocalReadWriteLockNamedLockFactory.NAME, new LocalReadWriteLockNamedLockFactory() );
        factories.put( LocalSemaphoreNamedLockFactory.NAME, new LocalSemaphoreNamedLockFactory() );
        factories.put( FileLockNamedLockFactory.NAME, new FileLockNamedLockFactory() );
        return Collections.unmodifiableMap( factories );
    }

    private static Map<String, NameMapper> getManuallyCreatedNameMappers()
    {
        HashMap<String, NameMapper> mappers = new HashMap<>();
        mappers.put( NameMappers.STATIC_NAME, NameMappers.staticNameMapper() );
        mappers.put( NameMappers.GAV_NAME, NameMappers.gavNameMapper() );
        mappers.put( NameMappers.DISCRIMINATING_NAME, NameMappers.discriminatingNameMapper() );
        mappers.put( NameMappers.FILE_GAV_NAME, NameMappers.fileGavNameMapper() );
        mappers.put( NameMappers.FILE_HGAV_NAME, NameMappers.fileHashingGavNameMapper() );
        return Collections.unmodifiableMap( mappers );
    }

    protected static final String FACTORY_KEY = "aether.syncContext.named.factory";

    protected static final String NAME_MAPPER_KEY = "aether.syncContext.named.nameMapper";

    protected final Logger logger = LoggerFactory.getLogger( getClass() );

    protected final Map<String, NamedLockFactory> factories;

    protected final String defaultFactoryName;

    protected final Map<String, NameMapper> nameMappers;

    protected final String defaultNameMapperName;

    /**
     * Default constructor for non Eclipse Sisu uses.
     *
     * @deprecated for use in SL only.
     */
    @Deprecated
    public NamedLockFactoryAdapterFactoryImpl()
    {
        this.factories = getManuallyCreatedFactories();
        this.defaultFactoryName = DEFAULT_FACTORY_NAME;
        this.nameMappers = getManuallyCreatedNameMappers();
        this.defaultNameMapperName = DEFAULT_NAME_MAPPER_NAME;
    }

    @Override
    public void initService( ServiceLocator locator )
    {
        locator.getService( RepositorySystemLifecycle.class ).addOnSystemEndedHandler( this::shutdown );
    }

    @Inject
    public NamedLockFactoryAdapterFactoryImpl( final Map<String, NamedLockFactory> factories,
                                               final Map<String, NameMapper> nameMappers,
                                               final RepositorySystemLifecycle lifecycle )
    {
        this( factories, DEFAULT_FACTORY_NAME, nameMappers, DEFAULT_NAME_MAPPER_NAME, lifecycle );
    }

    public NamedLockFactoryAdapterFactoryImpl( final Map<String, NamedLockFactory> factories,
                                               final String defaultFactoryName,
                                               final Map<String, NameMapper> nameMappers,
                                               final String defaultNameMapperName,
                                               final RepositorySystemLifecycle lifecycle )
    {
        this.factories = requireNonNull( factories );
        this.defaultFactoryName = requireNonNull( defaultFactoryName );
        this.nameMappers = requireNonNull( nameMappers );
        this.defaultNameMapperName = requireNonNull( defaultNameMapperName );
        lifecycle.addOnSystemEndedHandler( this::shutdown );

        logger.debug( "Created adapter factory; available factories {}; available name mappers {}",
                factories.keySet(), nameMappers.keySet() );
    }

    /**
     * Current implementation simply delegates to {@link #createAdapter(RepositorySystemSession)}.
     */
    @Override
    public NamedLockFactoryAdapter getAdapter( RepositorySystemSession session )
    {
        return createAdapter( session );
    }

    /**
     * Creates a new adapter instance, never returns {@code null}.
     */
    protected NamedLockFactoryAdapter createAdapter( RepositorySystemSession session )
    {
        final String nameMapperName = requireNonNull( getNameMapperName( session ) );
        final String factoryName = requireNonNull( getFactoryName( session ) );
        final NameMapper nameMapper = selectNameMapper( nameMapperName );
        final NamedLockFactory factory = selectFactory( factoryName );
        logger.debug( "Creating adapter using nameMapper '{}' and factory '{}'",
                nameMapperName, factoryName );
        return new NamedLockFactoryAdapter( nameMapper, factory );
    }

    /**
     * Returns the selected (user configured or default) named lock factory name, never {@code null}.
     */
    protected String getFactoryName( RepositorySystemSession session )
    {
        return ConfigUtils.getString( session, getDefaultFactoryName(), FACTORY_KEY );
    }

    /**
     * Returns the default named lock factory name, never {@code null}.
     */
    protected String getDefaultFactoryName()
    {
        return defaultFactoryName;
    }

    /**
     * Returns the selected (user configured or default) name mapper name, never {@code null}.
     */
    protected String getNameMapperName( RepositorySystemSession session )
    {
        return ConfigUtils.getString( session, getDefaultNameMapperName(), NAME_MAPPER_KEY );
    }

    /**
     * Returns the default name mapper name, never {@code null}.
     */
    protected String getDefaultNameMapperName()
    {
        return defaultNameMapperName;
    }

    /**
     * Selects a named lock factory, never returns {@code null}.
     */
    protected NamedLockFactory selectFactory( final String factoryName )
    {
        NamedLockFactory factory = factories.get( factoryName );
        if ( factory == null )
        {
            throw new IllegalArgumentException(
                    "Unknown NamedLockFactory name: '" + factoryName + "', known ones: " + factories.keySet() );
        }
        return factory;
    }

    /**
     * Selects a name mapper, never returns {@code null}.
     */
    protected NameMapper selectNameMapper( final String nameMapperName )
    {
        NameMapper nameMapper = nameMappers.get( nameMapperName );
        if ( nameMapper == null )
        {
            throw new IllegalArgumentException(
                    "Unknown NameMapper name: '" + nameMapperName + "', known ones: " + nameMappers.keySet() );
        }
        return nameMapper;
    }

    /**
     * To be invoked on repository system shut down. This method will shut down each {@link NamedLockFactory}.
     */
    protected void shutdown()
    {
        logger.debug( "Shutting down adapter factory; available factories {}; available name mappers {}",
                factories.keySet(), nameMappers.keySet() );
        ArrayList<Exception> exceptions = new ArrayList<>();
        for ( Map.Entry<String, NamedLockFactory> entry : factories.entrySet() )
        {
            try
            {
                logger.debug( "Shutting down '{}' factory", entry.getKey() );
                entry.getValue().shutdown();
            }
            catch ( Exception e )
            {
                exceptions.add( e );
            }
        }
        MultiRuntimeException.mayThrow( "Problem shutting down factories", exceptions );
    }
}