package org.openslx.imagemaster.serverconnection;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.security.KeyStore;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;

import org.apache.log4j.Logger;
import org.openslx.bwlp.thrift.iface.ImagePublishData;
import org.openslx.bwlp.thrift.iface.InvocationError;
import org.openslx.bwlp.thrift.iface.TInvocationException;
import org.openslx.bwlp.thrift.iface.TTransferRejectedException;
import org.openslx.filetransfer.Downloader;
import org.openslx.filetransfer.IncomingEvent;
import org.openslx.filetransfer.Listener;
import org.openslx.filetransfer.Uploader;
import org.openslx.filetransfer.util.AbstractTransfer;
import org.openslx.imagemaster.Globals;
import org.openslx.util.GrowingThreadPoolExecutor;

/**
 * Class to handle all incoming and outgoing connections.
 * Also handles the authentication and the saving/delivering of images.
 */
public class ConnectionHandler implements IncomingEvent
{

	private static final Logger LOGGER = Logger.getLogger( ConnectionHandler.class );

	private static final int MAX_TRANSFERS = 12;

	private static Map<String, IncomingTransfer> incomingTransfers = new ConcurrentHashMap<>();
	private static Map<String, AbstractTransfer> outgoingTransfers = new ConcurrentHashMap<>();
	private static IncomingEvent eventHandler = new ConnectionHandler();
	private final ExecutorService transferPool = new GrowingThreadPoolExecutor( 1, MAX_TRANSFERS * 2, 1, TimeUnit.MINUTES,
			new SynchronousQueue<Runnable>(),
			new PrioThreadFactory( "TransferPool", Thread.NORM_PRIORITY - 2 ) );

	private static final Listener plainListener;
	private static final Listener sslListener;

	static {
		LOGGER.debug( "Starting listener on port " + Globals.getFiletransferPortSsl() );
		Listener ssl = null;
		Listener plain = null;
		try {
			String pathToKeyStore = Globals.getSslKeystoreFile();
			char[] passphrase = Globals.getSslKeystorePassword().toCharArray();
			KeyStore keystore = KeyStore.getInstance( "JKS" );
			keystore.load( new FileInputStream( pathToKeyStore ), passphrase );
			KeyManagerFactory kmf = KeyManagerFactory.getInstance( KeyManagerFactory.getDefaultAlgorithm() );
			kmf.init( keystore, passphrase );
			SSLContext sslContext = SSLContext.getInstance( "TLSv1.2" );
			KeyManager[] keyManagers = kmf.getKeyManagers();
			sslContext.init( keyManagers, null, null );
			ssl = new Listener( eventHandler, sslContext, Globals.getFiletransferPortSsl(), Globals.getFiletransferTimeout() * 1000 );
			ssl.start();
			plain = new Listener( eventHandler, null, Globals.getFiletransferPortPlain(), Globals.getFiletransferTimeout() * 1000 );
			plain.start();
		} catch ( Exception e ) {
			LOGGER.error( "Initialization failed.", e );
			System.exit( 2 );
		}
		sslListener = ssl;
		plainListener = plain;
	}

	public static IncomingTransfer registerUpload( ImagePublishData img, List<ByteBuffer> blockHashes )
			throws TTransferRejectedException, TInvocationException
	{
		IncomingTransfer transfer;
		synchronized ( incomingTransfers ) {
			transfer = incomingTransfers.get( img.imageVersionId );
			if ( transfer == null ) {
				if ( getUploadConnectionCount() >= MAX_TRANSFERS ) {
					throw new TTransferRejectedException( "Too many active transfers" );
				}
				try {
					transfer = new IncomingTransfer( img, blockHashes );
				} catch ( FileNotFoundException e ) {
					LOGGER.warn( "Cannot init download", e );
					throw new TInvocationException( InvocationError.INTERNAL_SERVER_ERROR, "File access error" );
				}
				incomingTransfers.put( transfer.getId(), transfer );
				incomingTransfers.put( img.imageVersionId, transfer );
			}
		}
		return transfer;
	}

	public static IncomingTransfer getExistingUpload( ImagePublishData imageData, List<ByteBuffer> crcSums )
			throws TTransferRejectedException
	{
		IncomingTransfer transfer = incomingTransfers.get( imageData.imageVersionId );
		if ( transfer == null )
			return null;
		if ( transfer.getFileSize() != imageData.fileSize )
			throw new TTransferRejectedException( "File size mismatch" );
		if ( !transfer.hashesEqual( crcSums ) )
			throw new TTransferRejectedException( "Block hashes mismatch" );
		return transfer;
	}

	/**
	 * Server is uploading - client is downloading!
	 */
	@Override
	public void incomingDownloadRequest( final Uploader uploader )
	{
		// TODO
		uploader.sendErrorCode( "Too many concurrent uploads." );
		uploader.cancel();
	}

	/**
	 * Server is downloading - client is uploading!
	 */
	@Override
	public void incomingUploadRequest( final Downloader downloader ) throws IOException
	{
		IncomingTransfer transfer = incomingTransfers.get( downloader.getToken() );
		if ( transfer == null ) {
			downloader.sendErrorCode( "Unknown upload token." );
			downloader.cancel();
			return;
		}
		if ( getUploadConnectionCount() >= MAX_TRANSFERS ) {
			downloader.sendErrorCode( "Too many concurrent uploads." );
			downloader.cancel();
			return;
		}
		if ( !transfer.addConnection( downloader, transferPool ) ) {
			downloader.cancel();
		}
	}

	public static int getUploadConnectionCount()
	{
		final long now = System.currentTimeMillis();
		int active = 0;
		for ( IncomingTransfer t : incomingTransfers.values() ) {
			if ( t.countsTowardsConnectionLimit( now ) ) {
				active += t.getActiveConnectionCount();
			}
		}
		return active;
	}

}