package org.apache.maven.resolver.examples.util;

/*
 * 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.PrintStream;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.eclipse.aether.transfer.AbstractTransferListener;
import org.eclipse.aether.transfer.MetadataNotFoundException;
import org.eclipse.aether.transfer.TransferEvent;
import org.eclipse.aether.transfer.TransferResource;

import static java.util.Objects.requireNonNull;

/**
 * A simplistic transfer listener that logs uploads/downloads to the console.
 */
public class ConsoleTransferListener
    extends AbstractTransferListener
{

    private final PrintStream out;

    private final Map<TransferResource, Long> downloads = new ConcurrentHashMap<>();

    private int lastLength;

    public ConsoleTransferListener()
    {
        this( null );
    }

    public ConsoleTransferListener( PrintStream out )
    {
        this.out = ( out != null ) ? out : System.out;
    }

    @Override
    public void transferInitiated( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        String message = event.getRequestType() == TransferEvent.RequestType.PUT ? "Uploading" : "Downloading";

        out.println( message + ": " + event.getResource().getRepositoryUrl() + event.getResource().getResourceName() );
    }

    @Override
    public void transferProgressed( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        TransferResource resource = event.getResource();
        downloads.put( resource, event.getTransferredBytes() );

        StringBuilder buffer = new StringBuilder( 64 );

        for ( Map.Entry<TransferResource, Long> entry : downloads.entrySet() )
        {
            long total = entry.getKey().getContentLength();
            long complete = entry.getValue();

            buffer.append( getStatus( complete, total ) ).append( "  " );
        }

        int pad = lastLength - buffer.length();
        lastLength = buffer.length();
        pad( buffer, pad );
        buffer.append( '\r' );

        out.print( buffer );
    }

    private String getStatus( long complete, long total )
    {
        if ( total >= 1024 )
        {
            return toKB( complete ) + "/" + toKB( total ) + " KB ";
        }
        else if ( total >= 0 )
        {
            return complete + "/" + total + " B ";
        }
        else if ( complete >= 1024 )
        {
            return toKB( complete ) + " KB ";
        }
        else
        {
            return complete + " B ";
        }
    }

    private void pad( StringBuilder buffer, int spaces )
    {
        String block = "                                        ";
        while ( spaces > 0 )
        {
            int n = Math.min( spaces, block.length() );
            buffer.append( block, 0, n );
            spaces -= n;
        }
    }

    @Override
    public void transferSucceeded( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        transferCompleted( event );

        TransferResource resource = event.getResource();
        long contentLength = event.getTransferredBytes();
        if ( contentLength >= 0 )
        {
            String type = ( event.getRequestType() == TransferEvent.RequestType.PUT ? "Uploaded" : "Downloaded" );
            String len = contentLength >= 1024 ? toKB( contentLength ) + " KB" : contentLength + " B";

            String throughput = "";
            long duration = System.currentTimeMillis() - resource.getTransferStartTime();
            if ( duration > 0 )
            {
                long bytes = contentLength - resource.getResumeOffset();
                DecimalFormat format = new DecimalFormat( "0.0", new DecimalFormatSymbols( Locale.ENGLISH ) );
                double kbPerSec = ( bytes / 1024.0 ) / ( duration / 1000.0 );
                throughput = " at " + format.format( kbPerSec ) + " KB/sec";
            }

            out.println( type + ": " + resource.getRepositoryUrl() + resource.getResourceName() + " (" + len
                + throughput + ")" );
        }
    }

    @Override
    public void transferFailed( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        transferCompleted( event );

        if ( !( event.getException() instanceof MetadataNotFoundException ) )
        {
            event.getException().printStackTrace( out );
        }
    }

    private void transferCompleted( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        downloads.remove( event.getResource() );

        StringBuilder buffer = new StringBuilder( 64 );
        pad( buffer, lastLength );
        buffer.append( '\r' );
        out.print( buffer );
    }

    public void transferCorrupted( TransferEvent event )
    {
        requireNonNull( event, "event cannot be null" );
        event.getException().printStackTrace( out );
    }

    @SuppressWarnings( "checkstyle:magicnumber" )
    protected long toKB( long bytes )
    {
        return ( bytes + 1023 ) / 1024;
    }

}