/*
    * 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.
   */
  package org.apache.maven.resolver.examples.util;
  
  import java.io.PrintStream;
  import java.text.DecimalFormat;
  import java.text.DecimalFormatSymbols;
  import java.time.Duration;
  import java.time.Instant;
  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 = "";
             Duration duration = Duration.between(resource.getStartTime(), Instant.now());
             if (duration.toMillis() > 0) {
                 long bytes = contentLength - resource.getResumeOffset();
                 DecimalFormat format = new DecimalFormat("0.0", new DecimalFormatSymbols(Locale.ENGLISH));
                 double kbPerSec = (bytes / 1024.0) / duration.toSeconds();
                 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);
     }
 
     protected long toKB(long bytes) {
         return (bytes + 1023) / 1024;
     }
 }