/*
    * 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.eclipse.aether.transport.file;
  
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.file.Files;
  import java.nio.file.Path;
  
  import org.eclipse.aether.spi.connector.transport.AbstractTransporter;
  import org.eclipse.aether.spi.connector.transport.GetTask;
  import org.eclipse.aether.spi.connector.transport.PeekTask;
  import org.eclipse.aether.spi.connector.transport.PutTask;
  import org.eclipse.aether.spi.connector.transport.TransportTask;
  import org.eclipse.aether.transfer.NoTransporterException;
  
  /**
   * A transporter using {@link java.io.File}.
   */
  final class FileTransporter extends AbstractTransporter {
      /**
       * The file op transport can use.
       *
       * @since 2.0.2
       */
      enum FileOp {
          COPY,
          SYMLINK,
          HARDLINK;
      }
  
      private final Path basePath;
      private final FileOp fileOp;
  
      FileTransporter(Path basePath, FileOp fileOp) throws NoTransporterException {
          this.basePath = basePath;
          this.fileOp = fileOp;
      }
  
      Path getBasePath() {
          return basePath;
      }
  
      @Override
      public int classify(Throwable error) {
          if (error instanceof ResourceNotFoundException) {
              return ERROR_NOT_FOUND;
          }
          return ERROR_OTHER;
      }
  
      private FileOp effectiveFileOp(FileOp wanted, GetTask task) {
          if (task.getDataPath() != null) {
              return wanted;
          }
          // task carries no path, caller wants in-memory read, so COPY must be used
          return FileOp.COPY;
      }
  
      @Override
      protected void implPeek(PeekTask task) throws Exception {
          getPath(task, true);
      }
  
      @Override
      protected void implGet(GetTask task) throws Exception {
          Path path = getPath(task, true);
          long size = Files.size(path);
          FileOp effective = effectiveFileOp(fileOp, task);
          switch (effective) {
              case COPY:
                  utilGet(task, Files.newInputStream(path), true, size, false);
                  break;
              case SYMLINK:
              case HARDLINK:
                  Files.deleteIfExists(task.getDataPath());
                  task.getListener().transportStarted(0L, size);
                  if (effective == FileOp.HARDLINK) {
                      Files.createLink(task.getDataPath(), path);
                  } else {
                      Files.createSymbolicLink(task.getDataPath(), path);
                  }
                  if (size > 0) {
                     try (FileChannel fc = FileChannel.open(path)) {
                         try {
                             task.getListener().transportProgressed(fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size()));
                         } catch (UnsupportedOperationException e) {
                             // not all FS support mmap: fallback to "plain read loop"
                             ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 32);
                             while (fc.read(byteBuffer) != -1) {
                                 byteBuffer.flip();
                                 task.getListener().transportProgressed(byteBuffer);
                                 byteBuffer.clear();
                             }
                         }
                     }
                 }
                 break;
             default:
                 throw new IllegalStateException("Unknown fileOp" + fileOp);
         }
     }
 
     @Override
     protected void implPut(PutTask task) throws Exception {
         Path path = getPath(task, false);
         Files.createDirectories(path.getParent());
         try {
             utilPut(task, Files.newOutputStream(path), true);
         } catch (Exception e) {
             Files.deleteIfExists(path);
             throw e;
         }
     }
 
     private Path getPath(TransportTask task, boolean required) throws Exception {
         String path = task.getLocation().getPath();
         if (path.contains("../")) {
             throw new IllegalArgumentException("illegal resource path: " + path);
         }
         Path file = basePath.resolve(path);
         if (required && !Files.isRegularFile(file)) {
             throw new ResourceNotFoundException("Could not locate " + file);
         }
         return file;
     }
 
     @Override
     protected void implClose() {}
 }