package nom.tam.image.tile.operation;
   
   /*
    * #%L
    * nom.tam FITS library
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    * Copyright (C) 1996 - 2024 nom-tam-fits
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    * This is free and unencumbered software released into the public domain.
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   * distribute this software, either in source code form or as a compiled
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   * means.
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   * In jurisdictions that recognize copyright laws, the author or authors
   * of this software dedicate any and all copyright interest in the
   * software to the public domain. We make this dedication for the benefit
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   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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   */
  
  import java.nio.Buffer;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  
  import nom.tam.image.tile.operation.buffer.TileBuffer;
  import nom.tam.image.tile.operation.buffer.TileBufferFactory;
  import nom.tam.util.type.ElementType;
  
  /**
   * (<i>for internal use</i>) A base implementation of parallel processing of tiles. Each instance handles the processing
   * of a single 2D image tile, which is submitted to a thread pool for parallel processing of multiple tiles
   * simultaneously.
   */
  public abstract class AbstractTileOperation implements Runnable, ITileOperation {
  
      private final ITiledImageOperation tiledImageOperation;
  
      private Future<?> future;
  
      private TileBuffer tileBuffer;
  
      private final int tileIndex;
  
      private final TileArea area;
  
      /**
       * Creates a parallel tile processing operation for a specific 2D image tile.
       * 
       * @param operation the operation that is to be performed on the tile
       * @param tileIndex the sequential tile index
       * @param area      the location and size of tile in the full image.
       */
      public AbstractTileOperation(ITiledImageOperation operation, int tileIndex, TileArea area) {
          tiledImageOperation = operation;
          this.tileIndex = tileIndex;
          this.area = area;
      }
  
      /**
       * Performs the operation on the selected tile, by submitting it to a thread pool for parallel processing.
       * 
       * @param threadPool The thread pool in which the operation is to be processed.
       * 
       * @see              #waitForResult()
       */
      public void execute(ExecutorService threadPool) {
          future = threadPool.submit(this);
      }
  
      /**
       * Returns the location and size of the 2D image tile inside the entire image
       * 
       * @return the location and size of the tile in the full image.
       */
      public TileArea getArea() {
          return area;
      }
  
      /**
       * Returns the pixel count inside the tile that this operation is assigned to process.
       * 
       * @return the number of pixels in this tile.
       */
      public int getPixelSize() {
          return tileBuffer.getPixelSize();
      }
 
     /**
      * Returns the sequential index of the tile that this operations is assigned to process.
      * 
      * @return the sequential index of the tile
      */
     public int getTileIndex() {
         return tileIndex;
     }
 
     /**
      * Sets the buffer that describes the whole image and let the tile create a slice of it from the position where the
      * tile starts in the whole image. Attention this method is not thread-safe because it changes the position of the
      * buffer parameter.
      *
      * @param buffer the buffer that describes the whole image.
      */
     public void setWholeImageBuffer(Buffer buffer) {
         tileBuffer.setData(buffer);
     }
 
     /**
      * Wait for the result of the tile processing.
      * 
      * @see #execute(ExecutorService)
      */
     @Override
     public void waitForResult() {
         try {
             future.get();
         } catch (Exception e) {
             throw new IllegalStateException("could not process tile", e);
         }
     }
 
     /**
      * Returns the FITS element type of the image to be processed.
      * 
      * @return the FITS element type of the underlying image
      */
     protected ElementType<Buffer> getBaseType() {
         return tiledImageOperation.getBaseType();
     }
 
     /**
      * Returns the parallel tile operation whose tile index is one less than ours.
      * 
      * @return the parallel tile operation for the tile prior to ours.
      */
     protected ITileOperation getPreviousTileOperation() {
         return tiledImageOperation.getTileOperation(getTileIndex() - 1);
     }
 
     /**
      * Returns the buffer that is to be used for storing or retrieving the serialized tile image.
      * 
      * @return the linear buffer for the tile image.
      * 
      * @see    #setTileBuffer(TileBuffer)
      */
     protected TileBuffer getTileBuffer() {
         return tileBuffer;
     }
 
     /**
      * Returns the operation that is assigned to be performed on the image tile.
      * 
      * @return the operation to be performed on the associated image tile
      */
     protected ITiledImageOperation getTiledImageOperation() {
         return tiledImageOperation;
     }
 
     @SuppressWarnings("deprecation")
     @Override
     public ITileOperation setDimensions(int dataOffset, int width, int height) {
         setTileBuffer(TileBufferFactory.createTileBuffer(getBaseType(), //
                 dataOffset, //
                 tiledImageOperation.getImageWidth(), //
                 width, height));
         area.size(width, height);
         return this;
     }
 
     /**
      * Sets the buffer to be used for storing or retrieving the serialized tile image.
      * 
      * @param tileBuffer the linear buffer for the tile image.
      * 
      * @see              #getTileBuffer()
      */
     protected void setTileBuffer(TileBuffer tileBuffer) {
         this.tileBuffer = tileBuffer;
     }
 }