!include once #1027304 // Eclipse Collections

import java.nio.*;

import java.nio.channels.*;

// read-only, so far. should be thread-safe

final sclass BufferedDiskByteMemory64 implements IByteMemory64, AutoCloseable {

  File file;

  long size; // file size in ints

  RandomAccessFile raf;

  bool bigEndian = true;

  bool writable = false;

  bool debug;

  // byte buffers

  int byteBufferShift = 30; // each buffer is 1 GB

  int byteBufferSize = 1 << byteBufferShift;

  MappedByteBuffer[] byteBuffers;

  *(File *file) {

    this(file, false);

  }

  *(File *file, bool *writable) {

    load(file, writable);

  }

  void load(File file, bool writable default false) ctex {

    this.file = file;

    this.writable = writable;

    size = fileSize(file);

    raf = newRandomAccessFile(file, writable ? "rw" : "r");

    byteBuffers = new MappedByteBuffer[toInt(rightShift_ceil(size, byteBufferShift))];

    FileChannel channel = raf.getChannel();

    for i over byteBuffers: {

      long pos = (long) i << byteBufferShift;

      int len = toInt(min(1 << byteBufferShift, size-pos));

      //print("Mapping bytes " + longToHex(pos) + "-" + longToHex(pos+len));

      byteBuffers[i] = channel.map(FileChannel.MapMode.READ_ONLY, pos, len);

      byteBuffers[i].order(bigEndian ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);

    }

  }

  public void close {

    dispose raf;

  }

  public byte getByte(long idx) {

    rangeCheck(idx, size);

    ret byteBuffers[(int) (idx >> byteBufferShift)].get(((int) idx) & (byteBufferSize-1));

  }

  public int getInt(long idx) {

    int ofs = ((int) idx) & (byteBufferSize-1);

    // check if we are crossing a buffer boundary

    if (ofs > byteBufferSize-4)

      ret getInt_manual(idx);

    try {

      ret byteBuffers[(int) (idx >> byteBufferShift)].getInt(ofs);

    } on fail {

      print(+idx);

    }

  }

  public int getInt_manual(long idx) {

    assertTrue(+bigEndian);

    ret ubyteToInt(getByte(idx)) << 24 |

      ubyteToInt(getByte(idx+1)) << 16 |

      ubyteToInt(getByte(idx+2)) << 8 |

      ubyteToInt(getByte(idx+3));

  }

  public void set(long idx, int val) {

    checkWritable();

    fail("todo");

  }

  void checkWritable {

    if (!writable) fail("read-only");

  }

  public long size() {

    ret size;

  }

  public void ensureSize(int size) {

    this.size = max(this.size, size);

  }

}