Resize an area in a buffer

class BufferSampleClass
{
   // base buffer
   private Byte[] buffer = { 0, 0, 0, 0, 0, 8, 8, 1, 8, 8, 0, 0, 0, 0, 0 };

   // first valid index of the public accessible buffer area
   private Int32 firstIndex = 5;

   // current index in the public accessible buffer area
   private Int32 index = 7;

   // last valid index of the public accessible buffer area
   private Int32 lastIndex = 9;

   // length of the public accessible buffer area
   private Int32 length = 5;

   // resize the public accessible buffer at both sides
   public void Resize(Int32 frontSide, Int32 backSide)
   {
      Int32 newLength = frontSide + length + backSide;
      if (newLength < 0)
      {
         throw new ArgumentException();
      }
      Int32 newFirstIndex = firstIndex - frontSide;
      Int32 newLastIndex = lastIndex + backSide;

      // if newFirstIndex is lower than 0, move the current content
      // if newLastIndex is greater than buffer.Length, create a new buffer and copy the current content
      // combine both cases

      // update firstIndex and lastIndex
      throw new NotImplementedException();
   }

   // Read, Write, Seek, ... members to manipulate the content
}