#
#
#
class JpgBinWrite:

  soi_marker     = b'\xff\xd8'
  eof_marker     = b'\xff\xd9'
  picseal_marker = b'\xff\xef'
  # picseal_marker = b'\xff\xe0'

  #
  def __init__(self, jpg_in, jpg_out):
    self.fhr = jpg_in
    self.fhw = jpg_out

  #
  # input is the Crypto Sig class
  #
  def writeJpgPicSealPub(self, crypto_sig, fp):
    self.__writeJpgHeader()
   
    self.__writeJpgPicSeal(crypto_sig, crypto_sig.getPubKeyDER())

    self.__writeJpgImg(fp)
  
  #
  # input is the Crypto Sig class
  #
  def writeJpgPicSealPvt(self, crypto_sig, fp):
    self.__writeJpgHeader()

    self.__writeJpgPicSeal(crypto_sig, crypto_sig.getPvtKeyDER())

    self.__writeJpgImg(fp)


  #
  def __writeJpgPicSeal(self, crypto_sig, keyder):
    # must include 2 bytes of length too
    size = 2
    size += len(crypto_sig.hash_data)
    size += len(keyder)

    # write picseal marker
    self.fhw.write(JpgBinWrite.picseal_marker)
    # write the size of picseal record
    self.fhw.write(size.to_bytes(2, byteorder='big'))
    # write hash of image
    self.fhw.write(crypto_sig.hash_data)  
    # write the public key
    self.fhw.write(keyder)

  #
  def __writeJpgImg(self, fp):
    self.__writeJpgMetadata(fp.markers_meta)
    self.__writeJpgImgData(fp.markers_img)
    self.__writeJpgFooter()
    self.fhw.flush()
    self.fhw.close()

  #
  # array of the marker information
  #
  def __writeJpgMetadata(self, markers):
    for marker in markers:
      self.fhr.seek(marker.fpos)
      data = self.fhr.read(marker.len)
      self.fhw.write(data)
      self.fhw.flush()
    
  #
  # array of the marker information
  #
  def __writeJpgImgData(self, markers):
    for marker in markers:
      # most of the image data is sequential
      cpos = self.fhr.tell()
      if (marker.fpos != cpos):
        self.fhr.seek(marker.fpos)

      data = self.fhr.read(marker.len)
      self.fhw.write(data)
      self.fhw.flush()

  #
  def __writeJpgHeader(self):
    self.fhw.write(bytes(JpgBinWrite.soi_marker))

  #
  def __writeJpgFooter(self):
    self.fhw.write(bytes(JpgBinWrite.eof_marker))