class Zip::InputStream

def close
  @archive_io.close
end

def get_decompressor
  return ::Zip::NullDecompressor if @current_entry.nil?
  decompressed_size =
    if @current_entry.incomplete? && @current_entry.crc == 0 && @current_entry.size == 0 && @complete_entry
      @complete_entry.size
    else
      @current_entry.size
    end
  decompressor_class = ::Zip::Decompressor.find_by_compression_method(@current_entry.compression_method)
  if decompressor_class.nil?
    raise ::Zip::CompressionMethodError,
          "Unsupported compression method #{@current_entry.compression_method}"
  end
  decompressor_class.new(@decrypted_io, decompressed_size)
end

def get_decrypted_io
  header = @archive_io.read(@decrypter.header_bytesize)
  @decrypter.reset!(header)
  ::Zip::DecryptedIo.new(@archive_io, @decrypter)
end

def get_io(io_or_file, offset = 0)
  if io_or_file.respond_to?(:seek)
    io = io_or_file.dup
    io.seek(offset, ::IO::SEEK_SET)
    io
  else
    file = ::File.open(io_or_file, 'rb')
    file.seek(offset, ::IO::SEEK_SET)
    file
  end
end

def get_next_entry
  @archive_io.seek(@current_entry.next_header_offset, IO::SEEK_SET) if @current_entry
  open_entry
end

def initialize(context, offset = 0, decrypter = nil)
  super()
  @archive_io    = get_io(context, offset)
  @decompressor  = ::Zip::NullDecompressor
  @decrypter     = decrypter || ::Zip::NullDecrypter.new
  @current_entry = nil
end

def input_finished?
  @decompressor.eof
end

def open(filename_or_io, offset = 0, decrypter = nil)
  zio = new(filename_or_io, offset, decrypter)
  return zio unless block_given?
  begin
    yield zio
  ensure
    zio.close if zio
  end
end

def open_buffer(filename_or_io, offset = 0)
  warn 'open_buffer is deprecated!!! Use open instead!'
  ::Zip::InputStream.open(filename_or_io, offset)
end

def open_entry
  @current_entry = ::Zip::Entry.read_local_entry(@archive_io)
  if @current_entry && @current_entry.encrypted? && @decrypter.kind_of?(NullEncrypter)
    raise Error, 'password required to decode zip file'
  end
  if @current_entry && @current_entry.incomplete? && @current_entry.crc == 0 \
    && @current_entry.compressed_size == 0 \
    && @current_entry.size == 0 && !@complete_entry
    raise GPFBit3Error,
          'General purpose flag Bit 3 is set so not possible to get proper info from local header.' \
          'Please use ::Zip::File instead of ::Zip::InputStream'
  end
  @decrypted_io = get_decrypted_io
  @decompressor = get_decompressor
  flush
  @current_entry
end

def produce_input
  @decompressor.read(CHUNK_SIZE)
end

def rewind
  return if @current_entry.nil?
  @lineno = 0
  @pos    = 0
  @archive_io.seek(@current_entry.local_header_offset, IO::SEEK_SET)
  open_entry
end

def sysread(length = nil, outbuf = '')
  @decompressor.read(length, outbuf)
end