# -*- encoding : utf-8 -*-
# frozen_string_literal: true
########################################################
## Thoughts from reading the ISO 32000-1:2008
## this file is part of the CombinePDF library and the code
## is subject to the same license.
########################################################

module CombinePDF
  #:nodoc: all

  protected

  # @!visibility private

  # This is an internal class. you don't need it.
  module PDFFilter
    module_function

    # @!visibility private

    # deflate / compress an object.
    #
    # <b>isn't supported yet!</b>
    #
    # object:: object to compress.
    # filter:: filter to use.
    def deflate_object(_object = nil, _filter = :none)
      false
    end

    # inflate / decompress an object
    #
    # object:: object to decompress.
    def inflate_object(object = nil)
      return false unless object.is_a?(Hash)
      filter_array = object[:Filter]
      if filter_array.is_a?(Hash) && filter_array[:is_reference_only]
        filter_array = filter_array[:referenced_object]
      end
      filter_array = [filter_array] if filter_array.is_a?(Symbol)
      filter_array = [] if filter_array.nil?
      params_array = object[:DecodeParms]
      if params_array.is_a?(Hash) && params_array[:is_reference_only]
        params_array = params_array[:referenced_object]
      end
      params_array = [params_array] unless params_array.is_a?(Array)
      object[:Filter] = filter_array
      object[:DecodeParms] = params_array
      while filter_array[0]
        case filter_array[0]
        when :FlateDecode
          raise_unsupported_error params_array[0] unless params_array[0].nil?
          if params_array[0] && params_array[0][:Predictor].to_i > 1
            predictor = params_array[0][:Predictor].to_i
            # bits = params_array[0][:BitsPerComponent] || 8
            # columns = params_array[0][:Columns] || 1
            if (2..9).cover? predictor
              ####
              # prepare TIFF group
              raise_unsupported_error params_array[0]
            elsif (10..15).cover? predictor
              ####
              # prepare PNG group
              raise_unsupported_error params_array[0]
            end
          else
            inflator = Zlib::Inflate.new

            object[:raw_stream_content] = inflator.inflate object[:raw_stream_content]
            begin
              inflator.finish
            rescue
            end
            inflator.close
            object[:Length] = object[:raw_stream_content].bytesize
          end
        when nil
          true
        else
          return false
        end
        params_array.shift
        filter_array.shift
      end
      object.delete :Filter
      object.delete :DecodeParms
      true
    end

    protected

    def raise_unsupported_error(object = {})
      raise "Filter #{object} unsupported. couldn't deflate object"
    end
  end
end