# encoding: UTF-8

require 'rspec'
require 'json-write-stream'
require 'shared_examples'
require 'pry-byebug'

RSpec.configure do |config|
end

class RoundtripChecker
  class << self
    include RSpec::Matchers

    def check_roundtrip(obj, options = {})
      stream = StringIO.new
      writer = create_writer(stream, options)
      serialize(obj, writer)
      writer.close
      new_obj = JSON.parse(stream.string)
      compare(obj, new_obj)
    end

    private

    def compare(old_obj, new_obj)
      expect(old_obj.class).to equal(new_obj.class)

      case old_obj
        when Hash
          expect(old_obj.keys).to eq(new_obj.keys)

          old_obj.each_pair do |key, old_val|
            compare(old_val, new_obj[key])
          end
        when Array
          old_obj.each_with_index do |old_element, idx|
            compare(old_element, new_obj[idx])
          end
        else
          expect(old_obj).to eq(new_obj)
      end
    end
  end
end

class YieldingRoundtripChecker < RoundtripChecker
  class << self
    protected

    def create_writer(stream, options = {})
      JsonWriteStream::YieldingWriter.new(stream, options)
    end

    def serialize(obj, writer)
      case obj
        when Hash
          writer.write_object do |object_writer|
            serialize_object(obj, object_writer)
          end
        when Array
          writer.write_array do |array_writer|
            serialize_array(obj, array_writer)
          end
      end
    end

    def serialize_object(obj, writer)
      obj.each_pair do |key, val|
        case val
          when Hash
            writer.write_object(key) do |object_writer|
              serialize_object(val, object_writer)
            end
          when Array
            writer.write_array(key) do |array_writer|
              serialize_array(val, array_writer)
            end
          else
            writer.write_key_value(key, val)
        end
      end
    end

    def serialize_array(obj, writer)
      obj.each do |element|
        case element
          when Hash
            writer.write_object do |object_writer|
              serialize_object(element, object_writer)
            end
          when Array
            writer.write_array do |array_writer|
              serialize_array(element, array_writer)
            end
          else
            writer.write_element(element)
        end
      end
    end
  end
end

class StatefulRoundtripChecker < RoundtripChecker
  class << self
    protected

    def create_writer(stream, options = {})
      JsonWriteStream::StatefulWriter.new(stream, options)
    end

    def serialize(obj, writer)
      case obj
        when Hash
          writer.write_object
          serialize_object(obj, writer)
          writer.close_object
        when Array
          writer.write_array
          serialize_array(obj, writer)
          writer.close_array
      end
    end

    def serialize_object(obj, writer)
      obj.each_pair do |key, val|
        case val
          when Hash
            writer.write_object(key)
            serialize_object(val, writer)
            writer.close_object
          when Array
            writer.write_array(key)
            serialize_array(val, writer)
            writer.close_array
          else
            writer.write_key_value(key, val)
        end
      end
    end

    def serialize_array(obj, writer)
      obj.each do |element|
        case element
          when Hash
            writer.write_object
            serialize_object(element, writer)
            writer.close_object
          when Array
            writer.write_array
            serialize_array(element, writer)
            writer.close_array
          else
            writer.write_element(element)
        end
      end
    end
  end
end