class Sass::Compiler::Host::Protofier

def from_proto(proto)
  oneof = proto.value
  obj = proto.public_send(oneof)
  case oneof
  when :string
    Sass::Value::String.new(
      obj.text,
      quoted: obj.quoted
    )
  when :number
    Number.from_proto(obj)
  when :color
    obj.to_s if RUBY_ENGINE == 'jruby' # TODO: https://github.com/protocolbuffers/protobuf/issues/18807
    Sass::Value::Color.send(
      :for_space,
      obj.space,
      obj.has_channel1? ? obj.channel1 : nil,
      obj.has_channel2? ? obj.channel2 : nil,
      obj.has_channel3? ? obj.channel3 : nil,
      obj.has_alpha? ? obj.alpha : nil
    )
  when :argument_list
    Sass::Value::ArgumentList.new(
      obj.contents.map do |element|
        from_proto(element)
      end,
      obj.keywords.to_enum.with_object({}) do |(key, value), hash|
        hash[key.to_sym] = from_proto(value)
      end,
      ListSeparator.from_proto(obj.separator)
    ).instance_eval do
      @id = obj.id
      self
    end
  when :list
    Sass::Value::List.new(
      obj.contents.map do |element|
        from_proto(element)
      end,
      separator: ListSeparator.from_proto(obj.separator),
      bracketed: obj.has_brackets
    )
  when :map
    Sass::Value::Map.new(
      obj.entries.to_enum.with_object({}) do |entry, hash|
        hash[from_proto(entry.key)] = from_proto(entry.value)
      end
    )
  when :compiler_function
    Sass::Value::Function.new(nil).instance_eval do
      @id = obj.id
      self
    end
  when :host_function
    raise Sass::ScriptError, 'The compiler may not send Value.host_function to host'
  when :compiler_mixin
    Sass::Value::Mixin.send(:new).instance_eval do
      @id = obj.id
      self
    end
  when :calculation
    Calculation.from_proto(obj)
  when :singleton
    case obj
    when :TRUE
      Sass::Value::Boolean::TRUE
    when :FALSE
      Sass::Value::Boolean::FALSE
    when :NULL
      Sass::Value::Null::NULL
    else
      raise Sass::ScriptError, "Unknown Value.singleton #{obj}"
    end
  else
    raise Sass::ScriptError, "Unknown Value.value #{obj}"
  end
end

def initialize(function_registry)
  @function_registry = function_registry
end

def to_proto(obj)
  case obj
  when Sass::Value::String
    EmbeddedProtocol::Value.new(
      string: EmbeddedProtocol::Value::String.new(
        text: obj.text.to_str,
        quoted: obj.quoted?
      )
    )
  when Sass::Value::Number
    EmbeddedProtocol::Value.new(
      number: Number.to_proto(obj)
    )
  when Sass::Value::Color
    EmbeddedProtocol::Value.new(
      color: EmbeddedProtocol::Value::Color.new(
        channel1: obj.send(:channel0_or_nil),
        channel2: obj.send(:channel1_or_nil),
        channel3: obj.send(:channel2_or_nil),
        alpha: obj.send(:alpha_or_nil),
        space: obj.space
      )
    )
  when Sass::Value::ArgumentList
    EmbeddedProtocol::Value.new(
      argument_list: EmbeddedProtocol::Value::ArgumentList.new(
        id: obj.instance_eval { @id },
        contents: obj.to_a.map { |element| to_proto(element) },
        keywords: obj.keywords.each_with_object({}) { |(key, value), hash| hash[key.to_s] = to_proto(value) },
        separator: ListSeparator.to_proto(obj.separator)
      )
    )
  when Sass::Value::List
    EmbeddedProtocol::Value.new(
      list: EmbeddedProtocol::Value::List.new(
        contents: obj.to_a.map { |element| to_proto(element) },
        separator: ListSeparator.to_proto(obj.separator),
        has_brackets: obj.bracketed?
      )
    )
  when Sass::Value::Map
    EmbeddedProtocol::Value.new(
      map: EmbeddedProtocol::Value::Map.new(
        entries: obj.contents.map do |key, value|
          EmbeddedProtocol::Value::Map::Entry.new(
            key: to_proto(key),
            value: to_proto(value)
          )
        end
      )
    )
  when Sass::Value::Function
    if obj.instance_eval { @id }
      EmbeddedProtocol::Value.new(
        compiler_function: EmbeddedProtocol::Value::CompilerFunction.new(
          id: obj.instance_eval { @id }
        )
      )
    else
      EmbeddedProtocol::Value.new(
        host_function: EmbeddedProtocol::Value::HostFunction.new(
          id: @function_registry.register(obj.callback),
          signature: obj.signature
        )
      )
    end
  when Sass::Value::Mixin
    EmbeddedProtocol::Value.new(
      compiler_mixin: EmbeddedProtocol::Value::CompilerMixin.new(
        id: obj.instance_eval { @id }
      )
    )
  when Sass::Value::Calculation
    EmbeddedProtocol::Value.new(
      calculation: Calculation.to_proto(obj)
    )
  when Sass::Value::Boolean
    EmbeddedProtocol::Value.new(
      singleton: obj.value ? :TRUE : :FALSE
    )
  when Sass::Value::Null
    EmbeddedProtocol::Value.new(
      singleton: :NULL
    )
  else
    raise Sass::ScriptError, "Unknown Sass::Value #{obj}"
  end
end