# frozen_string_literal: true
require 'forwardable'

module Steam
  # Reads bytes from a given IO object.
  class ByteReader
    extend Forwardable

    attr_reader :io

    # Create a ByteReader object
    #
    # @param io [:read] an io object
    def initialize(io)
      @io = io
    end

    # Reads an unsigned 64 bit integer from the stream
    #
    # @return [Integer] The 64 bit integer
    def read_int64
      io.read(8).unpack('C*').each_with_index.reduce(0) do |sum, (byte, index)|
        sum + byte * (256**index)
      end
    end
    alias int64 read_int64

    # Reads an unsigned short from the stream
    #
    # @return [Integer] The short
    def read_short
      io.read(2).unpack('S*').first
    end
    alias short read_short

    # Reads a string of a given length from the stream
    #
    # @return [String] The read string
    def string(len)
      io.read(len)
    end

    # Reads a single bytes from the stream
    #
    # @return [Integer] The byte
    def byte
      io.read(1).ord
    end

    # Reads an unsigned 32 bit integer from the stream
    #
    # @return [Integer] The 32 bit integer
    def unsigned_int32
      io.read(4).unpack('<I*').first
    end

    # Reads an signed 32 bit integer from the stream
    #
    # @return [Integer] The 32 bit integer
    def signed_int32
      io.read(4).unpack('<i*').first
    end

    # Reads an signed 16 bit integer from the stream
    #
    # @return [Integer] The 16 bit integer
    def signed_int16
      io.read(2).unpack('<s*').first
    end

    def_delegator :@io, :read, :read
    def_delegator :@io, :readbyte, :readbyte
    def_delegator :@io, :eof?, :eof?
    def_delegator :@io, :tell, :tell
    def_delegator :@io, :lineno, :lineno
  end
end