class Terminal
  class Size; VERSION = '0.0.6'.freeze end
  class << self
    def size
      size_via_low_level_ioctl or size_via_stty or nil
    end

    def size!
      size or _height_width_hash_from 25, 80
    end

    # These are experimental
    def resize(direction, magnitude)
      tmux 'resize-pane', "-#{direction}", magnitude
    end

    def tmux *cmd
      system 'tmux', *cmd.map(&:to_s)
    end

    IOCTL_INPUT_BUF = "\x00" * 8
    def size_via_low_level_ioctl
      # Thanks to runpaint for the general approach to this
      return unless $stdin.respond_to? :ioctl

      code = tiocgwinsz_value_for RUBY_PLATFORM
      return unless code

      buf = IOCTL_INPUT_BUF.dup
      return if $stdout.ioctl(code, buf) != 0
      return if buf == IOCTL_INPUT_BUF

      got = buf.unpack('S4')[0..1]
      _height_width_hash_from(*got)
    rescue StandardError
      nil
    end

    def tiocgwinsz_value_for(platform)
      # This is as reported by <sys/ioctl.h>
      # Hard-coding because it seems like overkll to acutally involve C for this.
      {
        /linux/ => 0x5413,
        /darwin/ => 0x40087468 # thanks to brandon@brandon.io for the lookup!
      }.find { |k, _v| platform[k] }
    end

    def size_via_stty
      ints = `stty size`.scan(/\d+/).map(&:to_i)
      _height_width_hash_from(*ints)
    rescue StandardError
      nil
    end

    private

    def _height_width_hash_from *dimensions
      { height: dimensions[0], width: dimensions[1] }
    end
  end
end