#!/usr/bin/env ruby
# adapted from https://github.com/carnager/rofi-scripts/blob/master/monitor_layout.sh

require 'open3'

MONITORS = `xrandr`.split("\n").grep(/\Wconnected/) do |line|
  line.split(' ')[0]
end

def single_monitor_command(selected)
  command = "xrandr --output #{selected} --auto "
  MONITORS.each do |monitor|
    command += "--output #{monitor} --off" if monitor != selected
  end
  command
end

def single_monitor_commands
  result = {}
  MONITORS.each do |monitor|
    result["Only #{monitor}"] = single_monitor_command(monitor)
  end
  result
end

def dual_monitor_commands
  result = {}
  MONITORS.each do |a|
    MONITORS.each do |b|
      label = "Dual Screen #{a} -> #{b}"
      command = "xrandr --output #{a} --auto --output #{b} --auto --left-of #{a}"
      result[label] = command if a != b
    end
  end
  result
end

def clone_monitor_commands
  result = {}
  MONITORS.each do |a|
    MONITORS.each do |b|
      label = "Clone Screen #{a} -> #{b}"
      command = "xrandr --output #{a} --auto --output #{b} --auto --same-as #{a}"
      result[label] = command if a != b
    end
  end
  result
end

def monitor_commands
  default_commands = { 'Cancel' => nil }
  [default_commands, single_monitor_commands,
   dual_monitor_commands, clone_monitor_commands].reduce(:merge)
end

def pick_command
  commands = monitor_commands
  input = commands.keys.join("\n")
  output, = Open3.capture2('dmenu -l 15 -i', stdin_data: input)
  commands[output.chomp]
end

command = pick_command
if command
  system('pkill -x compton')
  system(command)
  system('compton')
  system('wallpaper')
end