screens.rb

#!/usr/bin/env ruby
#
# screens.rb
# @reednj, 2016-12-06
#
# This script will take a screenshot of the desktop on up to two monitors, and save it in the
# given location (usually Dropbox). It will only take a screenshot if the user is active.
#
# If there is already a screenshot that exists for that day, it will _sometimes_ overwrite it
# and make a new one. This is an attempt to get a screenshot at a random time each day.
#
require 'time'

class App
	def main
		@dir = "/Users/reednj/Dropbox/Transfer/desktop"
		# if we have been idle for more than 30 seconds, just exit
		if idletime > 30.0
			puts 'user not active'
			exit
		end

		if !exist?
			# if the screenshot for today doesn't already exist, then
			# take it
			puts 'first screenshot for the day'
			screenshot
		else
			# if the screenshot does exist, we overwrite it some of the time
			if one_in_n? 12
				puts 'replacement screenshot'
				screenshot
			end
		end
	end

	def exist?
		File.exist? filepath(1)
	end

	def filepath(i)
		File.join @dir, "#{Date.today.to_s}.#{i}.png"
	end

	def screenshot
		`screencapture -x #{filepath(1)} #{filepath(2)}`
	end

	def idletime
		`ioreg -c IOHIDSystem | awk '/HIDIdleTime/ {print $NF/1000000000; exit}'`.to_f
	end

	def one_in_n?(n)
		rand < (1.0 / n.to_f)
	end
end

App.new.main