#!/usr/bin/ruby
# Filename:	pulse-switch-out
# Author:	David Ljung Madison <DaveSource.com>
# See License:	http://MarginalHacks.com/License/
# Description:	Switch pulse audio output (sink) using pacmd

PACMD = %w(pacmd)

##################################################
# Usage
##################################################
def fatal(*msg)
	msg.each { |m| $stderr.puts "[#{$0.sub(/.*\//,'')}] ERROR: #{m}" }
	exit(-1);
end

def usage(*msg)
	msg.each { |m| $stderr.puts "ERROR: #{m}" }
	$stderr.puts <<-USAGE

Usage:  #{$0.sub(/.*\//,'')} [sink]
  Switch sound playback device for ALSA/pulseaudio

	[sink]   Specify sink number to use (see 'pacmd list-sinks')

	USAGE
	exit -1;
end

def parseArgs
	opt = Hash.new
	loop {
		if (arg=ARGV.shift)==nil then break
		elsif arg == '-h' then usage
		elsif arg == '-?' then usage
		#elsif arg == '-arg' then opt[:arg] = true
		elsif arg =~ /^(\d)$/ then opt[:sink] = arg.to_i
		else
			usage("Unknown arg [#{arg}]")
		end
	}

	opt
end

# Unfortunately you can't return or break from the yield without leaving
# the pipe open, maybe use some sort of ensure and figure out how to close?
def pipe(cmd)
		# This is leaving files open
	#IO.popen(cmd.join(' ')).each { |l|
	a = `#{cmd.join(' ')}`
	ret = $?
	a.each { |l|
		yield l
	}
	$?
end

def getSinks(ins=false)
	cmd = PACMD.dup
	cmd.push(ins ? 'list-sink-inputs' : 'list-sinks')
	curr = nil
	sinks = Array.new
	pipe(cmd) { |l|
		next unless l=~/\s*(\*)?\s*index:\s+(\d+)/
		i = $2.to_i
		sinks.push(i)
		curr = i if $1
	}
	return sinks,curr
end

##################################################
# Main code
##################################################
def main
	opt = parseArgs

	sinks,curr = getSinks

	usage("No sinks found?") if sinks.empty?
	usage("Only one sink found") if sinks.size==1

	if opt[:sink]
		usage("Unknown sink [#{opt[:sink]}] (out of #{sinks.join(' ')})") unless sinks.index(opt[:sink])
	else
		# Find next sink after curr
		opt[:sink] = sinks[0]
		sinks.each { |s|
			next unless s>curr
			opt[:sink] = s
			break
		}
	end

	# Set default sink
## For some reason this doesn't change the behavior of new apps.
	puts "Set sink: #{opt[:sink]}"
	system("#{PACMD} set-default-sink #{opt[:sink]} > /dev/null")
	usage("Couldn't set default sink [#{opt[:sink]}]") unless $?==0

	# And move all sink-inputs to the new sink
	ins,ignore = getSinks(true)
	ins.each { |i|
		puts "Move playback #{i} to sink #{opt[:sink]}"
		system("#{PACMD} move-sink-input #{i} #{opt[:sink]} > /dev/null")
		usage("Couldn't move playback #{i} to sink [#{opt[:sink]}]") unless $?==0
	}
end
main