#!/usr/bin/env luajit

--[[
This is part of the JackOnAllDevices project, JOAD for short.

The purpose is to scan for all ALSA / asound audio devices, and hook them
all up to JACK.  Then it starts up JACK, and hooks up any joysticks it
finds as MIDI controllers.


Alas ~/.asoundrc doesn't understand ~ or $HOME, or even "try the current
directory" it seems.  So you have to hard cade the path.  Make sure your
~/.asoundrc or /etc/asoundrc includes something like this -

</var/lib/JOAD/asoundrc>


Run this once as root to create that file, and each time you need to
change your devices.


TODO - Leave it running, and hotplug ALSA / asound audio devices. 
	a2jmidid takes care of hotplugging MIDI devices.
	Though I think I still need to deal with hotplugged joysticks.

NOTE - Seems both ALSA and JACK are per user.

]]


-- CHANGE these to suit.
local asoundrcPath = '/var/lib/JOAD'
local asoundrc = 'asoundrc'



-- This APT stuff was copied from apt-panopticon.
local APT = {}

APT.readCmd = function(cmd)
    local result = {}
    local output = io.popen(cmd)
    if nil ~= output then
	for l in output:lines() do
	    table.insert(result, l)
	end
    end
    return result
end


APT.exe = function(c)
    local exe = {status = 0, result = '', lines = {}, log = true, cmd = c .. ' ', command = c}

    function exe:log()
	self.log = true
	return self
    end
    function exe:Nice(c)
	if nil == c then
	    self.cmd = 'ionice -c3 nice -n 19 ' .. self.cmd
	else
	    self.cmd = self.cmd .. 'ionice -c3 nice -n 19 ' .. c .. ' '
	end
	return self
    end
    function exe:timeout(c)
	-- timeout returns a status of - command status if --preserve-status; "128+9" (actually 137) if --kill-after ends up being done; 124 if it had to TERM; command status if all went well.
	-- --kill-after means "send KILL after TERM fails.
	if nil == c then
	    self.cmd = 'timeout --kill-after=10.0 --foreground 42.0s ' .. self.cmd
	else
	    self.cmd = 'timeout --kill-after=10.0 --foreground ' .. c .. ' ' .. self.cmd
	end
	return self
    end
    function exe:also(c)
	if nil == c then c = '' else c = ' ' .. c end
	self.cmd = self.cmd .. ';' .. c .. ' '
	return self
    end
    function exe:And(c)
	if nil == c then c = '' else c = ' ' .. c end
	self.cmd = self.cmd .. '&&' .. c .. ' '
	return self
    end
    function exe:Or(c)
	if nil == c then c = '' end
	self.cmd = self.cmd .. '|| ' .. c .. ' '
	return self
    end
    function exe:noErr()
	self.cmd = self.cmd .. '2>/dev/null '
	return self
    end
    function exe:wait(w)
	self.cmd = self.cmd .. '&& touch ' .. w .. ' '
	return self
    end
    function exe:Do()
    --[[    "The condition expression of a control structure can return any
	    value. Both false and nil are considered false. All values different
	    from nil and false are considered true (in particular, the number 0
	    and the empty string are also true)."
	says the docs, I beg to differ.]]
	if true == self.log then D("  executing - &nbsp; <code>" .. self.cmd .. "</code>") end
	--[[ Damn os.execute()
	    Lua 5.1 says it returns "a status code, which is system-dependent"
	    Lua 5.2 says it returns true/nil, "exit"/"signal", the status code.
	    I'm getting 7168 or 0.  No idea what the fuck that is.
	local ok, rslt, status = os.execute(s)
	]]
	local f = APT.readCmd(self.cmd, 'r')
	-- The last line will be the command's returned status, collect everything else in result.
	self.status = ''	-- Otherwise the result starts with 0.
	self.result = '\n'
	self.lines = f
	for i,l in ipairs(f) do
	    self.result = self.result .. l .. "\n"
	end
	f = APT.readCmd('echo "$?"', 'r')
	for i,l in ipairs(f) do
	    self.status = tonumber(l)
	    if (137 == self.status) or (124 == self.status) then
		print("timeout killed " .. self.status .. ' ' .. self.command)
		E("timeout killed " .. self.status .. ' ' .. self.command)
	    elseif (0 ~= self.status) then
		print("status |" .. self.status .. '| ' .. self.command)
		E("status |" .. self.status .. '| ' .. self.command)
	    end
	end
	return self
    end
    function exe:fork(host)
	if nil ~= host then self.cmd = self.cmd .. ';  r=$?; if [ $r -ge 124 ]; then echo "$r ' .. host .. ' failed forked command ' .. string.gsub(self.cmd, '"', "'") .. '"; fi' end
	self.cmd = '{ ' .. self.cmd .. '; } &'
	if true == self.log then D("  forking - &nbsp; <code>" .. self.cmd .. "</code>") end
	os.execute(self.cmd)
	return self
    end
    return exe
end



local Cards = {}

print('Scanning for audio devices.')
local cards = APT.exe('ls -d1 /proc/asound/card[0-9]*'):noErr():Do()
for  i,l in ipairs(cards.lines) do
    local f, e = io.open(l .. '/id', "r")
    if nil == f then print("Could not open " .. l .. '/id') else
	Cards[l] = {path = l, name = f:read("*a"):sub(1, -2), devs = {}, captureDevs = {}, playbackDevs = {}}
	if "Loopback" ~= Cards[l]['name'] then
	    Cards[l]['capture'] = APT.exe('ls -d1 ' .. l .. '/pcm[0-9]*c*'):noErr():Do()
	    for  j,c in ipairs(Cards[l]['capture'].lines) do
		local n = c:match(".*pcm(%d+).*")
		Cards[l]['captureDevs'][j] = n
		Cards[l]['devs'][n] = n
		print("\tFound capture device: " .. Cards[l]['name'] .. "\tDEVICE: " .. Cards[l]['captureDevs'][j] .. ' ' .. n)
	    end
	    Cards[l]['playback'] = APT.exe('ls -d1 ' .. l .. '/pcm[0-9]*p*'):noErr():Do()
	    for  j,p in ipairs(Cards[l]['playback'].lines) do
		local n = p:match(".*pcm(%d+).*")
		Cards[l]['playbackDevs'][j] = n
		Cards[l]['devs'][n] = n
		print("\tFound playback device: " .. Cards[l]['name'] .. "\tDEVICE: " .. Cards[l]['playbackDevs'][j] .. ' ' .. n)
	    end
	end
    end
end

APT.exe('mkdir -p ' .. asoundrcPath):Do()
local a, e = io.open(asoundrcPath .. '/' .. asoundrc, "w")
if nil == a then print("Could not open " .. asoundrcPath .. '/' .. asoundrc) else
    for  i,C in pairs(Cards) do
	for  j,c in pairs(C['devs']) do
	    a:write("pcm." .. C['name'] .. j .. " {\n")
	    a:write("   type hw\n")
	    a:write("   card " .. C['name'] .. "\n")
	    a:write("   device " .. C['devs'][j] .. "\n")
	    a:write("}\n")
	    a:write("ctl." .. C['name'] .. j .. " {\n")
	    a:write("   type hw\n")
	    a:write("   card " .. C['name'] .. "\n")
	    a:write("   device " .. C['devs'][j] .. "\n")
	    a:write("}\n\n")
	end
    end
    a:write([[
#################################################################################################################################

# The complex way - https://alsa.opensrc.org/Jack_and_Loopback_device_as_Alsa-to-Jack_bridge

# More custom version, but it didn't work for me.
# hardware 0,0 : used for ALSA playback
#pcm.loophw00 {
#  type hw
#  card Loopback
#  device 0
#  subdevice 0
#  format S32_LE
#  rate 48000
#}

# playback PCM device: using loopback subdevice 0,0
# Don't use a buffer size that is too small. Some apps 
# won't like it and it will sound crappy 

#pcm.amix {
#  type dmix
#  ipc_key 219345
#  slave {
#    pcm loophw00
##    period_size 4096
##    periods 2
#  }
#}

# software volume
#pcm.asoftvol {
#  type softvol
#  slave.pcm "amix"

#  control { name PCM }

#  min_dB -51.0
#  max_dB   0.0
#}


# for jack alsa_in: looped-back signal at other ends
#pcm.cloop {
#  type hw
#  card Loopback
#  device 1
#  subdevice 0
#  format S32_LE
#  rate 48000
#}

# hardware 0,1 : used for ALSA capture
#pcm.loophw01 {
#  type hw
#  card Loopback
#  device 0
#  subdevice 1
#  format S32_LE
#  rate 48000
#}

# for jack alsa_out: looped-back signal at other end
#pcm.ploop {
#  type hw
#  card Loopback
#  device 1
#  subdevice 1
#  format S32_LE
#  rate 48000
#}

# duplex device combining our PCM devices defined above
#pcm.aduplex {
#  type asym
#  playback.pcm "asoftvol"
#  capture.pcm "loophw01"
#}

# default device
#pcm.!default {
#  type plug
#  slave.pcm aduplex

#  hint {
#       show on
#       description "Duplex Loopback"
#  }
#}



# Generic method seems to work better.
# playback PCM device: using loopback subdevice 0,0
pcm.amix {
  type dmix
  ipc_key 219345
  slave.pcm "hw:Loopback,0,0"
}

# capture PCM device: using loopback subdevice 0,1
pcm.asnoop {
  type dsnoop
  ipc_key 219346
  slave.pcm "hw:Loopback,0,1"
}

# duplex device combining our PCM devices defined above
pcm.aduplex {
  type asym
  playback.pcm "amix"
  capture.pcm "asnoop"
}

# ------------------------------------------------------
# for jack alsa_in and alsa_out: looped-back signal at other ends
pcm.ploop {
  type plug
  slave.pcm "hw:Loopback,1,1"
}

pcm.cloop {
  type dsnoop
  ipc_key 219348
  slave.pcm "hw:Loopback,1,0"
}

# ------------------------------------------------------
# default device

pcm.!default {
  type plug
  slave.pcm "aduplex"
}
	]])
a:close()
end