#!/bin/bash
#
# CallWeaver -- An open source telephony toolkit.
#
# Copyright (C) 2010, Eris Associates Limited, UK
#
# Mike Jagdis <mjagdis@eris-associates.co.uk>
#
# See http://www.callweaver.org for more information about
# the CallWeaver project. Please do not directly contact
# any of the maintainers of this project for assistance;
# the project provides a web site, mailing lists and IRC
# channels for your use.
#
# This program is free software, distributed under the terms of
# the GNU General Public License Version 2. See the LICENSE file
# at the top of the source tree.


# This is somewhat complicated. The idea is that the hardcoded defaults
# are overridden by values in the /etc/{sysconfig,default}/cw_mixer,
# which are in turn overridden by anything in the environment. It is
# made more complicated by the fact that we need to know the difference
# between a variable not existing in the environment and existing but
# having a null value. Anyway...

# Save config settings found in the environment
eval `export -p | while read word keyval; do
	# In bash-mode bash reports "declare -x ..." in sh-mode "export ..."
	[[ "$word" == 'declare' ]] && keyval="${keyval#-x }"
	case $keyval in
		CW_MIXER_*)
			echo "ENV_${keyval%%=*}=${keyval#*=}"
			;;
	esac
done`

# Set defaults. (This is boilerplate from the standard
# /etc/{sysconfig,default}/cw_mixer)

# If CW_MIXER_AUTOGAIN is set to 'yes' we will attempt to adjust the input
# files to give them similar average volumes before combining them. By
# preference we use "wavegain" to do this. If it isn't (and it doesn't come
# with all (any?) distributions but follow the link to the/a website from
# freshmeat, http://freshmeat.net/projects/wavegain/ if you want to install
# it) then we will try and use "normalize" (which comes with SuSE at least).
# If neither "wavegain" nor "normalize" are found no adjustment will be
# made regardless of the setting below.
#
# Note that both "wavegain" and "normalize" want to work with PCM data.
# The input files will be automatically converted as necessary however
# if you have WAV/GSM inputs and are outputting WAV the output will be
# WAV/PCM rather than WAV/GSM. i.e. in this case your output files will
# be significantly bigger with CW_MIXER_AUTOGAIN on and will almost certainly
# get transcoded if you play them back via any sort of telephony channel.
#
# You almost certainly want this enabled.
CW_MIXER_AUTOGAIN='yes'

# Set CW_MIXER_KEEP_INPUTS to 'yes' to retain the input files. Otherwise
# they will be deleted if the merged file _appears_ to have been successful.
#
# Set this to anything other than 'yes' at your own risk!
CW_MIXER_KEEP_INPUTS='yes'

# Set CW_MIXER_MERGETYPE to 'M' if you want the input files to be combined
# as separate channels in a stereo output file. Set to 'm' if you want the
# input files mixed to create a mono output file.
#
# This only works if you have a sufficiently recent version of "sox".
# Otherwise we will automatically fall back to "soxmix" which only mixes
# inputs to create a mono output. If neither "sox" nor "soxmix" appear to
# work there will, of course, be no output created.
CW_MIXER_MERGETYPE='M'

# CW_MIXER_EFFECTS can be used to apply effects such as companding to the
# input files. These effects are applied using sox to the input files
# individually _after_ any CW_MIXER_AUTOGAIN normalization but _before_
# mixing.
#
# A typical use might be to use the "compand" filter to smooth out
# volume changes (particularly useful for a conference call recording
# perhaps). In the example below the first filter attempts to even out
# fluctuations as different people speak, the second attempts to
# clamp down on short duration noises such as someone bumping the mic.
#
# You should probably not enable this unless you know what you are
# doing and are prepared to experiment. There is unlikely to be any
# one setting that suits all circumstances - and plenty that suit
# no circumstances!
#CW_MIXER_EFFECTS=(
#	compand 1,4 6:-80,-80,-75,-25,0,0 -5 -30 1
#	compand .03,.2 -80,-80,-15,-15,0,-15 -15 -40 .1
#)

# Override with any local preferences
[[ -r '/etc/sysconfig/cw_mixer' ]] && . '/etc/sysconfig/cw_mixer'
[[ -r '/etc/default/cw_mixer' ]] && . '/etc/default/cw_mixer'

# Override again with environment settings
for key in ${!ENV_CW_MIXER_*}; do
	eval "${key#ENV_}=\$$key"
done


# Map a CallWeaver file type to something sox understands
map_cw2sox()
{
	case $1 in
		ulaw)	echo 'ul' ;;
		alaw)	echo 'al' ;;
	esac
}


# Return the data format and rate of the contents of a WAV file
wav_info()
{
	local data=
	local rate=

	case ${2:-${3##*.}} in
		WAV|wav)
			set -- $( file "$3" )
			local prev=8000
			while [[ $# -gt 0 ]]; do
				case $1 in
					Hz)
						[[ $prev -gt $rate ]] && rate=$prev ;;
					PCM|GSM)
						data="$1" ;;
				esac
				prev="$1"
				shift
			done
			;;
	esac

	echo $data $rate
}


in1file="$1"
orig1file="$1"
in2file="$2"
orig2file="$2"
outfile="$3"

in1type=$( map_cw2sox "${1##*.}" )
in2type=$( map_cw2sox "${2##*.}" )
outtype=$( map_cw2sox "${3##*.}" )

pids=()

trap '
	[[ ${#pids[@]} -gt 0 ]] && kill "${pids[@]}"
	rm -rf /tmp/$$
' 0

mkdir /tmp/$$ || exit


if [[ "$CW_MIXER_AUTOGAIN" == 'yes' ]]; then
	wavegain=$( type -p wavegain )
	[[ -n "$wavegain" ]] || normalize=$( type -p normalize )

	if [[ -n "$wavegain" || -n "$normalize" ]]; then
		# Both want WAV/PCM as input.
		# You can't convert WAV/GSM to WAV/PCM in one go. Sox just sees "WAV"
		# for both input and output and simply copies the stream :-(
		rate=8000
		set -- $( wav_info "$rate" "$in1type" "$in1file" )
		data1="$1"
		[[ ${2:-8000} -gt $rate ]] && rate="$2"
		set -- $( wav_info "$rate" "$in2type" "$in2file" )
		data2="$1"
		[[ ${2:-8000} -gt $rate ]] && rate="$2"

		if [[ "$data1" != 'PCM' ]]; then
			sox ${in1type:+-t $in1type} "$in1file" -t raw -r $rate -s -2 - | sox -t raw -r $rate -s -2 - "/tmp/$$/1.norm.wav" &
			in1file="/tmp/$$/1.norm.wav"
			in1type=
		elif [[ -n "$wavegain" ]]; then
			cp "$in1file" "/tmp/$$/1.norm.wav"
			in1file="/tmp/$$/1.norm.wav"
		fi
		if [[ "$data2" != 'PCM' ]]; then
			sox ${in2type:+-t $in2type} "$in2file" -t raw -r $rate -s -2 - | sox -t raw -r $rate -s -2 - "/tmp/$$/2.norm.wav" &
			in2file="/tmp/$$/2.norm.wav"
			in2type=
		elif [[ -n "$wavegain" ]]; then
			cp "$in2file" "/tmp/$$/2.norm.wav"
			in1file="/tmp/$$/2.norm.wav"
		fi
		wait
	fi

	if [[ -n "$wavegain" ]]; then
		# Wavegain wants to create a temp output file in the local directory and then
		# rename it back to the original name so we have to be careful not to cross
		# filesystems. So in the wavegain case we have copied the source files to the
		# work directory even if they didn't need converting and will now change into
		# the work directory to run wavegain.
		( cd "/tmp/$$"; "$wavegain" -y "$in1file" "$in2file" )
	elif [[ -n "$normalize" ]]; then
		"$normalize" -v -m -- "$in1file" "$in2file"
	fi
fi


if [[ -n "$CW_MIXER_EFFECTS" ]]; then
	mknod "/tmp/$$/1" p
	mknod "/tmp/$$/2" p

	sox ${in1type:+-t $in1type} "$in1file" -t wav "/tmp/$$/1" "${CW_MIXER_EFFECTS[@]}" &
	pids[${#pids[@]}]=$!
	sox ${in2type:+-t $in2type} "$in2file" -t wav "/tmp/$$/2" "${CW_MIXER_EFFECTS[@]}" &
	pids[${#pids[@]}]=$!

	in1file="/tmp/$$/1"
	in1type='wav'
	in2file="/tmp/$$/2"
	in2type='wav'
fi

if ! sox -$CW_MIXER_MERGETYPE ${in1type:+-t $in1type} "$in1file" ${in1type:+-t $in1type} "$in2file" ${outtype:+-t $outtype} "$outfile"; then
	soxmix ${in1type:+-t $in1type} "$in1file" ${in1type:+-t $in1type} "$in2file" ${outtype:+-t $outtype} "$outfile"
fi

if [[ $? -eq 0 && "$CW_MIXER_KEEP_INPUTS" != 'yes' ]]; then
	set -- $( ls -l "$outfile" )
	if [[ $5 -gt 100 ]]; then
		rm -f "$orig1file" "$orig2file"
	fi
fi