#!/bin/bash
# -*-shell-script-*-

# Converts MPEG files to WAV using mpg123.
# Copyright (C) 2001  Ernest N. Mamikonyan
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.


# some defaults
readonly mpg123=mpg321  # mpg123 clone to use
force=false             # don't overwrite files without prompting
quiet=false             # produce progress output

usage() {
    echo "\
Usage: ${0##*/} [OPTIONS] [-] [FILE ...]
Convert MPEG files to WAV using the ${mpg123##*/} MPEG decoder.
  -f     never prompt before overwriting existent files
  -h     display this help message and exit
  -n     number the output files numerically, eg. 1.wav, 2.wav, ...
  -o     name of the output file or directory
  -q     suppress all diagnostic output and errors
  -V     display version information and exit
" >&2
    exit $1
}


rm() {
    local error=$(command rm -rf -- "$1" 2>&1)
    [[ -e "$1" ]] && { echo -e "Can't delete \`$1': $error"; exit 1; }
}


to_clobber() {
    [[ -e "$1" ]] || return 0
    if $force; then echo "$1 exists - overwriting!"; rm "$1"
    else
	read -n 1 -p "$1 exists - overwrite? " < /dev/tty
	if [[ "$REPLY" != [Yy] ]]; then
	    if [[ "$REPLY" ]]; then builtin echo -e \\bNo. >&2
	    else builtin echo -e No. >&2
	    fi
	    return 1
	fi
	builtin echo -e \\bYes! >&2
	rm "$1"
    fi
    return 0
}


convert() {

    local error

    to_clobber "$2" || return 1
    echo -en "$1 ==> $2:\e[70G"

    if [[ "$1" == '<STDIN>' ]]; then
	if [[ "$2" == '<STDOUT>' ]]; then "$mpg123" -qs -
	else error=$("$mpg123" -qw "$2" - 2>&1)
	fi
    else error=$("$mpg123" -qw "$2" -- "$1" 2>&1)
    fi

    if [[ $? != 0 || "$error" || ("$2" != '<STDOUT>' && ! -f "$2") ]]; then
	echo -e ' \e[1;31mfailed\e[0;39m\e[K'
	[[ "$error" ]] && echo -e "$error"
	return 1
    else echo -e ' \e[1;32mdone\e[0;39m\e[K'; return 0
    fi

}


rename_n_convert() {

    local mpeg wav

    for mpeg; do
	if (($number)); then wav="$dir$((number++)).wav"
	else wav="${mpeg##*/}"; wav="$dir${wav%.*}.wav"
	fi
	convert "$mpeg" "$wav"
    done

}


while getopts :fhno:qV option; do
    case $option in
    f) force=true;;
    h) usage 0;;
    n) typeset -i number=1;;
    o) output="$OPTARG";;
    q) quiet=true;;
    V) echo $'\
mpg2wav version 1.0, Copyright \251 2001  Ernest N. Mamikonyan.
mpg2wav comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions; see the source for details.
'
    exit 0
    ;;
    :) echo "The \`-$OPTARG' option requires an argument!" >&2; usage 1;;
    *) echo "\`-$OPTARG' is not a valid option!" >&2; usage 1;;
    esac
done

shift $((OPTIND-1))

$quiet && echo() { :; } || echo() { builtin echo "$@" >&2; }

if (($# == 0)); then
    if [[ "$output" ]]; then convert '<STDIN>' "$output"
    else convert '<STDIN>' '<STDOUT>'
    fi
    exit
elif [[ "$output" ]]; then
    if [[ $# > 1 || -d "$1" || -d "$output" ]]; then
	dir="${output%/}/"
	if [[ ! -d "$dir" ]]; then
	    to_clobber "$dir" || exit 1
	    error=$(mkdir -p -- "$dir" 2>&1)
	    if [[ ! -d "$dir" ]]; then
		echo -e "Can't make directory \`$dir': $error"; exit 1
	    fi
	fi
    else convert "$1" "$output"; exit
    fi
fi

for arg; do
    if [[ "$arg" == - ]]; then convert '<STDIN>' "$dir<STDIN>"
    elif [[ -d "$arg" ]]; then
	OIFS="$IFS"
	IFS=:
	rename_n_convert $(find "$arg" -type f -print0 | tr \\0 :)
	IFS="$OIFS"
    else rename_n_convert "$arg"
    fi
done