#!/bin/bash
#
# debextract - Wrapper to "dpkg-deb -x" for multiple files
#
#    Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
#
#    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 3 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, see <http://www.gnu.org/licenses/gpl.html>
#
# Wrapper to extract multiple debian packages (*.deb). It automatically chooses
# a destination directory based on the deb's filename and also extracts the
# control information files (the DEBIAN directory inside the package)

usage() {
cat <<- USAGE
	Usage: $self [${main} options] [options] FILE...
USAGE
if [[ "$1" ]] ; then
	cat <<- USAGE
		Try '$self --help' for more information.
	USAGE
	exit 1
fi
cat <<-USAGE

	Extracts Debian Package files (.deb) to a directory matching their filenames

	Options:
	-h|--help     - show this page.
	-v|--verbose  - print more details about what is being done. Also enables
	                 verbosity for ${main}. Use -X/+X to enable or disable this
	-X|--vextract - turns ON  verbosity for ${main}. Useful if -v is not set
	+X            - turns OFF verbosity for ${main}. Useful if -v is set
	--destdir DIR - sets a directory for extraction of all packages. If ommited
	                 or blank, destination will be each package's current
	                 directory. In all cases, package filename will be appended
	                 to the final destination path.
	--nocontrol      - do not extract the control files. (DEBIAN directory)
	--controldir DIR - set the destination directory for the control files, 
	                    relative to the extracted package directory. Ignored if
	                    --nocontrol is set. Default is DEBIAN.
	--onerror ACTION - What to do if an error occur when executing $main for a
	                    given file. Valid ACTION values are:
	          skip     - skip error and continue with next file, if any
	          quit     - quit immediately, do not extract any further files
	          ask      - if not last file, ask user what to do. Default action
	                   Regardless of the action chosen, in case of any error
	                   $self will always exit with ${main}'s last unsucessfull
	                   exit code
	${main} options:
	              - see ${main} --help or man ${main}

	FILE...       - package file(s) to extract, multiple files accepted

	The destination directory for extraction of each package will be the package
	filename without its extension (usually .deb). If the filename  has no
	extension, an error will occur, since this would be the same as executing
	${main} -x file file

	Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
	License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
USAGE
exit 0
}

opterror() { echo "$self: $1" ; usage 1 ; }
missing()  { opterror "missing ${1:+$1 }operand" ; }

testaction() {
	[[ "$1" ]] || missing "action"
	actions=( skip quit ask )
	for action in "${actions[@]}"; do [[ "$action" == "$1" ]] && return ; done
	opterror "invalid action '$1'. valid options are: ${actions[*]}"
}

handleerror() {
	code=$1
	(( verbose )) && echo "$self: error $code in $main"
	(( $2 > 1 )) || return 0 # Noting to handle if this is the last file
	case "$action" in
	skip) return 0 ;;
	quit) return 1 ;;
	ask )
		local choice
		read -rp "(Q)uit, (S)kip, or Skip (A)ll ? " choice
		case "$choice" in
		[Aa]*) action="skip" ; return 0 ;;
		[Ss]*) return 0 ;;
		    *) return 1 ;; # Educating users not to blindly hit Enter :)
		esac
	esac
}

declare -a opts=()
self="${0##*/}"
main="dpkg-deb"
action="ask"
destdir=""
control=1
controldir="DEBIAN"
verbose=0
dverb=0
dquiet=0
code=0
ext="--extract"

# Loop options
while (( $# )); do
	case "$1" in
	-h|--help     ) usage                   ;;
	-v|--verbose  ) verbose=1               ;;
	-X|--vextract ) dverb=1                 ;;
	+X            ) dquiet=1                ;;
	-x|--extract  )                         ;; #I'm not so naive.Silently ignore
	--nocontrol   ) control=0               ;;
	--controldir=*) controldir="${1#*=}"    ;;
	--controldir  ) shift ; controldir="$1" ;;
	--destdir=*   ) destdir="${1#*=}"       ;;
	--destdir     ) shift ; destdir="$1"    ;;
	--onerror=*   ) testaction "${1#*=}"    ;;
	--onerror     ) shift ; testaction "$1" ;;
	--            ) shift ; break           ;;
	-*            ) opts+=( "$1" )          ;;
	*             ) break                   ;;
	esac
	shift
done

# Basic parser tests
[[ "$controldir" ]] || missing "control directory"

# Handle dpkg verbosity (done via extract command)
if ((verbose && !dquiet)) || (( !verbose && dverb )); then ext="--vextract"; fi

# Loop file arguments
(( $# )) || missing "file"
while (( $# )); do
	#FIXME: extremely unlikely corner-case flaw: filename without extension, in
	#       a path that contains a dot.  /etc/dir.d/no-deb-ext
	filetitle="${1%.*}"
	if [[ "$destdir" ]] ; then
		path="${destdir}/${filetitle##*/}"
	else
		path="$filetitle"
	fi
	mkdir -p "$path" # make it easy for dpkg
	cmd1=("$main" "${opts[@]}" "$ext"    -- "$1" "${path//\/\///}"            )
	cmd2=("$main" "${opts[@]}" --control -- "$1" "${path//\/\///}/$controldir")
	if (( control )) ; then
		(( verbose )) && echo "$self: executing ${cmd1[@]} && ${cmd2[@]}"
		"${cmd1[@]}" && "${cmd2[@]}" || handleerror $? $# || break
	else
		(( verbose )) && echo "$self: executing ${cmd1[@]}"
		"${cmd1[@]}"                 || handleerror $? $# || break
	fi
	shift
done

(( verbose )) && (( code )) &&
	echo "$self: error(s) occurred, exiting with $main last error's code, $code"

exit $code