#!/bin/sh

# qpdf-decode-gui: a script using yad as graphic user interface for calling
# qpdf with a password to decrypt a pdf. If the operation succeeds, the output
# will be a default new file adding a suffix "_decrypted" to the source file
# name. Be careful: if the output file already exists, it will be overwritten
# without warning!
#
# Copyright © 2023 Daltux <https://daltux.net/>
#
# 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 <https://www.gnu.org/licenses/>.
#
# Dependencies:
#	0: qpdf-decode in $PATH or the same directory of this file
#	1: qpdf
#	2: yad

app_title='qPDF Decode'
app_version='0.2.0'
app_icon='application-pdf'
qpdfd_name='qpdf-decode'
qpdfd="$qpdfd_name"

if [ -n "$1" ] && ([ "$1" = '-h' ] || [ "${@#*"--help"}" != "$@" ]) ; then
	echo "$app_title (GUI) $app_version"
	echo
	echo "Copyright (C) 2023 Daltux <https://daltux.net>"
	echo "This program comes with ABSOLUTELY NO WARRANTY;"
	echo "This is Free Software, and you are welcome to redistribute it under certain conditions. For details, see the GNU General Public License, version 3 or later."
	echo
	echo "Usage:"
	echo "	$0 [optional: file to decode]"
	exit
fi

cmdExists() {
	command -v "$1" > /dev/null 2>&1
	return $?
}

yadExists() {
	if [ -z $yadExists ] ; then
		cmdExists yad
		yadExists=$?
	fi
	return $yadExists
}

myad() {
	yad --center --borders=10 --image-on-top --buttons-layout=edge \
		--title="$app_title" --window-icon="$app_icon" "$@"
}

errorDlg() {
	local errorMsg="$@"
	echo "$app_title ERROR: $errorMsg" >&2

	if yadExists ; then
		myad --close-on-unfocus \
			--image="dialog-error" \
			--escape-ok \
			--text="$errorMsg" \
			--button=gtk-close:30 \
			--timeout=10 \
			--timeoutindicator=top
	elif cmdExists notify-send ; then
		notify-send --icon=error "$app_title ERROR" "$errorMsg"
	fi
}

if ! cmdExists "$qpdfd" ; then
	qpdfd_path=$(realpath "$0")
	qpdfd=$(dirname "$qpdf_path")/"$qpdfd"
fi

if ! [ -x "$qpdfd" ] ; then
	errorDlg "Cannot find or run:\n<b>$qpdfd</b>"
	exit 30
fi

if ! yadExists ; then
	errorDlg "Cannot find or run:\n<b>yad</b>"
	exit 31
fi

if [ -n "$1" ] ; then
	infile=$1
else
	infile=$(myad --title="$app_title" \
		--window-icon="$app_icon" \
		--text="Select the <b>source</b> PDF file:" \
		--file --on-top)
fi

if [ -z "$infile" ] ; then
	errorDlg "No input file provided."
	exit 50
elif ! [ -e "$infile" ] ; then
	errorDlg "Input file not found:\n\n<tt>$infile</tt>"
	exit 51
fi

if cmdExists mimetype ; then
	mimecmd='mimetype'
	mimecmd_opts='-b'
elif cmdExists file ; then
	mimecmd='file'
	mimecmd_opts='-ib'
elif cmdExists xdg-mime ; then
	mimecmd='xdg-mime'
	mimecmd_opts='query filetype'
fi

pdfmime='application/pdf'
xpdfmime='application/x-pdf'

if [ -n "$mimecmd" ] && ! "$mimecmd" "$mimecmd_opts" "$infile" | grep -Fqs -e "$pdfmime" -e "$xpdfmime" ; then
	errorDlg "Media Type different than\n\"<tt>$pdfmime</tt>\" or \"<tt>$xpdfmime</tt>\":\n\n<tt>$infile</tt>"
	exit 52
fi

inpath=$(dirname "$infile")
outfile=$(myad \
	--text="Select the <b>output</b> PDF file:" \
	--on-top --file --save --add-preview --mime-filter="$pdfmime" --mime-filter="$xpdfmime" \
	--confirm-overwrite="Output file already exists. Do you want to overwrite it?")

pass=$(myad \
	--image="dialog-password" \
	--text="Enter passphrase for file\n<tt><b>$infile</b></tt>:" \
	--entry --hide-text --entry-label="Passphrase")

if [ -z $pass ] ; then
	errorDlg "Missing passphrase for decryption."
	exit 40
fi

#myad --form \
#	--text "Password for decrypting $infile" \
#	--image Frutas.jpg \
#	--field "Escolha uma fruta:CB" 'Pera!Uva!Maçã!Manga' \
#	--field Outra "" \
#	--field "Qtas vc come?:NUM" '1!1..10!1' \
#	--field "Arquivo:FL" \
#	--field "Como e chupo o caroço:CHK"

#outfile=${infile}_decrypted
#outfile=${3:-$outfile}

qpdfd_output=$( "$qpdfd" "$pass" "$infile" "$outfile" 2>&1 )
qpdfd_exit=$?

case $qpdfd_exit in
	0)
		[ -n "$qpdfd_output" ] && echo "$qpdfd_output"
		myad --text="Operation succeeded.\n\n<tt>$qpdfd_output</tt>" \
			--button="gtk-ok:0" \
			--image="dialog-information"
		;;
	1)
		errorDlg "Unable to run qpdf."
		;;
	2|3)
		errorDlg "QPDF error or warning:\n\n<tt>$qpdfd_output</tt>"
		;;
	4)
		errorDlg "Missing passphrase for decryption."
		;;
	5)
		errorDlg "Missing reference to source PDF file."
		;;
	*)
		errorDlg "Unspecified output:\n\n<tt>$qpdfd_output</tt>"
		;;
esac

exit $qpdfd_exit