#!/bin/sh
# Copyright (C) 2019-2021  June McEnroe <june@causal.agency>
#
# 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/>.

set -u

idle=
apply=
headers=
verbose=
host=$(git config fetchemail.imapServer)
port=$(git config fetchemail.imapServerPort)
user=$(git config fetchemail.imapUser)
pass=$(git config fetchemail.imapPass)
mailbox=$(git config fetchemail.imapMailbox)
subject=$(git config fetchemail.subject)
from=$(git config fetchemail.from)
to=$(git config fetchemail.to)
cc=$(git config fetchemail.cc)
unseen=$(git config --type bool fetchemail.unseen)
seen=$(git config --type bool fetchemail.markSeen)
move=$(git config fetchemail.moveTo)
[ "${unseen}" = 'false' ] && unseen=
[ "${seen}" = 'false' ] && seen=
: ${subject:='[PATCH'}

OPTS_SPEC="\
git fetch-email [<options>]
--
C,cc= fetch patches with matching Cc headers
F,from= fetch patches with matching From headers
H,headers fetch only patch headers
M,move-to= move patches to mailbox
S,subject= fetch patches with matching Subject headers
T,to= fetch patches with matching To headers
U,unseen fetch unseen patches
a,apply apply patches with git-am
h,host=! connect to IMAP on host
i,idle wait for matching patches
m,mailbox=! fetch patches from mailbox
p,port=! connect to IMAP on port
s,mark-seen mark matching patches as seen
u,user=! log in to IMAP as user
v,verbose log IMAP protocol to standard error
"
eval "$(echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?)"

while [ $# -gt 0 ]; do
	opt=$1
	shift
	case "${opt}" in
		(-C) cc=$1; shift;;
		(-F) from=$1; shift;;
		(-H) headers=yes;;
		(-M) move=$1; shift;;
		(-S) subject=$1; shift;;
		(-T) to=$1; shift;;
		(-U) unseen=true;;
		(-a) apply=yes;;
		(-h) host=$1; shift;;
		(-i) idle=yes;;
		(-m) mailbox=$1; shift;;
		(-p) port=$1; shift;;
		(-s) seen=true; shift;;
		(-u) user=$1; shift;;
		(-v) verbose=yes;;
		(--no-apply) apply=;;
		(--no-cc) cc=;;
		(--no-from) from=;;
		(--no-headers) headers=;;
		(--no-idle) idle=;;
		(--no-mark-seen) seen=;;
		(--no-move-to) move=;;
		(--no-subject) subject=;;
		(--no-to) to=;;
		(--no-unseen) unseen=;;
		(--no-verbose) verbose=;;
		(--) break;;
	esac
done
if [ -z "${user}" ]; then
	echo "${0}: username required" >&2
	exit 1
fi

description() {
	cat <<-EOF
		protocol=imaps
		host=${host:-${user#*@}}
		username=${user%@*}
		${pass:+password=${pass}}
	EOF
}

if [ -z "${pass}" ]; then
	pass=$(description | git credential fill | grep '^password=')
	pass=${pass#*=}
fi

fetch() {
	printf '%s' "${pass}" | imbox -w \
		${verbose:+-v} ${idle:+-i} ${headers:+-H} ${unseen:+-U} ${seen:+-s} \
		${host:+-h "${host}"} \
		${port:+-p "${port}"} \
		${mailbox:+-m "${mailbox}"} \
		${subject:+-S "${subject}"} \
		${from:+-F "${from}"} \
		${to:+-T "${to}"} \
		${cc:+-C "${cc}"} \
		${move:+-M "${move}"} \
		${user}
	status=$?
	if [ $status -ne 78 ]; then
		description | git credential approve
	else
		description | git credential reject
	fi
	return $status
}

if [ -n "${apply}" ]; then
	applySeen=$seen
	applyMove=$move
	seen=
	move=
	fetch | git am --patch-format=mboxrd "$@"
	status=$?
	if [ $status -eq 0 ] && [ -n "${applySeen}${applyMove}" ]; then
		seen=$applySeen
		move=$applyMove
		fetch >/dev/null
	fi
	exit $status
else
	fetch
fi