#!/bin/sh
# Copyright (C) 2019, 2020  C. 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

apply=
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)

OPTS_SPEC="\
git fetch-email [<options>]
--
C,cc= fetch patches with matching Cc headers
F,from= fetch patches with matching From headers
S,subject= fetch patches with matching Subject headers
T,to= fetch patches with matching To headers
a,apply apply patches with git-am
h,host=! connect to IMAP on host
m,mailbox=! fetch patches from mailbox
p,port=! connect to IMAP on port
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;;
		(-S) subject=$1; shift;;
		(-T) to=$1; shift;;
		(-a) apply=yes;;
		(-h) host=$1; shift;;
		(-m) mailbox=$1; shift;;
		(-p) port=$1; shift;;
		(-u) user=$1; shift;;
		(-v) verbose=yes;;
		(--no-apply) apply=;;
		(--no-cc) cc=;;
		(--no-from) from=;;
		(--no-subject) subject=;;
		(--no-to) to=;;
		(--no-verbose) verbose=;;
		(--) break;;
	esac
done
if [ -z "${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() {
	echo "${pass}" | imbox -w \
		${verbose:+-v} \
		${host:+-h "${host}"} \
		${port:+-p "${port}"} \
		${mailbox:+-m "${mailbox}"} \
		${subject:+-S "${subject}"} \
		${from:+-F "${from}"} \
		${to:+-T "${to}"} \
		${cc:+-C "${cc}"} \
		${user}
	status=$?
	if [ $status -ne 78 ]; then
		description | git credential approve
	else
		description | git credential reject
	fi
	return $status
}

if [ -n "${apply}" ]; then
	fetch | git am --patch-format=mboxrd "$@"
else
	fetch
fi