#!/bin/sh

# - Syncs mail for all accounts, or a single account given as an argument.
# - Displays a notification showing the number of new mails.
# - Displays a notification for each new mail with its subject displayed.
# - Runs notmuch to index new mail.
# - This script can be set up as a cron job for automated mail syncing.

# There are many arbitrary and ugly features in this script because it is
# inherently difficult to pass environmental variables to cronjobs and other
# issues. It also should at least be compatible with Linux (and maybe BSD) with
# Xorg and MacOS as well.

# Run only if not already running in other instance
pgrep mbsync >/dev/null && { echo "mbsync is already running."; exit ;}

# First, we have to get the right variables for the mbsync file, the pass
# archive, notmuch and the GPG home.  This is done by searching common profile
# files for variable assignments. This is ugly, but there are few options that
# will work on the maximum number of machines.
eval "$(grep -h -- \
	"^\s*\(export \)\?\(MBSYNCRC\|MPOPRC\|PASSWORD_STORE_DIR\|PASSWORD_STORE_GPG_OPTS\|NOTMUCH_CONFIG\|GNUPGHOME\|MAILSYNC_MUTE\|XDG_CONFIG_HOME\|XDG_DATA_HOME\)=" \
	"$HOME/.profile" "$HOME/.bash_profile" "$HOME/.zprofile"  "$HOME/.config/zsh/.zprofile" "$HOME/.zshenv" \
	"$HOME/.config/zsh/.zshenv" "$HOME/.bashrc" "$HOME/.zshrc" "$HOME/.config/zsh/.zshrc" \
	"$HOME/.pam_environment" 2>/dev/null)"

export GPG_TTY="$(tty)"

[ -n "$MBSYNCRC" ] && alias mbsync="mbsync -c $MBSYNCRC" || MBSYNCRC="$HOME/.mbsyncrc"
[ -n "$MPOPRC" ] || MPOPRC="$HOME/.config/mpop/config"

lastrun="${XDG_CONFIG_HOME:-$HOME/.config}/mutt/.mailsynclastrun"

# Settings are different for MacOS (Darwin) systems.
case "$(uname)" in
	Darwin) notify() { osascript -e "display notification \"$2\" with title \"$1\"" ;} ;;
	*)
	case "$(readlink -f /sbin/init)" in
		*systemd*|*openrc*) export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$(id -u)/bus ;;
	esac
	# remember if a display server is running since `ps` doesn't always contain a display
	pgrepoutput="$(pgrep -ax X\(\|org\|wayland\))"
	displays="$(echo "$pgrepoutput" | grep -wo "[0-9]*:[0-9]\+" | sort -u)"
	[ -z "$displays" ] && [ -d /tmp/.X11-unix ] && displays=$(cd /tmp/.X11-unix && for x in X*; do echo ":${x#X}"; done)

	notify() { [ -n "$pgrepoutput" ] && for x in ${displays:-:0}; do
			export DISPLAY="$x"
			notify-send --app-name="mutt-wizard" -- "$1" "$2"
		done ;}
	;;
esac

# Check account for new mail. Notify if there is new content.
syncandnotify() {
	case "$1" in
		imap) mbsync -q "$2" ;;
		pop) mpop -q "$2" ;;
	esac
	new=$(find\
		"$HOME/.local/share/mail/$2/"[Ii][Nn][Bb][Oo][Xx]/new/ \
		"$HOME/.local/share/mail/$2/"[Ii][Nn][Bb][Oo][Xx]/cur/ \
		-type f -newer "$lastrun" 2> /dev/null)
	newcount=$(echo "$new" | sed '/^\s*$/d' | wc -l)
	case 1 in
		$((newcount > 5)) )
			echo "$newcount new mail for $2."
			[ -z "$MAILSYNC_MUTE" ] && notify "New Mail!" "📬 $newcount new mail(s) in \`$2\` account."
			;;
		$((newcount > 0)) )
			echo "$newcount new mail for $2."
			[ -z "$MAILSYNC_MUTE" ] &&
			for file in $new; do
		    		# Extract and decode subject and sender from mail.
				subject="$(sed -n "/^Subject:/ s|Subject: *|| p" "$file" |
					perl -CS -MEncode -ne 'print decode("MIME-Header", $_)')"
				from="$(sed -n "/^From:/ s|From: *|| p" "$file" |
					perl -CS -MEncode -ne 'print decode("MIME-Header", $_)')"
				from="${from% *}" ; from="${from%\"}" ; from="${from#\"}"
				notify "📧$from:" "$subject"
			done
			;;
		*) echo "No new mail for $2." ;;
esac
}

allaccounts="$(grep -hs "^\(Channel\|account\)" "$MBSYNCRC" "$MPOPRC")"

# Get accounts to sync. All if no argument. Prefix with `error` if non-existent.
IFS='
'
if [ -z "$1" ]; then
	tosync="$allaccounts"
else
	tosync="$(for arg in "$@"; do for availacc in $allaccounts; do
		[ "$arg" = "${availacc##* }" ] && echo "$availacc" && break
	done || echo "error $arg"; done)"
fi

for account in $tosync; do
	case $account in
		Channel*) syncandnotify imap "${account##* }" & ;;
		account*) syncandnotify pop "${account##* }" & ;;
		error*) echo "ERROR: Account ${account##* } not found." ;;
	esac
done

wait

notmuch new --quiet

#Create a touch file that indicates the time of the last run of mailsync
touch "$lastrun"