matterhorn-notify-v2.sh

#! /usr/bin/env sh

# This is the sample Linux notifier for V2 notifications.

# The notification payload is a JSON object presented to standard input,
# having the fields version, sender, message and mentioned. Note that
# the JSON data is always UTF-8 encoded. The script is responsible for
# decoding it to Unicode.

# This script depends upon `jq(1)` to extract fields from the JSON
# notification and upon `notify-send(1)` to invoke the system notifier.

# See docs/notification-scripts.md for further details.

PGM="`basename $0`"
function fail {
	echo $PGM: "$@" >/dev/stderr
	exit 1
}

# Confirm presence of `jq(1)` and `notify-send(1)`.'
function has {
	which $1 >/dev/null 2>&1
}
has jq || fail 'jq(1) is required but not present'
has notify-send || fail 'notify-send(1) is required but not present'

# Extract the data to be notified. The data is in a JSON payload at stdin.
json=`cat`
version=`echo $json|jq -Mr .version`
[ "$version" = 2 ] || fail 'JSON payload has wrong version'
sender=`echo $json|jq -Mr .from`
message=`echo $json|jq -Mr .message`
mentioned=`echo $json|jq -Mr .mention`

# Now prepare the notification. The logic is essentially the same as for
# the V1 notifier.

# Configure the notifier.
ns_URGENCY_GENERAL=normal    # none, low, normal or critical
ns_URGENCY_MENTIONED=normal  # none, low, normal or critical
ns_CATEGORY=im.received
ns_HEADER="Matterhorn message from @$sender"
ns_BODY="$message"

case "$mentioned" in
false) ns_URGENCY=$ns_URGENCY_GENERAL ;;
true) ns_URGENCY=$ns_URGENCY_MENTIONED ;;
*) fail "mentioned: invalid value: $mentioned" ;;
esac

# Emit the notification.
case "$ns_URGENCY" in
none) ;;
low|normal|critical)
	notify-send -u $ns_URGENCY -c $ns_CATEGORY -- "$ns_HEADER" "$ns_BODY" ;;
*) fail "urgency not recognized: $ns_URGENCY" ;;
esac

# Log the JSON notification payload. To enable, define NOTIFY_JSON_LOG as
# a path to a file. The file need not exist; the directory must be writable.
NOTIFY_JSON_LOG=
[ -n "$NOTIFY_JSON_LOG" ] && {
	echo `date -Iminutes` $json >> $NOTIFY_JSON_LOG
}
true