#!/bin/sh -e

##### HARD-CODED CONFIG #####################################################

CONF_DIR=/etc/prometheus
CONF=$CONF_DIR/alertmanager.yml

##### GET SETTINGS ##########################################################

config="$(cat "$__object/parameter/config")"
retention_days="$(cat "$__object/parameter/retention-days")"
storage_path="$(cat "$__object/parameter/storage-path")"
# listen_address="$(cat "$__object/parameter/listen-address")"

##### INSTALL THE PACKAGE ###################################################

require_pkg=""  # what to require if I want to require "the package"
if [ -f "$__object/parameter/install-from-backports" ]; then
	os=$(cat "$__global/explorer/os")
	lsb_codename=$(cat "$__global/explorer/lsb_codename")

	case $os in
		devuan)
			if [ -z "$lsb_codename" ]; then
				echo "Command `lsb_release` not functional -- is package `lsb-release` installed?" >&2
				exit 1
			fi
			[ "$lsb_codename" = "n/a" ] && lsb_codename='ascii'  # TODO this is a devuan bug that should be fixed soon => remove when no longer needed
			__apt_source backports --uri http://auto.mirror.devuan.org/merged --distribution $lsb_codename-backports --component main
			require="$require __apt_source/backports" __package_apt prometheus-alertmanager --target-release $lsb_codename-backports
			require_pkg="__package_apt/prometheus-alertmanager"
		;;
		*)
			echo "--install-from-backports is only supported on Devuan -- ignoring" >&2
			echo "send a pull request if you require it" >&2
		;;
	esac
else
	__package prometheus-alertmanager
	require_pkg="__package/prometheus-alertmanager"
fi

##### PREPARE PATHS AND SUCH ################################################

require="$require $require_pkg" __directory "$storage_path" --owner prometheus --parents

# TODO this is a bug in the init script, patching it like this is awful and it should be reported
require="$require $require_pkg" \
__key_value alertmanager_fix_init_script --file /etc/init.d/prometheus-alertmanager --key="NAME" --value="prometheus-alertmanager" --delimiter "="


##### CONFIGURE #############################################################

FLAGS="--storage.path $storage_path --data.retention $(($retention_days*24))h --web.listen-address [::]:9093"

require="$require $require_pkg" \
__key_value alertmanager_args --file /etc/default/prometheus-alertmanager --key="ARGS" --value="\"$FLAGS\"" --delimiter "="

require="$require __directory/$storage_path $require_pkg" \
__config_file $CONF \
	--source $config \
	--group prometheus --mode 640 \
	--onchange "service prometheus-alertmanager reload"  # TODO when a config-check tool is available, check config here