hosts/options/status-email.nix

{ pkgs, lib, config, ... }:
let
    fromAddress = config.email.fromAddress;
    fromIdentity = config.email.fromIdentity;
    toAddress = config.email.adminEmail;
    cfg = config.services.statusEmail;
in
{
    options.services.statusEmail = {
        enable = lib.mkEnableOption "Send systemd status e-mails";
    };

    config = lib.mkIf cfg.enable {
        email.enable = true;
        systemd.services."status-email@" = let
            sendStatusEmail = pkgs.writeScript "send-status-email" ''
                #!${pkgs.bash}/bin/bash

                from="${fromIdentity}"
                to="${toAddress}"
                service="$1"
                full_status="$(systemctl status --full --lines 200 "$service")"
                exit_code="$(echo "$full_status" | head -n5 | tail -1 | sed -e 's/.*ExecStart=.*status=\(.*\))$/\1/g')"
                # state="$(systemctl is-failed "$service")"

                fail_priority=1
                fail_subject="Unit \"$service\" failure report (exit code $exit_code)"
                success_priority=3
                success_subject="Unit \"$service\" report (success)"

                shift
                while [ $# -gt 0 ] ; do
                    case "$1" in
                        '-s'|'--fail-subject')
                            fail_subject="$2"
                            shift 2
                            ;;
                        '-p'|'--fail-priority')
                            fail_priority="$2"
                            shift 2
                            ;;
                        *)
                            break
                            ;;
                    esac
                done

                if [ "$exit_code" != "0/SUCCESS" ] ; then
                    subject="$fail_subject"
                    priority="$fail_priority"
                else
                    subject="$success_subject"
                    priority="$success_priority"
                fi

                echo "Sending e-mail \"$subject\" to \"$to\"."

                ${pkgs.system-sendmail}/bin/sendmail -t -X - <<ERRMAIL
                To: $to
                From: $from
                Subject: $subject
                Content-Transfer-Encoding: 8bit
                Content-Type: text/plain; charset=UTF-8
                X-Priority: $priority

                $full_status

                ERRMAIL
            '';
        in
        {
            unitConfig = {
                Description = "Send a status e-mail for %I";
            };
            serviceConfig = {
                Type = "oneshot";
                ExecStart = "${sendStatusEmail} %i";
            };
        };
    };
}