# Periodic WAN speed test so ISP degradation shows up as a trend instead of a
# complaint. A timer runs librespeed-cli and writes the results as Prometheus
# metrics into node_exporter's textfile collector — they ride the existing
# 9100 scrape to VictoriaMetrics, where alerts.nix compares each run against
# the link's own 7-day median (no per-site threshold to maintain).
{
  config,
  lib,
  pkgs,
  ...
}:
let
  cfg = config.cnx.router;
  textfileDir = "/var/lib/speedtest";
in
{
  options.cnx.router.speedtest.interval = lib.mkOption {
    type = lib.types.str;
    default = "hourly";
    description = "systemd OnCalendar spec for the WAN speed test.";
  };

  config = lib.mkIf cfg.enable {
    services.prometheus.exporters.node.extraFlags = [
      "--collector.textfile.directory=${textfileDir}"
    ];

    systemd.services.speedtest = {
      description = "WAN speed test to Prometheus textfile metrics";
      after = [ "network-online.target" ];
      wants = [ "network-online.target" ];
      path = [
        pkgs.librespeed-cli
        pkgs.jq
      ];
      serviceConfig = {
        Type = "oneshot";
        StateDirectory = "speedtest";
        # One test at boot would race PPPoE and log a spurious failure.
        ExecCondition = "${pkgs.iproute2}/bin/ip link show ppp0";
      };
      script = ''
        tmp="${textfileDir}/.speedtest.prom.tmp"
        if result=$(librespeed-cli --json); then
          jq -r '.[0]
            | "speedtest_download_mbps \(.download)",
              "speedtest_upload_mbps \(.upload)",
              "speedtest_ping_ms \(.ping)",
              "speedtest_jitter_ms \(.jitter)",
              "speedtest_success 1"' <<<"$result" > "$tmp"
        else
          echo "speedtest_success 0" > "$tmp"
        fi
        mv "$tmp" "${textfileDir}/speedtest.prom"
      '';
    };

    systemd.timers.speedtest = {
      wantedBy = [ "timers.target" ];
      timerConfig = {
        OnCalendar = cfg.speedtest.interval;
        RandomizedDelaySec = "10m";
        Persistent = true;
      };
    };
  };
}