{ pkgs, lib, config, hostName, ... }:
let
  inherit (config.services) prometheus;
  listenAddress = "127.0.0.1";
in
{
services.prometheus = {
  enable = true;
  inherit listenAddress;
  port = 9090;
  extraFlags = [
    "--storage.tsdb.retention.time 30d"
  ];
  exporters = {
    apcupsd = {
      enable = true;
      inherit listenAddress;
    };
    node = {
      enable = true;
      inherit listenAddress;
      #enabledCollectors = [ "wifi" ];
    };
    smokeping = {
      #enable = true;
      inherit listenAddress;
      buckets = "0.0001,0.001,0.005,0.01,0.02,0.04,0.06,0.08,0.16,0.24,0.32,0.4,0.48,0.8,1.6,3.2,6.4";
      hosts = [ "www.fdn.fr" "8.8.8.8" ];
      pingInterval = "3s";
    };
    systemd = {
      enable = true;
      inherit listenAddress;
    };
    wireguard = {
      #enable = true;
      inherit listenAddress;
      withRemoteIp = true;
    };
  };
  scrapeConfigs = [
    {
      job_name = hostName;
      static_configs = [
        {
          targets = [
            "${listenAddress}:${toString prometheus.exporters.apcupsd.port}"
            "${listenAddress}:${toString prometheus.exporters.node.port}"
            #"[${listenAddress}:${toString prometheus.exporters.smokeping.port}"
            "${listenAddress}:${toString prometheus.exporters.systemd.port}"
            #"${listenAddress}:${toString prometheus.exporters.wireguard.port}"
          ];
        }
      ];
    }
  ];
  /*
  alertmanagers = [
    {
      static_configs = [ { targets = [ "${listenAddress}:9093" ]; } ];
    }
  ];
  alertmanager = {
    enable = true;
    inherit listenAddress;
    configuration = {
      global = {
        "smtp_smarthost" = "localhost:25";
        "smtp_require_tls" = false;
        "smtp_from" = "alertmanager@${domain}";
      };
      route = {
        "group_by" = [ "alertname" "alias" ];
        "group_wait" = "30s";
        "group_interval" = "2m";
        "repeat_interval" = "12h";
        "receiver" = "root";
      };
      receivers = [
        {
          "name" = "root";
          "email_configs" = [
            {
              "to" = "root+alertmanager@${domain}";
              "send_resolved" = true;
            }
          ];
        }
      ];
    };
  };
  rules = [
    ''
      groups:
        - name: custom_rules
          rules:
            - record: battery_percent
              expr: 100 * battery_energy_now / battery_energy_full
            - alert: battery_soon_out
              expr: predict_linear(battery_percent[30m], 3600) <= 10
              for: 5m
              labels:
                severity: warning
              annotations:
                summary: "Instance [{{ $labels.instance }}] battery about 1h left"
                description: "[{{ $labels.instance }}] battery in 1h estimated to {{ $value }}%"
    ''
  ];
  */
};
services.grafana = {
  enable = true;
  addr = listenAddress;
  port = 3000;
  analytics.reporting.enable = false;
  extraOptions = {
    ANALYTICS_CHECK_FOR_UPDATES = "false";
  };
};
# override systemd exporter execstart to enable option...
# FIXME: use extraFlags
systemd.services.prometheus-systemd-exporter.serviceConfig = {
  ExecStart = lib.mkForce ''
    ${pkgs.prometheus-systemd-exporter}/bin/systemd_exporter \
      --web.listen-address=${listenAddress}:${toString prometheus.exporters.systemd.port} \
      --collector.enable-ip-accounting \
      --collector.enable-restart-count
  '';
};
}