{ config, pkgs, lib, ... }:

with lib;

let
  hostname = config.networking.hostName;

  nginxVHosts = config.services.nginx.virtualHosts or {};
  allDomains = lib.attrNames nginxVHosts;
  httpsDomains = lib.map (d: "https://${d}") allDomains;
  domainsString = builtins.concatStringsSep "\n          "
    (map (d: "\"${d}\",") httpsDomains);
in {
  config = {
    # Systemd service for Blackbox Exporter
    systemd.services.blackbox-exporter = {
      description = "Blackbox Exporter";
      after = [ "network-online.target" ];
      wantedBy = [ "multi-user.target" ];
      serviceConfig.ExecStart = ''
        ${pkgs.prometheus-blackbox-exporter}/bin/blackbox_exporter \
          --config.file=/etc/blackbox_exporter/blackbox.yml
      '';
    };

    # Configuration file for Blackbox Exporter
    environment.etc."blackbox_exporter/blackbox.yml".text = ''
      modules:
        http_2xx:
          prober: http
    '';

    # Add scrape config for VictoriaMetrics agent
    services.victoriametrics.extraScrapeConfigs = [
      ''
        - job_name: "blackbox_http_all_domains"
          metrics_path: "/probe"
          params:
            module: ["http_2xx"]

          static_configs:
            - targets:
                [
                  ${domainsString}
                ]

          relabel_configs:
            - source_labels: ["__address__"]
              target_label: "__param_target"
              regex: '(.*)'
              replacement: "$1"
            - source_labels: ["__param_target"]
              target_label: "instance"
            - target_label: "__address__"
              replacement: "127.0.0.1:9115"
            - source_labels: ["__address__"]
              regex: "127\\.0\\.0\\.1:9115"
              target_label: "__scheme__"
              replacement: "http"
      ''
    ];
  };
}