{ config, lib, ... }:
with lib;
let
  cfg = config.services.xin-monitoring;
  inherit (builtins)
    readFile concatStringsSep attrValues mapAttrs replaceStrings;

  nginxCfg = config.services.nginx;
  buildFSChecker = fsList:
    (concatStringsSep "\n" (attrValues (mapAttrs (f: _: ''
      check filesystem ${replaceStrings [ "/" ] [ "_" ] f} with path ${f}
         if space usage > 90% then alert
         if inode usage > 90% then alert
    '') fsList)));
  buildNginxChecker = vhostList:
    (concatStringsSep "\n" (attrValues (mapAttrs (f: v: ''
      check host ${f} with address ${f}
          if failed port 80 protocol http then alert
          ${
            if v.enableACME then
              "if failed port 443 protocol https then alert"
            else
              ""
          }
    '') vhostList)));
  nginxChecks = if nginxCfg.enable then
    if config.networking.hostName == "h" then
      (buildNginxChecker nginxCfg.virtualHosts)
    else
      ""
  else
    "";

in {
  options = {
    services.xin-monitoring = {
      enable = mkOption {
        type = types.bool;
        default = true;
        description = "Enable Monitoring";
      };
      fs = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Create monitoring entry points from `config.fileSystems`.
        '';
      };
      nginx = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Create monitoring entry points from `services.nginx.virtualHosts`.
        '';
      };
    };
  };
  config = mkIf cfg.enable {
    sops.secrets = {
      monit_cfg = {
        sopsFile = config.xin-secrets.deploy;
        owner = "root";
        mode = "400";
      };
    };
    services.monit = {
      enable = true;
      config = concatStrings [
        (readFile ./monitrc)
        (optionalString cfg.fs (buildFSChecker config.fileSystems))
        (optionalString cfg.nginx nginxChecks)
      ];
    };
  };
}