{
  config,
  lib,
  pkgs,
  ...
}:
let
  cfg = config.services.awstats;
  package = pkgs.awstats;
  configOpts =
    { name, config, ... }:
    {
      options = {
        type = lib.mkOption {
          type = lib.types.enum [
            "mail"
            "web"
          ];
          default = "web";
          example = "mail";
          description = ''
            The type of log being collected.
          '';
        };
        domain = lib.mkOption {
          type = lib.types.str;
          default = name;
          description = "The domain name to collect stats for.";
          example = "example.com";
        };

        logFile = lib.mkOption {
          type = lib.types.str;
          example = "/var/log/nginx/access.log";
          description = ''
            The log file to be scanned.

            For mail, set this to
            ```
            journalctl $OLD_CURSOR -u postfix.service | ''${pkgs.perl}/bin/perl ''${pkgs.awstats.out}/share/awstats/tools/maillogconvert.pl standard |
            ```
          '';
        };

        logFormat = lib.mkOption {
          type = lib.types.str;
          default = "1";
          description = ''
            The log format being used.

            For mail, set this to
            ```
            %time2 %email %email_r %host %host_r %method %url %code %bytesd
            ```
          '';
        };

        hostAliases = lib.mkOption {
          type = lib.types.listOf lib.types.str;
          default = [ ];
          example = [ "www.example.org" ];
          description = ''
            List of aliases the site has.
          '';
        };

        extraConfig = lib.mkOption {
          type = lib.types.attrsOf lib.types.str;
          default = { };
          example = lib.literalExpression ''
            {
              "ValidHTTPCodes" = "404";
            }
          '';
          description = "Extra configuration to be appended to awstats.\${name}.conf.";
        };

        webService = {
          enable = lib.mkEnableOption "awstats web service";

          hostname = lib.mkOption {
            type = lib.types.str;
            default = config.domain;
            description = "The hostname the web service appears under.";
          };

          urlPrefix = lib.mkOption {
            type = lib.types.str;
            default = "/awstats";
            description = "The URL prefix under which the awstats pages appear.";
          };
        };
      };
    };
  webServices = lib.filterAttrs (name: value: value.webService.enable) cfg.configs;
in
{
  imports = [
    (lib.mkRemovedOptionModule [
      "services"
      "awstats"
      "service"
      "enable"
    ] "Please enable per domain with `services.awstats.configs.<name>.webService.enable`")
    (lib.mkRemovedOptionModule [
      "services"
      "awstats"
      "service"
      "urlPrefix"
    ] "Please set per domain with `services.awstats.configs.<name>.webService.urlPrefix`")
    (lib.mkRenamedOptionModule [ "services" "awstats" "vardir" ] [ "services" "awstats" "dataDir" ])
  ];

  options.services.awstats = {
    enable = lib.mkEnableOption "awstats, a real-time logfile analyzer";

    dataDir = lib.mkOption {
      type = lib.types.path;
      default = "/var/lib/awstats";
      description = "The directory where awstats data will be stored.";
    };

    configs = lib.mkOption {
      type = lib.types.attrsOf (lib.types.submodule configOpts);
      default = { };
      example = lib.literalExpression ''
        {
          "mysite" = {
            domain = "example.com";
            logFile = "/var/log/nginx/access.log";
          };
        }
      '';
      description = "Attribute set of domains to collect stats for.";
    };

    updateAt = lib.mkOption {
      type = lib.types.nullOr lib.types.str;
      default = null;
      example = "hourly";
      description = ''
        Specification of the time at which awstats will get updated.
        (in the format described by {manpage}`systemd.time(7)`)
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    environment.systemPackages = [ package.bin ];

    environment.etc = lib.mapAttrs' (
      name: opts:
      lib.nameValuePair "awstats/awstats.${name}.conf" {
        source = pkgs.runCommand "awstats.${name}.conf" { preferLocalBuild = true; } (
          ''
            sed \
          ''
          # set up mail stats
          + lib.optionalString (opts.type == "mail") ''
            -e 's|^\(LogType\)=.*$|\1=M|' \
            -e 's|^\(LevelForBrowsersDetection\)=.*$|\1=0|' \
            -e 's|^\(LevelForOSDetection\)=.*$|\1=0|' \
            -e 's|^\(LevelForRefererAnalyze\)=.*$|\1=0|' \
            -e 's|^\(LevelForRobotsDetection\)=.*$|\1=0|' \
            -e 's|^\(LevelForSearchEnginesDetection\)=.*$|\1=0|' \
            -e 's|^\(LevelForFileTypesDetection\)=.*$|\1=0|' \
            -e 's|^\(LevelForWormsDetection\)=.*$|\1=0|' \
            -e 's|^\(ShowMenu\)=.*$|\1=1|' \
            -e 's|^\(ShowSummary\)=.*$|\1=HB|' \
            -e 's|^\(ShowMonthStats\)=.*$|\1=HB|' \
            -e 's|^\(ShowDaysOfMonthStats\)=.*$|\1=HB|' \
            -e 's|^\(ShowDaysOfWeekStats\)=.*$|\1=HB|' \
            -e 's|^\(ShowHoursStats\)=.*$|\1=HB|' \
            -e 's|^\(ShowDomainsStats\)=.*$|\1=0|' \
            -e 's|^\(ShowHostsStats\)=.*$|\1=HB|' \
            -e 's|^\(ShowAuthenticatedUsers\)=.*$|\1=0|' \
            -e 's|^\(ShowRobotsStats\)=.*$|\1=0|' \
            -e 's|^\(ShowEMailSenders\)=.*$|\1=HBML|' \
            -e 's|^\(ShowEMailReceivers\)=.*$|\1=HBML|' \
            -e 's|^\(ShowSessionsStats\)=.*$|\1=0|' \
            -e 's|^\(ShowPagesStats\)=.*$|\1=0|' \
            -e 's|^\(ShowFileTypesStats\)=.*$|\1=0|' \
            -e 's|^\(ShowFileSizesStats\)=.*$|\1=0|' \
            -e 's|^\(ShowBrowsersStats\)=.*$|\1=0|' \
            -e 's|^\(ShowOSStats\)=.*$|\1=0|' \
            -e 's|^\(ShowOriginStats\)=.*$|\1=0|' \
            -e 's|^\(ShowKeyphrasesStats\)=.*$|\1=0|' \
            -e 's|^\(ShowKeywordsStats\)=.*$|\1=0|' \
            -e 's|^\(ShowMiscStats\)=.*$|\1=0|' \
            -e 's|^\(ShowHTTPErrorsStats\)=.*$|\1=0|' \
            -e 's|^\(ShowSMTPErrorsStats\)=.*$|\1=1|' \
          ''
          +
            # common options
            ''
              -e 's|^\(DirData\)=.*$|\1="${cfg.dataDir}/${name}"|' \
              -e 's|^\(DirIcons\)=.*$|\1="icons"|' \
              -e 's|^\(CreateDirDataIfNotExists\)=.*$|\1=1|' \
              -e 's|^\(SiteDomain\)=.*$|\1="${name}"|' \
              -e 's|^\(LogFile\)=.*$|\1="${opts.logFile}"|' \
              -e 's|^\(LogFormat\)=.*$|\1="${opts.logFormat}"|' \
            ''
          +
            # extra config
            lib.concatStringsSep "\n" (
              lib.mapAttrsToList (n: v: ''
                -e 's|^\(${n}\)=.*$|\1="${v}"|' \
              '') opts.extraConfig
            )
          + ''
            < '${package.out}/wwwroot/cgi-bin/awstats.model.conf' > "$out"
          ''
        );
      }
    ) cfg.configs;

    # create data directory with the correct permissions
    systemd.tmpfiles.rules = [
      "d '${cfg.dataDir}' 755 root root - -"
    ]
    ++ lib.mapAttrsToList (name: opts: "d '${cfg.dataDir}/${name}' 755 root root - -") cfg.configs
    ++ [ "Z '${cfg.dataDir}' 755 root root - -" ];

    # nginx options
    services.nginx.virtualHosts = lib.mapAttrs' (name: opts: {
      name = opts.webService.hostname;
      value = {
        locations = {
          "${opts.webService.urlPrefix}/css/" = {
            alias = "${package.out}/wwwroot/css/";
          };
          "${opts.webService.urlPrefix}/icons/" = {
            alias = "${package.out}/wwwroot/icon/";
          };
          "${opts.webService.urlPrefix}/" = {
            alias = "${cfg.dataDir}/${name}/";
            extraConfig = ''
              autoindex on;
            '';
          };
        };
      };
    }) webServices;

    # update awstats
    systemd.services = lib.mkIf (cfg.updateAt != null) (
      lib.mapAttrs' (
        name: opts:
        lib.nameValuePair "awstats-${name}-update" {
          description = "update awstats for ${name}";
          script =
            lib.optionalString (opts.type == "mail") ''
              if [[ -f "${cfg.dataDir}/${name}-cursor" ]]; then
                CURSOR="$(cat "${cfg.dataDir}/${name}-cursor" | tr -d '\n')"
                if [[ -n "$CURSOR" ]]; then
                  echo "Using cursor: $CURSOR"
                  export OLD_CURSOR="--cursor $CURSOR"
                fi
              fi
              NEW_CURSOR="$(journalctl $OLD_CURSOR -u postfix.service --show-cursor | tail -n 1 | tr -d '\n' | sed -e 's#^-- cursor: \(.*\)#\1#')"
              echo "New cursor: $NEW_CURSOR"
              ${package.bin}/bin/awstats -update -config=${name}
              if [ -n "$NEW_CURSOR" ]; then
                echo -n "$NEW_CURSOR" > ${cfg.dataDir}/${name}-cursor
              fi
            ''
            + ''
              ${package.out}/share/awstats/tools/awstats_buildstaticpages.pl \
                -config=${name} -update -dir=${cfg.dataDir}/${name} \
                -awstatsprog=${package.bin}/bin/awstats
            '';
          startAt = cfg.updateAt;
        }
      ) cfg.configs
    );
  };

}