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

with lib;

let
  cfg = config.services.postfix-mta-sts-resolver;
in {
  options = {
    services.postfix-mta-sts-resolver = {
      enable = mkEnableOption "mta-sts-daemon";
      package = mkPackageOption pkgs "postfix-mta-sts-resolver";

      redis = mkEnableOption "redis cache" // { default = true; example = false; };

      settings = mkOption {
        type = types.attrs;
      };
    };
  };

  config = mkIf cfg.enable {
    services.postfix-mta-sts-resolver.settings.path = "/run/postfix-mta-sts-resolver/map.sock";
    services.postfix-mta-sts-resolver.settings.mode = 432; # 0o0660
    
    services.postfix-mta-sts-resolver.settings.cache = mkIf cfg.redis {
      redis.url = "unix://${toString config.services.redis.servers.postfix-mta-sts-resolver.unixSocket}";
    };

    services.redis.servers.postfix-mta-sts-resolver = mkIf cfg.redis {
      enable = true;
    };

    users.users.postfix-mta-sts-resolver = {
      isSystemUser = true;
      group = "postfix-mta-sts-resolver";
    };
    users.groups.postfix-mta-sts-resolver = {
      members = ["postfix"];
    };

    systemd.services."postfix-mta-sts-resolver" = {
      wantedBy = ["postfix.service"];
      before = ["postfix.service"];

      serviceConfig = {
        ExecStart = "${pkgs.postfix-mta-sts-resolver}/bin/mta-sts-daemon -c ${pkgs.writeText "mta-sts-daemon.yml" (generators.toYAML {} cfg.settings)}";
        SupplementaryGroups = mkIf cfg.redis config.services.redis.servers.postfix-mta-sts-resolver.user;
        RuntimeDirectory = "postfix-mta-sts-resolver";

        User = "postfix-mta-sts-resolver";
        Group = "postfix-mta-sts-resolver";

        RemoveIPC = true;
        PrivateTmp = true;
        NoNewPrivileges = true;
        RestrictSUIDSGID = true;
        ProtectSystem = "strict";
        ProtectHome = "read-only";
        ReadWritePaths = mkIf cfg.redis ["/run/redis-postfix-mta-sts-resolver"];
      };
    };
  };
}