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


let
  cfg = config.bagel.services.forgejo;
  inherit (lib) mkIf mkEnableOption mkOption types;

  domain = "git.forkos.org";
in
{
  options.bagel.services.forgejo = {
    enable = mkEnableOption "Forgejo";
    sshBindAddr = mkOption {
      type = types.str;
    };
  };

  config = mkIf cfg.enable {
    services.forgejo = {
      enable = true;

      package = pkgs.callPackage ../../pkgs/forgejo { };

      database = {
        type = "postgres";
        createDatabase = true;
      };

      lfs.enable = true;

      settings = {
        DEFAULT = {
          APP_NAME = "ForkOS";
        };

        server = {
          PROTOCOL = "http+unix";
          ROOT_URL = "https://${domain}/";
          DOMAIN = "${domain}";

          BUILTIN_SSH_SERVER_USER = "git";
          SSH_PORT = 22;
          SSH_LISTEN_HOST = cfg.sshBindAddr;
          START_SSH_SERVER = true;
        };

        session = {
          PROVIDER = "db";
          COOKIE_NAME = "session";
        };

        service = {
          DISABLE_REGISTRATION = true;
          DEFAULT_KEEP_EMAIL_PRIVATE = true;
        };

        oauth2_client = {
          REGISTER_EMAIL_CONFIRM = false;
          ENABLE_AUTO_REGISTRATION = true;
        };

        # TODO: transactional mails
        # TODO: redis cache instead of default in-memory

        ui = {
          SHOW_USER_EMAIL = false;
        };

        repository = {
          # Forks in forgejo are suprisingly expensive because they are full git clones.
          # If we do want to enable forks, we can write a small patch that disables
          # only for repositories that are as large as nixpkgs.
          DISABLE_FORKS = true;
        };

        packages = {
          # Forgejo's various package registries can easily take up a lot of space.
          # We could either store the blobs on some slower disks but larger, or even
          # better, use an s3 bucket for it. But until we actually have a use-case for
          # this feature, we will simply keep it disabled for now.
          ENABLED = false;
        };

        indexer = {
          REPO_INDEXER_REPO_TYPES = "sources,mirrors,templates"; # skip forks
          REPO_INDEXER_ENABLED = true;
          ISSUE_INDEXER_TYPE = "bleve";
        };

        "git.timeout" = {
          MIGRATE = 3600; # increase from default 600 (seconds) for something as large as nixpkgs on a slow uplink
        };

        log = {
          LEVEL = "Warn";
        };
      };
    };

    systemd.services.forgejo = {
      serviceConfig = lib.optionalAttrs (config.services.forgejo.settings.server.SSH_PORT < 1024) {
        AmbientCapabilities = lib.mkForce "CAP_NET_BIND_SERVICE";
        CapabilityBoundingSet = lib.mkForce "CAP_NET_BIND_SERVICE";
        PrivateUsers = lib.mkForce false;
      };

      # start Forgejo *after* sshd.service, so in case Forgejo tries to wildcard bind :22 due to
      # a bug or whatever, we don't lose OpenSSH in a race.
      wants = [ "sshd.service" ];
      requires = [ "sshd.service" ];
    };

    services.nginx = {
      enable = true;
      virtualHosts.${domain} = {
        enableACME = true;
        forceSSL = true;
        locations."/".proxyPass = "http://unix:${config.services.forgejo.settings.server.HTTP_ADDR}";
      };
    };

    networking.firewall.allowedTCPPorts = [
      80
      443
      config.services.forgejo.settings.server.SSH_PORT
    ];
  };
}