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

let
  secrets = import ./secrets.nix { inherit lib config; };
  cfg = config.services.spacebarchat-server;
  jsonFormat = pkgs.formats.json { };
  configFile =
    let
      endpointSettings = {
        api = {
          endpointPublic = "http${if cfg.apiEndpoint.useSsl then "s" else ""}://${cfg.apiEndpoint.host}:${toString cfg.apiEndpoint.publicPort}";
        };
        cdn = {
          endpointPublic = "http${if cfg.cdnEndpoint.useSsl then "s" else ""}://${cfg.cdnEndpoint.host}:${toString cfg.cdnEndpoint.publicPort}";
          endpointPrivate = "http://127.0.0.1:${toString cfg.cdnEndpoint.localPort}";
        };
        gateway = {
          endpointPublic = "ws${if cfg.gatewayEndpoint.useSsl then "s" else ""}://${cfg.gatewayEndpoint.host}:${toString cfg.gatewayEndpoint.publicPort}";
        };
        general = {
          serverName = cfg.serverName;
        };
      }
      // (
        if cfg.enableAdminApi then
          {
            adminApi = {
              endpointPublic = "http${if cfg.adminApiEndpoint.useSsl then "s" else ""}://${cfg.adminApiEndpoint.host}:${toString cfg.adminApiEndpoint.publicPort}";
            };
          }
        else
          { }
      );
    in
    jsonFormat.generate "spacebarchat-server.json" (lib.recursiveUpdate endpointSettings cfg.settings);
in
{
  imports = [
    ./integration-nginx.nix
    ./users.nix
    (import ./cs/gateway-offload-cs.nix self)
  ];
  options.services.spacebarchat-server =
    let
      mkEndpointOptions = import ./options-subtypes/mkEndpointOptions.nix { inherit lib; };
    in
    {
      enable = lib.mkEnableOption "Spacebar server";
      enableAdminApi = lib.mkEnableOption "Spacebar server Admin API";
      enableCdnCs = lib.mkEnableOption "Spacebar's experimental CDN rewrite";
      package = lib.mkPackageOption self.packages.${pkgs.stdenv.hostPlatform.system} "spacebar-server" { default = "default"; };
      databaseFile = lib.mkOption {
        type = lib.types.nullOr lib.types.path;
        default = null;
        description = ''
          Path to a file containing a definition of the `DATABASE` environment variable database connection string.
          Example content: `DATABASE=postgres://username:password@host-IP:port/databaseName`.
          See https://docs.spacebar.chat/setup/server/database/.
        '';
      };

      serverName = lib.mkOption {
        type = lib.types.str;
        description = "The server name for this Spacebar instance (aka. common name, usually the domain where your well known is hosted).";
      };
      adminApiEndpoint = mkEndpointOptions "admin-api.sb.localhost" 3004;
      apiEndpoint = mkEndpointOptions "api.sb.localhost" 3001;
      gatewayEndpoint = mkEndpointOptions "gateway.sb.localhost" 3003;
      cdnEndpoint = mkEndpointOptions "cdn.sb.localhost" 3003;
      cdnPath = lib.mkOption {
        type = lib.types.str;
        default = "./files";
        description = "Path to store CDN files.";
      };

      extraEnvironment = lib.mkOption {
        default = { };
        description = ''
          Environment variables passed to spacebarchat-server.
          See https://docs.spacebar.chat/setup/server/configuration/env for supported values.
        '';
        type = lib.types.submodule {
          freeformType =
            with lib.types;
            attrsOf (oneOf [
              str
              bool
              int
            ]);
          options = {
            THREADS = lib.mkOption {
              type = lib.types.ints.positive;
              default = 1;
              description = "Number of threads to run Spacebar on when using bundle. Make sure you've enabled RabbitMQ if using more than one.";
            };
          };
        };
      };

      settings = lib.mkOption {
        type = jsonFormat.type;
        default = { };
        description = ''
          Configuration for spacebarchat-server.
          See https://docs.spacebar.chat/setup/server/configuration for supported values.
        '';
      };
    }
    // secrets.options;

  config = lib.mkIf cfg.enable (
    let
      makeServerTsService = (
        conf:
        lib.recursiveUpdate
          (lib.recursiveUpdate {
            documentation = [ "https://docs.spacebar.chat/" ];
            wantedBy = [ "multi-user.target" ];
            wants = [ "network-online.target" ];
            after = [ "network-online.target" ];
            environment = secrets.systemdEnvironment;
            serviceConfig = {
              LoadCredential = secrets.systemdLoadCredentials;

              User = "spacebarchat";
              Group = "spacebarchat";
              DynamicUser = false;

              LockPersonality = true;
              NoNewPrivileges = true;

              ProtectClock = true;
              ProtectControlGroups = true;
              ProtectHostname = true;
              ProtectKernelLogs = true;
              ProtectKernelModules = true;
              ProtectKernelTunables = true;
              PrivateDevices = true;
              PrivateMounts = true;
              PrivateUsers = true;
              RestrictAddressFamilies = [
                "AF_INET"
                "AF_INET6"
                "AF_UNIX"
              ];
              RestrictNamespaces = true;
              RestrictRealtime = true;
              SystemCallArchitectures = "native";
              SystemCallFilter = [
                "@system-service"
                "~@privileged"
                "@chown" # Required for copying files with FICLONE, apparently.
              ];
              CapabilityBoundingSet = [
                "~CAP_SYS_ADMIN"
                "~CAP_AUDIT_*"
                "~CAP_NET_(BIND_SERVICE|BROADCAST|RAW)"
                "~CAP_NET_ADMIN" # No use for this as we don't currently use iptables for enforcing instance bans
                "~CAP_SYS_TIME"
                "~CAP_KILL"
                "~CAP_(DAC_*|FOWNER|IPC_OWNER)"
                "~CAP_LINUX_IMMUTABLE"
                "~CAP_IPC_LOCK"
                "~CAP_BPF"
                "~CAP_SYS_TTY_CONFIG"
                "~CAP_SYS_BOOT"
                "~CAP_SYS_CHROOT"
                "~CAP_BLOCK_SUSPEND"
                "~CAP_LEASE"
                "~CAP_(CHOWN|FSETID|FSETFCAP)" # Check if we need CAP_CHOWN for `fchown()` (FICLONE)?
                "~CAP_SET(UID|GID|PCAP)"
                "~CAP_MAC_*"
                "~CAP_SYS_PTRACE"
                "~CAP_SYS_(NICE|RESOURCE)"
                "~CAP_SYS_RAWIO"
                "~CAP_SYSLOG"
              ];
              RestrictSUIDSGID = true;

              WorkingDirectory = "/var/lib/spacebar";
              StateDirectory = "spacebar";
              StateDirectoryMode = "0750";
              RuntimeDirectory = "spacebar";
              RuntimeDirectoryMode = "0750";
              ReadWritePaths = [ cfg.cdnPath ];
              NoExecPaths = [ cfg.cdnPath ];

              Restart = "on-failure";
              RestartSec = 10;
              StartLimitBurst = 5;
              UMask = "077";
            }
            // lib.optionalAttrs (cfg.databaseFile != null) { EnvironmentFile = cfg.databaseFile; };
          } conf)
          {
          }
      );
    in
    {
      assertions = [
        #        {
        #          assertion = lib.all (map (key: !(key == "CONFIG_PATH" || key == "CONFIG_READONLY" || key == "PORT" || key == "STORAGE_LOCATION")) (lib.attrNames cfg.extraEnvironment));
        #          message = "You cannot set CONFIG_PATH, CONFIG_READONLY, PORT or STORAGE_LOCATION in extraEnvironment, these are managed by the NixOS module.";
        #        }
      ];

      systemd.services.spacebar-api = makeServerTsService {
        description = "Spacebar Server - API";
        environment = builtins.mapAttrs (_: val: builtins.toString val) (
          {
            # things we set by default...
            EVENT_TRANSMISSION = "unix";
            EVENT_SOCKET_PATH = "/run/spacebar/";
          }
          // cfg.extraEnvironment
          // {
            # things we force...
            CONFIG_PATH = configFile;
            CONFIG_READONLY = 1;
            PORT = toString cfg.apiEndpoint.localPort;
            STORAGE_LOCATION = cfg.cdnPath;
          }
        );
        serviceConfig = {
          ExecStart = "${cfg.package}/bin/start-api";
        };
      };

      systemd.services.spacebar-gateway = makeServerTsService {
        description = "Spacebar Server - Gateway";
        environment = builtins.mapAttrs (_: val: builtins.toString val) (
          {
            # things we set by default...
            EVENT_TRANSMISSION = "unix";
            EVENT_SOCKET_PATH = "/run/spacebar/";
          }
          // cfg.extraEnvironment
          // {
            # things we force...
            CONFIG_PATH = configFile;
            CONFIG_READONLY = 1;
            PORT = toString cfg.gatewayEndpoint.localPort;
            STORAGE_LOCATION = cfg.cdnPath;
            APPLY_DB_MIGRATIONS = "false";
          }
        );
        serviceConfig = {
          ExecStart = "${cfg.package}/bin/start-gateway";
        };
      };

      systemd.services.spacebar-cdn = lib.mkIf (!cfg.enableCdnCs) (makeServerTsService {
        description = "Spacebar Server - CDN";
        environment = builtins.mapAttrs (_: val: builtins.toString val) (
          {
            # things we set by default...
            EVENT_TRANSMISSION = "unix";
            EVENT_SOCKET_PATH = "/run/spacebar/";
          }
          // cfg.extraEnvironment
          // {
            # things we force...
            CONFIG_PATH = configFile;
            CONFIG_READONLY = 1;
            PORT = toString cfg.cdnEndpoint.localPort;
            STORAGE_LOCATION = cfg.cdnPath;
            APPLY_DB_MIGRATIONS = "false";
          }
        );
        serviceConfig = {
          ExecStart = "${cfg.package}/bin/start-cdn";
        };
      });
    }
  );
}