# Workadventure NixOS module. Used to deploy fediventure-compatible instances.

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

with lib;

let
  cfg = config.services.workadventure;

  servicesBack = mapAttrs' (instanceName: instanceConfig: {
    name = "wa-back-${instanceName}";
    value = {
      description = "WorkAdventure backend ${instanceName}";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" ];
      # Hack to get node-grpc-precompiled to work on NixOS by adding getconf to
      # $PATH.
      #
      # It uses node-pre-gyp which attempts to select the right native module
      # via npmjs.com/package/detect-libc, which says 'yep, it's glibc' as long
      # as `getconf GNU_LIBC_VERSION` returns something sensible. This happens
      # during the build process (as stdenv.mkDerivation has enough of a glibc
      # dev env to make it work) but doesn't happen on production deployments
      # in which the environment is much more limited. This is regardless of
      # actual glibc ABI presence wrt. to /nix/store vs. /usr/lib64 paths.
      #
      # This should be fixed in workadventure-nix.
      path = [
        pkgs.getconf
      ];
      environment = {
        HTTP_PORT = toString instanceConfig.backend.httpPort;
        GRPC_PORT = toString instanceConfig.backend.grpcPort;
      };
      serviceConfig = {
        User = "workadventure-backend";
        Group = "workadventure-backend";
        DynamicUser = true; # Note: this implies a lot of other security features.
        ExecStart = "${instanceConfig.backend.package}/bin/workadventureback";
        Restart = "always";
        RestartSec = "10s";
      };
    };
  }) cfg.instances;

  servicesPusher = mapAttrs' (instanceName: instanceConfig: {
    name = "wa-pusher-${instanceName}";
    value = {
      description = "WorkAdventure pusher ${instanceName}";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" ];

      path = [
        pkgs.getconf
      ];
      environment = {
        PUSHER_HTTP_PORT = toString instanceConfig.pusher.port;
        API_URL = "localhost:${toString instanceConfig.backend.grpcPort}";
      };
      serviceConfig = {
        User = "workadventure-pusher";
        Group = "workadventure-pusher";
        DynamicUser = true;
        ExecStart = "${instanceConfig.pusher.package}/bin/workadventurepusher";
        Restart = "always";
        RestartSec = "10s";
      };
    };
  }) cfg.instances;

  frontPackage = mapAttrs (instanceName: instanceConfig:
    instanceConfig.frontend.package.override {
      environment = {
        API_URL = instanceConfig.frontend.urls.api;
        UPLOADER_URL = instanceConfig.frontend.urls.uploader;
        ADMIN_URL = instanceConfig.frontend.urls.admin;
        MAPS_URL = instanceConfig.frontend.urls.maps;
      } // (if instanceConfig.frontend.defaultMap == null then {} else { DEFAULT_MAP_URL = instanceConfig.frontend.defaultMap; });
    }
  ) cfg.instances;

  virtualHosts = mapAttrs (instanceName: instanceConfig:
    if instanceConfig.nginx.domain != null then {
      default = instanceConfig.nginx.default;
      serverName = instanceConfig.nginx.domain;
      root = frontPackage.${instanceName} + "/dist";
      locations = {
        "/_/" = {
          tryFiles = "/index.html =404";
        };

        "/pusher/" = {
          proxyPass = "http://localhost:${toString instanceConfig.pusher.port}/";
        };

        "/maps/" = mkIf instanceConfig.nginx.serveDefaultMaps {
          alias = instanceConfig.maps.path;
        };
      };
    } else
      # TODO: Configuration with separate domains is unsupported for now.
      # Not sure if there's any interest in that anyway.
      builtins.throw "Configurations with separate domains are not supported yet"
  ) cfg.instances;
in {
  options = {
    services.workadventure = rec {
      instances = mkOption {
        type = types.attrsOf (types.submodule (import ./instance-options.nix {
          inherit config lib;
        }));
        default = {};
        description = "Declarative WorkAdventure instance config";
      };
      nginx = {
        enable = mkOption {
          default = true;
          type = types.bool;
          description = "Whether to enable nginx and configure it to serve the instances";
        };
      };
    };
  };

  config = {
    assertions = mapAttrsToList (name: instance: {
      assertion = !cfg.nginx.enable
               || (instance.nginx.domain != null && all (d: d == null) (attrValues instance.nginx.domains))
               || (instance.nginx.domain == null && all (d: d != null) (attrValues instance.nginx.domains));
               message = "In instance ${name}, you have to either define nginx.domain or all attributes of nginx.domains";
    }) cfg.instances;
    systemd.services = servicesBack // servicesPusher;
    services.nginx = mkIf cfg.nginx.enable {
      inherit virtualHosts;
      enable = mkDefault true;
    };
  };
}