nixos/hosts/fw/modules/web/matrix.nix

{ pkgs, lib, config, ... }:
let
  hostname = "matrix";
  fqdn = "${hostname}.cloonar.com";
  baseUrl = "https://${fqdn}";
  clientConfig."m.homeserver".base_url = baseUrl;
  serverConfig."m.server" = "${fqdn}:443";
  mkWellKnown = data: ''
    default_type application/json;
    add_header Access-Control-Allow-Origin *;
    return 200 '${builtins.toJSON data}';
  '';
in {
  # Secrets for Synapse
  sops.secrets.synapse-oidc-client-secret = {
    owner = "matrix-synapse";
  };
  sops.secrets.mautrix-whatsapp-env = { };
  sops.secrets.mautrix-signal-env = { };
  sops.secrets.mautrix-discord-env = { };

  # PostgreSQL database for Synapse
  services.postgresql = {
    enable = true;
    # Synapse requires C locale for correct collation behavior
    initdbArgs = [ "--lc-collate=C" "--lc-ctype=C" ];
    ensureDatabases = [ "matrix-synapse" ];
    ensureUsers = [
      {
        name = "matrix-synapse";
        ensureDBOwnership = true;
      }
    ];
  };

  services.postgresqlBackup.enable = true;
  services.postgresqlBackup.databases = [ "matrix-synapse" ];

  # Synapse homeserver
  services.matrix-synapse = {
    enable = true;
    settings = {
      server_name = "cloonar.com";
      public_baseurl = baseUrl;

      listeners = [
        {
          port = 8008;
          bind_addresses = [ "::1" ];
          type = "http";
          tls = false;
          x_forwarded = true;
          resources = [
            {
              compress = true;
              names = [ "client" "federation" ];
            }
          ];
        }
      ];

      database = {
        name = "psycopg2";
        args = {
          host = "/run/postgresql";
          database = "matrix-synapse";
          user = "matrix-synapse";
        };
      };

      # Disable registration - users created via OIDC
      enable_registration = false;
      allow_guest_access = false;

      # OIDC SSO via Authelia
      oidc_providers = [
        {
          idp_id = "authelia";
          idp_name = "Authelia";
          discover = true;
          issuer = "https://auth.cloonar.com";
          user_profile_method = "userinfo_endpoint";
          client_id = "synapse";
          client_secret_path = config.sops.secrets.synapse-oidc-client-secret.path;
          scopes = [ "openid" "profile" "email" ];
          allow_existing_users = true;
          user_mapping_provider.config = {
            subject_claim = "sub";
            localpart_template = "{{ user.email | localpart_from_email }}";
            display_name_template = "{{ user.name }}";
            email_template = "{{ user.email }}";
          };
        }
      ];

    };
  };

  # Synapse runs inside an isolated microVM, so PrivateUsers provides minimal
  # additional security. Disabling it allows Synapse to read bridge registration
  # files via SupplementaryGroups (user namespace blocks mapped GIDs otherwise).
  systemd.services.matrix-synapse.serviceConfig.PrivateUsers = lib.mkForce false;

  # Element Web client
  services.nginx.virtualHosts."element.cloonar.com" = {
    forceSSL = true;
    enableACME = true;
    acmeRoot = null;
    root = pkgs.element-web.override {
      conf = {
        default_theme = "dark";
        default_server_config = {
          "m.homeserver" = {
            base_url = "https://matrix.cloonar.com";
            server_name = "cloonar.com";
          };
        };
        disable_custom_urls = true;
        disable_3pid_login = true;
        default_country_code = "AT";
      };
    };
  };

  # Synapse nginx reverse proxy
  services.nginx.virtualHosts."${fqdn}" = {
    forceSSL = true;
    enableACME = true;
    acmeRoot = null;
    locations."/".extraConfig = ''
      return 404;
    '';
    locations."= /.well-known/matrix/server".extraConfig = mkWellKnown serverConfig;
    locations."= /.well-known/matrix/client".extraConfig = mkWellKnown clientConfig;
    locations."/_matrix".proxyPass = "http://[::1]:8008";
    locations."/_synapse/client".proxyPass = "http://[::1]:8008";
  };

  #
  # Mautrix bridges (using NixOS modules)
  # Modules handle users, groups, registration files, Synapse integration,
  # and service ordering automatically via registerToSynapse.
  #

  # WhatsApp bridge
  services.mautrix-whatsapp = {
    enable = true;
    registerToSynapse = true;
    environmentFile = config.sops.secrets.mautrix-whatsapp-env.path;
    settings = {
      homeserver = {
        address = "http://[::1]:8008";
        domain = "cloonar.com";
      };
      bridge = {
        command_prefix = "!wa";
        permissions."*" = "relay";
        permissions."cloonar.com" = "user";
        relay.enabled = true;
      };
      encryption = {
        allow = true;
        default = true;
        require = true;
        pickle_key = "$MAUTRIX_WHATSAPP_PICKLE_KEY";
      };
    };
  };

  # Signal bridge
  services.mautrix-signal = {
    enable = true;
    registerToSynapse = true;
    environmentFile = config.sops.secrets.mautrix-signal-env.path;
    settings = {
      homeserver = {
        address = "http://[::1]:8008";
        domain = "cloonar.com";
      };
      bridge = {
        command_prefix = "!signal";
        permissions."*" = "relay";
        permissions."cloonar.com" = "user";
        relay.enabled = true;
      };
      encryption = {
        allow = true;
        default = true;
        require = true;
        pickle_key = "$MAUTRIX_SIGNAL_PICKLE_KEY";
      };
      matrix.sync_direct_chat_list = true;
    };
  };

  # Discord bridge
  services.mautrix-discord = {
    enable = true;
    registerToSynapse = true;
    environmentFile = config.sops.secrets.mautrix-discord-env.path;
    settings = {
      homeserver = {
        address = "http://[::1]:8008";
        domain = "cloonar.com";
      };
      bridge = {
        command_prefix = "!discord";
        permissions."*" = "relay";
        permissions."cloonar.com" = "user";
        relay.enabled = true;
      };
      # Override dummy token defaults so env var substitution writes real tokens
      # into the config and registration file (module defaults are placeholder strings)
      appservice = {
        as_token = "$MAUTRIX_DISCORD_AS_TOKEN";
        hs_token = "$MAUTRIX_DISCORD_HS_TOKEN";
      };
      encryption = {
        allow = true;
        default = true;
        require = true;
        pickle_key = "$MAUTRIX_DISCORD_PICKLE_KEY";
      };
    };
  };

}