# somewhat adapted from https://github.com/NixOS/nixpkgs/pull/59211
{ config, lib, pkgs, ... }:
let
  synapseCfg = config.services.matrix-synapse.settings;
in
let
  config = rec {
    homeserver = {
      address = synapseCfg.public_baseurl;
      domain = synapseCfg.server_name;
    };
    appservice = rec {
      hostname = "127.0.0.1";
      port = 29318;
      address = "http://${hostname}:${toString port}";
      provisioning.shared_secret = "disable";
      database = {
        type = "sqlite3";
        uri = "/var/lib/mautrix-whatsapp/mautrix-whatsapp.db";
      };
      id = "whatsapp";
      bot = {
        username = "whatsappbot";
        displayname = "WhatsApp bridge bot";
        avatar = "mxc://maunium.net/NeXNQarUbrlYBiPCpprYsRqr";
      };
    };
    whatsapp = {
      browser_name = "mx-wa";
      os_name = "Mautrix-WhatsApp bridge";
    };
    bridge = {
      command_prefix = "!wa";
      delivery_receipts = true;
      displayname_template = "{{if .FullName}}{{.FullName}}{{else if .Notify}}{{.Notify}}{{else}}{{.Jid}}{{end}} (WA)";
      history_sync = {
        backfill = true;
      };
      identity_change_notices = true;
      permissions = {
        # Only one user since using the name from the address book does not
        # work with multiple users
        "@simon:${homeserver.domain}" = 100;
      };
      private_chat_portal_meta = true;
      reaction_notices = true;
      relay.enable = false;
    };
    logging.print_level = "info";
  };

  generatedConfig = pkgs.runCommandNoCC "mautrix-whatsapp-config"
    {
      buildInputs = with pkgs; [ mautrix-whatsapp ];
    }
    ''
      mkdir $out
      cat ${pkgs.writeText "mautrix-whatsapp.yaml" (lib.generators.toYAML { } config)} > $out/config.yaml
      mautrix-whatsapp -c $out/config.yaml -g -r $out/registration.yaml
    '';
in
{
  systemd.services.mautrix-whatsapp = {
    description = "Mautrix-WhatsApp Service - A WhatsApp bridge for Matrix";
    after = [ "network.target" "matrix-synapse.service" ];
    wantedBy = [ "multi-user.target" ];

    serviceConfig = {
      DynamicUser = true;
      StateDirectory = "mautrix-whatsapp";
      WorkingDirectory = "/var/lib/mautrix-whatsapp";
      ExecStart = "${pkgs.mautrix-whatsapp}/bin/mautrix-whatsapp -c ${generatedConfig}/config.yaml";
      Restart = "on-failure";
    };
  };

  services.matrix-synapse.settings.app_service_config_files = lib.singleton "${generatedConfig}/registration.yaml";
}