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

with lib;
let
  backplane-auth = "/etc/nixos/static/backplane-auth.scm";

  cert-basedir = "/var/lib/ejabberd/certs";

  target-certs = ["key" "cert" "chain" "fullchain"];

  cert-origin = hostname: filename: "/var/lib/acme/${hostname}/${filename}.pem";
  cert-target = hostname: filename: "${cert-basedir}/${hostname}-${filename}.pem";

  move-server-certs = hostnames:
    let
      move-server-cert = hostname:
        map (filename: ''
          ensure_exists ${cert-origin hostname filename}
          cp -L ${cert-origin hostname filename} ${cert-target hostname filename}
        '')
          target-certs;
    in pkgs.writeShellScript "move-server-certs" ''
      function ensure_exists() {
        FILENAME=$1
        if [ ! -e $FILENAME ]; then
          echo "file does not exist: $FILENAME"
          exit 1
        fi
      }

      if [ -d ${cert-basedir} ]; then
        mkdir ${cert-basedir}
      fi

      ${concatStringsSep "\n" (concatMap move-server-cert hostnames)}

      chown -R ${config.services.ejabberd.user}:${config.services.ejabberd.group} ${cert-basedir}

      exit 0
    '';

  remove-server-certs = pkgs.writeShellScript "ejabberd-rm-combined-certs" ''
    rm ${cert-basedir}/*.pem
  '';


in {
  config = {

    security.acme.certs."fudo.im".email = "admin@fudo.org";
    security.acme.certs."backplane.fudo.org".email = "admin@fudo.org";

    systemd.services = {
      ejabberd-generate-certs = {
        enable = true;
        description = "Generate required SSL certs for ejabberd.";
        wantedBy = [ "ejabberd.service" ];
        after = [
          "acme-backplane.fudo.org.service"
          "acme-fudo.im.service"
        ];

        serviceConfig = {
          Type = "oneshot";
          ExecStart = "${move-server-certs ["fudo.im" "backplane.fudo.org"]}";
          RemainAfterExit = true;
          ExecStop = remove-server-certs;
          StandardOutput = "journal";
        };
      };

      ejabberd = {
        requires = [ "ejabberd-generate-certs.service" ];
        environment = {
          FUDO_HOST_PASSWD_FILE = "/srv/jabber/secret/hosts-passwd.scm";
          FUDO_SERVICE_PASSWD_FILE = "/srv/jabber/secret/services-passwd.scm";
        };
      };
    };

    services = {
      nginx = {
        virtualHosts = {
          "backplane.fudo.org" = {
            enableACME = true;
          };

          "fudo.im" = {
            enableACME = true;
          };
        };
      };

      ejabberd = {
        enable = true;

        configFile = pkgs.writeText "ejabberd-config.yml" (builtins.toJSON {
          loglevel = 4;

          access_rules = {
            c2s = { allow = "all"; };
            announce = { allow = "admin"; };
            configure = { allow = "admin"; };
            pubsub_createnode = { allow = "local"; };
          };

          acl = {
            admin = {
              user = [
                "niten@fudo.org"
              ];
            };
          };

          hosts = [
            "fudo.im"
            "backplane.fudo.org"
          ];

          listen = [
            {
              port = 5222;
              module = "ejabberd_c2s";
              ip = "0.0.0.0";
              starttls = true;
              starttls_required = true;
            }
          ];

          certfiles =
            concatMap (hostname: map (filename: cert-target hostname filename) target-certs)
              ["fudo.im" "backplane.fudo.org"];

          host_config = {
            "fudo.im" = {
              auth_method = "ldap";
              ldap_servers = ["auth.fudo.org"];
              ldap_port = 389;
              ldap_rootdn = "cn=jabber,dc=fudo,dc=org";
              ldap_password = fileContents /srv/jabber/secret/ldap.passwd;
              ldap_base = "ou=members,dc=fudo,dc=org";
              ldap_filter = "(objectClass=posixAccount)";
              ldap_uids = { uid = "%u"; };

              modules = {
                mod_adhoc = {};
                mod_announce = {};
                mod_avatar = {};
                mod_blocking = {};
                mod_caps = {};
                mod_carboncopy = {};
                mod_client_state = {};
                mod_configure = {};
                mod_disco = {};
                mod_fail2ban = {};
                mod_last = {};
                mod_offline = {
                  access_max_user_messages = 5000;
                };
                mod_ping = {};
                mod_privacy = {};
                mod_private = {};
                mod_pubsub = {
                  access_createnode = "pubsub_createnode";
                  ignore_pep_from_offline = true;
                  last_item_cache = false;
                  plugins = [
                    "flat"
                    "pep"
                  ];
                };
                mod_roster = {};
                mod_stream_mgmt = {};
                mod_time = {};
                mod_vcard = {
                  search = false;
                };
                mod_vcard_xupdate = {};
                mod_version = {};
              };
            };

            "backplane.fudo.org" = {
              auth_method = "external";
              extauth_program = "${pkgs.guile}/bin/guile -s ${backplane-auth}";
              extauth_pool_size = 3;
              auth_use_cache = true;

              modules = {
                mod_adhoc = {};
                mod_caps = {};
                mod_carboncopy = {};
                mod_client_state = {};
                mod_configure = {};
                mod_disco = {};
                mod_fail2ban = {};
                mod_last = {};
                mod_offline = {
                  access_max_user_messages = 5000;
                };
                mod_ping = {};
                mod_pubsub = {
                  access_createnode = "pubsub_createnode";
                  ignore_pep_from_offline = true;
                  last_item_cache = false;
                  plugins = [
                    "flat"
                    "pep"
                  ];
                };
                mod_roster = {};
                mod_stream_mgmt = {};
                mod_time = {};
                mod_version = {};
              };
            };
          };
        });
      };
    };
  };
}