import i18n, { InitOptions, TOptions } from "i18next";
import HttpBackend, { LoadPathOption } from "i18next-http-backend";
import { initReactI18next } from "react-i18next";
import type KeycloakAdminClient from "@keycloak/keycloak-admin-client";

import environment from "./environment";
import { getAuthorizationHeaders } from "./utils/getAuthorizationHeaders";
import { addTrailingSlash } from "./util";

export const DEFAULT_LOCALE = "en";

export async function initI18n(adminClient: KeycloakAdminClient) {
  const options = await initOptions(adminClient);
  await i18n.init(options);
}

const initOptions = async (
  adminClient: KeycloakAdminClient
): Promise<InitOptions> => {
  const constructLoadPath: LoadPathOption = (_, namespaces) => {
    if (namespaces[0] === "overrides") {
      return `${addTrailingSlash(adminClient.baseUrl)}admin/realms/${
        adminClient.realmName
      }/localization/{{lng}}?useRealmDefaultLocaleFallback=true`;
    } else {
      return `${environment.resourceUrl}/resources/{{lng}}/{{ns}}.json`;
    }
  };

  return {
    defaultNS: "common",
    fallbackLng: DEFAULT_LOCALE,
    preload: [DEFAULT_LOCALE],
    ns: [
      "common",
      "common-help",
      "attributes-group",
      "dashboard",
      "clients",
      "clients-help",
      "client-scopes",
      "client-scopes-help",
      "groups",
      "realm",
      "roles",
      "users",
      "users-help",
      "sessions",
      "events",
      "realm-settings",
      "realm-settings-help",
      "authentication",
      "authentication-help",
      "user-federation",
      "user-federation-help",
      "identity-providers",
      "identity-providers-help",
      "dynamic",
      "overrides",
    ],
    interpolation: {
      escapeValue: false,
    },
    postProcess: ["overrideProcessor"],
    backend: {
      loadPath: constructLoadPath,
      customHeaders: getAuthorizationHeaders(
        await adminClient.getAccessToken()
      ),
    },
  };
};

const configuredI18n = i18n
  .use({
    type: "postProcessor",
    name: "overrideProcessor",
    process: function (
      value: string,
      key: string,
      _: TOptions,
      translator: any
    ) {
      const override: string =
        translator.resourceStore.data[translator.language].overrides?.[key];
      return override || value;
    },
  })
  .use(initReactI18next)
  .use(HttpBackend);

export default configuredI18n;