keycloak_theme/src/account/i18n/i18n.tsx

import "minimal-polyfills/Object.fromEntries";
//NOTE for later: https://github.com/remarkjs/react-markdown/blob/236182ecf30bd89c1e5a7652acaf8d0bf81e6170/src/renderers.js#L7-L35
import { useEffect, useState, useRef } from "react";
import fallbackMessages from "./baseMessages/en";
import { getMessages } from "./baseMessages";
import { assert } from "tsafe/assert";
import type { KcContext } from "../kcContext/KcContext";
import { Markdown } from "keycloakify/tools/Markdown";

export const fallbackLanguageTag = "en";

export type KcContextLike = {
    locale?: {
        currentLanguageTag: string;
        supported: { languageTag: string; url: string; label: string }[];
    };
};

assert<KcContext extends KcContextLike ? true : false>();

export type MessageKey = keyof typeof fallbackMessages | keyof (typeof keycloakifyExtraMessages)[typeof fallbackLanguageTag];

export type GenericI18n<MessageKey extends string> = {
    /**
     * e.g: "en", "fr", "zh-CN"
     *
     * The current language
     */
    currentLanguageTag: string;
    /**
     * To call when the user switch language.
     * This will cause the page to be reloaded,
     * on next load currentLanguageTag === newLanguageTag
     */
    changeLocale: (newLanguageTag: string) => never;
    /**
     * e.g. "en" => "English", "fr" => "Français", ...
     *
     * Used to render a select that enable user to switch language.
     * ex: https://user-images.githubusercontent.com/6702424/186044799-38801eec-4e89-483b-81dd-8e9233e8c0eb.png
     * */
    labelBySupportedLanguageTag: Record<string, string>;
    /**
     * Examples assuming currentLanguageTag === "en"
     *
     * msg("access-denied") === <span>Access denied</span>
     * msg("impersonateTitleHtml", "Foo") === <span><strong>Foo</strong> Impersonate User</span>
     */
    msg: (key: MessageKey, ...args: (string | undefined)[]) => JSX.Element;
    /**
     * It's the same thing as msg() but instead of returning a JSX.Element it returns a string.
     * It can be more convenient to manipulate strings but if there are HTML tags it wont render.
     * msgStr("impersonateTitleHtml", "Foo") === "<strong>Foo</strong> Impersonate User"
     */
    msgStr: (key: MessageKey, ...args: (string | undefined)[]) => string;
    /**
     * Examples assuming currentLanguageTag === "en"
     * advancedMsg("${access-denied} foo bar") === <span>${msgStr("access-denied")} foo bar<span> === <span>Access denied foo bar</span>
     * advancedMsg("${access-denied}") === advancedMsg("access-denied") === msg("access-denied") === <span>Access denied</span>
     * advancedMsg("${not-a-message-key}") === advancedMsg(not-a-message-key") === <span>not-a-message-key</span>
     */
    advancedMsg: (key: string, ...args: (string | undefined)[]) => JSX.Element;
    /**
     * Examples assuming currentLanguageTag === "en"
     * advancedMsg("${access-denied} foo bar") === msg("access-denied") + " foo bar" === "Access denied foo bar"
     * advancedMsg("${not-a-message-key}") === advancedMsg(not-a-message-key") === "not-a-message-key"
     */
    advancedMsgStr: (key: string, ...args: (string | undefined)[]) => string;
};

export type I18n = GenericI18n<MessageKey>;

export function createUseI18n<ExtraMessageKey extends string = never>(extraMessages: {
    [languageTag: string]: { [key in ExtraMessageKey]: string };
}) {
    function useI18n(params: { kcContext: KcContextLike }): GenericI18n<MessageKey | ExtraMessageKey> | null {
        const { kcContext } = params;

        const [i18n, setI18n] = useState<GenericI18n<ExtraMessageKey | MessageKey> | undefined>(undefined);

        const refHasStartedFetching = useRef(false);

        useEffect(() => {
            if (refHasStartedFetching.current) {
                return;
            }

            refHasStartedFetching.current = true;

            (async () => {
                const { currentLanguageTag = fallbackLanguageTag } = kcContext.locale ?? {};

                setI18n({
                    ...createI18nTranslationFunctions({
                        "fallbackMessages": {
                            ...fallbackMessages,
                            ...(keycloakifyExtraMessages[fallbackLanguageTag] ?? {}),
                            ...(extraMessages[fallbackLanguageTag] ?? {})
                        } as any,
                        "messages": {
                            ...(await getMessages(currentLanguageTag)),
                            ...((keycloakifyExtraMessages as any)[currentLanguageTag] ?? {}),
                            ...(extraMessages[currentLanguageTag] ?? {})
                        } as any
                    }),
                    currentLanguageTag,
                    "changeLocale": newLanguageTag => {
                        const { locale } = kcContext;

                        assert(locale !== undefined, "Internationalization not enabled");

                        const targetSupportedLocale = locale.supported.find(({ languageTag }) => languageTag === newLanguageTag);

                        assert(targetSupportedLocale !== undefined, `${newLanguageTag} need to be enabled in Keycloak admin`);

                        window.location.href = targetSupportedLocale.url;

                        assert(false, "never");
                    },
                    "labelBySupportedLanguageTag": Object.fromEntries(
                        (kcContext.locale?.supported ?? []).map(({ languageTag, label }) => [languageTag, label])
                    )
                });
            })();
        }, []);

        return i18n ?? null;
    }

    return { useI18n };
}

function createI18nTranslationFunctions<MessageKey extends string>(params: {
    fallbackMessages: Record<MessageKey, string>;
    messages: Record<MessageKey, string>;
}): Pick<GenericI18n<MessageKey>, "msg" | "msgStr" | "advancedMsg" | "advancedMsgStr"> {
    const { fallbackMessages, messages } = params;

    function resolveMsg(props: { key: string; args: (string | undefined)[]; doRenderMarkdown: boolean }): string | JSX.Element | undefined {
        const { key, args, doRenderMarkdown } = props;

        const messageOrUndefined: string | undefined = (messages as any)[key] ?? (fallbackMessages as any)[key];

        if (messageOrUndefined === undefined) {
            return undefined;
        }

        const message = messageOrUndefined;

        const messageWithArgsInjectedIfAny = (() => {
            const startIndex = message
                .match(/{[0-9]+}/g)
                ?.map(g => g.match(/{([0-9]+)}/)![1])
                .map(indexStr => parseInt(indexStr))
                .sort((a, b) => a - b)[0];

            if (startIndex === undefined) {
                // No {0} in message (no arguments expected)
                return message;
            }

            let messageWithArgsInjected = message;

            args.forEach((arg, i) => {
                if (arg === undefined) {
                    return;
                }

                messageWithArgsInjected = messageWithArgsInjected.replace(new RegExp(`\\{${i + startIndex}\\}`, "g"), arg);
            });

            return messageWithArgsInjected;
        })();

        return doRenderMarkdown ? (
            <Markdown allowDangerousHtml renderers={{ "paragraph": "span" }}>
                {messageWithArgsInjectedIfAny}
            </Markdown>
        ) : (
            messageWithArgsInjectedIfAny
        );
    }

    function resolveMsgAdvanced(props: { key: string; args: (string | undefined)[]; doRenderMarkdown: boolean }): JSX.Element | string {
        const { key, args, doRenderMarkdown } = props;

        const match = key.match(/^\$\{([^{]+)\}$/);

        const keyUnwrappedFromCurlyBraces = match === null ? key : match[1];

        const out = resolveMsg({
            "key": keyUnwrappedFromCurlyBraces,
            args,
            doRenderMarkdown
        });

        return (out !== undefined ? out : doRenderMarkdown ? <span>{keyUnwrappedFromCurlyBraces}</span> : keyUnwrappedFromCurlyBraces) as any;
    }

    return {
        "msgStr": (key, ...args) => resolveMsg({ key, args, "doRenderMarkdown": false }) as string,
        "msg": (key, ...args) => resolveMsg({ key, args, "doRenderMarkdown": true }) as JSX.Element,
        "advancedMsg": (key, ...args) => resolveMsgAdvanced({ key, args, "doRenderMarkdown": true }) as JSX.Element,
        "advancedMsgStr": (key, ...args) => resolveMsgAdvanced({ key, args, "doRenderMarkdown": false }) as string
    };
}

const keycloakifyExtraMessages = {
    "en": {
        "shouldBeEqual": "{0} should be equal to {1}",
        "shouldBeDifferent": "{0} should be different to {1}",
        "shouldMatchPattern": "Pattern should match: `/{0}/`",
        "mustBeAnInteger": "Must be an integer",
        "notAValidOption": "Not a valid option",
        "newPasswordSameAsOld": "New password must be different from the old one",
        "passwordConfirmNotMatch": "Password confirmation does not match"
    },
    "fr": {
        /* spell-checker: disable */
        "shouldBeEqual": "{0} doit être égal à {1}",
        "shouldBeDifferent": "{0} doit être différent de {1}",
        "shouldMatchPattern": "Dois respecter le schéma: `/{0}/`",
        "mustBeAnInteger": "Doit être un nombre entier",
        "notAValidOption": "N'est pas une option valide",

        "logoutConfirmTitle": "Déconnexion",
        "logoutConfirmHeader": "Êtes-vous sûr(e) de vouloir vous déconnecter ?",
        "doLogout": "Se déconnecter",
        "newPasswordSameAsOld": "Le nouveau mot de passe doit être différent de l'ancien",
        "passwordConfirmNotMatch": "La confirmation du mot de passe ne correspond pas"
        /* spell-checker: enable */
    }
};