/**
 * Helper for spinning up a real `@suaveplan/i18n` `I18nInstance` plus
 * the `react-forms` recipe-default bundles for use inside tests. No
 * mocks — every test that needs a `<TranslationProvider>` builds a
 * real instance via this helper so wiring matches production.
 */

import { createI18n, type I18nInstance } from "@suaveplan/i18n/plugin";
import {
    reactFormsBundles,
    type SupportedFormsLocale,
} from "../../src/locales/locales.js";

export interface CreateTestI18nOptions {
    readonly locale?: SupportedFormsLocale;
}

type NestedTranslationRecord = {
    [key: string]: string | NestedTranslationRecord;
};

function nestFlatKeys(bag: Record<string, string>): NestedTranslationRecord {
    const out: NestedTranslationRecord = {};
    for (const [flatKey, value] of Object.entries(bag)) {
        const parts = flatKey.split(".");
        let cursor: NestedTranslationRecord = out;
        for (let i = 0; i < parts.length - 1; i += 1) {
            const seg = parts[i] as string;
            const existing = cursor[seg];
            if (
                typeof existing !== "object" ||
                existing === null ||
                Array.isArray(existing)
            ) {
                cursor[seg] = {};
            }
            cursor = cursor[seg] as NestedTranslationRecord;
        }
        cursor[parts[parts.length - 1] as string] = value;
    }
    return out;
}

export async function createTestI18n(
    options: CreateTestI18nOptions = {}
): Promise<I18nInstance> {
    const locale = options.locale ?? "en-GB";
    const i18n = createI18n({
        defaultLocale: locale,
        fallbackLocale: "en-GB",
    });
    for (const code of ["en-GB", "zh-CN", "ar-AE", "cy-GB", "ru-RU"] as const) {
        const bundle = await reactFormsBundles[code]();
        const nested = nestFlatKeys(bundle as Record<string, string>);
        i18n.catalog.mergeMessages(code, nested as Record<string, unknown>);
    }
    return i18n;
}