const test = require("node:test");
const assert = require("node:assert/strict");

const {
  DEFAULT_LANGUAGE,
  TRANSLATIONS,
  createI18n,
  detectLanguage,
  normalizeLanguage,
} = require("../i18n.js");

function createStorage(initialValue) {
  let value = initialValue;
  return {
    getItem() {
      return value;
    },
    setItem(key, nextValue) {
      value = nextValue;
    },
    removeItem() {
      value = undefined;
    },
  };
}

test("normalizes exact and base language tags", () => {
  assert.equal(normalizeLanguage("pt-PT"), "pt-PT");
  assert.equal(normalizeLanguage("pt-BR"), "pt-PT");
  assert.equal(normalizeLanguage("en-US"), "en");
  assert.equal(normalizeLanguage("fr"), null);
});

test("prefers a stored language over browser preferences", () => {
  const storage = createStorage("en");
  assert.equal(detectLanguage({ storage, languages: ["pt-PT"] }), "en");
});

test("uses the first supported browser language and otherwise falls back", () => {
  assert.equal(detectLanguage({ storage: createStorage(), languages: ["fr", "pt-BR"] }), "pt-PT");
  assert.equal(detectLanguage({ storage: createStorage(), languages: ["es-MX"] }), "es");
  assert.equal(detectLanguage({ storage: createStorage(), languages: ["fr"] }), DEFAULT_LANGUAGE);
});

test("persists language changes and interpolates translated values", () => {
  const storage = createStorage();
  const i18n = createI18n({ storage, languages: ["en"] });

  assert.equal(i18n.setLanguage("pt"), "pt-PT");
  assert.equal(storage.getItem(), "pt-PT");
  assert.equal(
    i18n.t("noParcelFound", { parcelNumber: "57" }),
    "Não foi encontrada a parcela com o número “57”.",
  );
});

test("browser-default mode removes the preference and follows the browser language", () => {
  const storage = createStorage("en");
  const i18n = createI18n({ storage, languages: ["pt-PT"] });

  assert.equal(i18n.setLanguage(null), "pt-PT");
  assert.equal(i18n.preference, null);
  assert.equal(storage.getItem(), undefined);
});

test("uses English for missing translations and the key for unknown messages", () => {
  const storage = createStorage("pt-PT");
  const originalTranslation = TRANSLATIONS["pt-PT"].zoomIn;
  delete TRANSLATIONS["pt-PT"].zoomIn;

  try {
    const i18n = createI18n({ storage, languages: [] });
    assert.equal(i18n.t("zoomIn"), TRANSLATIONS.en.zoomIn);
    assert.equal(i18n.t("notARealMessage"), "notARealMessage");
  } finally {
    TRANSLATIONS["pt-PT"].zoomIn = originalTranslation;
  }
});

test("all shipped languages contain the default translation keys", () => {
  const defaultKeys = Object.keys(TRANSLATIONS[DEFAULT_LANGUAGE]).sort();
  Object.entries(TRANSLATIONS).forEach(([language, translations]) => {
    assert.deepEqual(Object.keys(translations).sort(), defaultKeys, language);
  });
});