1 files changed, 142 insertions, 0 deletions
diff --git a/src/utils/locale.ts b/src/utils/locale.ts
new file mode 100644
index 0000000..cd1151a
--- /dev/null
+++ b/src/utils/locale.ts
@@ -0,0 +1,142 @@
+import type { Opt } from '@jet/environment';
+import { DEFAULT_STOREFRONT_CODE } from '~/constants/storefront';
+
+import type {
+    NormalizedLocale,
+    NormalizedStorefront,
+    NormalizedLanguage,
+} from '@jet-app/app-store/api/locale';
+import type { Locale } from '@jet-app/app-store/foundation/dependencies/locale/locale';
+
+import { TEXT_DIRECTION } from '@amp/web-app-components/src/constants';
+import { getLocAttributes } from '@amp/web-apps-localization';
+
+import { regions } from '~/utils/storefront-data';
+import { getJet } from '~/jet/svelte';
+
+export type NormalizedLocaleWithDefault = NormalizedLocale & {
+    isDefaultLanguage: boolean;
+};
+
+type LanguageDetails = {
+    languages: NormalizedLanguage[];
+    defaultLanguage: NormalizedLanguage;
+};
+
+export function normalizeStorefront(storefront: Opt<string>): {
+    storefront: NormalizedStorefront;
+    languages: NormalizedLanguage[];
+    defaultLanguage: NormalizedLanguage;
+} {
+    const storefronts: Record<NormalizedStorefront, LanguageDetails> = {};
+
+    for (const { locales } of regions) {
+        for (const { id, language, isDefault } of locales) {
+            if (isDefault) {
+                storefronts[id as NormalizedStorefront] = {
+                    languages: [],
+                    defaultLanguage: language as NormalizedLanguage,
+                };
+            }
+
+            if (id in storefronts) {
+                storefronts[id as NormalizedStorefront].languages.push(
+                    language as NormalizedLanguage,
+                );
+            }
+        }
+    }
+
+    const normalizedStorefront = (storefront || '').toLowerCase();
+    const chosenStorefront =
+        normalizedStorefront in storefronts
+            ? (normalizedStorefront as NormalizedStorefront)
+            : DEFAULT_STOREFRONT_CODE;
+
+    return {
+        storefront: chosenStorefront,
+        ...storefronts[chosenStorefront],
+    };
+}
+
+export function normalizeLanguage(
+    language: string,
+    languages: NormalizedLanguage[],
+    defaultLanguage: NormalizedLanguage,
+): { language: NormalizedLanguage; isDefaultLanguage: boolean } {
+    function annotateReturn(language: NormalizedLanguage): {
+        language: NormalizedLanguage;
+        isDefaultLanguage: boolean;
+    } {
+        return {
+            language,
+            isDefaultLanguage: language === defaultLanguage,
+        };
+    }
+
+    // Prefer an exact match (ex. en-US matches en-US)
+    const exactMatch = findMatch(language, languages, (a, b) => a === b);
+    if (exactMatch) {
+        return annotateReturn(exactMatch);
+    }
+
+    // Try partial match (ex. fr-CA or fr matches fr-FR)
+    const partialMatch = findMatch(
+        language,
+        languages,
+        (a, b) => a.split('-')[0] === b.split('-')[0],
+    );
+    if (partialMatch) {
+        return annotateReturn(partialMatch);
+    }
+
+    // The only remaining choice is the storefront default
+    return annotateReturn(defaultLanguage);
+}
+
+function findMatch<T extends string>(
+    needle: string,
+    haystack: T[],
+    matches: (a: string, b: string) => boolean,
+): Opt<T> {
+    return haystack.find((possibility) =>
+        matches(possibility.toLowerCase(), needle.toLowerCase()),
+    );
+}
+
+/**
+ * Gets the current Locale instance from the Svelte context.
+ *
+ * @return the active {@linkcode NormalizedLocale}
+ */
+export function getLocale(): NormalizedLocale {
+    let locale: Locale | undefined;
+
+    try {
+        const { objectGraph } = getJet();
+
+        locale = objectGraph.locale;
+    } catch {
+        throw new Error('`getLocale` called before `Jet.load`');
+    }
+
+    return {
+        storefront: locale.activeStorefront,
+        language: locale.activeLanguage,
+    };
+}
+
+/**
+ * Returns whether or not the document is in RTL mode, first based on the document's direction,
+ * with a fallback to the storefronts default writing direction.
+ */
+export function isRtl() {
+    const { storefront } = getLocale();
+    const { dir } = getLocAttributes(storefront);
+
+    return (
+        (typeof document !== 'undefined' &&
+            document.dir === TEXT_DIRECTION.RTL) ||
+        dir === TEXT_DIRECTION.RTL
+    );
+}