[+] Country code to emoji

AquaNet/src/libs/i18n.ts

@@ -61,3 +61,33 @@ export function getCountryName(code: keyof typeof enCountires) {
 
 export const GAME_TITLE: { [key in GameName]: string } =
   {chu3: t("game.chu3"), mai2: t("game.mai2"), ongeki: t("game.ongeki"), wacca: t("game.wacca")}
+
+/**
+ * Converts a two-letter country code to its corresponding flag emoji.
+ *
+ * The Unicode flag emoji is represented by two Regional Indicator Symbols.
+ * Each letter in the country code is transformed into a Regional Indicator Symbol
+ * by adding its alphabetical position (A = 0, B = 1, etc.) to the base code point U+1F1E6.
+ *
+ * @param countryCode - A two-letter ISO country code (e.g., "US", "GB").
+ * @returns The corresponding flag emoji if the country code is valid; otherwise, an empty string.
+ */
+export function countryCodeToEmoji(countryCode: string): string {
+  if (!countryCode) return ""
+  if (countryCode.length !== 2) return ""
+
+  // Convert the country code to uppercase to standardize it
+  const code = countryCode.toUpperCase();
+
+  // The base code point for Regional Indicator Symbol Letter A is 0x1F1E6.
+  const OFFSET = 0x1F1E6;
+  const firstCharCode = code.charCodeAt(0);
+  const secondCharCode = code.charCodeAt(1);
+
+  // 'A' has a char code of 65.
+  const firstIndicator = OFFSET + (firstCharCode - 65);
+  const secondIndicator = OFFSET + (secondCharCode - 65);
+
+  // Create and return the flag emoji string
+  return String.fromCodePoint(firstIndicator, secondIndicator);
+}