[Glitch] Provides legacy fallback for browser that don't support regex flag v

Port 28b0e5ee78 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/emoji/utils.ts

@@ -1,23 +1,32 @@
 import debug from 'debug';
 
-import {
-  CUSTOM_EMOJI_REGEX,
-  UNICODE_EMOJI_REGEX,
-  UNICODE_FLAG_EMOJI_REGEX,
-} from './constants';
+import { emojiRegexPolyfill } from '@/flavours/glitch/polyfills';
 
 export function emojiLogger(segment: string) {
   return debug(`emojis:${segment}`);
 }
 
 export function stringHasUnicodeEmoji(input: string): boolean {
-  return UNICODE_EMOJI_REGEX.test(input);
+  return new RegExp(EMOJI_REGEX, supportedFlags()).test(input);
 }
 
 export function stringHasUnicodeFlags(input: string): boolean {
-  return UNICODE_FLAG_EMOJI_REGEX.test(input);
+  if (supportsRegExpSets()) {
+    return new RegExp(
+      '\\p{RGI_Emoji_Flag_Sequence}|\\p{RGI_Emoji_Tag_Sequence}',
+      'v',
+    ).test(input);
+  }
+  return new RegExp(
+    // First range is regional indicator symbols,
+    // Second is a black flag + 0-9|a-z tag chars + cancel tag.
+    // See: https://en.wikipedia.org/wiki/Regional_indicator_symbol
+    '(?:\uD83C[\uDDE6-\uDDFF]){2}|\uD83C\uDFF4(?:\uDB40[\uDC30-\uDC7A])+\uDB40\uDC7F',
+  ).test(input);
 }
 
+// Constant as this is supported by all browsers.
+const CUSTOM_EMOJI_REGEX = /:([a-z0-9_]+):/i;
 export function stringHasCustomEmoji(input: string) {
   return CUSTOM_EMOJI_REGEX.test(input);
 }
@@ -25,3 +34,23 @@ export function stringHasCustomEmoji(input: string) {
 export function stringHasAnyEmoji(input: string) {
   return stringHasUnicodeEmoji(input) || stringHasCustomEmoji(input);
 }
+
+export function anyEmojiRegex() {
+  return new RegExp(
+    `${EMOJI_REGEX}|${CUSTOM_EMOJI_REGEX.source}`,
+    supportedFlags('gi'),
+  );
+}
+
+function supportsRegExpSets() {
+  return 'unicodeSets' in RegExp.prototype;
+}
+
+function supportedFlags(flags = '') {
+  if (supportsRegExpSets()) {
+    return `${flags}v`;
+  }
+  return flags;
+}
+
+const EMOJI_REGEX = emojiRegexPolyfill?.source ?? '\\p{RGI_Emoji}';