malice

const ZWJ = 0x200d;

const VS16 = 0xfe0f;

export function twemojiUrl(emoji: string): string {

  const points = Array.from(emoji, (c) => c.codePointAt(0) ?? 0);

  const kept = points.includes(ZWJ) ? points : points.filter((p) => p !== VS16);

  return `/twemoji/${kept.map((p) => p.toString(16)).join('-')}.svg`;

}

export interface TextSegment {

  text: string;

  emoji: boolean;

}

const MAYBE_EMOJI = /\p{Extended_Pictographic}|\p{Regional_Indicator}|\u20E3/u;

const PICTOGRAPHIC = /\p{Extended_Pictographic}/u;

const EMOJI_PRESENTATION = /\p{Emoji_Presentation}/u;

const KEYCAP = /^[0-9#*]\uFE0F\u20E3$/;

const FLAG = /^\p{Regional_Indicator}{2}$/u;

let segmenter: Intl.Segmenter | null = null;

function isEmojiGrapheme(g: string): boolean {

  if (KEYCAP.test(g) || FLAG.test(g)) return true;

  return PICTOGRAPHIC.test(g) && (EMOJI_PRESENTATION.test(g) || g.includes(String.fromCodePoint(VS16)) || g.includes(String.fromCodePoint(ZWJ)));

}

export function segmentEmoji(text: string): TextSegment[] {

  if (!MAYBE_EMOJI.test(text)) return [{ text, emoji: false }];

  segmenter ??= new Intl.Segmenter(undefined, { granularity: 'grapheme' });

  const out: TextSegment[] = [];

  for (const { segment } of segmenter.segment(text)) {

    const emoji = isEmojiGrapheme(segment);

    const last = out[out.length - 1];

    if (last && !emoji && !last.emoji) last.text += segment;

    else out.push({ text: segment, emoji });

  }

  return out;

}

export function isJumbo(segments: TextSegment[]): boolean {

  let count = 0;

  for (const s of segments) {

    if (s.emoji) count += 1;

    else if (s.text.trim() !== '') return false;

  }

  return count >= 1 && count <= 3;

}