export interface TextHighlight {
  text: string;
  color: string;
}

export interface HighlightedTextSegment {
  text: string;
  color: string | null;
}

export function highlightTextSegments(
  value: string,
  highlights: readonly TextHighlight[],
): HighlightedTextSegment[] {
  const rules = highlights
    .filter((highlight) => highlight.text.length > 0)
    .toSorted((left, right) => right.text.length - left.text.length);
  if (!rules.length) return [{ text: value, color: null }];

  const segments: HighlightedTextSegment[] = [];
  let cursor = 0;
  while (cursor < value.length) {
    let matchIndex = -1;
    let match: TextHighlight | undefined;
    for (const rule of rules) {
      const index = value.indexOf(rule.text, cursor);
      if (index !== -1 && (matchIndex === -1 || index < matchIndex)) {
        matchIndex = index;
        match = rule;
      }
    }
    if (!match || matchIndex === -1) {
      segments.push({ text: value.slice(cursor), color: null });
      break;
    }
    if (matchIndex > cursor) {
      segments.push({ text: value.slice(cursor, matchIndex), color: null });
    }
    segments.push({ text: match.text, color: match.color });
    cursor = matchIndex + match.text.length;
  }
  return segments;
}