generateHighlightedMarkupFirstMatch.ts

import escapeRegex from "./escapeRegex.js";
// @ts-expect-error
import encodeXML from "../sap/base/security/encodeXML.js";

/**
 * Generate markup for a raw string where the first match following StartsWithPerTerm pattern is wrapped with `<b>` tag.
 * StartsWithPerTerm pattern: finds the first word (at start or after whitespace) that starts with the search text.
 * All inputs to this function are considered literal text, and special characters will always be escaped.
 * @param {string} text The text to add highlighting to
 * @param {string} textToHighlight The text which should be highlighted (case-insensitive)
 * @return {string} the markup HTML which contains the first match surrounded with a `<b>` tag.
 */
function generateHighlightedMarkupFirstMatch(text: string, textToHighlight: string): string {
	const normalizedText = text || "";

	if (!normalizedText || !textToHighlight) {
		return encodeXML(normalizedText) as string;
	}

	const filterValue = textToHighlight.toLowerCase();
	const lowerText = normalizedText.toLowerCase();
	const matchLength = textToHighlight.length;

	// Find the first word that starts with textToHighlight (StartsWithPerTerm pattern)
	let matchIndex = lowerText.search(new RegExp(`(^|\\s)${escapeRegex(filterValue)}`));
	if (matchIndex !== -1 && lowerText[matchIndex] === " ") {
		matchIndex++; // Skip the space
	}

	// If no match found, return encoded text
	if (matchIndex === -1) {
		return encodeXML(normalizedText) as string;
	}

	// Build highlighted markup with only the first match
	const beforeMatch = encodeXML(normalizedText.substring(0, matchIndex)) as string;
	const match = encodeXML(normalizedText.substring(matchIndex, matchIndex + matchLength)) as string;
	const afterMatch = encodeXML(normalizedText.substring(matchIndex + matchLength)) as string;

	return `${beforeMatch}<b>${match}</b>${afterMatch}`;
}

export default generateHighlightedMarkupFirstMatch;