Function truncateToWidth

packages/pi-tui/src/utils.ts:941–1077

(
	text: string,
	maxWidth: number,
	ellipsis: string = "...",
	pad: boolean = false,
)

 * @returns Truncated text, optionally padded to exactly maxWidth
 */
export function truncateToWidth(
	text: string,
	maxWidth: number,
	ellipsis: string = "...",
	pad: boolean = false,
): string {
	if (maxWidth <= 0) {
		return "";
	}

	if (text.length === 0) {
		return pad ? " ".repeat(maxWidth) : "";
	}

	const ellipsisWidth = visibleWidth(ellipsis);
	if (ellipsisWidth >= maxWidth) {
		const textWidth = visibleWidth(text);
		if (textWidth <= maxWidth) {
			return pad ? text + " ".repeat(maxWidth - textWidth) : text;
		}

		const clippedEllipsis = truncateFragmentToWidth(ellipsis, maxWidth);
		if (clippedEllipsis.width === 0) {
			return pad ? " ".repeat(maxWidth) : "";
		}
		return finalizeTruncatedResult("", 0, clippedEllipsis.text, clippedEllipsis.width, maxWidth, pad);
	}

	if (isPrintableAscii(text)) {
		if (text.length <= maxWidth) {
			return pad ? text + " ".repeat(maxWidth - text.length) : text;
		}
		const targetWidth = maxWidth - ellipsisWidth;
		return finalizeTruncatedResult(text.slice(0, targetWidth), targetWidth, ellipsis, ellipsisWidth, maxWidth, pad);
	}

	const targetWidth = maxWidth - ellipsisWidth;
	let result = "";
	let pendingAnsi = "";
	let visibleSoFar = 0;
	let keptWidth = 0;
	let keepContiguousPrefix = true;
	let overflowed = false;
	let exhaustedInput = false;
	const hasAnsi = text.includes("\x1b");
	const hasTabs = text.includes("\t");

	if (!hasAnsi && !hasTabs) {
		for (const { segment } of graphemeSegmenter.segment(text)) {
			const width = graphemeWidth(segment);
			if (keepContiguousPrefix && keptWidth + width <= targetWidth) {
				result += segment;
				keptWidth += width;
			} else {
				keepContiguousPrefix = false;
			}
			visibleSoFar += width;
			if (visibleSoFar > maxWidth) {