/** Worker final-result presence and bounded model-facing excerpts. */

/**
 * R-EXEC-3: a run is complete when the child emitted `agent_settled` and a
 * non-empty final assistant message exists. Markdown shape is deliberately not
 * part of completion: useful free-form prose is a valid result.
 */
export function hasSemanticCompletion(settled: boolean, finalAssistantText: string | null): boolean {
	return settled && finalAssistantText !== null && finalAssistantText.trim().length > 0;
}

/** Longest prefix that fits without splitting a Unicode code point. */
function prefixToBytes(text: string, maxBytes: number): string {
	if (maxBytes <= 0) return "";
	if (Buffer.byteLength(text, "utf8") <= maxBytes) return text;
	let bytes = 0;
	let end = 0;
	for (const codePoint of text) {
		const next = Buffer.byteLength(codePoint, "utf8");
		if (bytes + next > maxBytes) break;
		bytes += next;
		end += codePoint.length;
	}
	return text.slice(0, end);
}

/** Longest suffix that fits without splitting a Unicode code point. */
function suffixToBytes(text: string, maxBytes: number): string {
	if (maxBytes <= 0) return "";
	if (Buffer.byteLength(text, "utf8") <= maxBytes) return text;
	let bytes = 0;
	let start = text.length;
	while (start > 0) {
		let nextStart = start - 1;
		const code = text.charCodeAt(nextStart);
		if (code >= 0xdc00 && code <= 0xdfff && nextStart > 0) {
			const previous = text.charCodeAt(nextStart - 1);
			if (previous >= 0xd800 && previous <= 0xdbff) nextStart -= 1;
		}
		const next = Buffer.byteLength(text.slice(nextStart, start), "utf8");
		if (bytes + next > maxBytes) break;
		bytes += next;
		start = nextStart;
	}
	return text.slice(start);
}

/**
 * R-WORK-10. `result.md` keeps the full final text. When model-visible content
 * must be bounded, preserve both the beginning and end of arbitrary prose and
 * point to the durable full result. No headings or outcome tokens are assumed.
 */
export function truncateReport(text: string, maxBytes: number, resultPath: string): string {
	if (Buffer.byteLength(text, "utf8") <= maxBytes) return text;
	if (maxBytes <= 0) return "";
	const fullPointer = `\n\n[… truncated; full result: ${resultPath} …]\n\n`;
	const boundedPointer = "\n\n[… truncated; inspect the full run result …]\n\n";
	// Content is the point of this projection. Include the exact path only when it
	// leaves at least half the budget for useful report head/tail; otherwise status
	// and tool details retain the exact durable path programmatically.
	const contentReserve = Math.max(2, Math.floor(maxBytes / 2));
	let pointer = Buffer.byteLength(fullPointer, "utf8") <= maxBytes - contentReserve ? fullPointer : boundedPointer;
	if (Buffer.byteLength(pointer, "utf8") > maxBytes - 2) pointer = "…";
	const pointerBytes = Buffer.byteLength(pointer, "utf8");
	if (pointerBytes > maxBytes) return prefixToBytes(text, maxBytes);
	const contentBytes = maxBytes - pointerBytes;
	const headBytes = Math.ceil(contentBytes / 2);
	const tailBytes = contentBytes - headBytes;
	return `${prefixToBytes(text, headBytes)}${pointer}${suffixToBytes(text, tailBytes)}`;
}