/**
 * Strip ANSI escape sequences, remove control characters / lone surrogates,
 * and normalize line endings.
 *
 * Bun-native implementation of the former native `sanitizeText` (see
 * `crates/pi-natives/src/text.rs::sanitize_text`). JavaScript strings are
 * already UTF-16 code-unit arrays. `toWellFormed()` handles the uncommon
 * malformed path; when it changes the input, replacement characters are
 * dropped and the normalized result goes through the well-formed sanitizer.
 *
 * Fast path: well-formed input with no controls or ANSI returns the original
 * string after the control probe.
 */

const ESC_CHAR = "\x1b";

// Well-formed strings only need control/ANSI detection: C0 (excl. \t \n),
// CR, DEL, and C1. ESC (0x1B) is in \x0B-\x1F.
const CONTROL_RE = /[\x00-\x08\x0B-\x1F\x7F-\x9F]/g;

const REPLACEMENT_CHAR = "\ufffd";

export function sanitizeText(text: string): string {
	const wellFormed = text.toWellFormed();
	if (wellFormed !== text) {
		return sanitizeWellFormedText(wellFormed.replaceAll(REPLACEMENT_CHAR, ""));
	}
	return sanitizeWellFormedText(text);
}

function sanitizeWellFormedText(text: string): string {
	CONTROL_RE.lastIndex = 0;
	if (CONTROL_RE.exec(text) === null) return text;

	const stripped = text.indexOf(ESC_CHAR) === -1 ? text : Bun.stripANSI(text);
	CONTROL_RE.lastIndex = 0;
	return stripped.replace(CONTROL_RE, "");
}

/**
 * Escape the three XML-significant characters (`&`, `<`, `>`) in text destined
 * for an XML/markup element body. Allocation-conscious: returns the input
 * unchanged (same reference) when nothing needs escaping. Quotes are left as-is
 * — use it for element text, not attribute values.
 */
export function escapeXmlText(input: string): string {
	let firstEscapable = -1;
	for (let index = 0; index < input.length; index++) {
		const char = input.charCodeAt(index);
		if (char === 38 || char === 60 || char === 62) {
			firstEscapable = index;
			break;
		}
	}
	if (firstEscapable === -1) return input;

	let output = input.slice(0, firstEscapable);
	for (let index = firstEscapable; index < input.length; index++) {
		const char = input[index];
		if (char === "&") output += "&amp;";
		else if (char === "<") output += "&lt;";
		else if (char === ">") output += "&gt;";
		else output += char;
	}
	return output;
}

/**
 * Escape XML-significant characters for an attribute VALUE: the three body
 * characters (`&`, `<`, `>`) plus the double quote (`"` → `&quot;`) that would
 * otherwise close the attribute. Allocation-conscious: returns the input
 * unchanged (same reference) when nothing needs escaping. Use it for attribute
 * values; {@link escapeXmlText} is for element bodies and leaves `"` intact.
 */
export function escapeXmlAttribute(input: string): string {
	let firstEscapable = -1;
	for (let index = 0; index < input.length; index++) {
		const char = input.charCodeAt(index);
		if (char === 38 || char === 60 || char === 62 || char === 34) {
			firstEscapable = index;
			break;
		}
	}
	if (firstEscapable === -1) return input;

	let output = input.slice(0, firstEscapable);
	for (let index = firstEscapable; index < input.length; index++) {
		const char = input[index];
		if (char === "&") output += "&amp;";
		else if (char === "<") output += "&lt;";
		else if (char === ">") output += "&gt;";
		else if (char === '"') output += "&quot;";
		else output += char;
	}
	return output;
}