Function extractAnsiCode

packages/pi-tui/src/utils.ts:316–354

(str: string, pos: number)

 * Extract ANSI escape sequences from a string at the given position.
 */
export function extractAnsiCode(str: string, pos: number): { code: string; length: number } | null {
	if (pos >= str.length || str[pos] !== "\x1b") return null;

	const next = str[pos + 1];

	// CSI sequence: ESC [ ... m/G/K/H/J
	if (next === "[") {
		let j = pos + 2;
		while (j < str.length && !/[mGKHJ]/.test(str[j]!)) j++;
		if (j < str.length) return { code: str.substring(pos, j + 1), length: j + 1 - pos };
		return null;
	}

	// OSC sequence: ESC ] ... BEL or ESC ] ... ST (ESC \)
	// Used for hyperlinks (OSC 8), window titles, etc.
	if (next === "]") {
		let j = pos + 2;
		while (j < str.length) {
			if (str[j] === "\x07") return { code: str.substring(pos, j + 1), length: j + 1 - pos };
			if (str[j] === "\x1b" && str[j + 1] === "\\") return { code: str.substring(pos, j + 2), length: j + 2 - pos };
			j++;
		}
		return null;
	}

	// APC sequence: ESC _ ... BEL or ESC _ ... ST (ESC \)
	// Used for cursor marker and application-specific commands
	if (next === "_") {
		let j = pos + 2;
		while (j < str.length) {
			if (str[j] === "\x07") return { code: str.substring(pos, j + 1), length: j + 1 - pos };
			if (str[j] === "\x1b" && str[j + 1] === "\\") return { code: str.substring(pos, j + 2), length: j + 2 - pos };
			j++;
		}
		return null;
	}

	return null;
}

type Osc8Terminator = "\x07" | "\x1b\\";