scroll/src/common/ansi.ts

/**
 * ANSI/VT terminal escape code handling
 */

export const ANSI_PREFIX = '\x1b[';

/**
 * ANSI escapes for various inputs
 */
export enum KeyCommand {
	ArrowUp = ANSI_PREFIX + 'A',
	ArrowDown = ANSI_PREFIX + 'B',
	ArrowRight = ANSI_PREFIX + 'C',
	ArrowLeft = ANSI_PREFIX + 'D',
	Delete = ANSI_PREFIX + '3~',
	PageUp = ANSI_PREFIX + '5~',
	PageDown = ANSI_PREFIX + '6~',

	// These keys have several possible escape sequences
	Home = 'LineHome',
	End = 'LineEnd',
}

export const Ansi = {
	ClearLine: ANSI_PREFIX + 'K',
	ClearScreen: ANSI_PREFIX + '2J',
	ResetCursor: ANSI_PREFIX + 'H',
	HideCursor: ANSI_PREFIX + '?25l',
	ShowCursor: ANSI_PREFIX + '?25h',
	GetCursorLocation: ANSI_PREFIX + '6n',
	moveCursor: function moveCursor(row: number, col: number): string {
		// Convert to 1-based counting
		row++;
		col++;

		return ANSI_PREFIX + `${row};${col}H`;
	},
	moveCursorForward: (col: number): string => ANSI_PREFIX + `${col}C`,
	moveCursorDown: (row: number): string => ANSI_PREFIX + `${row}B`,
};

/**
 * Convert input from ANSI escape sequences into a form
 * that can be more easily mapped to editor commands
 *
 * @param parsed - the decoded chunk of input
 */
export function readKey(parsed: string): string {
	// Return the input if it's unambiguous
	if (parsed in KeyCommand) {
		return parsed;
	}

	// Some keycodes have multiple potential inputs
	switch (parsed) {
		case '\x1b[1~':
		case '\x1b[7~':
		case '\x1bOH':
		case '\x1b[H':
			return KeyCommand.Home;

		case '\x1b[4~':
		case '\x1b[8~':
		case '\x1bOF':
		case '\x1b[F':
			return KeyCommand.End;

		default:
			return parsed;
	}
}

export default Ansi;