gai/src/tty-input.ts

// Shared TTY input utilities used by command handlers.
// Provides a simple line-input "ask" helper and a reusable inline
// raw-mode text editor (used by both commit message editing and
// interactive config editing).

import * as readline from "node:readline";
import { isStdinTTY } from "./tty";

// ── Simple line input (cooked mode) ──────────────────────────────────

export function ask(question: string): Promise<string> {
	const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
	return new Promise((resolve) => {
		rl.question(question, (answer) => {
			rl.close();
			resolve(answer.trim());
		});
	});
}

// ── Inline raw-mode editor ────────────────────────────────────────────
//
// Provides a simple line editor that runs in raw mode and supports:
//   - Left/Right arrows, Home/End for cursor movement
//   - Backspace / Delete for character removal
//   - Ctrl+A (beginning), Ctrl+E (end), Ctrl+K (kill to end), Ctrl+U (kill to start)
//   - Enter to confirm, Ctrl+C / Esc to cancel
//
// Returns the edited string, or null if the user cancelled.

export interface EditResult {
	value: string | null;
}

export async function editLine(initial: string): Promise<string | null> {
	if (!isStdinTTY()) return null;

	const savedRaw = process.stdin.isRaw;
	process.stdin.setRawMode(true);
	process.stdin.resume();

	let buffer = initial;
	let cursor = initial.length;

	function render() {
		// Clear line, move to start, show prompt + buffer, then reposition cursor
		process.stdout.write("\r\x1b[2K  > " + buffer);
		if (cursor < buffer.length) {
			process.stdout.write(`\x1b[${buffer.length - cursor}D`);
		}
	}

	process.stdout.write("  > " + buffer);

	return new Promise((resolve) => {
		let escapeBuf = "";

		function finish(value: string | null) {
			process.stdin.setRawMode(savedRaw === true);
			process.stdin.pause();
			process.stdin.removeAllListeners("data");
			process.stdout.write("\n");
			resolve(value);
		}

		function handleEscapeSeq(seq: string) {
			switch (seq) {
				case "\x1b[D": case "\x1bOD": // Left
					if (cursor > 0) { cursor--; process.stdout.write("\x1b[D"); }
					break;
				case "\x1b[C": case "\x1bOC": // Right
					if (cursor < buffer.length) { cursor++; process.stdout.write("\x1b[C"); }
					break;
				case "\x1b[H": case "\x1b[1~": case "\x1bOH": // Home
					if (cursor > 0) { process.stdout.write(`\x1b[${cursor}D`); cursor = 0; }
					break;
				case "\x1b[F": case "\x1b[4~": case "\x1bOF": // End
					if (cursor < buffer.length) { process.stdout.write(`\x1b[${buffer.length - cursor}C`); cursor = buffer.length; }
					break;
				case "\x1b[3~": // Delete
					if (cursor < buffer.length) { buffer = buffer.slice(0, cursor) + buffer.slice(cursor + 1); render(); }
					break;
			}
		}

		process.stdin.on("data", (data: Buffer) => {
			const key = data.toString();

			// Ctrl+C
			if (key === "\x03") { finish(null); return; }
			// Esc
			if (key === "\x1b") {
				if (escapeBuf) {
					// Already buffering — check if this completes a sequence
					const next = escapeBuf + key;
					if (/^(\x1b\[[0-9;]*[A-Za-z~]|\x1bO[A-Z])$/.test(next)) {
						handleEscapeSeq(next);
						escapeBuf = "";
					} else {
						// Treat lone Esc as cancel
						finish(null);
					}
					return;
				}
				escapeBuf = "\x1b";
				return;
			}

			// Buffering an escape sequence
			if (escapeBuf) {
				escapeBuf += key;
				// Check if this completes a valid sequence
				if (/^(\x1b\[[0-9;]*[A-Za-z~]|\x1bO[A-Z])$/.test(escapeBuf)) {
					handleEscapeSeq(escapeBuf);
					escapeBuf = "";
				} else if (escapeBuf.length > 10 || /^[A-Za-z~]$/.test(key)) {
					// Timeout or terminator that didn't match — discard
					escapeBuf = "";
				}
				return;
			}

			// Enter
			if (key === "\r" || key === "\n") {
				const result = buffer.trim();
				finish(result || null);
				return;
			}

			// Backspace
			if (key === "\x7f") {
				if (cursor > 0) {
					buffer = buffer.slice(0, cursor - 1) + buffer.slice(cursor);
					cursor--;
					render();
				}
				return;
			}

			// Ctrl+A → beginning of line
			if (key === "\x01") {
				if (cursor > 0) { process.stdout.write(`\x1b[${cursor}D`); cursor = 0; }
				return;
			}
			// Ctrl+E → end of line
			if (key === "\x05") {
				if (cursor < buffer.length) { process.stdout.write(`\x1b[${buffer.length - cursor}C`); cursor = buffer.length; }
				return;
			}
			// Ctrl+K → kill to end
			if (key === "\x0b") { buffer = buffer.slice(0, cursor); render(); return; }
			// Ctrl+U → kill to start
			if (key === "\x15") { buffer = buffer.slice(cursor); cursor = 0; render(); return; }

			// Printable characters
			if (key >= " " && key !== "\x7f") {
				buffer = buffer.slice(0, cursor) + key + buffer.slice(cursor);
				cursor += key.length;
				render();
			}
		});
	});
}