module.exports = {};

let inputBuffer = "";
let initialised = false, haveEOF = false;
let waitQueue = [];

function stdinDataListener(data) {
	data = data.toString();
	inputBuffer += data;

	if (waitQueue.length == 0) return;

	const idx = inputBuffer.indexOf("\n");
	if (idx == -1) return;

	waitQueue.shift()[0](inputBuffer.slice(0, idx));
	inputBuffer = inputBuffer.slice(idx + 1);
}

function stdinEndListener() {
	haveEOF = true;
	for (const [resolve, reject] of waitQueue) {
		reject("End-of-file reached");
	}
	waitQueue = [];
}

function init() {
	process.stdin.on("data", stdinDataListener);
	process.stdin.on("end", stdinEndListener);
	initialised = true;
}
module.exports.init = init;

function end() {
	process.stdin.removeListener("data", stdinDataListener);
	process.stdin.removeListener("end", stdinEndListener);
	process.stdin.end();
}
module.exports.end = end;

function getline() {
	return new Promise((resolve, reject) => {
		if (haveEOF) {
			reject("End-of-file reached");
			return;
		}

		const idx = inputBuffer.indexOf("\n");
		if (idx != -1) {
			const line = inputBuffer.slice(0, idx);
			inputBuffer = inputBuffer.slice(idx + 1);
			resolve(line);
		} else {
			waitQueue.push([resolve, reject]);
		}
	});
}
module.exports.getline = getline;

async function prompt(str) {
	process.stdout.write(str);
	return await getline();
}
module.exports.prompt = prompt;

function eof() {
	return haveEOF;
}
module.exports.eof = eof;