const path = require("node:path");
const fs = require("node:fs");

const midiDeviceRegExp = new RegExp("^midi[0-9]+$");

let openDevice;
let callback;

module.exports = {
	"list": function () {
		var deviceNodeList = fs.readdirSync("/dev").filter(d => d.match(midiDeviceRegExp));

		return deviceNodeList.map(d => path.join("/dev", d));
	},
	"open": function (device, eventCB) {
		if (openDevice) {
			openDevice["read"].close();
			openDevice["write"].close();
		}

		var deviceName = path.basename(device);
		var devicePath = path.join("/dev", deviceName);

		openDevice = {
			"read": fs.createReadStream(devicePath),
			"write": fs.createWriteStream(devicePath)
		};

		if (eventCB) {
			callback = eventCB;
			openDevice.read.on("data", function (chunk) {
				callback(chunk);
			});
		}
	},
	"send": function (message) {
		if (!openDevice) return;

		var data = Buffer.from(new Uint8Array(message));

		openDevice["write"].write(data);
	},
	"close": function () {
		if (!openDevice) return;

		openDevice["read"].close();
		openDevice["write"].close();

		delete openDevice;
		delete callback;
	}
};