const os = require("os");
const childProcess = require("child_process");
const psTree = require("ps-tree");
const streamToLogger = require("stream-to-logger");

module.exports = function runProcess(path, args, options) {
	if (options.logger != null) {
		options.logger.info(`Starting ${path}...`);
	}

	let proc = childProcess.spawn(path, args, options);

	if (options.logger != null) {
		proc.stdout.pipe(streamToLogger(options.logger.log));
		proc.stderr.pipe(streamToLogger(options.logger.error));
	}

	proc.on("error", (err) => {
		if (options.logger != null) {
			options.logger.error(err.stack);
		}
	});

	proc.on("close", (code, signal) => {
		if (code != null) {
			options.logger.info(`${path} exited with code ${code.toString()}.`);
		} else if (signal != null) {
			options.logger.info(`${path} exited due to signal ${signal}.`);
		} else {
			options.logger.info(`${path} exited for an unknown reason.`);
		}
	});

	let _kill = proc.kill.bind(proc);
	proc.kill = function(signal) {
		/* FIXME: Are other UNIX-y platforms also affected by the killing-children-of-children issue? And do they have `ps` with the same flags? */
		if (os.platform() === "linux") {
			psTree(proc.pid, (err, children) => {
				if (err != null) {
					console.error(`WARN: Could not kill children of PID ${proc.pid}: ${err.message}`);
					console.error(err.stack);
					_kill(signal);
				} else {
					childProcess.execFile("kill", children.map((child) => child.PID), (err, stdout, stderr) => {
						_kill(signal);
					});
				}
			})
		} else {
			_kill(signal);
		}
	}

	return proc;
}