var spawn = require("child_process").spawn;

module.exports = shell;
module.exports.safe = safe;

function shell(cmd, ...args) {
	console.log("running shell '"+cmd+" "+args.join(" ")+"'");
	return new Promise((resolve, reject) => {
		var child = spawn(cmd, args);

		function print(out, name) {
			return function(d) {
				var s = d.toString();
				if (s.trim() === "")
					return;
				out.write(cmd+": "+name+": "+s);
			}
		}
		child.stderr.on("data", print(process.stderr, "err"));
		child.stdout.on("data", print(process.stdout, "out"));

		child.on("error", reject);
		child.on("exit", resolve);
	});
}

async function safe(...args) {
	var code = await shell.apply(null, args);
	if (code !== 0 && code !== null)
		throw new Error("Command "+args[0]+" failed, exit code "+code);
	return code;
}