jpoo

#! /usr/bin/env node

// Usage cat some-file.json | jpoo path.to.Key
// Needed the ability to parse + fetch a key from a string of JSON sent to 
// stdin and be cross platfrom which ruled out jq, and should work with node 4 - BITE ME!

const stdin = process.stdin;

getStdin = () => {
	let ret = '';

	return new Promise(resolve => {
		if (stdin.isTTY) {
			resolve(ret);
			return;
		}

		stdin.setEncoding('utf8');

		stdin.on('readable', () => {
			let chunk;

			while ((chunk = stdin.read())) {
				ret += chunk;
			}

		});

		stdin.on('end', () => {
			resolve(ret);
		});
	});
};


getStdin().then( str => {
	try {
		const obj = JSON.parse(str)

		const path = process.argv[2].split('.')

		const res = path.reduce( (o, segment) =>{
			if (segment in o){
				return o[segment]
			}
			throw new Error(`Cannot find key "${segment}"`)
		}, obj)


		console.log(res)

	} catch ({ message }) {
		if(message.startsWith('Cannot read property \'split\' of undefined')) {
			console.error('Error: No path selector supplied')
		} else if(message === 'Unexpected end of JSON input') {
			console.error('Error: Invalid json supplied')
		} else {
			console.error(message)
		}
		process.exit(1)
	}

})