hw8.CampusPaths node interface

campus.js

/*
	This is a node api for the UW's CSE331 hw8.CampusPath's command-line interface.
	It probably only allows one concurrent user before weird shit happens.
	
	
	lives in a folder called `node` in the root of your svn repo:

	bin/
	doc/
	lib/
	node/
		campus.js
	src/

	call it from the `node` folder
 */

var path = require('path'),
	spawn = require('child_process').spawn,
	EventEmitter = require('events').EventEmitter;

var campusPaths = spawn('java', ['-cp', 'bin:lib/junit-4.11.jar', 'hw8.CampusPaths'], {
	cwd: path.join(__dirname, '..')
});

var cli = new EventEmitter();

var buffer = "";

campusPaths.stdout.on('data', function(data) {
	//add to the buffer
	buffer += data;

	//if we're "done", send an event and reset the buffer
	if (buffer.indexOf('Enter an option') !== -1) {
		var arr = buffer.substr(0, buffer.indexOf('Enter an option')).split('\n');
		prune(arr); //remove empty elements
		cli.emit('done', arr);
		buffer = "";
	}
});

function findPath(start, end, cb) {
	run(['r', start, end], function(data) {
		var path = [];
		var regex = /\tWalk ([0-9]+) feet ([NESW]{1,2}) to \(([0-9]+), ([0-9]+)\)/;
		try {
			//format the path
			for (var i = 1; i < data.length - 1; i++) {
				var matches = regex.exec(data[i]);
				path.push({
					coordinates: {
						x: new Number(matches[3]),
						y: new Number(matches[4])
					},
					length: new Number(matches[1]),
					direction: matches[2]
				});
			}
			var out = {
				request: {
					start: start,
					end: end
				},
				path: path,
				totalLength: new Number(data[data.length - 1].replace(/[^0-9]/g, ''))
			};
			cb(out);
		} catch (e) {
			//this happens if you load when the campuspaths process is doing something else
			cb('error, try again');
		}
	});
}

function listBuildings(cb) {
	run(['b'], function(data) {
		var out = [];
		for (var i = 0; i < data.length; i++) {
			var parts = data[i].split(': ');
			out.push({
				shortName: parts[0],
				longName: parts[1]
			});
		}
		cb(out);
	});
}

function killProcess(cb) {
	campusPaths.kill('SIGINT');
	campusPaths.on('close', function() {
		cb();
	});
}

module.exports = {
	path: findPath,
	list: listBuildings,
	close: killProcess
};

/* util */

function run(arr, cb) {
	//this method doesn't take into account for any concurrency in campuspaths access at all
	// i doubt more than one person can use this without weird concurrency issues

	cli.on('done', function(data) {
		cb(data);
		cli.removeAllListeners('done');
	});
	campusPaths.stdin.write(arr.join('\n') + '\n');
}

function prune(arr) {
	while (arr.indexOf('') != -1) {
		arr.splice(arr.indexOf(''), 1);
	}
}