gistfile1.js

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

module.exports = {
	createMonitor: createMonitor
};

function equalStats(a, b) {
	if(a && !b) return false;
	if(b && !a) return false;
	// if(a.atime.getTime() != b.atime.getTime()) return false;
	if(a.mtime.getTime() != b.mtime.getTime()) return false;
	if(a.ctime.getTime() != b.ctime.getTime()) return false;
	return equalValues(['mode', 'size'], a, b);
}

function equalValues(keys, a, b) {
	for(var i=0; i<keys.length; i++) {
		var key = keys[i];
		if(a[key] !== b[key]) {
			return false;
		}
	}
	return true;
}

function createMonitor() {
	var em = new EventEmitter();
		errors = {},
		stats = {},
		watchers = {};

	em.stat = stat;
	em.destroy = destroy;

	function destroy() {
		for (n in watchers) {
			unwatch(n);
		}
		stats = {};
		watchers = {};
		delete em;
	}

	function stat(p, cb) {
		if(cb == null) cb = function() {};
		
		if(typeof p !== 'string') {
			var pending = p.length;
			p.forEach(function(p) {
				stat(p, function() {
					if(!--pending) return cb();
				});
			});
			if(!pending) cb();
			return;
		}
		
		p = path.resolve(p);
		
		fs.stat(p, function(err, s) {
			
			if(err) {
				if(stats[p]) {
					unwatch(p);
					em.emit('remove', p, stats[p].current);
					em.emit(p, 'remove', stats[p].current);
					delete stats[p];
				} else {
					errors[p] = err;
				}
				return cb();
			}
			
			if(stats[p]) {
				if(!equalStats(s, stats[p].current)) {
					stats[p] = {
						previous: stats[p].current,
						current: s
					};
					em.emit('change', p, stats[p].current, stats[p].previous);
					em.emit(p, 'change', stats[p].current, stats[p].previous);
				}
			} else {
				stats[p] = {
					previous: s,
					current: s
				};
				em.emit('create', p, stats[p].current);
				em.emit(p, 'create', stats[p].current);
			}
			
			if(s.isDirectory()) {
				walk(p, function() {
					watch(p);
					cb();
				});
			} else {
				watch(p);
				cb();
			}
		});
	}
	
	function walk(p, cb) {
		fs.readdir(p, function(err, files) {
			if(err) {
				++em.numErrors;
				errors[p] = err;
				return cb();
			}
			
			var pending = files.length;
			
			files.forEach(function(file) {
				if(file.slice(0, 1) === '.') {
					--pending;
					return;
				}
				
				stat(path.join(p, file), function(err) {
					if(err) return cb(err);
					
					if(!--pending) return cb();
				});
			});
			
			if(!pending) return cb();
		});
	}
	
	function watch(p) {
		if(watchers[p]) return;
		watchers[p] = true;
		try {
			watchers[p] = fs.watch(p, {}, function(event, filename) {
				// unwatch(p);
				stat(p, function() {});
			}).on('error', function() {
				unwatch(p);
				stat(p, function() {});
			});
		} catch(err) {
			unwatch(p);
		}
	}
	
	function unwatch(p) {
		if(!watchers[p])
			return;
		if(watchers[p] !== true)
			watchers[p].close();
		delete watchers[p];
	}
	
	return em;
}