server.js

var express = require('express'),
	app = express(),
	fs = require('fs'),
	path = require('path'),
	exec = require('child_process').exec,
	imageinfo = require('imageinfo');

app.configure(function() {
	app.use(express.static(__dirname + '/public'));
	app.use(express.bodyParser());
});


var isNumber = function(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
};

/*var tiles = [
	[
		{img: 'img/grass.png'},
		{img: 'img/mountains.png'},
		{img: 'img/cave-20.png'},
		{img: 'img/cave-21.png'},
		{img: 'img/cave-22.png'}
	]
];*/

var world = null;

var splitImage = function(path) {
	var cmd = 'convert ' + path + ' -crop 16x16 -filter Point -resize x32 +antialias ' + path;
	exec(cmd, function(err, stdout, stderr) {
		if (err) {
			if (err.message.indexOf('Invalid Parameter') !== -1) {
				throw 'Must install imagemagick';
			} else {
				throw err;
			}
			//console.log(err.message);
			//throw err;
		}
		console.log('cropped');
	});
};

var getRelativePath = function(path) {
	var pieces = path.split('\\');
	var index = pieces.indexOf('public');
	var relativePath = pieces.slice(index).join('\\');
	//var relativePath = pieces[pieces.length-2] + '\\' + pieces[pieces.length-1];
	return relativePath;
};

var tryMakeFolder = function(folderPath, callback) {
	fs.stat(folderPath, function(err, stats) {
		var exists = false;

		if (err && err.code !== 'ENOENT') {
			throw err;
		} else if (stats && stats.isDirectory()) {
			exists = true;
		}

		if (!exists) {
			fs.mkdir(folderPath, function(err) {
				if (err) throw err;
				callback();
			});
		} else {
			callback();
		}
	});
};

var saveFile = function(req, callback) {
	var targetFolder = path.resolve('./public/img/' + req.body.fileName);
	tryMakeFolder(targetFolder, function() {
		var tempPath = req.files.file.path,
			targetPath = targetFolder + '\\' + req.body.fileName + '.png';

		// if (path.extname(req.files.file.name).toLowerCase() === '.png') {
		//console.log(req.files.file)
		if (req.files.file.headers['content-type'] === 'image/png') {
			fs.rename(tempPath, targetPath, function(err) {
				if (err) throw err;
				console.log("Upload completed!");
				var relativePath = getRelativePath(targetPath);
				console.log(relativePath);
				splitImage(relativePath);
				callback();
			});
		} else {
			fs.unlink(tempPath, function (err) {
				if (err) throw err;
				console.error("Only .png files are allowed!");
				callback();
			});
		}
	});
};

var getSprites = function(directory, type, callback) {
	fs.readdir(directory, function(err, files) {
		if (err) throw err;

		var images = files.filter(function(file) {
			return file.split('.').pop() === type;
		});

		//console.log(JSON.stringify(images, null, 2));

		var tiles = images.sort(function (a, b) {
			var aNum = parseInt(a.split('-').pop().split('.')[0]);
			var bNum = parseInt(b.split('-').pop().split('.')[0]);
			return bNum - aNum;
		});

		var source = tiles.pop();
		var folder = directory.split('/').pop();

		tiles = tiles.reverse().map(function (tile) {
			return {img: 'img/' + folder + '/' + tile};
		});

		if (!source || !tiles || tiles.length === 0) {
			return callback([]);
		}

		fs.readFile(directory + '/' + source, function (err, data) {
			if (err) throw err;
			info = imageinfo(data);
			/*console.log("Data is type:", info.mimeType);
			console.log("  Size:", data.length, "bytes");*/
			var tilesPerRow = info.width / 16;
			var arrangedTiles = [];
			tiles.forEach(function(tile, i) {
				var row = Math.floor(i / tilesPerRow);
				var column = i - row * tilesPerRow;
				if (column === 0) {
					arrangedTiles[row] = [];
				}
				arrangedTiles[row].push(tile);
			});

			callback(arrangedTiles);
		});
	});
};

app.get('/tiles', function(req, res) {
	getSprites('./public/img/cave', 'png', function (tiles) {
		res.send(tiles);
	});
});

app.post('/world', function(req, res) {
	world = req.body;
	res.send('success');
});

app.get('/world', function(req, res) {
	res.send(world);
});

app.post('/upload', function (req, res) {
	res.setHeader('Content-Type', 'text/html');

	if (req.files.length === 0 || req.files.file.size === 0) {
		res.send({ msg: 'No file uploaded at ' + new Date().toString() });
	} else {
		var file = req.files.file;
		saveFile(req, function() {
			res.send({ msg: '<b>"' + file.name + '"</b> uploaded to the server at ' + new Date().toString() });
		});
	}
});

app.get('/tilesets', function (req, res) {
	fs.readdir('./public/img', function (err, files) {
		if (err) throw err;

		var folders = files.filter(function (file) {
			return file.split('.').length === 1;
		}).map(function (file) {
			return {
				img: 'img/' + file + '/' + file + '.png',
				name: file
			};
		});

		var pending = folders.length;
		folders.forEach(function(folder) {
			getSprites('./public/img/' + folder.name, 'png', function (tiles) {
				folder.tiles = tiles;
				if (!--pending) res.send(folders);
			});
		});

		//res.send(folders);
	});
});

app.get('/stat', function (req, res) {
	getSprites('./uploads', 'png', function (tiles) {
		console.log(JSON.stringify(tiles, null, 2));
	});
});

app.get('/read', function (req, res) {
	fs.readFile('./uploads/cave.png', function (err, data) {
		if (err) throw err;
		info = imageinfo(data);
		/*console.log("Data is type:", info.mimeType);
		console.log("  Size:", data.length, "bytes");*/
		var tilesPerRow = info.width / 16;
		console.log("There are", tilesPerRow, "tiles per row");
	});
});


app.listen(9999);
console.log('listening on port 9999...');