sequencer.js

var fs = require('fs');

// i'm fairly sure i didn't write this, but i don't remember where i got it
// performs a natural sort, so 10 comes after 2.
function naturalCompare(a, b) 
{
	var i, codeA, codeB = 1, posA = 0, posB = 0, alphabet = String.alphabet;

	function getCode(str, pos, code) {
		if (code) {
			for (i = pos; code = getCode(str, i), code < 76 && code > 65;) ++i;
			return +str.slice(pos - 1, i);
		}
		code = alphabet && alphabet.indexOf(str.charAt(pos))
		return code > -1 ? code + 76 : ((code = str.charCodeAt(pos) || 0), code < 45 || code > 127) ? code
			: code < 46 ? 65               // -
			: code < 48 ? code - 1
			: code < 58 ? code + 18        // 0-9
			: code < 65 ? code - 11
			: code < 91 ? code + 11        // A-Z
			: code < 97 ? code - 37
			: code < 123 ? code + 5        // a-z
			: code - 63
	}


	if ((a+="") != (b+="")) for (;codeB;) {
		codeA = getCode(a, posA++);
		codeB = getCode(b, posB++);

		if (codeA < 76 && codeB < 76 && codeA > 66 && codeB > 66) {
			codeA = getCode(a, posA, posA);
			codeB = getCode(b, posB, posA = i);
			posB = i;
		}

		if (codeA != codeB) return (codeA < codeB) ? -1 : 1;
	}
	return 0;
}

function pad(num, size) 
{
    var s = num+"";
    while (s.length < size) s = "0" + s;
    return s;
}

var stats = {};
// find only images
var files = fs.readdirSync('.').filter(function(f) {
	if(['jpg','png','jpeg'].indexOf(f.split('.').slice(-1)[0].toLowerCase()) == -1)
		return false;
	var stat = fs.statSync(f);
	stats[f] = stat;
	return !stat.isDirectory();
});

// find all command line switches
var argvOptions = process.argv.slice(2);

files = files.sort(function(a, b) { 
	// allow sorting by time downloaded instead of filename
	if(argvOptions.indexOf("time") != -1)
	{
		if(stats[a].birthtime > stats[b].birthtime)
			return 1;
		if(stats[a].birthtime < stats[b].birthtime)
			return -1;
		return 0;
	}
	else
	{
		return naturalCompare(a, b);
	}
});

var commit = false;
// don't do anything unless the user has made sure the result was correct
if(argvOptions.indexOf("commit") != -1)
{
	commit = true;
}
else
{
	console.log("showing a PREVIEW. type 'sequencer commit' to actually rename things.");
}

var padTo = (files.length < 1000 ? 3 : files.length.toString().length);
// sequence
for(var i = 0; i < files.length; i++)
{
	(function() {
		// compute new filename
		var file = files[i];
		var ext = file.split('.').slice(-1)[0].toLowerCase();
		var newFile = pad(i + 1, padTo) + "." + ext;
		if(newFile != file && fs.existsSync(newFile))
			throw new Error("File exists: " + file + " -> " + newFile);

		// if we're supposed to do something, rename the file
		if(commit)
		{
			fs.rename(file, newFile, function(err) {
				if(err) throw err;
				console.log(file + " -> " + newFile);
			});
		}
		else
		{
			console.log(file + " -> " + newFile);
		}
	})();
}