dechanify.js

var fs     = require('graceful-fs'), 
    crypto = require('crypto'), 
    path   = require('path');

// compute the sha1 hash of the file
function hashFile(name, cb)
{ 
	var hash = crypto.createHash('sha1'),
    stream = fs.createReadStream(name);

	stream.on('data', function (data) {
		hash.update(data);
	});

	stream.on('end', function () {
		cb(hash.digest('hex'));
	});
}

// find all non-directory files
var files = fs.readdirSync('.');
var chans = files.filter(function(f) { 
	return !(fs.statSync(f).isDirectory()); 
});

// if we're not hashing every file, filter them
if(process.argv[2] != 'all')
{
	chans = chans.filter(function(f) { 
		// only hash the files that have filenames that don't appear to be hashes (not 32-char long hex)
		return !(/^[0-9a-f]{32}.\w{3,4}/.test(f));
	});
}

// if no files, don't do anything
if(chans.length == 0)
{
	console.log('no files');
	process.exit(0);
}

console.log('found ' + chans.length + ' files');

var numComplete = 0;
function complete()
{
	console.log(numComplete + ' files done');
	process.exit(0);
}

// hash each file
chans.forEach(function(f) {
	var ext = path.extname(f);
	hashFile(f, function(hash) {
		// if nothing changed, don't do anything
		if(hash + ext == f)
		{
			console.log(hash + ext + ', no changes made.');
			numComplete++;
			if(numComplete >= chans.length)
				complete();
		}
		// if the new filename exists (there's a duplicate), don't do anything
		else if(fs.existsSync(hash + ext))
		{
			numComplete++;
			console.log(f + ' -> ' + hash + ext + ' failed, file exists');
			if(numComplete >= chans.length)
				complete();
		}
		// rename the file to the hash
		else
		{
			fs.rename(f, hash + ext, function(e) { 
				if(e) throw e; 
				numComplete++;
				console.log(f + ' -> ' + hash + ext);
				if(numComplete >= chans.length)
					complete();
			});
		}
	});
});