function in cordova to encrypt media with custom plugin

encryptMedia.js

function initFS() {
    //init and maintain fs, look into removing
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fs) {
        appFileSystem = fs;
        
        fs.root.getDirectory("Wanagogo", {create: true, exclusive: false}, function(dirEntry) {
            mainAppDir = dirEntry
            k('defining main app dir', dirEntry)
            //look at downloads
            mainAppDir.getDirectory("downloads", {create: true, exclusive: false}, function(dirEntry) {
                wggApi.logEvent({
                    eventType: "loadedFilesystem",
                    elapsed: ((Date.now() - window.deviceReadyTime) /1000).toFixed(2)
                    // elapsed: Math.round((Date.now() - window.deviceReadyTime) /1000)
                })

                downloadDir = dirEntry;

                //audit downloads
                var directoryReader = dirEntry.createReader()
                directoryReader.readEntries( function(entries) {
                    auditDownloads(entries)
                }, fsError)

            }, fsError)

            if (device.platform == 'Android') {
                // window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fileSystem) {
                mainAppDir.getFile('wggLog.txt', {create:true}, function(file) {
                    WGGLOG = file
                    k("got the file", JSON.stringify(file));
                }, fsError)
            }
        }, fsError)
    }, fsError)
}

function encryptMedia(SKU) {
    
    k('process media file: ' + SKU)
    var self = this
    var theBegin = Date.now()
    
    var fileName = SKU + '.mp4'
    var random = randString(32)
    var encryptObj = {
        fileName: fileName,
        key: random,
        mutated: false
    }
    wggApi.localStore(SKU, JSON.stringify(encryptObj))
    k('mutate fileName: ', fileName) // wngg_MCPP00VL0004D.mp4
    
    //look at downloads
    mainAppDir.getDirectory("downloads", {create: true, exclusive: false}, function(dirEntry) {
        dirEntry.getFile(fileName, {"create": true, "exclusive": false}, function(fileEntry) {
            var filepath = fileEntry.toURL();
            k('mutate filepath: ', filepath) // ms-appdata:///local//Wanagogo/downloads/wngg_MCPP00VL0004D.mp4
            MutateFile.mutate(filepath, encryptObj.key, function (message) {
                k("mutate success: " + message)
                
                encryptObj.mutated = true;
                encryptObj.filePath = filepath;
                wggApi.localStore(SKU, JSON.stringify(encryptObj))
            }, function (e) {
                k("mutate fail: ", e)
            })
        }, fsError)
    }, fsError)
}