gistfile1.txt

function deleteTempFile(uri) {
        fs.unlink(uri, function(err) {
            if (err) return console.log('error deleting file ' + err);
            console.log('file deleted successfully');
        });
    }

    function downloadFile(uri, filename, callback) {
        request.head(uri, function(err, res, body) {
            try {
                var r = request(uri).pipe(fs.createWriteStream(filename));
                r.on('close', callback);
            } catch (e) {
            }
        });
    };

    function checkLocalFile(filepath){
        console.log('check filename =' + filepath);

        let flag = true;
        try {
            fs.accessSync(filepath, fs.F_OK);
        } catch(e) {
            flag = false;
        }

        return flag;
    }

    function checkRemoteURL(remotePath, res) {
        let flag = true;

        try {
            //valid url?
            if (remotePath == '' || !req.query.imageurl || !validUrl.isUri(req.query.imageurl)) {
                //no
                res.status(400).send('error, please specify a valid image url');
                flag = false;
            } else {
                //yes, check ext
                console.log('File path = ' + path.extname(removeQueryString(remotePath)));

                //valid file ext?
                if (path.extname(removeQueryString(remotePath)) != '.jpg' && path.extname(removeQueryString(remotePath)) != '.png') {
                    res.status(400).send('error, invalid file extension, not supported');
                    flag = false;
                } else {
                    flag = true;
                }
            }
        } catch (e) {
            flag = false;
        }

        return flag;
    }

    function removeQueryString(mUrl) {
        var obj = url.parse(mUrl);
        obj.search = obj.query = "";

        return url.format(obj);
    }