window.ctMaxUploadFiles = 20;
    var _ctPdfMergeQueue = [];
    var _ctPdfMergeTimer = null;

    function _ctReadBlobAsArrayBuffer(blob) {
        return new Promise(function(resolve, reject) {
            var reader = new FileReader();
            reader.onload = function(e) { resolve(e.target.result); };
            reader.onerror = reject;
            reader.readAsArrayBuffer(blob);
        });
    }

    function _ctMergePdfBatch(files) {
        if (!files || !files.length) return;
        loadScriptPromise('https://cdn.jsdelivr.net/npm/pdf-lib@1.17.1/dist/pdf-lib.min.js').then(async function() {
            try {
                if (!window.PDFLib || !PDFLib.PDFDocument) {
                    alert('PDF library failed to load.');
                    return;
                }

                var merged = await PDFLib.PDFDocument.create();
                for (var i = 0; i < files.length; i++) {
                    var item = files[i];
                    var srcBytes = await _ctReadBlobAsArrayBuffer(item.blob);
                    var srcDoc = await PDFLib.PDFDocument.load(srcBytes, { ignoreEncryption: true });
                    var copied = await merged.copyPages(srcDoc, srcDoc.getPageIndices());
                    for (var p = 0; p < copied.length; p++) merged.addPage(copied[p]);
                }

                var mergedBytes = await merged.save();
                var firstName = (files[0] && files[0].name) ? files[0].name : 'merged';
                var baseName = firstName.replace(/\.pdf$/i, '');
                add_file_output(URL.createObjectURL(new Blob([mergedBytes], { type: 'application/pdf' })), baseName + '-merged.pdf');
            } catch (err) {
                alert('Could not merge one or more PDF files. Encrypted PDFs are not supported.');
            }
        }).catch(function() {
            alert('Could not load PDF tools in your browser.');
        });
    }

    function processFiles(files) {
        var batch = [];
        for (var i = 0; i < files.length; i++) {
            batch.push({ blob: files[i], name: files[i].name || ('file-' + (i + 1) + '.pdf') });
        }
        _ctMergePdfBatch(batch);
    }

    function processFile(blob, fileName) {
        _ctPdfMergeQueue.push({ blob: blob, name: fileName || 'file.pdf' });
        if (_ctPdfMergeTimer) clearTimeout(_ctPdfMergeTimer);
        _ctPdfMergeTimer = setTimeout(function() {
            var batch = _ctPdfMergeQueue.slice(0);
            _ctPdfMergeQueue = [];
            _ctMergePdfBatch(batch);
        }, 180);
    }







var _loadedScripts = {};
function loadScriptPromise(url) {
    if (_loadedScripts[url]) return _loadedScripts[url];
    _loadedScripts[url] = new Promise(function (resolve, reject) {
        var s = document.createElement('script');
        s.src = url;
        s.onload = resolve;
        s.onerror = reject;
        document.head.appendChild(s);
    });
    return _loadedScripts[url];
}

function replaceAll(find, replace, str) {
    return str.replace(new RegExp(find, 'g'), replace);
}

function beautify(str) {


    var result = '';

    var length = str.length;

    var i = 0;

    var braceCountLeft = 0;
    var braceCountRight = 0;

    var withinQuotes = false;

    while (i < length) {

        var c = str[i];

        if (c == '"' && (i == 0 || c[i - 1] != '\\')) {
            // non-escaped quotes
            withinQuotes = !withinQuotes;
        }

        if (!withinQuotes && (c == '}' || c == '{' || c == ',')) {

            console.log('Start####' + result);

            // look back and remove carriage returns and whitespace that are already there

            var resultIndex = result.length - 1;
            while (resultIndex >= 0 && (result[resultIndex] == ' ' || result[resultIndex] == '\r' || result[resultIndex] == '\n' || result[resultIndex] == '\t')) {

                resultIndex = resultIndex - 1;
                result = result.substr(0, resultIndex + 1);

                console.log('char ' + result[resultIndex] + '-----' + result + 'zzz ' + result.length + ' ' + resultIndex);

            }


            if (c == '{') {
                braceCountLeft++;
                result += c + '\r' + GetTabs(braceCountLeft - braceCountRight);
            } else if (c == '}') {
                braceCountRight++;
                // precede with carriage return
                result += '\r' + GetTabs(braceCountLeft - braceCountRight) + c;
            } else if (c == ',') {
                result += c + '\r' + GetTabs(braceCountLeft - braceCountRight);
            }

            var nextChar = '';

            // advance through whitespace and remove carriage returns that are already there
            while (i < length && (str[i + 1] == ' ' || str[i + 1] == '\r' || str[i + 1] == '\n' || str[i + 1] == '\t')) {
                i++;
            }

        } else {

            result += str[i];

        }


        i++;

    }

    return result;

}

function GetTabs(count) {

    var result = '';

    for (var i = 0; i < count; i++) {
        result += '    ';
    }

    return result;

}