function _ctDiffLcs(a, b) {
        var m = a.length, n = b.length;
        var dp = new Array(m + 1);
        for (var i = 0; i <= m; i++) dp[i] = new Int32Array(n + 1);
        for (var i = 1; i <= m; i++) {
            for (var j = 1; j <= n; j++) {
                if (a[i-1] === b[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
                else dp[i][j] = dp[i-1][j] >= dp[i][j-1] ? dp[i-1][j] : dp[i][j-1];
            }
        }
        return dp;
    }

    function _ctDiffOps(aText, bText) {
        var a = (aText || '').split('\n');
        var b = (bText || '').split('\n');
        var dp = _ctDiffLcs(a, b);
        var i = a.length, j = b.length;
        var ops = [];
        while (i > 0 && j > 0) {
            if (a[i-1] === b[j-1]) { ops.push({op:'=', text:a[i-1]}); i--; j--; }
            else if (dp[i-1][j] >= dp[i][j-1]) { ops.push({op:'-', text:a[i-1]}); i--; }
            else { ops.push({op:'+', text:b[j-1]}); j--; }
        }
        while (i > 0) { ops.push({op:'-', text:a[i-1]}); i--; }
        while (j > 0) { ops.push({op:'+', text:b[j-1]}); j--; }
        ops.reverse();
        return ops;
    }

    function _ctEscDiff(s) {
        return (s == null ? '' : String(s)).replace(/[&<>]/g, function(c){
            return ({'&':'&amp;','<':'&lt;','>':'&gt;'})[c];
        });
    }

    function _ctRunDiff() {
        var aEl = document.getElementById('diff-input-a');
        var bEl = document.getElementById('diff-input-b');
        var outEl = document.getElementById('diff-output');
        var statsEl = document.getElementById('diff-stats');
        if (!aEl || !bEl || !outEl) return;
        var aVal = aEl.value || '';
        var bVal = bEl.value || '';
        if (!aVal && !bVal) {
            outEl.innerHTML = '<span class="diff-eq">(paste text in both boxes to compare)</span>';
            if (statsEl) statsEl.textContent = '';
            return;
        }
        var ops = _ctDiffOps(aVal, bVal);
        var html = '';
        var adds = 0, dels = 0;
        for (var k = 0; k < ops.length; k++) {
            var o = ops[k];
            if (o.op === '+') { html += '<span class="diff-add">+ ' + _ctEscDiff(o.text) + '</span>\n'; adds++; }
            else if (o.op === '-') { html += '<span class="diff-del">- ' + _ctEscDiff(o.text) + '</span>\n'; dels++; }
            else { html += '<span class="diff-eq">&nbsp;&nbsp;' + _ctEscDiff(o.text) + '</span>\n'; }
        }
        outEl.innerHTML = html || '<span class="diff-eq">(both texts are identical)</span>';
        if (statsEl) {
            if (adds === 0 && dels === 0) statsEl.textContent = 'texts are identical';
            else statsEl.textContent = adds + ' added, ' + dels + ' removed';
        }
    }

    function convert(input) {
        _ctRunDiff();
        return '';
    }

    $(function(){
        $('#diff-input-a, #diff-input-b').on('input change', function(){ _ctRunDiff(); });
        setTimeout(_ctRunDiff, 50);
    });







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;

}