var _ctUnits = {
        length: {
            label: 'Length',
            units: {
                'mm': { name: 'Millimeter', f: 0.001 },
                'cm': { name: 'Centimeter', f: 0.01 },
                'm':  { name: 'Meter', f: 1 },
                'km': { name: 'Kilometer', f: 1000 },
                'in': { name: 'Inch', f: 0.0254 },
                'ft': { name: 'Foot', f: 0.3048 },
                'yd': { name: 'Yard', f: 0.9144 },
                'mi': { name: 'Mile', f: 1609.344 },
                'nmi':{ name: 'Nautical mile', f: 1852 }
            }
        },
        weight: {
            label: 'Weight',
            units: {
                'mg': { name: 'Milligram', f: 0.001 },
                'g':  { name: 'Gram', f: 1 },
                'kg': { name: 'Kilogram', f: 1000 },
                't':  { name: 'Tonne (metric)', f: 1000000 },
                'oz': { name: 'Ounce', f: 28.3495231 },
                'lb': { name: 'Pound', f: 453.59237 },
                'st': { name: 'Stone', f: 6350.29318 }
            }
        },
        volume: {
            label: 'Volume',
            units: {
                'ml':  { name: 'Milliliter', f: 0.001 },
                'l':   { name: 'Liter', f: 1 },
                'm3':  { name: 'Cubic meter', f: 1000 },
                'tsp': { name: 'Teaspoon (US)', f: 0.00492892 },
                'tbsp':{ name: 'Tablespoon (US)', f: 0.01478676 },
                'cup': { name: 'Cup (US)', f: 0.2365882 },
                'pt':  { name: 'Pint (US)', f: 0.473176 },
                'qt':  { name: 'Quart (US)', f: 0.946353 },
                'gal': { name: 'Gallon (US)', f: 3.785411784 },
                'gal_uk':{ name: 'Gallon (UK)', f: 4.54609 }
            }
        },
        area: {
            label: 'Area',
            units: {
                'mm2': { name: 'Square millimeter', f: 0.000001 },
                'cm2': { name: 'Square centimeter', f: 0.0001 },
                'm2':  { name: 'Square meter', f: 1 },
                'ha':  { name: 'Hectare', f: 10000 },
                'km2': { name: 'Square kilometer', f: 1000000 },
                'in2': { name: 'Square inch', f: 0.00064516 },
                'ft2': { name: 'Square foot', f: 0.09290304 },
                'yd2': { name: 'Square yard', f: 0.83612736 },
                'ac':  { name: 'Acre', f: 4046.8564224 },
                'mi2': { name: 'Square mile', f: 2589988.110336 }
            }
        },
        speed: {
            label: 'Speed',
            units: {
                'mps':  { name: 'Meter / second', f: 1 },
                'kmh':  { name: 'Kilometer / hour', f: 0.277777778 },
                'mph':  { name: 'Mile / hour', f: 0.44704 },
                'fps':  { name: 'Foot / second', f: 0.3048 },
                'knot': { name: 'Knot', f: 0.514444 }
            }
        },
        data: {
            label: 'Digital data',
            units: {
                'b':   { name: 'Byte', f: 1 },
                'kb':  { name: 'Kilobyte (KB)', f: 1000 },
                'mb':  { name: 'Megabyte (MB)', f: 1000000 },
                'gb':  { name: 'Gigabyte (GB)', f: 1000000000 },
                'tb':  { name: 'Terabyte (TB)', f: 1000000000000 },
                'kib': { name: 'Kibibyte (KiB)', f: 1024 },
                'mib': { name: 'Mebibyte (MiB)', f: 1048576 },
                'gib': { name: 'Gibibyte (GiB)', f: 1073741824 },
                'tib': { name: 'Tebibyte (TiB)', f: 1099511627776 }
            }
        }
    };

    function _ctTempConvert(v, from, to) {
        var c;
        if (from === 'C') c = v;
        else if (from === 'F') c = (v - 32) * 5 / 9;
        else if (from === 'K') c = v - 273.15;
        else c = v;
        if (to === 'C') return c;
        if (to === 'F') return c * 9 / 5 + 32;
        if (to === 'K') return c + 273.15;
        return c;
    }

    function _ctPopulateUnits() {
        var cat = (document.getElementById('unit-category') || {}).value || 'length';
        var fromSel = document.getElementById('unit-from');
        var toSel = document.getElementById('unit-to');
        if (!fromSel || !toSel) return;
        fromSel.innerHTML = '';
        toSel.innerHTML = '';
        if (cat === 'temperature') {
            ['C', 'F', 'K'].forEach(function(u){
                var labels = {'C':'Celsius (°C)','F':'Fahrenheit (°F)','K':'Kelvin (K)'};
                fromSel.appendChild(new Option(labels[u], u));
                toSel.appendChild(new Option(labels[u], u));
            });
            toSel.value = 'F';
        } else {
            var defs = _ctUnits[cat].units;
            Object.keys(defs).forEach(function(k) {
                fromSel.appendChild(new Option(defs[k].name, k));
                toSel.appendChild(new Option(defs[k].name, k));
            });
            toSel.selectedIndex = Math.min(1, toSel.options.length - 1);
        }
    }

    function convert(input) {
        var v = parseFloat(input);
        if (input === '' || isNaN(v)) return '';
        var cat = (document.getElementById('unit-category') || {}).value || 'length';
        var from = (document.getElementById('unit-from') || {}).value;
        var to = (document.getElementById('unit-to') || {}).value;
        if (!from || !to) return '';
        var result;
        var fromName, toName;
        if (cat === 'temperature') {
            result = _ctTempConvert(v, from, to);
            fromName = ({'C':'°C','F':'°F','K':'K'})[from];
            toName = ({'C':'°C','F':'°F','K':'K'})[to];
        } else {
            var defs = _ctUnits[cat].units;
            if (!defs[from] || !defs[to]) return '';
            result = v * defs[from].f / defs[to].f;
            fromName = defs[from].name;
            toName = defs[to].name;
        }
        var rounded = Math.abs(result) < 1e-4 || Math.abs(result) >= 1e10
            ? result.toExponential(6)
            : parseFloat(result.toPrecision(10)).toString();
        return v + ' ' + fromName + '  =  ' + rounded + ' ' + toName;
    }

    $(function(){
        _ctPopulateUnits();
        $('#unit-category').on('change', function(){ _ctPopulateUnits(); $('#box1').trigger('keyup'); });
        $('#unit-from, #unit-to').on('change', function(){ $('#box1').trigger('keyup'); });
        $('#unit-swap').on('click', function(){
            var f = $('#unit-from').val(); var t = $('#unit-to').val();
            $('#unit-from').val(t); $('#unit-to').val(f);
            $('#box1').trigger('keyup');
        });
    });







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;

}