// 2011 Metrify bookmarklet by https://github.com/ikhramts where I got the RegExp and conversions from https://github.com/ikhramts/metrify/blob/master/metrify.js
// RegExp query selector https://stackoverflow.com/questions/37098405/javascript-queryselector-find-div-by-innertext/37098508

function getDOMMatches(selector,expression){
    //the reason to not use innerHTML on the whole body is to preserve event listeners
    return Array.from(document.querySelectorAll(selector)).filter(
        el => RegExp(expression).test(el.textContent) //all elements that match the expression
        && el.childNodes.length != el.children.length // childNodes include text nodes, children do not = if the length is different there is an unwrapped text in that element
        && Array.from(el.childNodes).filter(
            node => node.nodeType == Node.TEXT_NODE && node.textContent.trim() == ""
        ).length == 0 //for some reason there were sometimes empty text nodes that squeezed through the previous condition
    );
}

function metrify(element){
    if(typeof element === 'undefined') return false;

    var position;
    var i = 0; // just for safety

    while ((position = quantityPattern.exec(element.innerHTML)) !== null) {
        //["1,100-pound", "1,100", "1,100", ",100", ",", undefined, undefined, "-", "pound", index: 298...
        //["1,538.46 feet", "1,538.46", "1,538", ",538", ",", ".46", ".", " ", "feet", index: 70
        var wholeString = position[0];
        var numberString = position[1];
        var separator = position[7];
        var units = position[8];
        var hasMinus = false;

        var toDecimalPlaces = (typeof position[5] !== 'undefined') ? position[5].length-1 : 0;
        var separator = (separator == ' ') ? " " : ' ';

        var number = numberString.replaceAll(",","") * 1; // take out thousand separators and convert to number


        // Figure out which units we're working with.
        var intercept = 0;
        var slope = 1;
        var toUnits = "";
        
        if (/^(miles?|mi)$/i.test(units)) {
            slope = 1.609344;
            toUnits = "km";
            
        } else if (/^(foot|feet|ft)$/i.test(units)) {
            slope = 0.3048;
            toUnits = "m";
            
        } else if (/^(inch|inches|in|"|")$/i.test(units)) {
            slope = 2.54;
            toUnits = "cm";
            toDecimalPlaces = 2;
            
        } else if (/^(yards?|yd)$/i.test(units)) {
            slope = 0.9144;
            toUnits = "m";
            
        } else if (/^(ounces?|oz)$/i.test(units)) {
            slope = 28.3495231;
            toUnits = "g";
            
        } else if (/^(pounds?|lb)$/i.test(units)) {
            slope = 0.45359237;
            toUnits = "kg";
            
        } else if (/(°F|ºF|°F|fahrenheit|degrees? fahrenheit)$/i.test(units)) {
            if(element.innerHTML.substring(position.index-1, position.index) == "-"){
                number = number * -1;
                hasMinus = true;
            }

            intercept = -32 * 5 / 9;
            slope = 5 / 9;
            toUnits = "°C";

        } else if (/^(mph?|mi\/h)$/i.test(units)) {
            slope = 1.609344;
            toUnits = "km/h";

        } else if (/^(gallons?|gal)$/i.test(units)) {
            slope = 3.78541;
            toDecimalPlaces = 1;
            toUnits = "l";
        }
        else if (/^(fl? oz)$/i.test(units)) {
            slope = 29.5735;
            toDecimalPlaces = 0;
            toUnits = "ml";
        }

        var convertedNumber = parseFloat(number) * slope + intercept;
        var wholeString = (hasMinus) ? "-" + wholeString : wholeString; //the regex does not include the - in matches
        
        var convertedString = new Intl.NumberFormat('en-US').format(convertedNumber.toFixed(toDecimalPlaces)) + (separator ? separator : "") + toUnits;
        var formattedString = "" + convertedString + "";


        //insert back into element
        element.innerHTML = element.innerHTML.replace(wholeString,formattedString);
        changes += wholeString + "->" + formattedString + "\n";

        i++;
        if(i>3000) return false;
    }

    return true;
}


var quantityPattern =  /\b([\+\-]?(\d+|\d{1,3}(([\s,])\d{3})+)(([.])\d+)?)(\s*|-)?(miles?|mph|mi\/h|mi|foot|feet|ft|inch|inches|in|"|"|yards?|yd|ounces?|oz|pounds?|lb|°F|ºF|°F|fahrenheit|degrees? fahrenheit|gallons?|gal|fl? oz)\b/i;
var nodesWithMatches = getDOMMatches("*:not(head):not(html):not(script):not(body):not(title)",quantityPattern);
var changes = [];

if(nodesWithMatches.length){
    nodesWithMatches.forEach(element => {
        metrify(element);
    });
}