// ==UserScript==
// @name         Amazon show absolute review numbers
// @namespace    graphen
// @version      0.3.1
// @description  Adds the number of reviews to each rating separately
// @author       Graphen
// @include      /^https?:\/\/www\.amazon\.(cn|in|co\.jp|sg|fr|de|it|nl|es|co\.uk|ca|com(\.(mx|au|br))?)\/.*(dp|gp\/(product|video)|exec\/obidos\/ASIN|o\/ASIN)\/.*$/
// @icon         https://www.amazon.com/favicon.ico
// @grant        none
// @noframes
// @downloadURL none
// ==/UserScript==
/* jshint esversion: 6 */

(function() {
    'use strict';

    var totalReviewCount = document.querySelector('h2[data-hook="total-review-count"]').innerText;
    // Sanitize totalReviewCount
    // Remove all non-digits
    totalReviewCount = totalReviewCount.replace(/\D/g, '');
    // Convert string to integer
    totalReviewCount = parseInt(totalReviewCount, 10);
    // Most reviewed product has ~100000 at the moment
    if (totalReviewCount < 250000) {
        const arrPercentages = Array.from(document.querySelectorAll("#histogramTable .a-text-right > *:first-child"));
        for (var e of arrPercentages) {
            let v = e.innerText;
            // Get rid of percentage sign and convert string to integer
            v = parseInt(v, 10);
            // Calculate absolute review count
            v = Math.round(v * totalReviewCount / 100);
            // Cancel if nonsense
            if (v > totalReviewCount || v < 0) {
                break;
            }
            // Append calculated value to visible node
            e.textContent += " (" + v + ")";
        }
    }

})();