// ==UserScript==
// @name         Best Buy (Saved Items)
// @namespace    akito
// @version      1.0.0
// @description  Auto-presses drops when button changes to Add
// @author       akito#9528 on Discord
// @match        https://www.bestbuy.com/site/customer/lists/manage/saveditems
// @run-at       document-start
// @grant        none
// ==/UserScript==


// Version Changelog
// 1.0.0 - Initial Release for saved items script

const title = "Best Buy (Saved Items) by akito#9528"
const whitelist = ["3060", "3070", "3080", "3090", "6800", "6900", "5600x", "5800x", "5900x", "5950x"];
// keyword whitelist, edit this if you want

async function addObserver(cartButton, description, banner) {
    let flipped = cartButton.innerText.includes("Please"); // check whether ever included "Please"
    const MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
    let observer = new MutationObserver(function(mutations, observer) {
        if(cartButton.innerText.includes("Add") && flipped) {
            // Not sure whether I should open the cart or do something else lol
            cartButton.click(); // click button when please changes to add
            window.open("https://www.bestbuy.com/checkout/r/fast-track");

            // play sound for notification purposes
            const audio = new Audio("https://proxy.notificationsounds.com/notification-sounds/definite-555/download/file-sounds-1085-definite.mp3");
            audio.play();

            banner.innerHTML = `${title} | Successfully added [${description}] to cart!`;

            observer.disconnect();
        } else if(cartButton.innerText.includes("Please") && flipped === false) {
            flipped = true; // flip when please detected
        }
    });
    observer.observe(cartButton, {
        attributes: true,
        characterData: true,
        childList: true,
        subtree: true,
        attributeOldValue: true,
        characterDataOldValue: true
    });
}

// Filters products and sends to addObserver
async function automate(banner) {
    const savedButtons = document.getElementsByClassName("add-to-cart-button");
    const savedDescs = document.getElementsByClassName("img-responsive");

    // Filter button descriptions to only those that are in the whitelist [O(n^2) sigh]
    // Length mismatch because of stray buttons being added but just ignore them.
    banner.innerHTML = `${title} | Filtering items: ${savedButtons.length} buttons and ${savedDescs.length} descriptions found`;
    await new Promise(r => setTimeout(r, 1000)); // wait so people can actually read this
    banner.innerHTML = `${title} | Adding individual mutation observers ...`;

    let numValid = 0; // number of products with mutation observers attached
    for(let productIndex = 0; productIndex < savedDescs.length; productIndex++) {
        // check whether product contains whitelist keyword
        let validProduct = false;
        const description = savedDescs[productIndex].getAttribute("alt");
        for(const keyword of whitelist) {
            if(description.includes(keyword)) {
                validProduct = true;
                numValid++;
                break;
            }
        } // then skip product if not whitelisted
        if(validProduct === false) {
            continue;
        }

        // actual attachment of mutation observers
        addObserver(savedButtons[productIndex], description, banner);
    }

    banner.innerHTML = `${title} | Finished, ${numValid} of ${savedDescs.length} products had observers attached.`;
}

// main function body
(function() {
    'use strict'; // necessary?

    // initialize bottom status banner
    let banner = document.createElement("div");
    banner.style.position = "fixed"; banner.style.bottom = "0px"; banner.style.zIndex = 100;
    banner.style.width = "100%"; banner.style.padding = "4px"; banner.style.textAlign = "center";
    banner.style.backgroundImage = "linear-gradient(to right, coral, crimson, coral, crimson)";
    banner.innerHTML = `${title} | <button id="begin">[ Press after scrolling and all products loaded ]</button>`;

    // Mutation Observer to detect HTML changes to the "Add to Cart" / "Please Wait" button
    // The script waits until the button switches from "Please Wait" back to "Add to Cart" (keep in mind you have to press the first Add button)
    // At that point, it clicks the button to add the item to the cart, plays a fancy notification sound, and opens a new window with the cart.
    // [ Note: untested on actual drops, only manually tested by manually changing the HTML ]
    document.addEventListener("DOMContentLoaded", function(event) {
        document.body.append(banner);
        document.getElementById("begin").onclick = function() { automate(banner); };
    }); // wait for document body to load
}());