// ==UserScript==
// @name         Quizlet Auto Reject + Checkout Safe
// @namespace    http://tampermonkey.net/
// @version      2026-04-28
// @match        https://quizlet.com/*
// @grant        none
// @run-at       document-idle
// ==/UserScript==

(function () {
    'use strict';

    const CHECK_INTERVAL = 500;
    const CHECK_TIMEOUT = 20000;

    const CHECKOUT_URL =
        "https://quizlet.com/checkout?source=header_teacher&signupOrigin=upgrade-teacher-above-the-fold-start-trial";

    function waitClick(selectors, name) {
        const start = Date.now();

        const timer = setInterval(() => {
            for (const selector of selectors) {
                const el = document.querySelector(selector);
                if (el && !el.disabled) {
                    el.click();
                    console.log("[TM] Clicked:", name);
                    clearInterval(timer);
                    return true;
                }
            }

            if (Date.now() - start > CHECK_TIMEOUT) {
                clearInterval(timer);
                console.log("[TM] Not found:", name);
            }
        }, CHECK_INTERVAL);
    }

    function rejectCookies() {
        waitClick([
            '#ketch-banner-button-tertiary',
            'button[aria-label="Reject All"]',
            'button[aria-label="Từ chối tất cả"]'
        ], "Reject cookies");
    }

    function clickTrial() {
        waitClick([
            'button[data-testid="assembly-button-upgrade"]',
            'button[aria-label="Dùng thử miễn phí"]',
            'button[title="Dùng thử miễn phí"]'
        ], "Trial");
    }

    function clickCancelFinish() {
        waitClick([
            'button[aria-label="Hoàn tất việc hủy"]',
            'button[data-testid="assembly-button-primary"]'
        ], "Cancel finish");
    }

    function handleUrl() {
        const url = location.href;
        console.log("[TM] URL:", url);

        if (url.startsWith("https://quizlet.com/settings/manage-subscription/cancellation-survey")) {
            console.log("[TM] Cancellation survey reached.");
            return;
        }

        if (url.startsWith("https://quizlet.com/upgrade/success")) {
            location.replace("https://quizlet.com/settings/manage-subscription?step=cancel");
            return;
        }

        if (
            url.startsWith("https://quizlet.com/settings/manage-subscription") &&
            url.includes("step=cancel")
        ) {
            clickCancelFinish();
            return;
        }

        if (url.startsWith("https://quizlet.com/checkout")) {
            console.log("[TM] Checkout reached. Please click Google Pay manually.");
            rejectCookies();
            return;
        }

        if (url.startsWith("https://quizlet.com/upgrade")) {
            clickTrial();
            return;
        }

        if (url.startsWith("https://quizlet.com/settings")) {
            location.replace(CHECKOUT_URL);
            return;
        }

        rejectCookies();
    }

    handleUrl();

    let lastUrl = location.href;

    setInterval(() => {
        if (location.href !== lastUrl) {
            lastUrl = location.href;
            handleUrl();
        }
    }, 500);

})();