// ==UserScript==
// @name         mathtrainer.ai auto solve
// @namespace    http://tampermonkey.net/
// @version      1
// @description  :p
// @author       elias
// @match        https://mathtrainer.ai/*
// @grant        none
// ==/UserScript==

// made by elias @ 15 sep. 2025

(function() {
    'use strict';

    let lastExpression = '';
    let isProcessing = false;
    let InputEvents = {};

    function hook(element) {
        element.addEventListener = new Proxy(element.addEventListener, {
            apply(target, _this, args) {
                const [type, listener] = args;
                if (_this.tagName === 'SECTION' && _this.classList.contains('answer')) {
                    InputEvents[type] = listener;
                }
                return target.apply(_this, args);
            }
        });
    }
    hook(HTMLElement.prototype);

    function keypress(target, key) {
        const event = new KeyboardEvent('keydown', {
            key: key,
            code: key.length === 1 ? `Digit${key}` : (key === 'Enter' ? 'Enter' : 'Unknown'),
            bubbles: true,
            cancelable: true
        });

        if (InputEvents.keydown) {
            InputEvents.keydown({
                target: target,
                key: key,
                type: 'keydown',
                preventDefault: () => {},
                stopPropagation: () => {}
            });
        }

        target.dispatchEvent(event);
    }

    function evaluateMath(expression) {
        if (!expression) return null;
        expression = expression
            .replace(/\\times/g, '*')
            .replace(/×/g, '*')
            .replace(/÷/g, '/')
            .replace(/−/g, '-')
            .replace(/\\div/g, '/')
            .replace(/\\sqrt\{(\d+)\}/g, 'Math.sqrt($1)')
            .replace(/\\sqrt\[(\d+)\]\{(\d+)\}/g, 'Math.pow($2, 1/$1)')
            .replace(/\^/g, '**')
            .replace(/\s+/g, '');
        try {
            const result = Function('"use strict"; return (' + expression + ')')();
            if (Number.isFinite(result)) {
                if (Math.abs(result - Math.round(result)) < 1e-10) {
                    return Math.round(result); // round near-integers (39.99999.. -> 40)
                } 
                return result;
            }
            return null;
        } catch (e) {
            return null;
        }
    }

    function randomDelay(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min;
    }

    async function inputAnswer(answerSection, result) {
        const resultStr = String(result);

        await new Promise(resolve => setTimeout(resolve, randomDelay(300, 500)));

        for (let i = 0; i < resultStr.length; i++) {
            keypress(answerSection, resultStr[i]);

            if (i < resultStr.length - 1) {
                await new Promise(resolve => setTimeout(resolve, randomDelay(300, 500)));
            }
        }

        await new Promise(resolve => setTimeout(resolve, randomDelay(300, 500)));
    }

    async function processQuestion() {
        if (isProcessing) return;
        isProcessing = true;

        try {
            const annotation = document.querySelector('annotation[encoding="application/x-tex"]');
            if (!annotation) {
                isProcessing = false;
                return;
            }

            const expression = annotation.textContent.trim();
            if (!expression || expression === lastExpression) {
                isProcessing = false;
                return;
            }

            lastExpression = expression;

            const result = evaluateMath(expression);
            if (result === null) {
                isProcessing = false;
                return;
            }

            // console.log("Detected:", expression);
            // console.log("Answer:", result);

            const answerSection = document.querySelector('section.answer');
            if (!answerSection) {
                isProcessing = false;
                return;
            }

            await inputAnswer(answerSection, result);

            // keypress(answerSection, 'Enter');
            // not needed as it gets auto-entered
            isProcessing = false;

        } catch (e) {
            isProcessing = false;
        }
    }

    const observer = new MutationObserver(() => {
        processQuestion();
    });

    observer.observe(document.body, {
        childList: true,
        subtree: true,
        attributes: true
    });

    // sometimes observer doesnt catch it :(
    // use interval loop as fallback
    setInterval(() => {
        if (!isProcessing) {
            processQuestion();
        }
    }, 500);
})();