// ==UserScript==
// @name         WeLearn 时长助手
// @namespace    https://bbs.tampermonkey.net.cn/
// @version      1.0.5
// @author       恶搞之家 (modified by AI)
// @description  自动刷Welearn时长，自动章节跳转和循环，可配置滑动间隔并在submit按钮和direction区域间交替滑动。
// @match        *://welearn.sflep.com/Student/StudyCourse.aspx*
// @match        *://welearn.sflep.com/student/StudyCourse.aspx*
// @match        *://welearn.sflep.com/student/studyCourse.aspx*
// @match        *://welearn.sflep.com/student/Studycourse.aspx*
// @match        *://welearn.sflep.com/student/studycourse.aspx*
// @match        *://welearn.sflep.com/course/trycourse.aspx*
// @grant        none
// @run-at       document-idle
// ==/UserScript==

(function () {
    'use strict';


    window.wtb_waitTimerActive = false;
    window.wtb_waitTimerInterval = null;
    window.wtb_defaultWaitTimeMinutes = 30;
    window.wtb_defaultScrollIntervalMinutes = 10;
    window.wtb_autoCycleActive = false;
    window.wtb_lastScrollTarget = 'image';


    const wtb_sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
    const wtb_createEvent = (type, options = {}) => new Event(type, { bubbles: true, cancelable: true, ...options });



    async function tryScrollToElement(docContext, windowContext, selector, elementName) {
        const maxRetries = 3;
        const retryDelay = 300;
        let element = null;

        for (let i = 0; i < maxRetries; i++) {
            element = docContext.querySelector(selector);
            if (element) {

                const style = windowContext.getComputedStyle(element);
                if (style.display !== 'none' &&
                    style.visibility !== 'hidden' &&
                    parseFloat(style.opacity) > 0 &&
                    element.getClientRects().length > 0) {
                    console.log(`[WTB] ${elementName} found and visible on attempt ${i + 1}.`);
                    break;
                } else {
                    console.log(`[WTB] ${elementName} found on attempt ${i + 1} but appears hidden (display: ${style.display}, visibility: ${style.visibility}, opacity: ${style.opacity}, rects: ${element.getClientRects().length}).`);
                    element = null;
                }
            }
            if (i < maxRetries - 1 && !element) {
                console.log(`[WTB] ${elementName} not found/visible on attempt ${i + 1}/${maxRetries}. Waiting ${retryDelay}ms.`);
                await wtb_sleep(retryDelay);
            }
        }

        if (element) {
            try {
                element.scrollIntoView({ behavior: 'smooth', block: 'start' });
                console.log(`[WTB] Scrolled to ${elementName}.`);
                await wtb_sleep(1000);
                return true;
            } catch (e) {
                console.error(`[WTB] Error scrolling to ${elementName} (selector: ${selector}):`, e);
                return false;
            }
        } else {
            console.log(`[WTB] ${elementName} (selector: ${selector}) not found or not visible after retries.`);
            return false;
        }
    }

    async function wtb_autoScrollPage() {
        console.log('[WTB] Auto scroll initiated.');

        const iframe = document.getElementById('contentFrame');
        let docCtx = document;
        let winCtx = window;

        if (iframe) {
            try {
                const iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
                if (iframeDoc && iframe.contentWindow) {
                    docCtx = iframeDoc;
                    winCtx = iframe.contentWindow;
                    console.log('[WTB] Scrolling within iframe#contentFrame.');
                } else {
                    console.log('[WTB] Could not fully access iframe#contentFrame. Using main page for scroll.');
                }
            } catch (e) {
                console.error('[WTB] Error accessing iframe for scrolling: ', e);
                console.log('[WTB] Using main page for scroll due to error.');
            }
        } else {
            console.log('[WTB] iframe#contentFrame not found. Using main page for scroll.');
        }

        const submitSelector = 'a[data-controltype="submit"].cmd.cmd_submit';
        const imageSelector = 'div.direction';
        let scrolledToSpecific = false;

        if (window.wtb_lastScrollTarget === 'image') {
            console.log('[WTB] Last scroll was to image (or initial). Attempting to scroll to submit button.');
            if (await tryScrollToElement(docCtx, winCtx, submitSelector, 'Submit Button')) {
                window.wtb_lastScrollTarget = 'submit';
                scrolledToSpecific = true;
            } else {
                console.log('[WTB] Failed to scroll to submit button, trying image/direction div as fallback.');
                if (await tryScrollToElement(docCtx, winCtx, imageSelector, 'Image/Direction Div')) {
                    window.wtb_lastScrollTarget = 'image';
                    scrolledToSpecific = true;
                }
            }
        } else {
            console.log('[WTB] Last scroll was to submit. Attempting to scroll to image/direction div.');
            if (await tryScrollToElement(docCtx, winCtx, imageSelector, 'Image/Direction Div')) {
                window.wtb_lastScrollTarget = 'image';
                scrolledToSpecific = true;
            } else {
                console.log('[WTB] Failed to scroll to image/direction div, trying submit button as fallback.');
                if (await tryScrollToElement(docCtx, winCtx, submitSelector, 'Submit Button')) {
                    window.wtb_lastScrollTarget = 'submit';
                    scrolledToSpecific = true;
                }
            }
        }

        if (!scrolledToSpecific) {
            console.log('[WTB] Neither specific element found/scrolled. Performing generic scroll.');
            await wtb_performGenericScroll(docCtx, winCtx);

        }
    }


    async function wtb_performGenericScroll(docContext, windowContext) {
        const scrollAmount = windowContext.innerHeight / 4;
        const currentScroll = windowContext.scrollY;

        const bodyElement = docContext.body;
        if (!bodyElement) {
            console.log('[WTB] Document body not found for generic scroll.');
            return;
        }
        const maxScroll = bodyElement.scrollHeight - windowContext.innerHeight;

        let targetScroll = currentScroll + scrollAmount;
        if (targetScroll > maxScroll) {
            targetScroll = Math.max(0, currentScroll - scrollAmount);
        }

        if (maxScroll > 0 && currentScroll !== targetScroll) {
            windowContext.scrollTo({ top: targetScroll, behavior: 'smooth' });
            await wtb_sleep(2000);
            if (targetScroll > currentScroll && targetScroll > 100) {
                windowContext.scrollTo({ top: targetScroll - 50, behavior: 'smooth' });
            } else if (targetScroll < currentScroll && currentScroll > 100) {
                windowContext.scrollTo({ top: targetScroll + 50, behavior: 'smooth' });
            }
            console.log('[WTB] Generic page scroll completed within the given context.');
        } else {
            console.log('[WTB] No scroll needed for generic scroll (page too short or already at target) within the given context.');
        }
    }

    async function wtb_executeWaitTimer(callback) {
        const timeInput = document.getElementById('wtb_waitTimeInput');
        const countdownDisplay = document.getElementById('wtb_countdownDisplay');
        const scrollIntervalInput = document.getElementById('wtb_scrollIntervalInput');

        let waitTimeMinutes = parseInt(timeInput?.value || window.wtb_defaultWaitTimeMinutes);
        if (isNaN(waitTimeMinutes) || waitTimeMinutes < 1) {
            waitTimeMinutes = window.wtb_defaultWaitTimeMinutes;
            if (timeInput) timeInput.value = window.wtb_defaultWaitTimeMinutes.toString();
        } else {
            window.wtb_defaultWaitTimeMinutes = waitTimeMinutes;
        }

        let scrollIntervalMinutes = parseInt(scrollIntervalInput?.value || window.wtb_defaultScrollIntervalMinutes);
        if (isNaN(scrollIntervalMinutes) || scrollIntervalMinutes < 1) {
            scrollIntervalMinutes = window.wtb_defaultScrollIntervalMinutes;
            if (scrollIntervalInput) scrollIntervalInput.value = window.wtb_defaultScrollIntervalMinutes.toString();
        } else {
            window.wtb_defaultScrollIntervalMinutes = scrollIntervalMinutes;
        }

        if (waitTimeMinutes <= 0) {
            if (typeof callback === 'function') await callback();
            return;
        }

        let totalWaitTimeInSeconds = waitTimeMinutes * 60;
        let remainingTimeInSeconds = totalWaitTimeInSeconds;
        const scrollIntervalSeconds = scrollIntervalMinutes * 60;

        if (countdownDisplay) {
            const minutes = Math.floor(remainingTimeInSeconds / 60);
            const seconds = remainingTimeInSeconds % 60;
            countdownDisplay.textContent = `${minutes}:${seconds.toString().padStart(2, '0')}`;
            countdownDisplay.style.color = '#80cbc4';
            countdownDisplay.classList.remove('wtb-status-update');
        }

        if (window.wtb_waitTimerInterval) {
            clearInterval(window.wtb_waitTimerInterval);
        }

        window.wtb_waitTimerActive = true;
        wtb_updateTimerButtonState();


        if (totalWaitTimeInSeconds > scrollIntervalSeconds) {
            await wtb_autoScrollPage();
        }

        return new Promise(resolve => {
            window.wtb_waitTimerInterval = setInterval(async () => {
                remainingTimeInSeconds--;
                const elapsedTimeInSeconds = totalWaitTimeInSeconds - remainingTimeInSeconds;

                if (countdownDisplay) {
                    const minutes = Math.floor(remainingTimeInSeconds / 60);
                    const seconds = remainingTimeInSeconds % 60;
                    countdownDisplay.textContent = `${minutes}:${seconds.toString().padStart(2, '0')}`;
                    if (remainingTimeInSeconds <= 10 && remainingTimeInSeconds > 0) {
                        countdownDisplay.style.color = '#ff6b6b';
                    }
                }


                if (window.wtb_waitTimerActive &&
                    elapsedTimeInSeconds > 0 &&
                    elapsedTimeInSeconds % scrollIntervalSeconds === 0) {
                    if (remainingTimeInSeconds > 5) {
                        console.log(`[WTB] Periodic scroll trigger. Elapsed: ${elapsedTimeInSeconds}s. Interval: ${scrollIntervalSeconds}s. Remaining: ${remainingTimeInSeconds}s. Calling wtb_autoScrollPage.`);
                        await wtb_autoScrollPage();
                    } else {
                        console.log(`[WTB] Periodic scroll trigger. Elapsed: ${elapsedTimeInSeconds}s. Interval: ${scrollIntervalSeconds}s. Remaining: ${remainingTimeInSeconds}s. SKIPPED (too close to end).`);
                    }
                }

                if (remainingTimeInSeconds <= 0) {
                    clearInterval(window.wtb_waitTimerInterval);
                    window.wtb_waitTimerInterval = null;
                    window.wtb_waitTimerActive = false;
                    wtb_updateTimerButtonState();

                    if (countdownDisplay) {
                        countdownDisplay.textContent = '完成!';
                        countdownDisplay.style.color = '#4CAF50';
                        countdownDisplay.classList.add('wtb-status-update');
                        setTimeout(() => {
                            if (countdownDisplay) {
                                countdownDisplay.textContent = '未开始';
                                countdownDisplay.style.color = '#80cbc4';
                                countdownDisplay.classList.remove('wtb-status-update');
                            }
                        }, 3000);
                    }
                    if (typeof callback === 'function') await callback();
                    resolve();
                }
            }, 1000);
        });
    }

    function wtb_cancelWaitTimer() {
        if (window.wtb_waitTimerInterval) {
            clearInterval(window.wtb_waitTimerInterval);
            window.wtb_waitTimerInterval = null;
        }
        window.wtb_waitTimerActive = false;
        window.wtb_autoCycleActive = false;
        wtb_updateTimerButtonState();

        const countdownDisplay = document.getElementById('wtb_countdownDisplay');
        if (countdownDisplay) {
            countdownDisplay.textContent = '已取消';
            countdownDisplay.style.color = '#ff9800';
            countdownDisplay.classList.add('wtb-status-update');
            setTimeout(() => {
                if (countdownDisplay) {
                    countdownDisplay.textContent = '未开始';
                    countdownDisplay.style.color = '#80cbc4';
                     countdownDisplay.classList.remove('wtb-status-update');
                }
            }, 3000);
        }
        console.log('[WTB] 计时器已取消。');
        return false;
    }

    async function wtb_autoNextSection() {
        console.log('[WTB] 准备自动跳转到下一章节 (将在主页面执行操作)...');
        await wtb_sleep(1500);



        let transitionStarted = false;


        if (typeof window.NextSCO === 'function') {
            try {
                console.log('[WTB] 尝试在主页面直接执行NextSCO函数');
                window.NextSCO();
                transitionStarted = true;
                console.log('[WTB] NextSCO函数已在主页面执行。');
            } catch (e) {
                console.log('[WTB] 在主页面执行NextSCO函数失败:', e);
            }
        }


        if (!transitionStarted) {
            const navLinks = document.querySelectorAll('a[href*="javascript:NextSCO()"], a[href*="javascript:PrevSCO()"]');
            if (navLinks.length > 0) {
                const nextLink = Array.from(navLinks).find(link =>
                    link.href.includes('NextSCO') &&
                    !link.href.includes('PrevSCO') &&
                    (link.offsetParent !== null || link.clientWidth > 0 || link.clientHeight > 0)
                );
                if (nextLink) {
                    console.log('[WTB] 找到NextSCO链接，在主页面尝试点击');
                    nextLink.click();
                    transitionStarted = true;
                } else {
                    console.log('[WTB] NextSCO链接在主页面找到，但不可见或不符合条件。');
                }
            } else {
                console.log('[WTB] 未在主页面找到NextSCO链接。');
            }
        }

        if (transitionStarted) {
            console.log('[WTB] 已成功触发跳转，等待新页面加载。');
            await wtb_sleep(3000);
            return true;
        }

        console.log('[WTB] 所有在主页面的跳转尝试都失败。');
        return false;
    }

    async function wtb_runCycle() {
        if (!window.wtb_autoCycleActive) {
            console.log('[WTB] Auto-cycle is not active. Stopping.');
            wtb_updateTimerButtonState();
            return;
        }

        console.log('[WTB] Starting a new cycle leg: Running timer.');
        try {
            await wtb_executeWaitTimer(async () => {
                if (!window.wtb_autoCycleActive) {
                    console.log('[WTB] Timer finished, but auto-cycle was stopped during timer. No transition.');
                    return;
                }
                console.log('[WTB] Timer finished. Attempting to go to next section.');
                const navigationSuccess = await wtb_autoNextSection();

                if (navigationSuccess && window.wtb_autoCycleActive) {
                    console.log('[WTB] Navigation successful. Waiting for page load and then restarting cycle...');

                    const countdownDisplay = document.getElementById('wtb_countdownDisplay');
                    if (countdownDisplay) {
                        countdownDisplay.textContent = '加载中...';
                        countdownDisplay.style.color = '#80cbc4';
                        countdownDisplay.classList.remove('wtb-status-update');
                    }
                    await wtb_sleep(5000);
                    if (window.wtb_autoCycleActive) {
                        console.log('[WTB] Restarting cycle.');
                        wtb_runCycle();
                    } else {
                        console.log('[WTB] Auto-cycle stopped during page load wait.');
                        wtb_updateTimerButtonState();
                    }
                } else if (!navigationSuccess && window.wtb_autoCycleActive) {
                    console.log('[WTB] Navigation failed. Stopping auto-cycle.');
                    window.wtb_autoCycleActive = false;
                    wtb_updateTimerButtonState();

                    const cdDisplay = document.getElementById('wtb_countdownDisplay');
                    if (cdDisplay) {
                        cdDisplay.textContent = '跳转失败';
                        cdDisplay.style.color = '#ff6b6b';
                    }
                } else {
                    console.log('[WTB] Navigation was successful but auto-cycle was stopped, or navigation failed and cycle already stopped.');
                    wtb_updateTimerButtonState();
                }
            });
        } catch (error) {
            console.error('[WTB] Error during wtb_executeWaitTimer in wtb_runCycle:', error);
            window.wtb_autoCycleActive = false;
            wtb_updateTimerButtonState();
            wtb_cancelWaitTimer();
        }
    }



    function wtb_createSimpleUI() {
        const panelId = 'wtbHelperPanel';
        if (document.getElementById(panelId)) {
             console.log('[WTB] UI Panel already exists.');
             return document.getElementById(panelId);
        }

        const globalStyle = document.createElement('style');
        globalStyle.id = 'wtb-helper-style';
        globalStyle.textContent = `
            #${panelId} {
                position: fixed; top: 20px; left: 20px; z-index: 9999;
                background: rgba(35, 35, 38, 0.88); backdrop-filter: blur(10px) saturate(150%);
                border-radius: 10px; box-shadow: 0 6px 20px rgba(0,0,0,0.3);
                padding: 15px; color: #dadada; font-size: 13px; width: 260px;
                display: flex; flex-direction: column; gap: 12px;
                border: 1px solid rgba(255,255,255,0.1);
                font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
                transition: transform 0.3s ease, box-shadow 0.3s ease;
            }
            #${panelId}:hover { transform: translateY(-2px); box-shadow: 0 8px 25px rgba(0,0,0,0.35); }
            .${panelId}-title-bar {
                display: flex; justify-content: space-between; align-items: center;
                border-bottom: 1px solid rgba(255,255,255,0.12); padding-bottom: 8px; margin-bottom: 5px; cursor: grab;
            }
            .${panelId}-title { font-weight: 500; font-size: 16px; color: #f0f0f0; }
            .${panelId}-minimize-btn {
                background: rgba(255,255,255,0.1); border: none; color: #bbb; font-size: 16px; font-weight: bold;
                cursor: pointer; width: 22px; height: 22px; display: flex; align-items: center; justify-content: center;
                border-radius: 50%; transition: all 0.25s ease;
            }
            .${panelId}-minimize-btn:hover { background-color: rgba(255,255,255,0.2); color: #fff; transform: scale(1.1); }
            .${panelId}-content { display: flex; flex-direction: column; gap: 12px; }
            .${panelId}-row { display: flex; align-items: center; gap: 8px; }
            .${panelId}-label { flex-shrink: 0; font-size: 13px; }
            .${panelId}-input {
                width: 60px; padding: 6px 8px; border-radius: 5px; border: 1px solid rgba(255,255,255,0.2);
                background-color: rgba(0,0,0,0.25); text-align: center; font-weight: 500; color: #e0e0e0;
                transition: all 0.2s ease;
            }
            .${panelId}-input:focus { border-color: #00aaff; background-color: rgba(0,0,0,0.35); box-shadow: 0 0 7px rgba(0,170,255,0.4); }
            .${panelId}-countdown { font-weight: 500; font-size: 14px; color: #80cbc4; margin-left: auto; min-width: 50px; text-align: right; }
            .${panelId}-button {
                flex: 1; padding: 8px 12px; border: none; border-radius: 6px; cursor: pointer;
                font-weight: 500; font-size: 13px; transition: all 0.2s ease;
                background: linear-gradient(135deg, #0088cc 0%, #005599 100%); color: white;
                text-shadow: 0 1px 1px rgba(0,0,0,0.2);
            }
            .${panelId}-button:hover { background: linear-gradient(135deg, #0099e6 0%, #0066b3 100%); transform: translateY(-1px); box-shadow: 0 3px 10px rgba(0,136,204,0.25); }
            .${panelId}-button:active { transform: scale(0.98); }
            .${panelId}-button.stop { background: linear-gradient(135deg, #cc4444 0%, #aa2222 100%); }
            .${panelId}-button.stop:hover { background: linear-gradient(135deg, #dd5555 0%, #bb3333 100%); box-shadow: 0 3px 10px rgba(204,68,68,0.25); }
            .${panelId}-status { font-size: 11px; color: #888; text-align: center; padding-top: 5px; border-top: 1px solid rgba(255,255,255,0.08); margin-top: 5px; }
            .wtb-status-update { animation: wtbStatusPop 0.4s ease-out; }
            @keyframes wtbStatusPop { 0% { opacity:0; transform: scale(0.9); } 100% { opacity:1; transform: scale(1); } }
        `;
        document.head.appendChild(globalStyle);

        const mainPanel = document.createElement('div');
        mainPanel.id = panelId;

        const titleBar = document.createElement('div');
        titleBar.className = `${panelId}-title-bar`;
        const title = document.createElement('div');
        title.className = `${panelId}-title`;
        title.textContent = 'WeLearn 时长助手';
        const minimizeBtn = document.createElement('button');
        minimizeBtn.className = `${panelId}-minimize-btn`;
        minimizeBtn.textContent = '-';
        const contentDiv = document.createElement('div');
        contentDiv.className = `${panelId}-content`;

        minimizeBtn.onclick = () => {
            if (contentDiv.style.display === 'none') {
                contentDiv.style.display = 'flex';
                minimizeBtn.textContent = '-';
            } else {
                contentDiv.style.display = 'none';
                minimizeBtn.textContent = '+';
            }
        };
        titleBar.appendChild(title);
        titleBar.appendChild(minimizeBtn);
        mainPanel.appendChild(titleBar);
        mainPanel.appendChild(contentDiv);


        const timerRow = document.createElement('div');
        timerRow.className = `${panelId}-row`;
        const timerLabel = document.createElement('span');
        timerLabel.className = `${panelId}-label`;
        timerLabel.textContent = '刷课时长:';
        const timeInput = document.createElement('input');
        timeInput.id = 'wtb_waitTimeInput';
        timeInput.className = `${panelId}-input`;
        timeInput.type = 'number';
        timeInput.min = '1';
        timeInput.value = window.wtb_defaultWaitTimeMinutes.toString();
        const minutesLabel = document.createElement('span');
        minutesLabel.className = `${panelId}-label`;
        minutesLabel.textContent = '分钟';
        const countdownDisplay = document.createElement('div');
        countdownDisplay.id = 'wtb_countdownDisplay';
        countdownDisplay.className = `${panelId}-countdown`;
        countdownDisplay.textContent = '未开始';
        timerRow.appendChild(timerLabel);
        timerRow.appendChild(timeInput);
        timerRow.appendChild(minutesLabel);
        timerRow.appendChild(countdownDisplay);
        contentDiv.appendChild(timerRow);

        timeInput.addEventListener('change', function() {
            const newTime = parseInt(this.value, 10);
            if (!isNaN(newTime) && newTime > 0) {
                window.wtb_defaultWaitTimeMinutes = newTime;
            } else {
                this.value = window.wtb_defaultWaitTimeMinutes.toString();
            }
        });


        const scrollIntervalRow = document.createElement('div');
        scrollIntervalRow.className = `${panelId}-row`;
        const scrollIntervalLabel = document.createElement('span');
        scrollIntervalLabel.className = `${panelId}-label`;
        scrollIntervalLabel.textContent = '滑动间隔:';
        const scrollIntervalInput = document.createElement('input');
        scrollIntervalInput.id = 'wtb_scrollIntervalInput';
        scrollIntervalInput.className = `${panelId}-input`;
        scrollIntervalInput.type = 'number';
        scrollIntervalInput.min = '1';
        scrollIntervalInput.value = window.wtb_defaultScrollIntervalMinutes.toString();
        const scrollMinutesLabel = document.createElement('span');
        scrollMinutesLabel.className = `${panelId}-label`;
        scrollMinutesLabel.textContent = '分钟';
        scrollIntervalRow.appendChild(scrollIntervalLabel);
        scrollIntervalRow.appendChild(scrollIntervalInput);
        scrollIntervalRow.appendChild(scrollMinutesLabel);
        contentDiv.appendChild(scrollIntervalRow);

        scrollIntervalInput.addEventListener('change', function() {
            const newInterval = parseInt(this.value, 10);
            if (!isNaN(newInterval) && newInterval > 0) {
                window.wtb_defaultScrollIntervalMinutes = newInterval;
            } else {
                this.value = window.wtb_defaultScrollIntervalMinutes.toString();
            }
        });



        const buttonsRow = document.createElement('div');
        buttonsRow.className = `${panelId}-row`;
        const timerButton = document.createElement('button');
        timerButton.id = 'wtb_timerButton';
        timerButton.className = `${panelId}-button`;

        function timerButtonHandler() {
            if (window.wtb_autoCycleActive) {
                console.log('[WTB] User requested to stop auto-cycle.');
                window.wtb_autoCycleActive = false;
                wtb_cancelWaitTimer();
            } else {
                console.log('[WTB] User requested to start auto-cycle.');
                window.wtb_autoCycleActive = true;
                wtb_updateTimerButtonState();
                wtb_runCycle();
            }
        }

        timerButton.onclick = timerButtonHandler;
        buttonsRow.appendChild(timerButton);
        contentDiv.appendChild(buttonsRow);


        const statusContainer = document.createElement('div');
        statusContainer.className = `${panelId}-status`;
        statusContainer.textContent = '恶搞之家 (时长助手版)';
        contentDiv.appendChild(statusContainer);


        let isDragging = false, initialX, initialY, xOffset = 0, yOffset = 0;
        titleBar.addEventListener('mousedown', e => {
            if (e.target === titleBar || e.target === title) {
                isDragging = true;
                initialX = e.clientX - xOffset;
                initialY = e.clientY - yOffset;
                titleBar.style.cursor = 'grabbing';
            }
        });
        document.addEventListener('mousemove', e => {
            if (isDragging) {
                e.preventDefault();
                xOffset = e.clientX - initialX;
                yOffset = e.clientY - initialY;
                mainPanel.style.transform = `translate3d(${xOffset}px, ${yPosOffset}px, 0)`;
            }
        });
        document.addEventListener('mouseup', () => {
            if (isDragging) {
                isDragging = false;
                titleBar.style.cursor = 'grab';
            }
        });
         mainPanel.style.transform = 'translate3d(0px, 0px, 0)';
         let yPosOffset = 0;
         titleBar.addEventListener('mousedown', e => {
             if (e.target === titleBar || e.target === title) {
                 isDragging = true;
                 initialX = e.clientX - parseFloat(mainPanel.style.transform.split(',')[0].split('(')[1] || '0');
                 initialY = e.clientY - parseFloat(mainPanel.style.transform.split(',')[1] || '0');
                 titleBar.style.cursor = 'grabbing';
             }
         });
         document.addEventListener('mousemove', e => {
             if (isDragging) {
                 e.preventDefault();
                 const currentX = e.clientX - initialX;
                 const currentY = e.clientY - initialY;
                 mainPanel.style.transform = `translate3d(${currentX}px, ${currentY}px, 0)`;
             }
         });


        return mainPanel;
    }

    function wtb_updateTimerButtonState() {
        const timerButton = document.getElementById('wtb_timerButton');
        const panelId = 'wtbHelperPanel';
        if (timerButton) {
            if (window.wtb_autoCycleActive) {
                timerButton.textContent = '停止自动循环';
                timerButton.classList.add('stop');
            } else {
                timerButton.textContent = '开始自动循环';
                timerButton.classList.remove('stop');
            }
        }
    }

    function wtb_removeExistingUI() {
        const panelId = 'wtbHelperPanel';
        const existingPanel = document.getElementById(panelId);
        if (existingPanel) {
            existingPanel.remove();
        }
        const existingStyle = document.getElementById('wtb-helper-style');
        if (existingStyle) {
            existingStyle.remove();
        }
    }

    function wtb_addButton() {
        if (window !== window.top) {
            console.log('[WTB] 在iframe中，不添加UI。');
            return;
        }
        wtb_removeExistingUI();
        const uiPanel = wtb_createSimpleUI();
        if (uiPanel) {
             document.body.appendChild(uiPanel);
             wtb_updateTimerButtonState();
        }
    }

    function wtb_handlePageLoad() {
        console.log('[WTB] 页面加载完成，初始化时长助手。');
        if (window === window.top) {
            wtb_addButton();
        }
    }

    function wtb_initialize() {
        if (window.wtb_scriptInitialized) {
            console.log('[WTB] 时长助手已初始化，跳过。');
            return;
        }
        window.wtb_scriptInitialized = true;
        console.log('[WTB] 初始化 WeLearn 时长助手');

        if (document.readyState === 'complete') {
            wtb_handlePageLoad();
        } else {
            window.addEventListener('load', wtb_handlePageLoad);
        }









    }


    wtb_initialize();

})();