Offline for Lezhin

Downloads and saves Lezhin chapter images to a ZIP file for offline reading

スクリプトをインストールするには、Tampermonkey, GreasemonkeyViolentmonkey のような拡張機能のインストールが必要です。

You will need to install an extension such as Tampermonkey to install this script.

スクリプトをインストールするには、TampermonkeyViolentmonkey のような拡張機能のインストールが必要です。

スクリプトをインストールするには、TampermonkeyUserscripts のような拡張機能のインストールが必要です。

このスクリプトをインストールするには、Tampermonkeyなどの拡張機能をインストールする必要があります。

このスクリプトをインストールするには、ユーザースクリプト管理ツールの拡張機能をインストールする必要があります。

(ユーザースクリプト管理ツールは設定済みなのでインストール!)

このスタイルをインストールするには、Stylusなどの拡張機能をインストールする必要があります。

このスタイルをインストールするには、Stylus などの拡張機能をインストールする必要があります。

このスタイルをインストールするには、Stylus tなどの拡張機能をインストールする必要があります。

このスタイルをインストールするには、ユーザースタイル管理用の拡張機能をインストールする必要があります。

このスタイルをインストールするには、ユーザースタイル管理用の拡張機能をインストールする必要があります。

このスタイルをインストールするには、ユーザースタイル管理用の拡張機能をインストールする必要があります。

(ユーザースタイル管理ツールは設定済みなのでインストール!)

作者のサイトでサポートを受ける。または、このスクリプトの質問や評価の投稿はこちら通報はこちらへお寄せください
// ==UserScript==
// @name         Offline for Lezhin
// @namespace    https://github.com/OsborneLabs
// @version      1.1.0
// @description  Downloads and saves Lezhin chapter images to a ZIP file for offline reading
// @author       Osborne Labs
// @license      GPL-3.0-only
// @homepageURL  https://github.com/OsborneLabs/Offline
// @icon         data:image/svg+xml;base64,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
// @match        https://*.lezhinus.com/*
// @match        https://*.lezhin.com/*
// @match        https://*.lezhin.es/*
// @match        https://*.lezhin.jp/*
// @match        https://*.lezhinde.com/*
// @match        https://*.lezhinfr.com/*
// @match        https://*.lezhinth.com/*
// @match        https://*.lezhinx.com/*
// @match        https://*.beltoon.jp/*
// @match        https://*.bomtoon.com/*
// @match        https://*.bomtoon.tw/*
// @match        https://*.boomtoon.com/*
// @run-at       document-start
// @connect      ccdn.lezhin.com
// @connect      rcdn.lezhin.com
// @supportURL   https://github.com/OsborneLabs/Offline/issues
// @require      https://cdn.jsdelivr.net/npm/[email protected]/umd/index.min.js
// @grant        GM_xmlhttpRequest
// ==/UserScript==

/* jshint esversion: 11 */
/* global fflate */

(() => {
    'use strict';

    const SCRIPT_NAME_DEBUG = "OFFLINE FOR LEZHIN";
    const SCRIPT_VERSION =
        typeof GM_info !== 'undefined' ?
        GM_info.script.version :
        'unknown';
    const UI_AUTO_REFRESH_FLAG = 'autoRefresh';
    const UI_TOAST_DURATION_MS = 8000;
    const UI_BUTTON_RESET_DELAY_MS = 3000;
    const UI_BUTTON_LABELS = {
        DEFAULT: 'Download',
        COLLECTING: c => c === 0 ? 'Starting...' : `Collecting: ${c}`,
        DOWNLOADING: (c, t) => `Downloading: ${c}/${t}`,
        CONVERTING: (c, t) => t && c >= t - 1 ? 'Finishing...' : c === 0 ? 'Converting...' : t ? `Converting: ${c}/${t}` : `Converting: ${c}`,
        COMPLETE: 'Complete!'
    };

    const VIEWER_ALTERNATE_DOMAINS = [
        'beltoon.jp', 'bomtoon.com', 'bomtoon.tw', 'lezhin.es', 'lezhinde.com', 'lezhinfr.com', 'lezhinth.com'
    ];

    const VIEWER_ROUTE_REGEX_JP =
        /^\/comic\/([^\/]+)\/chapter\/([^\/]+)\/viewer\/?$/;

    const RENDER_DETECTORS = {
        webp: {
            detect(wrapper) {
                if (wrapper.querySelector('canvas')) {
                    return false;
                }
                if (wrapper.querySelector("img[src^='blob:']")) {
                    return false;
                }
                const imgs = [...wrapper.querySelectorAll('img')]
                    .filter(img =>
                        img.src &&
                        !img.src.startsWith('blob:') &&
                        !isPromoImage(img)
                    );
                if (imgs.length < 5) {
                    return false;
                }
                return true;
            }
        },
        canvas: {
            detect(wrapper) {
                return !!wrapper.querySelector('canvas');
            }
        },
        blob: {
            detect(wrapper) {
                return [...wrapper.querySelectorAll('img')]
                    .some(img => img.src?.startsWith('blob:'));
            }
        }
    };

    const RENDER_PAGE_SELECTORS_HORIZONTAL = {
        horizontalWrapper: 'div[class^="pageView__cutWrap"]',
        horizontalNavNext: 'button[class*="nav--right"]'
    };

    const RENDER_PAGE_SELECTORS = [
        RENDER_PAGE_SELECTORS_HORIZONTAL.horizontalWrapper,
        'div[class^="ImageContainer__Container-"]',
        'div[class^="sc-"][width][height]',
        'div[class^="scrollViewCut__"]',
        'div[class^="VerticalViewer_page_container"]'
    ];

    const DOWNLOAD_ERROR_MAP = {
        BLOB_CAPTURE_FAILED: {
            code: 'blob-capture-failed',
            message: 'Failed to capture blob images'
        },
        DOWNLOAD_ABORTED: {
            code: 'download-aborted',
            message: 'Download error occurred'
        },
        IMAGE_COUNT_MISMATCH: {
            code: 'image-count-mismatch',
            message: 'Failed to collect all images'
        },
        JPEG_CONVERSION_FAILED: {
            code: 'jpeg-conversion-failed',
            message: 'Failed to convert JPEG images'
        },
        MOBILE_DEVICES_NOT_SUPPORTED: {
            code: 'mobile-devices-not-supported',
            message: 'Mobile devices are not supported'
        },
        NO_IMAGES_COLLECTED: {
            code: 'no-images-collected',
            message: 'No images were collected'
        },
        TOTAL_PAGE_COUNT_NOT_FOUND: {
            code: 'total-page-count-not-found',
            message: 'Could not find page count'
        },
        UNKNOWN_ERROR: {
            code: 'unknown-error',
            message: 'An unexpected error occurred'
        },
        VIEWER_CONTAINER_NOT_FOUND: {
            code: 'viewer-container-not-found',
            message: 'Could not find view container'
        },
        ZIP_CREATION_FAILED: {
            code: 'zip-creation-failed',
            message: 'Failed to create ZIP file'
        }
    };

    const DOWNLOAD_ERROR_INDEX = Object.fromEntries(
        Object.values(DOWNLOAD_ERROR_MAP).map(e => [e.code, e])
    );

    const IS_MOBILE_DEVICE = isMobileDevice();
    if (IS_MOBILE_DEVICE) {
        handleDownloadError(new Error(
            DOWNLOAD_ERROR_MAP.MOBILE_DEVICES_NOT_SUPPORTED.code
        ));
    }

    const state = {
        ui: {
            isDownloading: false,
            phase: 'idle',
            activeDownload: null,
            spaNavigated: false,
            images: new Map()
        },
        canvas: {
            enabled: false,
            lastDrawTs: 0,
            idleTimer: null,
            idleResolver: null,
            buffer: new Map(),
            pages: new Map()
        },
        blob: {
            enabled: false,
            buffer: new Map(),
            pages: new Map()
        },
        viewer: {
            detected: false,
            type: null,
            url: null,
            initialRenderingLogged: false,
            notFoundToastShown: false
        }
    };

    function createStyles() {
        const style = document.createElement('style');
        style.textContent = `
            :root {
                --color-app-button-default: #ED1C24;
                --color-app-button-hover: #C4161C;
                --color-app-button-disabled: #FF5254;
                --color-app-button-popup-default: #1F1F1F;
                --color-app-text-default: white;
                --size-text-body-default: 13px;
                --size-text-popup-default: 12px;
            }
            @keyframes toast-slide-in {
                from {
                    opacity: 0;
                    transform: translateY(-10px);
                }
                to {
                    opacity: 1;
                    transform: translateY(0);
                }
            }
            @keyframes toast-slide-out {
                from {
                    opacity: 1;
                    transform: translateY(0);
                }
                to {
                    opacity: 0;
                    transform: translateY(-10px);
                }
            }
            #lezhin-toast-container {
                display: flex;
                position: fixed;
                top: 20px;
                left: 50%;
                z-index: 9999;
                flex-direction: column;
                gap: 10px;
                transform: translateX(-50%);
                pointer-events: none;
            }
            .lezhin-toast {
                display: flex;
                align-items: center;
                justify-content: space-between;
                min-width: 260px;
                max-width: 360px;
                padding: 10px 14px;
                border-radius: 16px;
                font-size: 14px;
                color: white;
                background: var(--color-app-button-default);
                box-shadow: 0 2px 12px rgba(0,0,0,0.25);
                pointer-events: auto;
                user-select: none;
                animation: toast-slide-in 0.2s ease-out;
            }
            .lezhin-toast.closing {
                animation: toast-slide-out 0.2s ease-in forwards;
            }
            .lezhin-toast-close {
                position: relative;
                bottom: 1px;
                padding: 0;
                border: none;
                font-size: 20px;
                line-height: 1;
                color: white;
                background: none;
                cursor: pointer;
                user-select: auto;
            }
            .download-button {
                display: inline-flex;
                align-items: center;
                justify-content: center;
                height: 28px;
                padding: 6px 10px;
                border: none;
                border-radius: 20px;
                z-index: 9998;
                font-size: var(--size-text-body-default);
                font-weight: 500;
                color: var(--color-app-text-default);
                background: var(--color-app-button-default);
                cursor: pointer;
                user-select: none;
                transition: background-color 0.20s ease;
            }
            .download-button-custom {
                position: relative;
                bottom: 1px;
                margin-left: 15px;
            }
            .download-button-default {
                position: fixed;
                top: 3.5%;
                left: 50%;
                transform: translate(-50%, -50%);
            }
            .download-button:hover:not(:disabled) {
                background: var(--color-app-button-hover);
            }
            .download-button:disabled {
                background: var(--color-app-button-disabled);
                cursor: not-allowed;
            }
            .download-wrapper {
                display: inline-block;
                position: relative;
            }
            .download-popup {
                position: fixed;
                z-index: 9998;
                transform: translateX(-50%);
                min-width: 150px;
                padding: 12px;
                border-radius: 16px;
                font-size: var(--size-text-popup-default);
                color: white;
                background: var(--color-app-button-popup-default);
                box-shadow: 0 2px 12px rgba(0,0,0,0.25);
                opacity: 0;
                visibility: hidden;
                pointer-events: none;
                user-select: none;
                transition: opacity 0.20s ease, visibility 0.20s ease;
            }
            .download-popup.visible {
                opacity: 1;
                visibility: visible;
                pointer-events: auto;
            }
            .download-popup-version {
                margin-bottom: 10px;
            }
            body.lock-site-ui * {
                pointer-events: none !important;
                user-select: none !important;
            }
            body.lock-site-ui .download-button {
                pointer-events: auto !important;
            }
        `;
        document.head.appendChild(style);
    }

    function init() {
        sessionStorage.removeItem(UI_AUTO_REFRESH_FLAG);
        createStyles();
        observeURLMutation();
        initDownloadButtonObserver();
        initCanvasDrawHook();
        initBlobBackgroundCollector();
        createDownloadButton();
    }

    function observeURLMutation() {
        let previousPath = location.pathname;
        let headerObserver = null;
        let initObserver = null;
        const onRealNavigation = () => {
            if (location.pathname === previousPath) return;
            const wasChapterPage = isChapterPage(previousPath);
            const isChapterNow = isChapterPage();
            previousPath = location.pathname;
            console.clear();
            if (wasChapterPage && !isChapterNow) {
                removeDownloadButton();
            }
            normalizeChapterNavigation();
            resetChapterState();
            if (isChapterNow) {
                onChapterEnter();
            }
        };
        const resetChapterState = () => {
            abortDownloadSession();
            state.ui.images.clear();
            state.viewer.detected = false;
            state.viewer.type = null;
            state.viewer.url = null;
            state.viewer.notFoundToastShown = false;
            if (headerObserver) {
                headerObserver.disconnect();
                headerObserver = null;
            }
            if (initObserver) {
                initObserver.disconnect();
                initObserver = null;
            }
        };
        const onChapterEnter = () => {
            let initialized = false;
            const relocateButtonToHeader = () => {
                const header = getViewerHeaderContainer();
                if (!header) return;
                const btn = document.querySelector('.download-button');
                if (!btn) return;
                if (btn.parentElement !== header) {
                    btn.classList.remove('download-button-default');
                    btn.classList.add('download-button-custom');
                    header.appendChild(btn);
                }
            };
            const tryInit = () => {
                if (initialized) return;
                const viewer = getViewerContainer();
                if (!viewer) return;
                initialized = true;
                if (initObserver) {
                    initObserver.disconnect();
                    initObserver = null;
                }
                createDownloadButton();
                detectRenderType();
                relocateButtonToHeader();
                setSinglePageLayout();
            };
            initObserver = new MutationObserver(tryInit);
            initObserver.observe(document.body, {
                childList: true,
                subtree: true
            });
            headerObserver = new MutationObserver(relocateButtonToHeader);
            headerObserver.observe(document.body, {
                childList: true,
                subtree: true
            });
            tryInit();
        };
        window.addEventListener('popstate', onRealNavigation);
        window.addEventListener('hashchange', onRealNavigation);
        const hookHistory = type => {
            const original = history[type];
            history[type] = function(...args) {
                const ret = original.apply(this, args);
                onRealNavigation();
                return ret;
            };
        };
        hookHistory('pushState');
        hookHistory('replaceState');
        if (isChapterPage()) {
            normalizeChapterNavigation();
            onChapterEnter();
        }
    }

    function normalizeChapterNavigation() {
        if (!isChapterPage()) return;
        if (sessionStorage.getItem('lezhin-hard-loaded')) {
            sessionStorage.removeItem('lezhin-hard-loaded');
            state.ui.spaNavigated = false;
            return;
        }
        if (state.ui.spaNavigated) {
            sessionStorage.setItem('lezhin-hard-loaded', '1');
            location.reload();
        }
    }

    function isChapterPage(url = location.pathname) {
        const usesStringChapterId =
            isAlternateViewerLayout() ||
            /(^|\.)lezhinx\.com$/.test(location.hostname);
        let viewerRegex;
        if (usesStringChapterId) {
            viewerRegex = /^\/viewer\/[^\/]+\/[^\/]+\/?$/;
        } else {
            viewerRegex = /^\/viewer\/[^\/]+\/\d+\/?$/;
        }
        return (
            /^\/(?:[a-z]{2}\/)?comic\/[^\/]+\/[^\/]+\/?$/.test(url) ||
            /^\/comic\/[^\/]+\/chapter\/[^\/]+\/viewer\/?$/.test(url) ||
            viewerRegex.test(url)
        );
    }

    function isAlternateViewerLayout() {
        const host = location.hostname;
        return VIEWER_ALTERNATE_DOMAINS.some(d => host.endsWith(d));
    }

    function isHorizontalViewerLayout() {
        const {
            horizontalWrapper,
            horizontalNavNext
        } = RENDER_PAGE_SELECTORS_HORIZONTAL;
        return !!document.querySelector(horizontalWrapper) &&
            !!document.querySelector(horizontalNavNext);
    }

    function getViewerLayoutConfig() {
        const host = location.hostname;
        const isAlternate = isAlternateViewerLayout();
        const isLezhinx = host.endsWith('lezhinx.com');
        const useCutsAsSource =
            isAlternate || isLezhinx;
        const cuts = useCutsAsSource ?
            getIndexedComicCuts({
                ensureIndex: true
            }) :
            null;
        return {
            type: useCutsAsSource ? 'cut-based' : 'standard',
            pageSource: useCutsAsSource ? 'cuts' : 'dom',
            cuts,
            scroll: {
                preventLastScroll: isLezhinx,
                offset: isLezhinx ? 500 : 0
            }
        };
    }

    function isMobileDevice() {
        const userAgentCheck = /Mobi|Android|iPhone|iPad|iPod/i.test(navigator.userAgent);
        const hasTouch = 'ontouchstart' in window || navigator.maxTouchPoints > 0;
        const smallViewport = window.matchMedia('(max-width: 768px)').matches;
        const coarsePointer = window.matchMedia('(pointer: coarse)').matches;
        return userAgentCheck || (hasTouch && (smallViewport || coarsePointer));
    }

    function detectRenderType() {
        if (!isChapterPage()) return null;
        if (state.viewer.detected && state.viewer.url === location.pathname) {
            return state.viewer.type;
        }
        const wrapper = getViewerContainer();
        if (!wrapper) {
            if (
                !state.viewer.notFoundToastShown &&
                document.readyState === 'complete'
            ) {
                state.viewer.notFoundToastShown = true;
                setTimeout(() => {
                    if (!getViewerContainer()) {
                        handleDownloadError(
                            new Error(DOWNLOAD_ERROR_MAP.VIEWER_CONTAINER_NOT_FOUND.code)
                        );
                    } else {
                        state.viewer.notFoundToastShown = false;
                    }
                }, 800);
            }
            return null;
        }
        const priority = ['canvas', 'blob', 'webp'];
        const tryDetect = () => {
            for (const type of priority) {
                const renderer = RENDER_DETECTORS[type];
                if (renderer?.detect(wrapper)) {
                    setRenderType(type);
                    return true;
                }
            }
            return false;
        };
        if (tryDetect()) return state.viewer.type;
        const observer = new MutationObserver(() => {
            if (tryDetect()) observer.disconnect();
        });
        observer.observe(wrapper, {
            childList: true,
            subtree: true
        });
        return null;
    }

    function resolveRenderType() {
        const wrapper = getViewerContainer();
        if (!wrapper) return state.viewer.type;
        if (wrapper.querySelector('canvas')) {
            setRenderType('canvas');
            return 'canvas';
        }
        if (wrapper.querySelector("img[src^='blob:']")) {
            setRenderType('blob');
            return 'blob';
        }
        setRenderType('webp');
        return 'webp';
    }

    function setRenderType(type) {
        if (!state.viewer.initialRenderingLogged) {
            state.viewer.initialRenderingLogged = true;
            const wrapper = getViewerContainer();
            console.log(
                `${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - INITIAL RENDERING METHOD: %c${type.toUpperCase()}`,
                'font-weight:bold;', {
                    images: wrapper ? wrapper.querySelectorAll('img').length : 0,
                    blobImages: wrapper ? wrapper.querySelectorAll("img[src^='blob:']").length : 0,
                    canvases: wrapper ? wrapper.querySelectorAll('canvas').length : 0
                }
            );
        }
        state.viewer.type = type;
        state.viewer.detected = true;
        state.viewer.url = location.pathname;
    }

    function getViewerContainer() {
        const containers = [
            '[class^="CoreViewer_viewer_wrapper__"]',
            'div[class^="ImageContainer__Container"]',
            'div[class^="pageView__"]',
            'div[class^="sc-"]',
            'div[class^="scrollViewWrapper__"]',
        ];
        for (const selector of containers) {
            const el = document.querySelector(selector);
            if (el) return el;
        }
        return null;
    }

    function getViewerScroller() {
        return (
            document.querySelector('.no-scrollbar-viewer') ||
            document.scrollingElement ||
            document.documentElement
        );
    }

    function getViewerHeaderContainer() {
        const viewerHeader = document.querySelector('#viewer-header');
        if (!viewerHeader) return null;
        const title = viewerHeader.querySelector('span[class^="vh__title__"]');
        if (!title) return null;
        return title.parentElement;
    }

    function applyViewerHeaderOverride() {
        const viewerHeader = document.getElementById('viewer-header');
        if (!viewerHeader) return null;
        const existing = document.getElementById('download-header-override');
        if (existing) return existing;
        const style = document.createElement('style');
        style.id = 'download-header-override';
        style.textContent = `
            #viewer-header {
                transform: none !important;
                opacity: 1 !important;
            }
        `;
        document.head.appendChild(style);
        return style;
    }

    function getIndexedComicCuts({
        ensureIndex = true
    } = {}) {
        for (const selector of RENDER_PAGE_SELECTORS) {
            const cuts = [...document.querySelectorAll(selector)];
            if (!cuts.length) continue;
            if (ensureIndex) {
                let index = 1;
                for (const cut of cuts) {
                    if (!cut.dataset.cutIndex) {
                        cut.dataset.cutIndex = String(index);
                    }
                    index++;
                }
            }
            return cuts;
        }
        return [];
    }

    function getVisiblePageIndex(canvas) {
        const canvasRect = canvas.getBoundingClientRect();
        const canvasMidY = canvasRect.top + canvasRect.height / 2;
        const special = getViewerLayoutConfig();
        const cutsToUse = special.enabled ?
            special.safeCuts :
            getIndexedComicCuts();
        for (const cut of cutsToUse) {
            const rect = cut.getBoundingClientRect();
            if (canvasMidY >= rect.top && canvasMidY <= rect.bottom) {
                const index = Number(cut.dataset.cutIndex);
                return Number.isFinite(index) ? index : null;
            }
        }
        return null;
    }

    function getAllPageIndexes() {
        return getIndexedComicCuts()
            .map(c => Number(c.dataset.cutIndex))
            .filter(Number.isFinite);
    }

    function getTotalPageCount() {
        const layout = getViewerLayoutConfig();
        if (layout.pageSource === 'cuts') {
            if (layout.cuts && layout.cuts.length) {
                return layout.cuts.length;
            }
        }
        const sources = [
            () => {
                const slider = document.querySelector(
                    'input[type="range"][max]'
                );
                if (!slider) return null;
                const max = Number(slider.max);
                return Number.isFinite(max) ? max + 1 : null;
            },
            () => {
                const slider = document.querySelector(
                    '[class^="lzSlider__"] button[data-max]'
                );
                const max = slider && Number(slider.dataset.max);
                return Number.isFinite(max) ? max : null;
            },
            () => {
                const footer = document.querySelector(
                    'div[class^="Footer_footerContainer__"]'
                );
                const match = footer?.textContent?.match(/\/\s*(\d+)/);
                const max = match && Number(match[1]);
                return Number.isFinite(max) ? max : null;
            }
        ];
        for (const getMax of sources) {
            const max = getMax();
            if (max) return max;
        }
        throwDownloadError('TOTAL_PAGE_COUNT_NOT_FOUND');
    }

    function isPromoImage(img) {
        if (!(img instanceof HTMLImageElement) || !img.src) return true;
        const PROMO_IMAGE_URL_BLOCKLIST = [
            'cover', 'banner', 'notice_contents', 'promotion'
        ];
        const PROMO_IMAGE_CLASS_BLOCKLIST = [
            'promotion', 'thumbnail'
        ];
        try {
            if (PROMO_IMAGE_URL_BLOCKLIST.some(p => img.src.includes(p))) {
                return true;
            }
            if (PROMO_IMAGE_CLASS_BLOCKLIST.some(p =>
                    img.closest(`[class*="${p}"]`)
                )) {
                return true;
            }
            return false;
        } catch {
            return true;
        }
    }

    function scrollToComicPage(index, {
        instant = false,
        allowLastPage = false
    } = {}) {
        const cuts = getIndexedComicCuts();
        if (!cuts.length) return false;
        if (!Number.isFinite(index)) {
            index = Number(cuts[0]?.dataset.cutIndex);
        }
        const targetCut = cuts.find(c =>
            Number(c.dataset.cutIndex) === index
        );
        if (!targetCut) return false;
        const domainBehavior = getViewerLayoutConfig();
        let scrollTarget = targetCut.offsetTop;
        const lastCut = cuts.at(-1);
        const lastIndex = Number(lastCut?.dataset.cutIndex);
        if (
            domainBehavior.active &&
            domainBehavior.preventLastScroll &&
            !allowLastPage &&
            index === lastIndex
        ) {
            scrollTarget = Math.max(
                0,
                targetCut.offsetTop - domainBehavior.scrollOffset
            );
        }
        const scroller = getViewerScroller();
        const behavior = instant ? 'auto' : 'smooth';
        if (scroller && scroller !== document.body) {
            scroller.scrollTo({
                top: scrollTarget,
                behavior
            });
        } else {
            window.scrollTo({
                top: scrollTarget,
                behavior
            });
        }
        return true;
    }

    function scrollToTop() {
        const scroller = getViewerScroller();
        if (!scroller) return;
        scroller.scrollTop = 0;
        scroller.dispatchEvent(new Event('scroll'));
    }

    async function setSinglePageLayout() {
        try {
            const SINGLE_LAYOUT_DOMAINS = [
                /\.?lezhin\.com$/,
            ];
            const SINGLE_LAYOUT_LABELS = [
                '두 쪽 보기',
            ];
            const shouldApply = SINGLE_LAYOUT_DOMAINS.some(regex =>
                regex.test(location.hostname)
            );
            if (!shouldApply) return;
            if (!document.querySelector(RENDER_PAGE_SELECTORS_HORIZONTAL.horizontalWrapper)) {
                return;
            }
            const wait = ms => new Promise(r => setTimeout(r, ms));
            const waitFor = (fn, timeout = 4000) => {
                return new Promise(resolve => {
                    const existing = fn();
                    if (existing) return resolve(existing);
                    const observer = new MutationObserver(() => {
                        const el = fn();
                        if (el) {
                            observer.disconnect();
                            resolve(el);
                        }
                    });
                    observer.observe(document.body, {
                        childList: true,
                        subtree: true
                    });
                    setTimeout(() => {
                        observer.disconnect();
                        resolve(null);
                    }, timeout);
                });
            };
            const gearButton = document.querySelector(
                'button[class*="viewerToolbar__iconButton"]'
            );
            if (!gearButton) return;
            gearButton.click();
            const modal = await waitFor(() =>
                document.querySelector('.lzModalContainer')
            );
            if (!modal) return;
            await wait(150);
            const rows = [...modal.querySelectorAll('div.flex')];
            const targetRow = rows.find(row => {
                const p = row.querySelector('p');
                if (!p) return false;
                const text = p.textContent.trim();
                return SINGLE_LAYOUT_LABELS.includes(text);
            });
            if (!targetRow) {
                modal.querySelector('button[class*="absolute"]')?.click();
                return;
            }
            const switchEl = targetRow.querySelector('.lzSwitch');
            if (!switchEl) return;
            const currentState = switchEl.getAttribute('data-switch');
            if (currentState === 'off') {
                modal.querySelector('button[class*="absolute"]')?.click();
                return;
            }
            switchEl.dispatchEvent(
                new MouseEvent('click', {
                    bubbles: true,
                    cancelable: true
                })
            );
            await wait(300);
            modal.querySelector('button[class*="absolute"]')?.click();
        } catch (e) {
            console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION}: ERROR SETTING SINGLE PAGE LAYOUT\n`, e);
        }
    }

    function getSeriesTitle() {
        const hostname = location.hostname;
        const ogTitle = document
            .querySelector('meta[property="og:title"]')
            ?.getAttribute('content')
            ?.trim();
        const pageTitle = document.title?.trim();

        function formatTitle(input) {
            if (!input) return null;
            return sanitizeFileNamePart(input.trim());
        }
        if (hostname.endsWith('lezhin.com') && ogTitle) {
            const parts = ogTitle.split(' - ').map(p => p.trim());
            if (parts.length >= 1) {
                return formatTitle(parts[0]);
            }
        }
        if (hostname.endsWith('lezhinus.com') && ogTitle) {
            const parts = ogTitle.split(' - ').map(p => p.trim());
            if (parts.length >= 3) return formatTitle(parts[0]);
        }
        if (hostname.endsWith('beltoon.jp') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*.*?\s*-\s*BeLTOON/i);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('bomtoon.com') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*.*?\s*-\s*봄툰$/i);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('bomtoon.tw') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*.*?\s*-\s*BOMTOON/i);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('lezhin.es') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*(.*?)$/);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('lezhin.jp')) {
            const match = location.pathname.match(VIEWER_ROUTE_REGEX_JP);
            if (match) {
                const seriesSlug = match[1];
                return formatTitle(seriesSlug);
            }
        }
        if (hostname.endsWith('lezhinde.com') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*.*?\s*-\s*Lezhin/i);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('lezhinfr.com') && pageTitle) {
            const match = pageTitle.match(/^(.*?)\s*-\s*(.*?)\s*-/);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('lezhinth.com') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*.*?\s*-\s*LEZHIN\s*TH$/i);
            if (match) return formatTitle(match[1]);
        }
        if (hostname.endsWith('lezhinx.com') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*(.*?)\s*-\s*Lezhin\s*X$/i);
            if (match) return formatTitle(match[1]);
        }
        return 'Unknown Series';
    }

    function getSeriesChapter() {
        const hostname = location.hostname;
        const ogTitle = document
            .querySelector('meta[property="og:title"]')
            ?.getAttribute('content')
            ?.trim();
        const pageTitle = document.title?.trim();

        function formatChapter(input) {
            if (!input) return null;
            const cleaned = input.trim();
            const numberMatch = cleaned.match(/\d+/);
            if (numberMatch) {
                return numberMatch[0].padStart(2, '0');
            }
            return sanitizeFileNamePart(cleaned);
        }
        if (hostname.endsWith('lezhin.com') && ogTitle) {
            return formatChapter(ogTitle.split(' - ')[1]?.replace(/화$/, ''));
        }
        if (hostname.endsWith('lezhinus.com') && ogTitle) {
            const parts = ogTitle.split(' - ').map(p => p.trim());
            if (parts.length >= 3) {
                return formatChapter(parts[1] || parts[2]);
            }
        }
        if (hostname.endsWith('beltoon.jp') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-\s*BeLTOON/i);
            if (match) return formatChapter(match[1]);
        }
        if (hostname.endsWith('bomtoon.com') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-\s*봄툰$/i);
            if (match) {
                const chapterTitle = match[1].replace(/화$/, '');
                return formatChapter(chapterTitle);
            }
        }
        if (hostname.endsWith('bomtoon.tw') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-\s*BOMTOON/i);
            if (match) return formatChapter(match[1]);
        }
        if (hostname.endsWith('lezhin.es') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)$/i);
            if (match) return formatChapter(match[1]);
        }
        if (hostname.endsWith('lezhin.jp')) {
            const match = location.pathname.match(VIEWER_ROUTE_REGEX_JP);
            if (match) {
                const chapterId = match[2];
                return sanitizeFileNamePart(chapterId.trim());
            }
        }
        if (hostname.endsWith('lezhinde.com') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-\s*Lezhin\s*DE$/i);
            if (match) return formatChapter(match[1]);
        }
        if (hostname.endsWith('lezhinfr.com') && pageTitle) {
            const match = pageTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-/);
            if (match) return formatChapter(match[1]);
        }
        if (hostname.endsWith('lezhinth.com') && ogTitle) {
            const match = ogTitle.match(/^\s*.*?\s*-\s*(.*?)\s*-\s*LEZHIN\s*TH$/i);
            if (match) {
                let chapterTitle = match[1].replace(/^ตอนที่\s*/i, '');
                return formatChapter(chapterTitle);
            }
        }
        if (hostname.endsWith('lezhinx.com') && ogTitle) {
            const match = ogTitle.match(/^(.*?)\s*-\s*(.*?)\s*-\s*Lezhin\s*X$/i);
            if (match) return formatChapter(match[2]);
        }
        return 'Unknown Chapter';
    }

    function sanitizeFileNamePart(str) {
        return str
            .replace(/[\\/:*?"<>|]/g, '_')
            .replace(/\s+/g, ' ')
            .trim();
    }

    function generateImageFileName(index, total, format = 'jpg') {
        const digits = total >= 100 ? 3 : 2;
        const paddedIndex = String(index).padStart(digits, '0');
        return `${paddedIndex}.${format}`;
    }

    function initDownloadButtonObserver() {
        const observer = new MutationObserver(() => {
            if (!isChapterPage()) return;
            if (isMobileDevice()) return;
            if (!document.querySelector('.download-button')) {
                createDownloadButton();
            }
        });
        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    }

    function createDownloadButton() {
        if (!isChapterPage()) return;
        if (document.querySelector('.download-button')) return;
        if (isMobileDevice()) {
            throwDownloadError('MOBILE_DEVICE_NOT_SUPPORTED');
            return;
        }
        const globalHeader = getViewerHeaderContainer();
        let insertTarget;
        let regionClass;
        if (globalHeader) {
            insertTarget = globalHeader;
            regionClass = 'download-button-custom';
        } else {
            insertTarget = document.body;
            regionClass = 'download-button-default';
        }
        const btn = document.createElement('button');
        btn.classList.add('download-button', regionClass);
        btn.textContent = UI_BUTTON_LABELS.DEFAULT;
        btn.onclick = () => {
            detectRenderType();
            executeDownloadPipeline(btn);
        };
        insertTarget.appendChild(btn);
        const popup = document.createElement('div');
        popup.className = 'download-popup';
        popup.innerHTML = `
            <div class="download-popup-title"><strong>${SCRIPT_NAME_DEBUG}</strong></div>
            <div class="download-popup-version">
                <a href="https://github.com/OsborneLabs/Offline" target="_blank" rel="noopener noreferrer">Osborne</a>
                &nbsp;·&nbsp;
                v${SCRIPT_VERSION}
            </div>
            <div class="download-popup-links">
                <a href="https://github.com/OsborneLabs/Offline/issues" 
                target="_blank" 
                rel="noopener noreferrer" 
                style="text-decoration: underline;">
                Submit an issue
                </a>
            </div>
            <div class="download-popup-links">
                <a href="https://greasyfork.org/en/scripts/568060-offline-for-lezhin" 
                target="_blank" 
                rel="noopener noreferrer" 
                style="text-decoration: underline;">
                Update
                </a>
            </div>
        `;
        document.body.appendChild(popup);
        let showTimer = null;
        let hideTimer = null;

        function showPopup() {
            if (btn.disabled) return;
            const rect = btn.getBoundingClientRect();
            popup.style.top = rect.bottom + 8 + 'px';
            popup.style.left = rect.left + rect.width / 2 + 'px';
            popup.classList.add('visible');
        }

        function hidePopup() {
            popup.classList.remove('visible');
        }
        btn.addEventListener('mouseenter', () => {
            if (btn.disabled) return;
            clearTimeout(hideTimer);
            showTimer = setTimeout(showPopup, 1000);
        });
        btn.addEventListener('mouseleave', () => {
            clearTimeout(showTimer);
            hideTimer = setTimeout(hidePopup, 25);
        });
        popup.addEventListener('mouseenter', () => {
            clearTimeout(hideTimer);
        });
        popup.addEventListener('mouseleave', () => {
            hideTimer = setTimeout(hidePopup, 25);
        });
    }

    function removeDownloadButton() {
        const btn = document.querySelector('.download-button');
        if (btn) {
            btn.remove();
        }
    }

    function updateDownloadButton(btn, text) {
        btn.textContent = text;
    }

    function resetDownloadButton(btn) {
        setTimeout(() => {
            btn.textContent = UI_BUTTON_LABELS.DEFAULT;
        }, UI_BUTTON_RESET_DELAY_MS);
    }

    function lockPageInteraction() {
        document.body.classList.add('lock-site-ui');
    }

    function unlockPageInteraction() {
        document.body.classList.remove('lock-site-ui');
    }

    function lockPageScroll() {
        document.body.style.overflow = 'hidden';
    }

    function unlockPageScroll() {
        document.body.style.overflow = '';
    }

    function startDownloadSession() {
        return {
            cancelled: false,
            cancel() {
                this.cancelled = true;
            }
        };
    }

    function abortDownloadSession() {
        if (state.ui.activeDownload) {
            state.ui.activeDownload.cancel();
            state.ui.activeDownload = null;
        }
        state.canvas.buffer.clear();
        state.canvas.pages.clear();
        state.canvas.enabled = false;
        for (const img of state.blob.pages.values()) {
            if (img instanceof HTMLImageElement && img.src.startsWith('blob:')) {
                try {
                    URL.revokeObjectURL(img.src);
                } catch {}
            }
        }
        state.blob.buffer.clear();
        state.blob.pages.clear();
        state.blob.enabled = false;
    }

    function validateCollectedPageCount(collectedCount) {
        const renderType = state.viewer.type;
        const renderTypeLabel = (renderType || 'UNKNOWN').toUpperCase();
        let total;
        try {
            total = getTotalPageCount();
        } catch {
            total = getIndexedComicCuts().length;
        }
        const expected = collectedCount;
        const promoCount = Math.max(0, total - collectedCount);
        console.debug(
            `${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - ` +
            `TOTAL IMAGES: ${total} | ` +
            `PROMO IMAGES: ${promoCount} | ` +
            `EXPECTED IMAGES: ${expected} | ` +
            `COLLECTED IMAGES: ${collectedCount} | ` +
            `FINAL RENDERING METHOD: ${renderTypeLabel}`
        );
        return collectedCount === expected;
    }

    function validateCollectedImages(session, images) {
        if (session.cancelled) {
            throwDownloadError('DOWNLOAD_ABORTED');
        }
        if (!images || !images.length) {
            console.debug(
                `${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - NO IMAGES COLLECTED`
            );
            throwDownloadError('NO_IMAGES_COLLECTED');
        }
        const isValidCount = validateCollectedPageCount(images.length);
        if (!isValidCount) {
            console.debug(
                `${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - IMAGE COUNT MISMATCH`
            );
            throwDownloadError('IMAGE_COUNT_MISMATCH');
        }
        return images;
    }

    function findMissingPages(collectedMap) {
        if (!(collectedMap instanceof Map)) return [];
        const collected = new Set(collectedMap.keys());
        const expected = getAllPageIndexes();
        return expected.filter(index => !collected.has(index));
    }

    async function retryMissingPages(
        session,
        collectedMap,
        onProgress, {
            maxAttempts = 6,
            scrollDelay = 350,
            beforeAttempt = null,
            afterAttempt = null,
            idleWait = false,
            nudgeScroll = false
        } = {}
    ) {
        let previousMissingCount = Infinity;
        const delayMs = scrollDelay;
        for (let attempt = 0; attempt < maxAttempts && !session.cancelled; attempt++) {
            const missing = findMissingPages(collectedMap);
            if (!missing.length) break;
            if (missing.length >= previousMissingCount) break;
            previousMissingCount = missing.length;
            if (beforeAttempt) await beforeAttempt(missing);
            for (const index of missing) {
                if (session.cancelled) break;
                scrollToComicPage(index, {
                    instant: true,
                    allowLastPage: false
                });

                await new Promise(r => setTimeout(r, delayMs));
                onProgress(collectedMap.size, null);
            }
            if (nudgeScroll) {
                window.scrollBy(0, 1);
                window.scrollBy(0, -1);
            }
            if (afterAttempt) await afterAttempt(missing);
            if (idleWait) {
                const isFirstRetry = attempt === 0;
                const fewMissing = missing.length <= 2;
                await waitForCanvasIdle(
                    isFirstRetry ? 250 : (fewMissing ? 120 : 150),
                    isFirstRetry ? 900 : (fewMissing ? 400 : 500)
                );
            }
        }
    }

    async function collectWebpPages(session, onProgress) {
        const wrapper = getViewerContainer();
        if (!wrapper || session.cancelled) return [];
        state.ui.images.clear();
        const promoCheck = isPromoImage;
        const special = getViewerLayoutConfig();
        const cutsToUse = special.enabled ?
            special.safeCuts :
            getIndexedComicCuts();
        const stableCuts = [...cutsToUse];

        function waitForImageInjection(cut, timeout = 1500) {
            return new Promise(resolve => {
                const start = performance.now();

                function check() {
                    const img = cut.querySelector('img');
                    if (img && img.src && !img.src.startsWith('blob:')) {
                        return resolve(true);
                    }
                    if (performance.now() - start > timeout) {
                        return resolve(false);
                    }
                    requestAnimationFrame(check);
                }
                check();
            });
        }
        for (const cut of stableCuts) {
            if (session.cancelled || state.ui.phase !== 'collecting') break;
            const index = Number(cut.dataset.cutIndex);
            if (!Number.isFinite(index)) continue;
            scrollToComicPage(index, {
                instant: true
            });
            await waitForImageInjection(cut, 1500);
            const img = [...cut.querySelectorAll('img')].find(i =>
                i.src &&
                !i.src.startsWith('blob:') &&
                !promoCheck(i)
            );
            if (img && !state.ui.images.has(index)) {
                state.ui.images.set(index, img.src);
                onProgress(state.ui.images.size);
            }
        }
        return session.cancelled ? [] :
            getOrderedWebpPageList();
    }

    async function collectHorizontalWebpPages(session, onProgress) {
        state.ui.images.clear();
        const wrapper = document.querySelector(RENDER_PAGE_SELECTORS_HORIZONTAL.horizontalWrapper);
        const sliderBtn = document.querySelector(
            '[role="slider"][data-max][data-value]'
        );
        if (!wrapper || !sliderBtn || session.cancelled) {
            console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - CHAPTER SLIDER OR BUTTON NOT FOUND`);
            return [];
        }
        const getIndex = () => Number(sliderBtn.getAttribute('data-value'));
        const total = Number(sliderBtn.getAttribute('data-max'));
        const navPrev = wrapper.querySelector('button[class*="nav--left"]');
        const navNext = wrapper.querySelector('button[class*="nav--right"]');
        const getActiveImage = () => {
            const activeCut = wrapper.querySelector('[class*="cut--active"]');
            return activeCut?.querySelector('img') || null;
        };
        const waitForIndexChange = (previousIndex, timeout = 3000) => {
            return new Promise(resolve => {
                const start = Date.now();
                const tick = () => {
                    if (session.cancelled) return resolve(false);
                    const current = getIndex();
                    if (current !== previousIndex) {
                        return resolve(true);
                    }
                    if (Date.now() - start > timeout) {
                        return resolve(false);
                    }
                    requestAnimationFrame(tick);
                };
                tick();
            });
        };
        const waitForImageChange = (previousSrc, timeout = 3000) => {
            return new Promise(resolve => {
                const start = Date.now();
                const tick = () => {
                    if (session.cancelled) return resolve(false);
                    const img = getActiveImage();
                    if (img && img.src && img.src !== previousSrc) {
                        return resolve(true);
                    }
                    if (Date.now() - start > timeout) {
                        return resolve(false);
                    }
                    requestAnimationFrame(tick);
                };
                tick();
            });
        };
        let safety = 0;
        while (getIndex() > 1 && safety < 30 && !session.cancelled) {
            const prevIndex = getIndex();
            const prevSrc = getActiveImage()?.src;
            navPrev?.click();
            await Promise.all([
                waitForIndexChange(prevIndex),
                waitForImageChange(prevSrc)
            ]);
            safety++;
        }
        while (!session.cancelled) {
            const index = getIndex();
            const img = getActiveImage();
            console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - CURRENT INDEX:`, index);
            if (img && img.src && !state.ui.images.has(index)) {
                if (!isPromoImage(img)) {
                    state.ui.images.set(index, img.src);
                    onProgress(state.ui.images.size);
                }
            }
            if (index >= total) break;
            const previousIndex = index;
            const previousSrc = img?.src;
            navNext?.click();
            await Promise.all([
                waitForIndexChange(previousIndex),
                waitForImageChange(previousSrc)
            ]);
        }
        console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - TOTAL COLLECTED:`, state.ui.images.size);
        return session.cancelled ? [] : getOrderedWebpPageList();
    }

    function getOrderedWebpPageList() {
        return [...state.ui.images.entries()]
            .sort(([a], [b]) => a - b)
            .map(([, url]) => url);
    }

    async function convertWebpPagesToJpeg(session, urls, onProgress) {
        const files = {};
        const total = urls.length;
        let completed = 0;
        onProgress(0, total);
        const workerCount = getOptimalWorkerCount();
        const CAN_USE_OFFSCREEN =
            typeof OffscreenCanvas !== 'undefined' &&
            OffscreenCanvas.prototype.convertToBlob &&
            typeof createImageBitmap === 'function';
        const idleYield = () => new Promise(r => requestAnimationFrame(r));
        async function convertWebpToJpeg(webpBytes, quality = 0.92) {
            if (CAN_USE_OFFSCREEN) {
                const blob = new Blob([webpBytes], {
                    type: 'image/webp'
                });
                const bitmap = await createImageBitmap(blob);
                const canvas = new OffscreenCanvas(bitmap.width, bitmap.height);
                const ctx = canvas.getContext('2d', {
                    alpha: false
                });
                ctx.drawImage(bitmap, 0, 0);
                const jpegBlob = await canvas.convertToBlob({
                    type: 'image/jpeg',
                    quality
                });
                return new Uint8Array(await jpegBlob.arrayBuffer());
            }
            return new Promise((resolve, reject) => {
                const blob = new Blob([webpBytes], {
                    type: 'image/webp'
                });
                const img = new Image();
                const url = URL.createObjectURL(blob);
                img.onload = () => {
                    URL.revokeObjectURL(url);
                    const canvas = document.createElement('canvas');
                    canvas.width = img.naturalWidth;
                    canvas.height = img.naturalHeight;
                    const ctx = canvas.getContext('2d');
                    ctx.drawImage(img, 0, 0);
                    canvas.toBlob(async jpegBlob => {
                        if (!jpegBlob) {
                            return reject(
                                new Error(
                                    DOWNLOAD_ERROR_MAP.JPEG_CONVERSION_FAILED.code
                                )
                            );
                        }
                        resolve(
                            new Uint8Array(
                                await jpegBlob.arrayBuffer()
                            )
                        );
                    }, 'image/jpeg', quality);
                };
                img.onerror = () => {
                    URL.revokeObjectURL(url);
                    reject(
                        new Error(
                            DOWNLOAD_ERROR_MAP.JPEG_CONVERSION_FAILED.code
                        )
                    );
                };
                img.src = url;
            });
        }
        const jobs = urls.map((url, index) => ({
            url,
            index
        }));
        const results = await taskQueue(workerCount, jobs, async ({
            url,
            index
        }) => {
            if (session.cancelled) return null;
            const webp = await getImageData(url);
            if (session.cancelled) return null;
            const jpeg = await convertWebpToJpeg(webp).catch(() => {
                throwDownloadError('JPEG_CONVERSION_FAILED');
            });
            if (session.cancelled) return null;
            completed++;
            onProgress(completed, total);
            if (completed % 2 === 0) await idleYield();
            return {
                name: generateImageFileName(index + 1, total, 'jpg'),
                data: jpeg
            };
        });
        for (const r of results) {
            if (r) files[r.name] = r.data;
        }
        return files;
    }

    function initCanvasDrawHook() {
        if (CanvasRenderingContext2D.prototype.__lezhinHooked) return;
        CanvasRenderingContext2D.prototype.__lezhinHooked = true;
        const originalDrawImage = CanvasRenderingContext2D.prototype.drawImage;
        CanvasRenderingContext2D.prototype.drawImage = function(img, ...args) {
            originalDrawImage.apply(this, [img, ...args]);
            state.canvas.lastDrawTs = performance.now();
            if (state.canvas.idleTimer) {
                clearTimeout(state.canvas.idleTimer);
            }
            state.canvas.idleTimer = setTimeout(() => {
                const resolver = state.canvas.idleResolver;
                state.canvas.idleResolver = null;
                if (resolver) resolver(true);
            }, state.canvas.idleWaitMs || 700);
            if (!img?.src || isPromoImage(img)) return;
            const op = getCanvasImageData(img, args);
            if (!op) return;
            const pageIndex = getVisiblePageIndex(this.canvas);
            if (!pageIndex) return;
            const store = state.canvas.enabled ?
                state.canvas.pages :
                state.canvas.buffer;
            if (!store.has(pageIndex)) {
                store.set(pageIndex, {
                    pageIndex,
                    url: img.src,
                    width: this.canvas.width,
                    height: this.canvas.height,
                    ops: []
                });
            }
            store.get(pageIndex).ops.push(op);
        };
    }

    function getCanvasImageData(img, a) {
        switch (a.length) {
            case 2:
                return {
                    sx: 0, sy: 0, sw: img.width, sh: img.height, dx: a[0], dy: a[1], dw: img.width, dh: img.height
                };
            case 4:
                return {
                    sx: 0, sy: 0, sw: img.width, sh: img.height, dx: a[0], dy: a[1], dw: a[2], dh: a[3]
                };
            case 8:
                return {
                    sx: a[0], sy: a[1], sw: a[2], sh: a[3], dx: a[4], dy: a[5], dw: a[6], dh: a[7]
                };
            default:
                return null;
        }
    }

    async function waitForCanvasIdle(ms = 700, timeout = 6000) {
        state.canvas.idleWaitMs = ms;
        if (!state.canvas.lastDrawTs) {
            return true;
        }
        return new Promise(resolve => {
            const timeoutId = setTimeout(() => {
                state.canvas.idleResolver = null;
                resolve(false);
            }, timeout);
            state.canvas.idleResolver = () => {
                clearTimeout(timeoutId);
                resolve(true);
            };
        });
    }

    async function collectCanvasPages(session, onProgress) {
        scrollToComicPage(null, 'smooth');
        state.canvas.pages = new Map(state.canvas.buffer);
        state.canvas.buffer.clear();
        state.canvas.enabled = true;
        const special = getViewerLayoutConfig();
        const cuts = special.enabled ?
            special.safeCuts :
            getIndexedComicCuts();
        const total = cuts.length;
        await new Promise(r => setTimeout(r, 300));
        for (const cut of cuts) {
            if (session.cancelled) break;
            scrollToComicPage(
                Number(cut.dataset.cutIndex),
                'smooth'
            );
            await new Promise(r => setTimeout(r, 300));
            onProgress(state.canvas.pages.size, total);
        }
        const missingInitial = findMissingPages(state.canvas.pages);
        if (!missingInitial.length) {
            state.canvas.enabled = false;
            return [...state.canvas.pages.values()]
                .filter(p => p.ops.length)
                .sort((a, b) => a.pageIndex - b.pageIndex);
        }
        state.canvas.enabled = false;
        let previousMissingCount = Infinity;
        for (let attempt = 0; attempt < 4 && !session.cancelled; attempt++) {
            const missing = findMissingPages(state.canvas.pages);
            if (!missing.length) break;
            if (missing.length >= previousMissingCount) break;
            previousMissingCount = missing.length;
            await retryMissingPages(
                session,
                state.canvas.pages,
                onProgress, {
                    beforeAttempt: async () => {
                        state.canvas.enabled = true;
                    },
                    afterAttempt: async () => {
                        state.canvas.enabled = false;
                    },
                    idleWait: true,
                    nudgeScroll: true
                }
            );
        }
        return [...state.canvas.pages.values()]
            .filter(p => p.ops.length)
            .sort((a, b) => a.pageIndex - b.pageIndex);
    }

    async function convertCanvasToPng(page) {
        const webpBytes = await getImageData(page.url);
        const blob = new Blob([webpBytes], {
            type: 'image/webp'
        });
        const img = new Image();
        const url = URL.createObjectURL(blob);
        img.src = url;
        await new Promise((resolve, reject) => {
            img.onload = () => {
                URL.revokeObjectURL(url);
                resolve();
            };
            img.onerror = e => {
                URL.revokeObjectURL(url);
                reject(e);
            };
        });
        const canvas = document.createElement('canvas');
        canvas.width = page.width;
        canvas.height = page.height;
        const ctx = canvas.getContext('2d');
        page.ops.forEach(op => {
            ctx.drawImage(
                img,
                op.sx, op.sy, op.sw, op.sh,
                op.dx, op.dy, op.dw, op.dh
            );
        });
        return new Promise(resolve => {
            canvas.toBlob(async blob => {
                const buf = await blob.arrayBuffer();
                resolve(new Uint8Array(buf));
            }, 'image/png');
        });
    }

    async function streamCanvasImagesToZip(session, pages, zip, onProgress) {
        const total = pages.length;
        let completed = 0;
        onProgress(0, total);
        const workerCount = getOptimalWorkerCount();
        await taskQueue(workerCount, pages, async (page, index) => {
            if (session.cancelled) return;
            const png = await convertCanvasToPng(page);
            if (!png || session.cancelled) return;
            const name = generateImageFileName(index + 1, total, 'png');
            const file = new fflate.ZipDeflate(name, {
                level: 6
            });
            zip.add(file);
            file.push(png, true);
            completed++;
            onProgress(completed, total);
        });
        return !session.cancelled;
    }

    function initBlobBackgroundCollector() {
        if (state.blob.observerInitialized) return;
        state.blob.observerInitialized = true;

        function getPageContainers() {
            for (const selector of RENDER_PAGE_SELECTORS) {
                const nodes = document.querySelectorAll(selector);
                if (nodes.length) return nodes;
            }
            return [];
        }

        function captureVisibleBlobs() {
            const containers = getPageContainers();
            if (!containers.length) return;
            containers.forEach((el, i) => {
                const index = i + 1;
                if (state.blob.pages.has(index)) return;
                const img = el.querySelector('img[src^="blob:"]');
                if (!img) return;
                if (!img.complete) return;
                state.blob.pages.set(index, img);
                console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION} - BACKGROUND BLOB STORED: ${index}`);
            });
        }
        const observer = new MutationObserver(() => {
            captureVisibleBlobs();
        });
        observer.observe(document.body, {
            childList: true,
            subtree: true,
            attributes: true,
            attributeFilter: ['src']
        });
        captureVisibleBlobs();
    }

    async function collectBlobPages(session, onProgress) {
        async function collectBlobPagesDeterministic() {
            const WAIT_AFTER_SCROLL_MS = 120;
            const MAX_IDLE_ROUNDS = 60;
            const collected = new Map();
            const layout = getViewerLayoutConfig();
            let lastCount = 0;
            let idleRounds = 0;

            function getPageContainers() {
                for (const selector of RENDER_PAGE_SELECTORS) {
                    const nodes = document.querySelectorAll(selector);
                    if (nodes.length) {
                        return nodes;
                    }
                }
                return [];
            }

            function extractHydratedBlobs(containers) {
                const results = [];
                containers.forEach((el, i) => {
                    const img = el.querySelector('img[src^="blob:"]');
                    if (!img) return;
                    if (!img.complete) return;
                    const index = i + 1;
                    results.push({
                        index,
                        img
                    });
                });
                return results;
            }

            function scrollToLastCollected(totalContainers) {
                if (!collected.size) {
                    scrollToComicPage(1);
                    return;
                }
                const maxIndex = Math.max(...collected.keys());
                if (
                    layout.scroll.preventLastScroll &&
                    maxIndex >= totalContainers
                ) {
                    return;
                }
                scrollToComicPage(maxIndex, {
                    instant: false,
                    allowLastPage: !layout.scroll.preventLastScroll,
                    offset: layout.scroll.offset
                });
            }
            while (!session.cancelled) {
                const containers = getPageContainers();
                const totalContainers = containers.length;
                const blobs = extractHydratedBlobs(containers);
                blobs.forEach(({
                    index,
                    img
                }) => {
                    if (!collected.has(index)) {
                        collected.set(index, img);
                    }
                });
                onProgress?.(collected.size);
                if (
                    totalContainers > 0 &&
                    collected.size === totalContainers
                ) {
                    break;
                }
                if (collected.size === lastCount) {
                    idleRounds++;
                    if (idleRounds > MAX_IDLE_ROUNDS) {
                        break;
                    }
                } else {
                    idleRounds = 0;
                    lastCount = collected.size;
                }
                if (collected.size < totalContainers) {
                    scrollToLastCollected(totalContainers);
                    await new Promise(r =>
                        setTimeout(r, WAIT_AFTER_SCROLL_MS)
                    );
                }
            }
            return collected;
        }
        const collected = await collectBlobPagesDeterministic();
        for (const [index, img] of collected.entries()) {
            if (!state.blob.pages.has(index)) {
                state.blob.pages.set(index, img);
            }
        }
        return state.blob.pages;
    }

    function getOrderedBlobPageList(blobMap) {
        return [...blobMap.entries()]
            .sort(([a], [b]) => a - b)
            .map(([, img]) => img);
    }

    async function convertBlobImageToPng(img) {
        if (img.decode) {
            try {
                await img.decode();
            } catch {}
        } else if (!img.complete) {
            await new Promise(resolve => {
                img.onload = resolve;
                img.onerror = resolve;
            });
        }
        const canvas = document.createElement("canvas");
        canvas.width = img.naturalWidth;
        canvas.height = img.naturalHeight;
        const ctx = canvas.getContext("2d");
        ctx.drawImage(img, 0, 0);
        return new Promise(resolve => {
            canvas.toBlob(async blob => {
                const buf = await blob.arrayBuffer();
                resolve(new Uint8Array(buf));
            }, "image/png");
        });
    }

    async function buildBlobImageFiles(session, images, onProgress) {
        const files = {};
        const total = images.length;
        onProgress(0, total);
        const workerCount = getOptimalWorkerCount();
        let completed = 0;
        const jobs = images.map((img, index) => ({
            img,
            index
        }));
        const results = await taskQueue(
            workerCount,
            jobs,
            async ({
                img,
                index
            }) => {
                if (session.cancelled) return null;
                const pngData = await convertBlobImageToPng(img);
                if (session.cancelled) return null;
                completed++;
                onProgress(completed, total);
                return {
                    name: generateImageFileName(index + 1, total, 'png'),
                    data: pngData
                };
            }
        );
        for (const r of results) {
            if (r) {
                files[r.name] = r.data;
            }
        }
        return files;
    }

    function createStreamingZip(series, chapter) {
        const chunks = [];
        let resolveFinal;
        let rejectFinal;
        const donePromise = new Promise((resolve, reject) => {
            resolveFinal = resolve;
            rejectFinal = reject;
        });
        const zip = new fflate.Zip((err, data, final) => {
            if (err) {
                console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION}: ZIP STREAM ERROR\n`, err);
                rejectFinal(new Error(
                    DOWNLOAD_ERROR_MAP.ZIP_CREATION_FAILED.code
                ));
                return;
            }
            if (data) {
                chunks.push(data);
            }
            if (final) {
                try {
                    const blob = new Blob(chunks, {
                        type: 'application/zip'
                    });
                    const url = URL.createObjectURL(blob);
                    const a = document.createElement('a');
                    a.href = url;
                    a.download = `${series} - ${chapter}.zip`;
                    a.click();
                    setTimeout(() => URL.revokeObjectURL(url), 1000);
                    resolveFinal();
                } catch (e) {
                    console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION}: ZIP FINALIZE ERROR\n`, e);
                    rejectFinal(new Error(
                        DOWNLOAD_ERROR_MAP.ZIP_CREATION_FAILED.code
                    ));
                }
            }
        });
        return {
            zip,
            donePromise
        };
    }

    function getOptimalWorkerCount() {
        const cores = navigator.hardwareConcurrency || 4;
        const memory = navigator.deviceMemory || 4;
        const isMobile = isMobileDevice();
        let workers = Math.floor(cores / 2);
        if (memory <= 2) {
            workers = 2;
        } else if (memory <= 4) {
            workers = Math.min(workers, 3);
        }
        if (isMobile) {
            workers = Math.min(workers, 3);
        }
        workers = Math.max(2, Math.min(6, workers));
        return workers;
    }

    async function taskQueue(limit, items, worker) {
        const results = [];
        const executing = [];
        const runWorker = worker;
        for (let i = 0; i < items.length; i++) {
            const item = items[i];
            const index = i;
            const p = Promise.resolve().then(() => runWorker(item, index));
            results.push(p);
            if (limit <= items.length) {
                const e = p.then(() => {
                    executing.splice(executing.indexOf(e), 1);
                });
                executing.push(e);
                if (executing.length >= limit) {
                    await Promise.race(executing);
                }
            }
        }
        return Promise.all(results);
    }

    function getImageData(url) {
        return new Promise((resolve, reject) => {
            GM_xmlhttpRequest({
                method: 'GET',
                url,
                responseType: 'arraybuffer',
                onload: r =>
                    r.status === 200 ?
                    resolve(new Uint8Array(r.response)) : reject(r.status),
                onerror: reject
            });
        });
    }

    async function executeDownloadPipeline(btn) {
        if (state.ui.isDownloading) return;
        const renderType = resolveRenderType();
        if (!renderType) return;
        state.ui.isDownloading = true;
        state.ui.phase = 'collecting';
        const session = startDownloadSession();
        state.ui.activeDownload = session;
        const headerOverrideStyle = applyViewerHeaderOverride();
        btn.disabled = true;
        const setLabel = label => updateDownloadButton(btn, label);
        const onCollect = c => setLabel(UI_BUTTON_LABELS.COLLECTING(c));
        const onConvert = (c, t) =>
            setLabel(UI_BUTTON_LABELS.CONVERTING(c, t));
        const finalizeZip = async (zip, donePromise) => {
            try {
                zip.end();
                await donePromise;
            } catch {
                throwDownloadError('ZIP_CREATION_FAILED');
            }
        };
        const createZipInstance = () =>
            createStreamingZip(
                getSeriesTitle(),
                getSeriesChapter()
            );
        setLabel(UI_BUTTON_LABELS.COLLECTING(0));
        await new Promise(requestAnimationFrame);
        let completed = false;
        try {
            lockPageScroll();
            lockPageInteraction();
            scrollToTop();
            await new Promise(r => setTimeout(r, 300));
            let files = null;
            if (renderType === 'webp') {
                const images = isHorizontalViewerLayout() ?
                    await collectHorizontalWebpPages(session, onCollect) :
                    await collectWebpPages(session, onCollect);
                validateCollectedImages(session, images);
                await retryMissingPages(
                    session,
                    state.ui.images,
                    onCollect
                );
                const finalImages = validateCollectedImages(
                    session,
                    getOrderedWebpPageList()
                );
                state.ui.phase = 'downloading';
                files = await convertWebpPagesToJpeg(
                    session,
                    finalImages,
                    onConvert
                );
            }
            if (renderType === 'canvas') {
                const pages = await collectCanvasPages(
                    session,
                    onCollect
                );
                const validPages = validateCollectedImages(
                    session,
                    pages
                );
                state.ui.phase = 'downloading';
                const {
                    zip,
                    donePromise
                } =
                createZipInstance();
                const success =
                    await streamCanvasImagesToZip(
                        session,
                        validPages,
                        zip,
                        onConvert
                    );
                if (!success) {
                    throwDownloadError('DOWNLOAD_ABORTED');
                }
                await finalizeZip(zip, donePromise);
            }
            if (renderType === 'blob') {
                const layout = getViewerLayoutConfig();
                const expectedCount =
                    layout.pageSource === 'cuts' ?
                    getAllPageIndexes().length :
                    getTotalPageCount();
                if (state.blob.pages.size !== expectedCount) {
                    state.blob.pages.clear();
                    for (const [index, data] of state.blob.buffer) {
                        const blob = new Blob([data], {
                            type: 'image/png'
                        });
                        const url =
                            URL.createObjectURL(blob);
                        const img = new Image();
                        img.src = url;
                        state.blob.pages.set(index, img);
                    }
                    state.blob.enabled = true;
                    state.blob.buffer.clear();
                    await collectBlobPages(
                        session,
                        onCollect
                    );
                }
                const orderedImages =
                    validateCollectedImages(
                        session,
                        getOrderedBlobPageList(
                            state.blob.pages
                        )
                    );
                state.ui.phase = 'downloading';
                files = await buildBlobImageFiles(
                    session,
                    orderedImages,
                    onConvert
                );
            }
            if (renderType !== 'canvas') {
                if (session.cancelled || !files) {
                    throwDownloadError('DOWNLOAD_ABORTED');
                }
                if (!Object.keys(files).length) {
                    throwDownloadError('NO_IMAGES_COLLECTED');
                }
                const {
                    zip,
                    donePromise
                } =
                createZipInstance();
                const entries = Object.entries(files);
                let completedCount = 0;
                const total = entries.length;
                for (const [name, data] of entries) {
                    if (session.cancelled) break;
                    const file = new fflate.ZipDeflate(
                        name, {
                            level: 6
                        }
                    );
                    zip.add(file);
                    file.push(data, true);
                    completedCount++;
                    onConvert(completedCount, total);
                }
                await finalizeZip(zip, donePromise);
            }
            setLabel(UI_BUTTON_LABELS.COMPLETE);
            resetDownloadButton(btn);
            completed = true;
        } catch (e) {
            handleDownloadError(e);
            setLabel(UI_BUTTON_LABELS.DEFAULT);
        } finally {
            state.ui.phase = 'idle';
            state.ui.isDownloading = false;
            if (state.ui.activeDownload === session) {
                state.ui.activeDownload = null;
            }
            btn.disabled = false;
            unlockPageScroll();
            unlockPageInteraction();
            if (headerOverrideStyle) {
                headerOverrideStyle.remove();
            }
            if (
                completed &&
                !sessionStorage.getItem(
                    UI_AUTO_REFRESH_FLAG
                )
            ) {
                sessionStorage.setItem(
                    UI_AUTO_REFRESH_FLAG,
                    '1'
                );
                window.scrollTo({
                    top: 0,
                    behavior: 'smooth'
                });
                setTimeout(() => {
                    location.reload();
                }, 700);
            }
        }
    }

    function createToastContainer() {
        if (document.getElementById('lezhin-toast-container')) return;
        const container = document.createElement('div');
        container.id = 'lezhin-toast-container';
        document.body.appendChild(container);
    }

    function showToast(message) {
        createToastContainer();
        const toast = document.createElement('div');
        toast.className = 'lezhin-toast';
        const text = document.createElement('span');
        text.textContent = message;
        const close = document.createElement('button');
        close.className = 'lezhin-toast-close';
        close.textContent = '×';
        close.onclick = () => closeToast(toast);
        toast.appendChild(text);
        toast.appendChild(close);
        document
            .getElementById('lezhin-toast-container')
            .appendChild(toast);
        setTimeout(() => {
            closeToast(toast);
        }, UI_TOAST_DURATION_MS);
    }

    function closeToast(toast) {
        if (toast.classList.contains('closing')) return;
        toast.classList.add('closing');
        toast.addEventListener(
            'animationend',
            () => toast.remove(), {
                once: true
            }
        );
    }

    function showErrorMessage(message) {
        showToast(message, 'error');
    }

    function throwDownloadError(error) {
        if (error instanceof Error) {
            if (DOWNLOAD_ERROR_INDEX[error.message]) {
                throw error;
            }
            throw new Error(
                DOWNLOAD_ERROR_MAP.UNKNOWN_ERROR.code
            );
        }
        if (error?.code) {
            throw new Error(error.code);
        }
        if (typeof error === 'string' && DOWNLOAD_ERROR_MAP[error]) {
            throw new Error(
                DOWNLOAD_ERROR_MAP[error].code
            );
        }
        if (typeof error === 'string' && DOWNLOAD_ERROR_INDEX[error]) {
            throw new Error(error);
        }
        throw new Error(
            DOWNLOAD_ERROR_MAP.UNKNOWN_ERROR.code
        );
    }

    function handleDownloadError(error) {
        const known = DOWNLOAD_ERROR_INDEX[error?.message];
        if (known) {
            showErrorMessage(known.message);
            return;
        }
        console.debug(`${SCRIPT_NAME_DEBUG} v${SCRIPT_VERSION}: DOWNLOAD ERROR OCCURRED\n`, error);
        showErrorMessage(
            DOWNLOAD_ERROR_MAP.UNKNOWN_ERROR.message
        );
    }

    window.addEventListener('load', init);

})();