HentaiNexus Infinite Reader

Infinite scroll reader for HentaiNexus with auto image loading and reading position tracking.
Ask a question, post a review, or report the script.
Wrap lines
// ==UserScript==
// @name         HentaiNexus Infinite Reader
// @name:ja      HentaiNexus 無限スクロールリーダー
// @name:zh-CN   HentaiNexus 无限滚动阅读器
// @namespace    https://hentainexus.com/
// @version      1.0
// @author       L1Z4RD
// @license      MIT
// @match        https://hentainexus.com/read/*
// @run-at       document-idle
// @grant        none
// @description  Infinite scroll reader for HentaiNexus with auto image loading and reading position tracking.
// @description:ja  画像の自動読み込みと読書位置の追跡に対応したHentaiNexus用無限スクロールリーダー。
// @description:zh-CN  支持自动加载图片并记录阅读位置的 HentaiNexus 无限滚动阅读器。
// ==/UserScript==
(function () {
    'use strict';

    const LOAD_BUFFER = 6;
    const UNLOAD_BUFFER = 10;

    let initialized = false;
    let currentHash = null;

    const wait = setInterval(() => {
        if (window.pageData && window.pageData.length && !initialized) {
            initialized = true;
            console.log("✅ pageData detected");

            buildReader(window.pageData);
            clearInterval(wait);
        }
    }, 100);

    function getStartIndex(data) {
        const hash = location.hash.replace('#', '');

        if (!hash) return 0;
        if (hash === 'end') return data.length - 1;

        const index = data.findIndex(p => p.url_label === hash);
        return index >= 0 ? index : 0;
    }

    function buildReader(data) {
        console.log("🚀 Building infinite reader...");

        const startIndex = getStartIndex(data);

        const old = document.getElementById('reader_section');
        if (old) old.remove();

        const container = document.createElement('div');
        container.style.maxWidth = '900px';
        container.style.margin = '0 auto';
        container.style.display = 'flex';
        container.style.flexDirection = 'column';
        container.style.gap = '16px';

        document.body.appendChild(container);

        data.forEach((page, index) => {
            if (page.type !== 'image') return;

            const wrapper = document.createElement('div');
            wrapper.dataset.index = index;
            wrapper.style.minHeight = '300px';

            const img = document.createElement('img');
            img.dataset.src = page.image;
            img.style.width = '100%';
            img.style.opacity = '0';
            img.style.transition = 'opacity 0.3s';

            wrapper.appendChild(img);
            container.appendChild(wrapper);
        });

        setupObserver(container, data);
        setupScrollTracking(container, data);

        setTimeout(() => {
            const target = container.querySelector(`[data-index="${startIndex}"]`);
            if (target) {
                target.scrollIntoView({ behavior: 'instant', block: 'start' });
            }

            maintainMemory(container, startIndex);
        }, 100);
    }

    function setupObserver(container, data) {
        const observer = new IntersectionObserver(entries => {
            entries.forEach(entry => {
                const wrapper = entry.target;
                const img = wrapper.querySelector('img');
                const index = parseInt(wrapper.dataset.index);

                if (!img) return;

                if (entry.isIntersecting) {
                    loadImage(img);
                    maintainMemory(container, index);
                }
            });
        }, {
            rootMargin: '1200px'
        });

        container.querySelectorAll('[data-index]').forEach(el => observer.observe(el));
    }

    function setupScrollTracking(container, data) {
        let ticking = false;

        window.addEventListener('scroll', () => {
            if (!ticking) {
                requestAnimationFrame(() => {
                    updateCurrentPage(container, data);
                    ticking = false;
                });
                ticking = true;
            }
        });
    }

    function updateCurrentPage(container, data) {
        const wrappers = container.querySelectorAll('[data-index]');
        const viewportCenter = window.innerHeight / 2;

        let closest = null;
        let closestDistance = Infinity;

        wrappers.forEach(wrapper => {
            const rect = wrapper.getBoundingClientRect();
            const elementCenter = rect.top + rect.height / 2;
            const distance = Math.abs(viewportCenter - elementCenter);

            if (distance < closestDistance) {
                closestDistance = distance;
                closest = wrapper;
            }
        });

        if (!closest) return;

        const index = parseInt(closest.dataset.index);
        const label = data[index]?.url_label;

        if (!label || currentHash === label) return;

        currentHash = label;

        history.replaceState(null, '', '#' + label);
    }

    function loadImage(img) {
        if (img.src) return;

        img.src = img.dataset.src;

        img.onload = () => {
            img.style.opacity = '1';
        };

        img.onerror = () => {
            setTimeout(() => {
                img.src = img.dataset.src;
            }, 1000);
        };
    }

    function unloadImage(img) {
        if (!img.src) return;

        img.style.opacity = '0';
        setTimeout(() => {
            img.removeAttribute('src');
        }, 200);
    }

    function maintainMemory(container, currentIndex) {
        const wrappers = container.querySelectorAll('[data-index]');

        wrappers.forEach(wrapper => {
            const index = parseInt(wrapper.dataset.index);
            const img = wrapper.querySelector('img');

            if (!img) return;

            if (Math.abs(index - currentIndex) <= LOAD_BUFFER) {
                loadImage(img);
            }

            if (Math.abs(index - currentIndex) > UNLOAD_BUFFER) {
                unloadImage(img);
            }
        });
    }

})();