class NovelReader {
    /**
     * 创建一个小说阅读器。
     * @param {Array} chapters - 小说的章节数组。
     * @param {number} pageSize - 每页的字符数。
     * @param {string} chapterElementId - 显示章节内容的元素选择器。
     * @param {string} prevPageButtonIdTop - 顶部上一页按钮元素的选择器。
     * @param {string} nextPageButtonIdTop - 顶部下一页按钮元素的选择器。
     * @param {string} prevPageButtonIdBottom - 底部上一页按钮元素的选择器。
     * @param {string} nextPageButtonIdBottom - 底部下一页按钮元素的选择器。
     * @param {string} switchButtonId - 自动滚动开关按钮元素的选择器。
     * @param {number} scrollStep - 自动滚动每次滚动的像素值。
     */
    constructor(chapters, pageSize, chapterElementId, prevPageButtonIdTop, nextPageButtonIdTop, prevPageButtonIdBottom, nextPageButtonIdBottom, switchButtonId, scrollStep = 50) {
        this.chapters = chapters;
        this.pageSize = pageSize;
        this.currentChapterIndex = 0;
        this.currentPageIndex = 0;
        this.pages = [];
        this.intervalId = null;
        this.isScrolling = false;
        this.scrollStep = scrollStep;

        this.chapterElement = document.querySelector(chapterElementId);
        this.prevPageButtonTop = document.querySelector(prevPageButtonIdTop);
        this.nextPageButtonTop = document.querySelector(nextPageButtonIdTop);
        this.prevPageButtonBottom = document.querySelector(prevPageButtonIdBottom);
        this.nextPageButtonBottom = document.querySelector(nextPageButtonIdBottom);
        this.switchButton = document.querySelector(switchButtonId);

        this.init();
    }

    /**
     * 初始化小说阅读器。
     */
    init() {
        this.pages = this.paginateChapter(this.chapters[this.currentChapterIndex]);
        this.loadPage(0);

        this.prevPageButtonTop.addEventListener('click', this.prevPage.bind(this));
        this.nextPageButtonTop.addEventListener('click', this.nextPage.bind(this));
        this.prevPageButtonBottom.addEventListener('click', this.prevPage.bind(this));
        this.nextPageButtonBottom.addEventListener('click', this.nextPage.bind(this));
        this.switchButton.addEventListener('click', this.toggleScrolling.bind(this));

        // 检查本地存储中的自动播放设置
        const autoPlay = localStorage.getItem('autoPlay');
        if (autoPlay === 'true') {
            this.startScrolling();
            $(this.switchButton).addClass('van-switch--on').attr('aria-checked', 'true');
        }

        // 监听用户滚动
        window.addEventListener('scroll', () => {
            if (!this.isScrolling && window.scrollY === 0 && autoPlay === 'true') {
                this.startScrolling();
            }
        });
    }

    /**
     * 将章节分页，确保标签不会被切割。
     * @param {string} chapter - 章节内容。
     * @return {Array} - 切分成页的章节内容。
     */
    paginateChapter(chapter) {
        const pages = [];
        let currentPage = '';
        let currentIndex = 0;

        while (currentIndex < chapter.length) {
            const nextSlice = chapter.slice(currentIndex, currentIndex + this.pageSize);
            const lastOpenTagIndex = nextSlice.lastIndexOf('<');
            const lastCloseTagIndex = nextSlice.lastIndexOf('>');

            if (lastOpenTagIndex > lastCloseTagIndex) {
                const nextCloseTagIndex = chapter.indexOf('>', currentIndex + this.pageSize);
                if (nextCloseTagIndex === -1) {
                    currentPage += chapter.slice(currentIndex);
                    currentIndex = chapter.length;
                } else {
                    currentPage += chapter.slice(currentIndex, nextCloseTagIndex + 1);
                    currentIndex = nextCloseTagIndex + 1;
                }
            } else {
                currentPage += nextSlice;
                currentIndex += this.pageSize;
            }

            if (currentPage.length >= this.pageSize || currentIndex >= chapter.length) {
                pages.push(currentPage);
                currentPage = '';
            }
        }

        return pages;
    }

    /**
     * 加载指定的页面。
     * @param {number} index - 要加载的页码。
     */
    loadPage(index) {
        if (index >= 0 && index < this.pages.length) {
            this.chapterElement.innerHTML = this.pages[index];
            this.currentPageIndex = index;
        }
        this.updateNavButtons();
        // 获取元素
        let element = document.querySelector('#app');
        // 获取元素距离浏览器滚动到顶部的距离
        let distanceToTop = element.getBoundingClientRect().top + window.scrollY;
        //console.log('距离顶部的距离:', distanceToTop);
        $(window).scrollTop(distanceToTop);
    }

    /**
     * 更新导航按钮。
     * @param {HTMLElement} prevButton - 上一页按钮元素。
     * @param {HTMLElement} nextButton - 下一页按钮元素。
     */
    updateButtonState(prevButton, nextButton) {
        if (this.currentPageIndex === 0) {
            prevButton.textContent = '上一章';
        } else {
            prevButton.textContent = '上一页';
        }
        prevButton.disabled = this.currentPageIndex === 0 && this.currentChapterIndex === 0;

        if (this.currentPageIndex === this.pages.length - 1) {
            nextButton.textContent = '下一章';
        } else {
            nextButton.textContent = '下一页';
        }
        nextButton.disabled = this.currentPageIndex === this.pages.length - 1 && this.currentChapterIndex === this.chapters.length - 1;
    }

    /**
     * 根据当前页面和章节更新导航按钮。
     */
    updateNavButtons() {
        this.updateButtonState(this.prevPageButtonTop, this.nextPageButtonTop);
        this.updateButtonState(this.prevPageButtonBottom, this.nextPageButtonBottom);
    }

    /**
     * 导航到上一页或上一章。
     */
    prevPage() {
        if (this.currentPageIndex > 0) {
            this.loadPage(this.currentPageIndex - 1);
        } else if (this.currentChapterIndex > 0) {
            this.currentChapterIndex -= 1;
            this.pages = this.paginateChapter(this.chapters[this.currentChapterIndex]);
            this.loadPage(this.pages.length - 1);
        }else{
            // 更新 URL
            let strUpdatedUrl = this.updateChapterId(location.href,intPre);
            location.href=strUpdatedUrl
        }
    }

    /**
     * 导航到下一页或下一章。
     */
    nextPage() {
        if (this.currentPageIndex < this.pages.length - 1) {
         
            this.loadPage(this.currentPageIndex + 1);
        } else if (this.currentChapterIndex < this.chapters.length - 1) {
            this.currentChapterIndex += 1;
            this.pages = this.paginateChapter(this.chapters[this.currentChapterIndex]);
       
            this.loadPage(0);
        } else {
            
            // 更新 URL
            let strUpdatedUrl = this.updateChapterId(location.href,intNext);
            //console.log(strUpdatedUrl)
            location.href=strUpdatedUrl
            //this.stopScrolling(); // 如果没有下一页和下一章，则停止滚动
        }

    }

    updateChapterId(url,intChapterId) {
        const urlObj = new URL(url);
        const params = urlObj.searchParams;
    
        if (params.has('chapter_id')) {
            // 如果存在 chapter_id 参数，则将其值改为 1
            params.set('chapter_id', intChapterId);
        } else {
            // 如果不存在 chapter_id 参数，则追加该参数
            params.append('chapter_id', intChapterId);
        }
    
        // 返回更新后的 URL
        return urlObj.toString();
    }

    /**
     * 启动自动滚动。
     */
    startScrolling() {
        var interval = parseInt($('.van-stepper__input').val()) * 1000; // 将秒转换为毫秒
        //console.log('启动滚动，间隔:', interval);
        this.isScrolling = true;
        localStorage.setItem('autoPlay', 'true');
        this.intervalId = setInterval(() => {
            var scrollTop = $(window).scrollTop();
            var scrollHeight = $(document).height();
            var clientHeight = $(window).height();
            //console.log('scrollTop:', scrollTop, 'scrollHeight:', scrollHeight, 'clientHeight:', clientHeight);
            if (scrollTop + clientHeight >= scrollHeight) {
                console.log('到达底部，触发下一页或下一章');
                this.nextPage();
            } else {
                $(window).scrollTop(scrollTop + this.scrollStep); // 向下滚动50px
                //console.log('滚动到:', scrollTop + this.scrollStep);
            }
        }, interval);
    }

    /**
     * 停止自动滚动。
     */
    stopScrolling() {
        clearInterval(this.intervalId);
        this.intervalId = null;
        this.isScrolling = false;
        localStorage.setItem('autoPlay', 'false');
        //console.log('滚动停止');
    }

    /**
     * 切换自动滚动状态。
     */
    toggleScrolling() {
        if (this.isScrolling) {
            this.stopScrolling();
            $(this.switchButton).removeClass('van-switch--on').attr('aria-checked', 'false');
        } else {
            this.startScrolling();
            $(this.switchButton).addClass('van-switch--on').attr('aria-checked', 'true');
        }
    }
}

// 初始化小说阅读器
document.addEventListener('DOMContentLoaded', function () {

    let element = document.getElementById('novel_content')

    // 获取元素的文本内容
    let text = element.textContent;

    const chapters = [
        text
    ];

    const pageSize = 1000; // 每页的字数
    new NovelReader(chapters, pageSize, '.novel-content pre', '.prevPageTop', '.nextPageTop', '.prevPageBottom', '.nextPageBottom', '.van-switch', 300);
});