/**
 * PhoneImageEngine - 手机图片排版引擎
 *
 * 将文章HTML内容自动分页并渲染为手机尺寸图片
 * 依赖: jQuery, html2canvas (项目已有)
 *
 * 渲染宽度540px, html2canvas scale=2 输出1080px
 * 小红书: 540x720 (输出1080x1440)
 * 抖音: 540x960 (输出1080x1920)
 */
var PhoneImageEngine = (function () {

    // ===== 配置 =====
    var config = {
        size: 'xiaohongshu',
        fontSize: 14,
        watermark: '',
        pageAlignments: {},  // key=页码(1-based), value='top'|'center'
        sizes: {
            xiaohongshu: { width: 540, height: 720 },
            douyin: { width: 540, height: 960 }
        },
        contentPadding: 20
    };

    // ===== 文章数据 =====
    var postData = {
        id: 0,
        title: '',
        desc: '',
        coverText: '',       // 封面文案
        content_html: '',
        poster: '',
        author_name: '',
        create_time: '',
        category_name: ''
    };

    // ===== 分页结果 =====
    var pages = [];

    /**
     * 确保隐藏渲染区域存在
     */
    function ensureStaging() {
        if ($('#render-staging').length === 0) {
            $('<div id="render-staging">').css({
                position: 'fixed',
                left: '-9999px',
                top: 0,
                visibility: 'hidden'
            }).appendTo('body');
        }
    }

    /**
     * 初始化引擎
     * @param {Object} options - {postId, title, desc, coverText, contentHtml, poster, authorName, createTime, categoryName}
     * @param {Object} userConfig - {size, fontSize, watermark}
     */
    function init(options, userConfig) {
        postData.id = options.postId || 0;
        postData.title = options.title || '';
        postData.desc = options.desc || '';
        postData.coverText = options.coverText || '';
        postData.content_html = options.contentHtml || '';
        postData.poster = options.poster || '';
        postData.author_name = options.authorName || '';
        postData.create_time = options.createTime || '';
        postData.category_name = options.categoryName || '';

        if (userConfig) {
            $.extend(config, userConfig);
        }

        // 内容流事件委托（只绑定一次）
        $(document).off('click', '.break-inserter-btn');
        $(document).off('click', '.remove-break-btn');
        $(document).off('click', '.thumb-alignment-toggle');

        $(document).on('click', '.break-inserter-btn', function () {
            var afterIndex = parseInt($(this).parent().data('after-index'), 10);
            insertPageBreak(afterIndex);
        });

        $(document).on('click', '.remove-break-btn', function () {
            var index = parseInt($(this).data('index'), 10);
            removePageBreak(index);
        });

        $(document).on('click', '.thumb-alignment-toggle', function () {
            var pageNum = parseInt($(this).data('page-num'), 10);
            var currentAlign = (config.pageAlignments && config.pageAlignments[pageNum]) || 'top';
            var newAlign = currentAlign === 'top' ? 'center' : 'top';

            setPageAlignment(pageNum, newAlign);
            render();
        });
    }

    /**
     * 渲染排版预览 - 生成分页后的HTML
     * 两遍遍历: 先算总页数, 再带页码生成
     * @returns {jQuery Deferred} resolves with pages array
     */
    function render() {
        var deferred = $.Deferred();
        pages = [];
        var sizeConfig = config.sizes[config.size] || config.sizes.xiaohongshu;
        var pageHeight = sizeConfig.height;
        var contentAreaHeight = pageHeight - (config.contentPadding * 2);

        var cleanHtml = preprocessContent(postData.content_html);
        var blocks = parseHtmlToBlocks(cleanHtml);

        // 封面页
        pages.push(generateCoverPage(sizeConfig));

        // 内容分页
        var contentPages = paginateContent(blocks, contentAreaHeight, sizeConfig);
        pages = pages.concat(contentPages);

        // 尾页
        pages.push(generateSummaryPage(sizeConfig, pages.length));

        // 两遍遍历: 现在知道了总页数, 给每页补上 N/M 页码
        var totalPages = pages.length;
        for (var i = 0; i < pages.length; i++) {
            if (pages[i].type === 'content') {
                // 在页脚中添加 N/M 格式页码
                pages[i].html = pages[i].html.replace(
                    '<span>' + pages[i].pageNum + '</span>',
                    '<span class="page-number-indicator">' + (i + 1) + '/' + totalPages + '</span>'
                );
            }
        }

        // 渲染内容流（中间栏）- 同步
        renderContentFlow(blocks);

        // 渲染缩略图（右侧）- 异步截图
        renderThumbnails(sizeConfig).then(function () {
            deferred.resolve(pages);
        }).catch(function (err) {
            deferred.reject(err);
        });

        return deferred.promise();
    }

    /**
     * 预处理HTML内容
     */
    function preprocessContent(html) {
        if (!html) return '';
        html = html.replace(/<script[^>]*>[\s\S]*?<\/script>/gi, '');
        html = html.replace(/<style[^>]*>[\s\S]*?<\/style>/gi, '');
        // 清除空段落
        html = html.replace(/<p[^>]*>\s*<\/p>/gi, '');

        // 处理图片: 清除内联样式, 强制 max-width:100%
        html = html.replace(/<img([^>]*?)>/gi, function (match, attrs) {
            // 移除 style, width, height 内联属性
            attrs = attrs.replace(/\s*style\s*=\s*"[^"]*"/gi, '');
            attrs = attrs.replace(/\s*style\s*=\s*'[^']*'/gi, '');
            attrs = attrs.replace(/\s*width\s*=\s*"[^"]*"/gi, '');
            attrs = attrs.replace(/\s*width\s*=\s*'[^']*'/gi, '');
            attrs = attrs.replace(/\s*height\s*=\s*"[^"]*"/gi, '');
            attrs = attrs.replace(/\s*height\s*=\s*'[^']*'/gi, '');
            return '<img' + attrs + ' style="max-width:100%;height:auto;display:block;margin:10px 0;">';
        });

        return html;
    }

    /**
     * 将HTML解析为块级元素数组
     * 每个块: { type, html, estimatedHeight }
     */
    function parseHtmlToBlocks(html) {
        var blocks = [];
        if (!html) return blocks;

        var $temp = $('<div>').html(html);

        // 展平嵌套的包装元素 (div, section, article, main, header, footer)
        // 将其内部内容提取为直接子元素
        var wrapperTags = ['div', 'section', 'article', 'main', 'header', 'footer', 'span'];
        var changed = true;
        var maxIterations = 10;
        while (changed && maxIterations > 0) {
            changed = false;
            maxIterations--;
            $temp.children().each(function () {
                var $el = $(this);
                var tagName = $el.prop('tagName').toLowerCase();
                if ($.inArray(tagName, wrapperTags) !== -1) {
                    // 将此包装元素的子内容替换自身
                    var $children = $el.children();
                    if ($children.length > 0) {
                        $el.replaceWith($children);
                        changed = true;
                    }
                }
            });
        }

        var children = $temp.children();

        if (children.length === 0) {
            // 纯文本内容，按段落分割
            var text = $temp.text().trim();
            if (text) {
                var paragraphs = text.split(/\n\s*\n|\n/);
                for (var i = 0; i < paragraphs.length; i++) {
                    var p = paragraphs[i].trim();
                    if (p) {
                        blocks.push({
                            type: 'p',
                            html: '<p>' + p + '</p>',
                            estimatedHeight: estimateTextHeight(p, config.fontSize)
                        });
                    }
                }
            }
            return blocks;
        }

        children.each(function () {
            var $el = $(this);
            var tagName = $el.prop('tagName').toLowerCase();
            var block = {
                type: tagName,
                html: $el[0].outerHTML
            };

            switch (tagName) {
                case 'hr':
                    block.type = 'page-break';
                    block.html = '';
                    block.estimatedHeight = 0;
                    break;
                case 'h1':
                case 'h2':
                case 'h3':
                case 'h4':
                case 'h5':
                case 'h6':
                    block.type = tagName;
                    block.estimatedHeight = estimateHeadingHeight(tagName, $el.text());
                    break;
                case 'table':
                    block.type = 'table';
                    block.html = $el[0].outerHTML;
                    block.estimatedHeight = estimateTableHeight($el);
                    break;
                case 'img':
                    block.estimatedHeight = estimateImageHeight($el);
                    block.$img = $el;
                    break;
                case 'ul':
                case 'ol':
                    block.estimatedHeight = estimateListHeight($el);
                    break;
                case 'blockquote':
                    block.estimatedHeight = estimateBlockquoteHeight($el);
                    break;
                case 'p':
                default:
                    block.type = 'p';
                    block.estimatedHeight = estimateTextHeight($el.text(), config.fontSize);
                    break;
            }

            blocks.push(block);
        });

        return blocks;
    }

    // ===== 高度估算 =====

    /**
     * 获取内容区可用宽度 (540 - 40px padding)
     */
    function getContentWidth() {
        return 500;
    }

    /**
     * 估算文本高度
     * @param {string} text
     * @param {number} fontSize
     * @returns {number} px
     */
    function estimateTextHeight(text, fontSize) {
        var charCount = text.length;
        if (charCount === 0) return 0;
        var charsPerLine = Math.floor(getContentWidth() / (fontSize * 1.0));
        if (charsPerLine < 1) charsPerLine = 1;
        var lines = Math.ceil(charCount / charsPerLine);
        return lines * fontSize * 1.8 + 10; // 1.8行高 + 10px段落间距
    }

    /**
     * 估算标题高度
     */
    function estimateHeadingHeight(tag, text) {
        var sizeMap = { h1: 28, h2: 24, h3: 20, h4: 18, h5: 16, h6: 14 };
        var hSize = sizeMap[tag] || 20;
        var charsPerLine = Math.floor(getContentWidth() / (hSize * 1.0));
        if (charsPerLine < 1) charsPerLine = 1;
        var lines = Math.ceil(text.length / charsPerLine);
        return lines * hSize * 1.4 + 20; // heading行高1.4 + 20px上下间距
    }

    /**
     * 估算图片高度
     * 默认按内容区宽度的60%估算
     */
    function estimateImageHeight($img) {
        var w = parseInt($img.attr('width'), 10);
        var h = parseInt($img.attr('height'), 10);
        if (w > 0 && h > 0) {
            // 按比例缩放到内容宽度
            var ratio = getContentWidth() / w;
            return Math.round(h * ratio) + 10;
        }
        // 无尺寸信息时默认300px
        return 310;
    }

    /**
     * 估算列表高度
     */
    function estimateListHeight($list) {
        var items = $list.find('li').length;
        return items * (config.fontSize * 1.8 + 5) + 15;
    }

    /**
     * 估算引用块高度
     */
    function estimateBlockquoteHeight($bq) {
        var text = $bq.text();
        return estimateTextHeight(text, config.fontSize) + 10;
    }

    /**
     * 估算表格高度
     */
    function estimateTableHeight($table) {
        var rows = $table.find('tr').length;
        return rows * 36 + 20; // 36px per row (35px content + 1px border) + 20px margin
    }

    // ===== 分页核心算法 =====

    /**
     * 将块级元素按高度累加，超过可用高度时分页
     * 支持 <hr> 强制分页和超大块拆分（超长文本拆成多段）
     */
    function paginateContent(blocks, contentAreaHeight, sizeConfig) {
        var contentPages = [];
        var currentPageBlocks = [];
        var currentHeight = 0;
        var pageNumber = 1;

        for (var i = 0; i < blocks.length; i++) {
            var block = blocks[i];

            // 强制分页标记
            if (block.type === 'page-break') {
                // 结束当前页
                if (currentPageBlocks.length > 0) {
                    contentPages.push(generateContentPage(
                        currentPageBlocks, pageNumber, sizeConfig, false
                    ));
                    currentPageBlocks = [];
                    currentHeight = 0;
                    pageNumber++;
                }
                continue;  // 跳过这个 page-break 块本身
            }

            // 超大块处理：单个块超过整页高度时需要拆分
            if (block.estimatedHeight > contentAreaHeight) {
                // 先把当前页已有的内容推出去
                if (currentPageBlocks.length > 0) {
                    contentPages.push(generateContentPage(
                        currentPageBlocks, pageNumber, sizeConfig, false
                    ));
                    currentPageBlocks = [];
                    currentHeight = 0;
                    pageNumber++;
                }

                // 尝试拆分超大块
                var splitBlocks = splitOversizedBlock(block, contentAreaHeight);
                for (var s = 0; s < splitBlocks.length; s++) {
                    var sb = splitBlocks[s];
                    if (currentHeight + sb.estimatedHeight > contentAreaHeight && currentPageBlocks.length > 0) {
                        contentPages.push(generateContentPage(
                            currentPageBlocks, pageNumber, sizeConfig, false
                        ));
                        currentPageBlocks = [];
                        currentHeight = 0;
                        pageNumber++;
                    }
                    currentPageBlocks.push(sb);
                    currentHeight += sb.estimatedHeight;
                }
                continue;
            }

            // 正常块：判断是否需要换页
            if (currentHeight + block.estimatedHeight > contentAreaHeight && currentPageBlocks.length > 0) {
                contentPages.push(generateContentPage(
                    currentPageBlocks, pageNumber, sizeConfig, false
                ));
                currentPageBlocks = [];
                currentHeight = 0;
                pageNumber++;
            }

            currentPageBlocks.push(block);
            currentHeight += block.estimatedHeight;
        }

        // 最后一页
        if (currentPageBlocks.length > 0) {
            contentPages.push(generateContentPage(
                currentPageBlocks, pageNumber, sizeConfig, true
            ));
        }

        return contentPages;
    }

    /**
     * 拆分超大块（超长段落文本拆成多段）
     * @param {Object} block - 块级元素
     * @param {number} pageHeight - 可用内容高度
     * @returns {Array} 拆分后的块数组
     */
    function splitOversizedBlock(block, pageHeight) {
        // 图片块不拆分，保留原样（会被截断但保持完整）
        if (block.type === 'img') {
            return [block];
        }

        // 表格块不拆分，保留原样
        if (block.type === 'table') {
            return [block];
        }

        // 文本类块：按句子拆分
        var text = '';
        var wrapperTag = 'p';
        if (block.type === 'blockquote') {
            text = $(block.html).text();
            wrapperTag = 'blockquote';
        } else {
            text = $(block.html).text();
        }

        if (!text || text.length === 0) {
            return [block];
        }

        // 按句子拆分：句号、问号、叹号、换行
        var sentences = text.split(/(?<=[。！？\n])/);
        if (sentences.length <= 1) {
            // 无法按句子拆分，按固定字符数拆分
            sentences = [];
            var chunkSize = Math.floor(getContentWidth() / config.fontSize) *
                Math.floor(pageHeight / (config.fontSize * 1.8));
            if (chunkSize < 10) chunkSize = 10;
            for (var ci = 0; ci < text.length; ci += chunkSize) {
                sentences.push(text.substring(ci, ci + chunkSize));
            }
        }

        var result = [];
        for (var j = 0; j < sentences.length; j++) {
            var s = sentences[j].trim();
            if (!s) continue;
            var h = estimateTextHeight(s, config.fontSize);
            result.push({
                type: wrapperTag === 'blockquote' ? 'blockquote' : 'p',
                html: '<' + wrapperTag + '>' + s + '</' + wrapperTag + '>',
                estimatedHeight: h
            });
        }

        return result.length > 0 ? result : [block];
    }

    // ===== 页面HTML生成 =====

    /**
     * 检查是否有有效的封面图（排除默认头像占位图）
     */
    function hasValidPoster() {
        if (!postData.poster) return false;
        // 排除默认头像占位图
        var defaultPatterns = ['/static/images/avatar.png', '/static/images/avatar.jpeg', '/static/images/avatar.jpg'];
        for (var i = 0; i < defaultPatterns.length; i++) {
            if (postData.poster.indexOf(defaultPatterns[i]) !== -1) return false;
        }
        return true;
    }

    /**
     * 生成封面页HTML
     */
    function generateCoverPage(sizeConfig) {
        var hasCover = hasValidPoster();
        var html = '<div class="phone-image-page page-cover';
        if (hasCover) {
            html += ' has-cover-image';
        } else {
            html += ' no-cover-image';
        }
        html += '" style="width:' + sizeConfig.width + 'px;height:' + sizeConfig.height + 'px;">';

        if (hasCover) {
            html += '<img class="cover-image" src="' + postData.poster + '" alt="">';
            html += '<div class="cover-title">' + escapeHtml(postData.title) + '</div>';
            if (postData.desc) {
                html += '<div class="cover-subtitle">' + escapeHtml(postData.desc) + '</div>';
            }
            // 封面文案（有封面图）
            if (postData.coverText) {
                html += '<div style="font-size:14px;color:#1890ff;margin-top:8px;">' + escapeHtml(postData.coverText) + '</div>';
            }
            html += '<div class="cover-meta">';
            if (postData.category_name) {
                html += escapeHtml(postData.category_name) + ' | ';
            }
            if (postData.author_name) {
                html += escapeHtml(postData.author_name) + ' | ';
            }
            if (postData.create_time) {
                html += postData.create_time;
            }
            html += '</div>';
        } else {
            // 无封面图: 大标题+摘要+装饰线条排版
            html += '<div class="cover-decor-line cover-decor-top"></div>';
            html += '<div class="cover-no-img-content">';
            html += '<div class="cover-no-img-title">' + escapeHtml(postData.title) + '</div>';
            html += '<div class="cover-decor-divider"></div>';
            if (postData.desc) {
                html += '<div class="cover-no-img-desc">' + escapeHtml(postData.desc) + '</div>';
            }
            // 封面文案（无封面图）
            if (postData.coverText) {
                html += '<div style="font-size:14px;color:#1890ff;margin-top:10px;padding:0 30px;word-break:break-word;">' + escapeHtml(postData.coverText) + '</div>';
            }
            html += '<div class="cover-no-img-meta">';
            if (postData.category_name) {
                html += '<span>' + escapeHtml(postData.category_name) + '</span>';
            }
            if (postData.author_name) {
                html += '<span>' + escapeHtml(postData.author_name) + '</span>';
            }
            if (postData.create_time) {
                html += '<span>' + postData.create_time + '</span>';
            }
            html += '</div>';
            html += '</div>';
            html += '<div class="cover-decor-line cover-decor-bottom"></div>';
        }

        html += '</div>';

        return { type: 'cover', html: html };
    }

    /**
     * 生成内容页HTML（含逐页对齐支持）
     */
    function generateContentPage(blocks, pageNum, sizeConfig, isLast) {
        // 读取逐页对齐配置
        var alignment = (config.pageAlignments && config.pageAlignments[pageNum]) || 'top';
        var valignClass = alignment === 'center' ? ' valign-center' : '';

        var html = '<div class="phone-image-page page-body' + valignClass + '" style="width:' +
            sizeConfig.width + 'px;height:' + sizeConfig.height + 'px;">';

        // 页头（仅第一页内容页显示标题）
        if (pageNum === 1) {
            html += '<div class="page-header">';
            html += '<div class="page-title">' + escapeHtml(postData.title) + '</div>';
            html += '</div>';
        }

        // 正文内容区
        html += '<div class="page-content">';
        for (var i = 0; i < blocks.length; i++) {
            html += blocks[i].html;
        }
        html += '</div>';

        // 页脚 - 占位，render() 中会替换页码
        html += '<div class="page-footer">';
        html += '<span>' + escapeHtml(postData.author_name || '') + '</span>';
        html += '<span>' + pageNum + '</span>';
        html += '</div>';

        html += '</div>';
        return { type: 'content', html: html, pageNum: pageNum };
    }

    /**
     * 生成尾页/总结页HTML
     */
    function generateSummaryPage(sizeConfig, totalPages) {
        var html = '<div class="phone-image-page page-summary" style="width:' +
            sizeConfig.width + 'px;height:' + sizeConfig.height + 'px;">';
        html += '<div class="summary-title">感谢阅读</div>';
        html += '<div class="summary-text">' + escapeHtml(postData.title) + '</div>';

        if (postData.desc) {
            html += '<div class="summary-text" style="font-size:12px;">' + escapeHtml(postData.desc) + '</div>';
        }

        html += '<div class="summary-footer">';
        html += '共 ' + totalPages + ' 页';
        if (postData.author_name) {
            html += ' | ' + escapeHtml(postData.author_name);
        }
        html += '</div>';
        html += '</div>';

        return { type: 'summary', html: html };
    }

    // ===== DOM渲染 =====

    /**
     * 将 #render-staging 中的代码块转为图片
     * 使用 prismjs 高亮 + html2canvas 截图替换
     * @returns {jQuery Deferred} resolves when all code blocks are converted
     */
    function convertCodeBlocks() {
        var deferred = $.Deferred();
        var $staging = $('#render-staging');

        // 检查 Prism 是否可用
        if (typeof Prism === 'undefined') {
            deferred.resolve();
            return deferred.promise();
        }

        // 给没有语言类的代码块添加默认语言
        $staging.find('pre > code:not([class*="language-"])').addClass('language-plaintext');

        // 高亮所有代码块
        $staging.find('pre code').each(function () {
            Prism.highlightElement(this);
        });

        // 找到所有代码块，逐个截图替换
        var $preBlocks = $staging.find('pre');
        if ($preBlocks.length === 0) {
            deferred.resolve();
            return deferred.promise();
        }

        var idx = 0;
        var total = $preBlocks.length;

        function convertNext() {
            if (idx >= total) {
                deferred.resolve();
                return;
            }

            var $pre = $preBlocks.eq(idx);
            html2canvas($pre[0], {
                scale: 2,
                useCORS: true,
                backgroundColor: '#f5f5f5',
                logging: false
            }).then(function (canvas) {
                var imgData = canvas.toDataURL('image/jpeg', 0.92);
                var $img = $('<img>');
                $img.attr('src', imgData);
                $img.css({
                    maxWidth: '100%',
                    height: 'auto',
                    display: 'block',
                    margin: '10px 0'
                });
                $pre.replaceWith($img);
                idx++;
                convertNext();
            }).catch(function () {
                // 截图失败则保留原始代码块
                idx++;
                convertNext();
            });
        }

        convertNext();
        return deferred.promise();
    }

    /**
     * 将 #render-staging 中的表格转为图片
     * 使用 html2canvas 截图替换（与 convertCodeBlocks 模式相同）
     * @returns {jQuery Deferred} resolves when all tables are converted
     */
    function convertTables() {
        var deferred = $.Deferred();
        var $staging = $('#render-staging');

        var $tables = $staging.find('.page-content table');
        if ($tables.length === 0) {
            deferred.resolve();
            return deferred.promise();
        }

        var idx = 0;
        var total = $tables.length;

        function convertNext() {
            if (idx >= total) {
                deferred.resolve();
                return;
            }

            var $table = $tables.eq(idx);
            html2canvas($table[0], {
                scale: 2,
                useCORS: true,
                backgroundColor: '#ffffff',
                logging: false
            }).then(function (canvas) {
                var imgData = canvas.toDataURL('image/jpeg', 0.92);
                var $img = $('<img>');
                $img.attr('src', imgData);
                $img.css({
                    maxWidth: '100%',
                    height: 'auto',
                    display: 'block',
                    margin: '10px 0'
                });
                $table.replaceWith($img);
                idx++;
                convertNext();
            }).catch(function () {
                idx++;
                convertNext();
            });
        }

        convertNext();
        return deferred.promise();
    }

    // ===== 纯图片页优化 =====

    /**
     * 检测staging区域中的页面元素是否为纯图片页
     * 纯图片页: .page-body 内 .page-content 只含1个img且无文字内容
     * @param {jQuery} $pageElem - .phone-image-page 元素
     * @returns {boolean}
     */
    function isPureImagePage($pageElem) {
        // 仅内容页
        if (!$pageElem.hasClass('page-body')) return false;
        var $content = $pageElem.find('.page-content');
        if (!$content.length) return false;

        // 检查是否有文字内容（排除纯空白文本节点）
        var textContent = $content.text().replace(/\s/g, '');
        if (textContent.length > 0) return false;

        // 检查img数量: 必须恰好1个img
        var $imgs = $content.find('img');
        if ($imgs.length !== 1) return false;

        // img必须有有效src
        var src = $imgs.first().attr('src');
        return src && src.length > 0;
    }

    /**
     * 从纯图片页元素中获取img的src
     * @param {jQuery} $pageElem
     * @returns {string}
     */
    function getPureImageSrc($pageElem) {
        var $img = $pageElem.find('.page-content img').first();
        return $img.attr('src') || '';
    }

    /**
     * 将原始图片绘制到canvas（用于高质量保存路径）
     * @param {string} src - 图片src
     * @param {number} width - 目标宽度
     * @param {number} height - 目标高度
     * @returns {jQuery Deferred} resolves with canvas
     */
    function renderPureImageToCanvas(src, width, height) {
        var deferred = $.Deferred();
        var img = new Image();
        img.crossOrigin = 'anonymous';
        img.onload = function () {
            if (img.naturalWidth === 0 || img.naturalHeight === 0) {
                deferred.reject('Image has zero dimensions');
                return;
            }
            var canvas = document.createElement('canvas');
            canvas.width = width * 2;  // scale:2 高质量
            canvas.height = height * 2;
            var ctx = canvas.getContext('2d');
            // 白色背景
            ctx.fillStyle = '#ffffff';
            ctx.fillRect(0, 0, canvas.width, canvas.height);
            // 缩放绘制
            ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
            deferred.resolve(canvas);
        };
        img.onerror = function () {
            deferred.reject('Image load failed');
        };
        img.src = src;
        return deferred.promise();
    }

    /**
     * 渲染到隐藏区域 → 截图 → 显示缩略图
     * @param {Object} sizeConfig
     * @returns {jQuery Deferred} resolves with pages array
     */
    function renderThumbnails(sizeConfig) {
        var deferred = $.Deferred();
        ensureStaging();

        var $staging = $('#render-staging');
        $staging.empty();

        // 渲染所有页面到隐藏区域（使用wrapper以便html2canvas正确渲染）
        var sizeClass = 'size-' + config.size;
        var $wrapper = $('<div class="phone-image-container ' + sizeClass + '">');
        for (var i = 0; i < pages.length; i++) {
            $wrapper.append(pages[i].html);
        }
        $staging.append($wrapper);

        // 等待一帧确保 DOM 渲染完成
        requestAnimationFrame(function () {
            // html2canvas会跳过visibility:hidden的元素，临时切换为可见
            $staging.css({ visibility: 'visible' });
            // 先转换代码块为图片
            convertCodeBlocks().then(function () {
                return convertTables();
            }).then(function () {
                var $pageElems = $staging.find('.phone-image-page');
                if ($pageElems.length === 0) {
                    $staging.css({ visibility: 'hidden' });
                    displayThumbnails([], sizeConfig);
                    deferred.resolve(pages);
                    return;
                }

                // 串行截图每一页
                var thumbnailDataUrls = [];
                var idx = 0;
                var total = $pageElems.length;

                function captureNext() {
                    if (idx >= total) {
                        $staging.empty();
                        $staging.css({ visibility: 'hidden' });
                        displayThumbnails(thumbnailDataUrls, sizeConfig);
                        deferred.resolve(pages);
                        return;
                    }

                    var $elem = $pageElems.eq(idx);
                    // 纯图片页优化: 跳过html2canvas，直接用原图src
                    if (isPureImagePage($elem)) {
                        var pureSrc = getPureImageSrc($elem);
                        if (pureSrc) {
                            thumbnailDataUrls.push(pureSrc);
                            idx++;
                            captureNext();
                            return;
                        }
                    }
                    html2canvas($elem[0], {
                        scale: 1,
                        useCORS: true,
                        backgroundColor: '#ffffff',
                        width: $elem.outerWidth(),
                        height: $elem.outerHeight(),
                        logging: false
                    }).then(function (canvas) {
                        thumbnailDataUrls.push(canvas.toDataURL('image/jpeg', 0.85));
                        idx++;
                        captureNext();
                    }).catch(function (err) {
                        $staging.css({ visibility: 'hidden' });
                        deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                    });
                }

                captureNext();
            }).catch(function () {
                // 代码块转换失败，继续转换表格并截图流程
                convertTables().then(function () {
                    var $pageElems = $staging.find('.phone-image-page');
                    if ($pageElems.length === 0) {
                        $staging.css({ visibility: 'hidden' });
                        displayThumbnails([], sizeConfig);
                        deferred.resolve(pages);
                        return;
                    }

                    var thumbnailDataUrls = [];
                    var idx = 0;
                    var total = $pageElems.length;

                    function captureNext() {
                        if (idx >= total) {
                            $staging.empty();
                            $staging.css({ visibility: 'hidden' });
                            displayThumbnails(thumbnailDataUrls, sizeConfig);
                            deferred.resolve(pages);
                            return;
                        }

                        var $elem = $pageElems.eq(idx);
                        // 纯图片页优化: 跳过html2canvas，直接用原图src
                        if (isPureImagePage($elem)) {
                            var pureSrc = getPureImageSrc($elem);
                            if (pureSrc) {
                                thumbnailDataUrls.push(pureSrc);
                                idx++;
                                captureNext();
                                return;
                            }
                        }
                        html2canvas($elem[0], {
                            scale: 1,
                            useCORS: true,
                            backgroundColor: '#ffffff',
                            width: $elem.outerWidth(),
                            height: $elem.outerHeight(),
                            logging: false
                        }).then(function (canvas) {
                            thumbnailDataUrls.push(canvas.toDataURL('image/jpeg', 0.85));
                            idx++;
                            captureNext();
                        }).catch(function (err) {
                            $staging.css({ visibility: 'hidden' });
                            deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                        });
                    }

                    captureNext();
                });
            });
        });

        return deferred.promise();
    }

    /**
     * 在右侧显示缩略图
     * @param {Array} dataUrls - base64 图片数据
     * @param {Object} sizeConfig
     */
    function displayThumbnails(dataUrls, sizeConfig) {
        var $preview = $('#paginated-preview');
        if (!$preview.length) return;

        $preview.empty();
        if (dataUrls.length === 0) return;

        // 计算缩放比例：缩略图高度 = 容器高度 - 40(页码标签) - 40(上下padding)
        var containerHeight = $preview.parent().height() || 700;
        var scaleRatio = (containerHeight - 80) / sizeConfig.height;
        var thumbWidth = Math.round(sizeConfig.width * scaleRatio);

        for (var i = 0; i < dataUrls.length; i++) {
            var $item = $('<div class="preview-thumb-item" data-page-index="' + i + '">');
            $item.css('width', thumbWidth + 'px');

            var $img = $('<img>');
            $img.attr('src', dataUrls[i]);
            $img.css('width', thumbWidth + 'px');
            $item.append($img);

            // 页码
            var $pageNum = $('<span class="preview-thumb-page-num">' + (i + 1) + '/' + dataUrls.length + '</span>');
            $item.append($pageNum);

            // 对齐按钮（仅内容页）
            if (pages[i] && pages[i].type === 'content') {
                var pageNum = pages[i].pageNum || (i);
                var currentAlign = (config.pageAlignments && config.pageAlignments[pageNum]) || 'top';
                var isActiveCenter = currentAlign === 'center';
                var $toggle = $('<button class="thumb-alignment-toggle' + (isActiveCenter ? ' active-center' : '') + '" data-page-index="' + i + '" data-page-num="' + pageNum + '">' +
                    (isActiveCenter ? '\u2195' : '\u2191') +
                    '</button>');
                $item.append($toggle);
            }

            $preview.append($item);
        }
    }

    /**
     * 将页面渲染到隐藏区域并高质量截图（用于保存）
     * @returns {jQuery Deferred} resolves with canvas array
     */
    function capturePagesFromStaging() {
        var deferred = $.Deferred();
        ensureStaging();

        var $staging = $('#render-staging');
        $staging.empty();

        var sizeConfig = config.sizes[config.size] || config.sizes.xiaohongshu;

        // 添加 size class wrapper
        var sizeClass = 'size-' + config.size;
        var $wrapper = $('<div class="phone-image-container ' + sizeClass + '">');
        for (var i = 0; i < pages.length; i++) {
            $wrapper.append(pages[i].html);
        }
        $staging.append($wrapper);

        requestAnimationFrame(function () {
            // html2canvas会跳过visibility:hidden的元素，临时切换为可见
            $staging.css({ visibility: 'visible' });
            // 先转换代码块为图片
            convertCodeBlocks().then(function () {
                return convertTables();
            }).then(function () {
                var $pageElems = $staging.find('.phone-image-page');
                if ($pageElems.length === 0) {
                    $staging.css({ visibility: 'hidden' });
                    deferred.reject('没有可渲染的页面');
                    return;
                }

                var canvases = [];
                var idx = 0;
                var total = $pageElems.length;

                function captureNext() {
                    if (idx >= total) {
                        $staging.empty();
                        $staging.css({ visibility: 'hidden' });
                        deferred.resolve(canvases);
                        return;
                    }

                    var $elem = $pageElems.eq(idx);
                    // 纯图片页优化: 直接绘制原图到canvas
                    if (isPureImagePage($elem)) {
                        var pureSrc = getPureImageSrc($elem);
                        if (pureSrc) {
                            renderPureImageToCanvas(pureSrc, sizeConfig.width, sizeConfig.height).then(function (canvas) {
                                canvases.push(canvas);
                                idx++;
                                captureNext();
                            }).catch(function () {
                                // 加载失败，回退到html2canvas
                                html2canvas($elem[0], {
                                    scale: 2,
                                    useCORS: true,
                                    backgroundColor: '#ffffff',
                                    width: $elem.outerWidth(),
                                    height: $elem.outerHeight(),
                                    logging: false
                                }).then(function (canvas) {
                                    canvases.push(canvas);
                                    idx++;
                                    captureNext();
                                }).catch(function (err) {
                                    $staging.css({ visibility: 'hidden' });
                                    deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                                });
                            });
                            return;
                        }
                    }
                    html2canvas($elem[0], {
                        scale: 2,
                        useCORS: true,
                        backgroundColor: '#ffffff',
                        width: $elem.outerWidth(),
                        height: $elem.outerHeight(),
                        logging: false
                    }).then(function (canvas) {
                        canvases.push(canvas);
                        idx++;
                        captureNext();
                    }).catch(function (err) {
                        $staging.css({ visibility: 'hidden' });
                        deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                    });
                }

                captureNext();
            }).catch(function () {
                // 代码块转换失败，继续转换表格并截图流程
                convertTables().then(function () {
                    var $pageElems = $staging.find('.phone-image-page');
                    if ($pageElems.length === 0) {
                        $staging.css({ visibility: 'hidden' });
                        deferred.reject('没有可渲染的页面');
                        return;
                    }

                    var canvases = [];
                    var idx = 0;
                    var total = $pageElems.length;

                    function captureNext() {
                        if (idx >= total) {
                            $staging.empty();
                            $staging.css({ visibility: 'hidden' });
                            deferred.resolve(canvases);
                            return;
                        }

                        var $elem = $pageElems.eq(idx);
                        // 纯图片页优化: 直接绘制原图到canvas
                        if (isPureImagePage($elem)) {
                            var pureSrc = getPureImageSrc($elem);
                            if (pureSrc) {
                                renderPureImageToCanvas(pureSrc, sizeConfig.width, sizeConfig.height).then(function (canvas) {
                                    canvases.push(canvas);
                                    idx++;
                                    captureNext();
                                }).catch(function () {
                                    // 加载失败，回退到html2canvas
                                    html2canvas($elem[0], {
                                        scale: 2,
                                        useCORS: true,
                                        backgroundColor: '#ffffff',
                                        width: $elem.outerWidth(),
                                        height: $elem.outerHeight(),
                                        logging: false
                                    }).then(function (canvas) {
                                        canvases.push(canvas);
                                        idx++;
                                        captureNext();
                                    }).catch(function (err) {
                                        $staging.css({ visibility: 'hidden' });
                                        deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                                    });
                                });
                                return;
                            }
                        }
                        html2canvas($elem[0], {
                            scale: 2,
                            useCORS: true,
                            backgroundColor: '#ffffff',
                            width: $elem.outerWidth(),
                            height: $elem.outerHeight(),
                            logging: false
                        }).then(function (canvas) {
                            canvases.push(canvas);
                            idx++;
                            captureNext();
                        }).catch(function (err) {
                            $staging.css({ visibility: 'hidden' });
                            deferred.reject('截图失败(第' + (idx + 1) + '页): ' + err);
                        });
                    }

                    captureNext();
                });
            });
        });

        return deferred.promise();
    }

    /**
     * 渲染内容流到 #content-flow 容器
     * @param {Array} blocks - parseHtmlToBlocks 返回的块数组
     */
    function renderContentFlow(blocks) {
        var $flow = $('#content-flow');
        if (!$flow.length) return;

        $flow.empty();

        for (var i = 0; i < blocks.length; i++) {
            var block = blocks[i];

            // 分页标记
            if (block.type === 'page-break') {
                var $marker = $('<div class="page-break-marker">' +
                    '<span class="break-marker-label">-- 分页标记 --</span>' +
                    '<button class="remove-break-btn" data-index="' + i + '" title="删除分页">&times;</button>' +
                    '</div>');
                $flow.append($marker);
                continue;
            }

            // 内容块
            var $block = $('<div class="content-flow-block" data-index="' + i + '">' + block.html + '</div>');
            $flow.append($block);

            // 块与块之间的分页插入区域（不在最后一个块之后添加）
            if (i < blocks.length - 1) {
                var $inserter = $('<div class="break-inserter" data-after-index="' + i + '">' +
                    '<button class="break-inserter-btn" title="插入分页">+</button>' +
                    '</div>');
                $flow.append($inserter);
            }
        }
    }

    /**
     * 在指定位置插入分页标记
     * 修改 postData.content_html，在对应位置插入 <hr>
     * @param {number} blockIndex - 在哪个块之后插入 (对应 break-inserter 的 data-after-index)
     */
    function insertPageBreak(blockIndex) {
        var cleanHtml = preprocessContent(postData.content_html);
        var $temp = $('<div>').html(cleanHtml);
        var children = $temp.children();

        // 在 blockIndex 位置的元素之后插入 <hr>
        if (blockIndex >= 0 && blockIndex < children.length) {
            $(children[blockIndex]).after('<hr>');
        } else {
            $temp.append('<hr>');
        }

        postData.content_html = $temp.html();

        // 重新渲染
        render();
    }

    /**
     * 删除指定位置的分页标记
     * @param {number} blockIndex - 分页标记的 data-index
     */
    function removePageBreak(blockIndex) {
        // 统计这是第几个 page-break
        var cleanHtml = preprocessContent(postData.content_html);
        var $temp = $('<div>').html(cleanHtml);
        var hrElements = $temp.find('hr');

        // 在 blocks 数组中找到这个 page-break 是第几个
        var breakOrder = 0;
        var currentBlocks = parseHtmlToBlocks(cleanHtml);
        for (var i = 0; i < currentBlocks.length && i < blockIndex; i++) {
            if (currentBlocks[i].type === 'page-break') breakOrder++;
        }

        if (breakOrder < hrElements.length) {
            $(hrElements[breakOrder]).remove();
            postData.content_html = $temp.html();
            render();
        }
    }

    // ===== 图片生成 =====

    /**
     * 逐页截图生成图片（使用隐藏渲染区域高质量截图）
     * @param {Function} [onProgress] 进度回调 function(currentIndex, totalPages, canvas)
     * @returns {Promise} jQuery Deferred, resolves with array of canvas objects
     */
    function generateImages(onProgress) {
        var deferred = $.Deferred();

        if (pages.length === 0) {
            deferred.reject('没有可渲染的页面');
            return deferred.promise();
        }

        if (onProgress) onProgress(0, pages.length, null);

        capturePagesFromStaging().then(function (canvases) {
            if (onProgress) onProgress(canvases.length, canvases.length, null);
            deferred.resolve(canvases);
        }).catch(function (err) {
            deferred.reject(err);
        });

        return deferred.promise();
    }

    /**
     * 将canvas转为base64并保存到服务端
     * @param {number} postId 文章ID
     * @param {Object} saveConfig 配置信息
     * @param {Function} [onProgress] 生成进度回调 function(current, total, canvas)
     * @returns {Promise} jQuery Deferred
     */
    function saveImages(postId, saveConfig, onProgress) {
        var deferred = $.Deferred();

        capturePagesFromStaging().then(function (canvases) {
            if (onProgress) onProgress(canvases.length, canvases.length, null);
            var pagesData = [];
            for (var i = 0; i < canvases.length; i++) {
                pagesData.push(canvases[i].toDataURL('image/jpeg', 0.92));
            }

            $.ajax({
                url: '/index.php/admin/post/savePostOutput',
                type: 'POST',
                data: JSON.stringify({
                    post_id: postId,
                    output_type: 'phone_image',
                    config: saveConfig || config,
                    content_html: postData.content_html,
                    pages: pagesData
                }),
                contentType: 'application/json',
                success: function (result) {
                    if (result.code === 0) {
                        deferred.resolve(result.data);
                    } else {
                        deferred.reject(result.msg || '保存失败');
                    }
                },
                error: function (xhr) {
                    deferred.reject('网络错误: ' + xhr.statusText);
                }
            });
        }).catch(function (err) {
            deferred.reject(err);
        });

        return deferred.promise();
    }

    /**
     * 将生成的canvas数组显示为缩略图
     * @param {Array} canvases canvas对象数组
     * @param {string} containerSelector 容器选择器
     */
    function showGeneratedThumbnails(canvases, containerSelector) {
        var $container = $(containerSelector);
        $container.empty();

        for (var i = 0; i < canvases.length; i++) {
            var thumb = canvases[i].toDataURL('image/jpeg', 0.5);
            var $item = $('<div class="phone-thumb-item" data-index="' + i + '">' +
                '<img src="' + thumb + '" alt="第' + (i + 1) + '页">' +
                '<span class="phone-thumb-page">' + (i + 1) + '</span>' +
                '</div>');
            $container.append($item);
        }
    }

    // ===== 配置切换 =====

    /**
     * 切换尺寸
     */
    function switchSize(name) {
        config.size = name;
    }

    // ===== 逐页对齐 =====

    /**
     * 设置指定页的对齐方式
     * @param {number} pageNum 页码(1-based)
     * @param {string} align 'top'|'center'
     */
    function setPageAlignment(pageNum, align) {
        if (!config.pageAlignments) {
            config.pageAlignments = {};
        }
        config.pageAlignments[pageNum] = align;
    }

    /**
     * 导出内容流为长图
     */
    function exportLongImage() {
        var deferred = $.Deferred();
        var $flow = $('#content-flow');
        if (!$flow.length) {
            deferred.reject('内容流容器不存在');
            return deferred.promise();
        }

        // 临时隐藏交互元素
        $flow.find('.break-inserter').hide();
        $flow.find('.page-break-marker').hide();

        // 获取内容流的实际高度
        var flowWidth = $flow.outerWidth();
        var flowHeight = $flow[0].scrollHeight;

        html2canvas($flow[0], {
            scale: 2,
            useCORS: true,
            backgroundColor: '#ffffff',
            width: flowWidth,
            height: flowHeight,
            logging: false
        }).then(function (canvas) {
            // 恢复交互元素
            $flow.find('.break-inserter').show();
            $flow.find('.page-break-marker').show();

            // 触发下载
            var link = document.createElement('a');
            link.download = 'phone-image-long-' + Date.now() + '.png';
            link.href = canvas.toDataURL('image/png');
            link.click();

            deferred.resolve(canvas);
        }).catch(function (err) {
            // 恢复交互元素
            $flow.find('.break-inserter').show();
            $flow.find('.page-break-marker').show();
            deferred.reject('长图导出失败: ' + err);
        });

        return deferred.promise();
    }

    // ===== 工具方法 =====

    /**
     * HTML转义
     */
    function escapeHtml(text) {
        if (!text) return '';
        var div = document.createElement('div');
        div.appendChild(document.createTextNode(text));
        return div.innerHTML;
    }

    /**
     * 获取当前配置
     */
    function getConfig() {
        return $.extend({}, config);
    }

    /**
     * 获取分页结果
     */
    function getPages() {
        return pages.slice();
    }

    // ===== 公开API =====
    return {
        init: init,
        render: render,
        generateImages: generateImages,
        saveImages: saveImages,
        showGeneratedThumbnails: showGeneratedThumbnails,
        switchSize: switchSize,
        getConfig: getConfig,
        getPages: getPages,
        setPageAlignment: setPageAlignment,
        renderContentFlow: renderContentFlow,
        insertPageBreak: insertPageBreak,
        removePageBreak: removePageBreak,
        exportLongImage: exportLongImage
    };
})();