/**
 * 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',
        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);
        }
    }

    /**
     * 渲染排版预览 - 生成分页后的HTML
     * 管线: editorHtml -> parseHtmlToBlocks -> captureEditorBlocks -> generatePages -> renderThumbnails
     * 带并发锁：防止多次 render 同时执行造成数据混乱
     * @returns {jQuery Deferred} resolves with pages array
     */
    function render() {
        var deferred = $.Deferred();

        // 防止并发渲染
        if (render._locked) {
            // 标记有待处理的渲染请求，当前渲染完成后会自动重试
            render._pending = true;
            return deferred.reject('rendering').promise();
        }
        render._locked = true;

        pages = [];
        var sizeConfig = config.sizes[config.size] || config.sizes.xiaohongshu;
        var pageHeight = sizeConfig.height;
        var contentAreaHeight = pageHeight - (config.contentPadding * 2);

        // 从 wangeditor 读取内容
        var editorHtml = window.phoneImageEditor ? window.phoneImageEditor.getHtml() : postData.content_html;
        var cleanHtml = preprocessContent(editorHtml);
        var blocks = parseHtmlToBlocks(cleanHtml);

        // 空内容检测
        if (blocks.length === 0) {
            $('#paginated-preview').html('<div style="text-align:center;padding:60px 20px;color:#999;">文章正文内容为空</div>');
            render._locked = false;
            return deferred.resolve([]).promise();
        }

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

        // 内容分页（使用 captureEditorBlocks，T3 会完善截图逻辑）
        captureEditorBlocks(editorHtml, blocks, contentAreaHeight, sizeConfig).then(function(contentPages) {
            pages = pages.concat(contentPages);

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

            // 页码 N/M
            var totalPages = pages.length;
            for (var i = 0; i < pages.length; i++) {
                if (pages[i].type === 'content') {
                    pages[i].html = pages[i].html.replace(
                        '<span>' + pages[i].pageNum + '</span>',
                        '<span class="page-number-indicator">' + (i + 1) + '/' + totalPages + '</span>'
                    );
                }
            }

            // 渲染缩略图
            renderThumbnails(sizeConfig).then(function() {
                render._locked = false;
                if (render._pending) {
                    render._pending = false;
                    render().catch(function() {});
                }
                deferred.resolve(pages);
            }).catch(function(err) {
                render._locked = false;
                deferred.reject(err);
            });
        }).catch(function(err) {
            render._locked = false;
            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, '');

        // 移除不支持的媒体标签
        html = html.replace(/<iframe[\s\S]*?<\/iframe>/gi, '[媒体内容]');
        html = html.replace(/<video[\s\S]*?<\/video>/gi, '[媒体内容]');
        html = html.replace(/<svg[\s\S]*?<\/svg>/gi, '');
        html = html.replace(/<embed[^>]*>/gi, '');
        html = html.replace(/<object[\s\S]*?<\/object>/gi, '');

        // 清除空段落
        html = html.replace(/<p[^>]*>\s*<\/p>/gi, '');

        // 处理图片: 保留原始尺寸到data属性, 强制 max-width:100%
        html = html.replace(/<img([^>]*?)>/gi, function (match, attrs) {
            // 移除内联style
            attrs = attrs.replace(/\s*style\s*=\s*"[^"]*"/gi, '');
            attrs = attrs.replace(/\s*style\s*=\s*'[^']*'/gi, '');
            // 提取原始width/height值, 保存到data属性
            var widthVal = '';
            var heightVal = '';
            var widthMatch = attrs.match(/\swidth\s*=\s*"([^"]*)"/i) ||
                             attrs.match(/\swidth\s*=\s*'([^']*)'/i);
            var heightMatch = attrs.match(/\sheight\s*=\s*"([^"]*)"/i) ||
                              attrs.match(/\sheight\s*=\s*'([^']*)'/i);
            if (widthMatch) widthVal = widthMatch[1];
            if (heightMatch) heightVal = heightMatch[1];
            // 移除原始width/height属性
            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, '');
            // 添加data属性保存原始尺寸(用于比例计算)
            if (widthVal) attrs += ' data-original-width="' + widthVal + '"';
            if (heightVal) attrs += ' data-original-height="' + heightVal + '"';
            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: 40
                        });
                    }
                }
            }
            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 = 40;
                    break;
                case 'table':
                    block.type = 'table';
                    block.html = $el[0].outerHTML;
                    block.estimatedHeight = 0;
                    block.needsMeasurement = true;
                    break;
                case 'pre':
                    block.type = 'pre';
                    block.html = $el[0].outerHTML;
                    block.estimatedHeight = 0;
                    block.needsMeasurement = true;
                    break;
                case 'img':
                    // 尝试从data属性计算比例高度, 否则标记需要DOM测量
                    var imgW = parseInt($el.attr('data-original-width'), 10);
                    var imgH = parseInt($el.attr('data-original-height'), 10);
                    if (imgW > 0 && imgH > 0) {
                        var imgRatio = 500 / imgW;
                        block.estimatedHeight = Math.round(imgH * imgRatio) + 20;
                    } else {
                        block.estimatedHeight = 0;
                        block.needsMeasurement = true;
                    }
                    break;
                case 'ul':
                case 'ol':
                    block.estimatedHeight = 40;
                    break;
                case 'blockquote':
                    block.estimatedHeight = 40;
                    break;
                case 'p':
                default:
                    block.type = 'p';
                    block.estimatedHeight = 40;
                    break;
            }

            blocks.push(block);
        });

        return blocks;
    }

    // ===== wangeditor 集成层 =====

    /**
     * 获取 wangeditor 编辑区的子元素
     * @returns {Array} DOM元素数组
     */
    function getEditorChildren() {
        var editorArea = document.querySelector('#editor-text-area [data-slate-editor]');
        if (!editorArea) return [];

        var children = editorArea.children;
        // wangeditor v5: [data-slate-editor] 下可能有一层 div 包装
        // 如果只有一个 child 且是 div，则取其子元素
        if (children.length === 1 && children[0].tagName.toLowerCase() === 'div') {
            return Array.prototype.slice.call(children[0].children);
        }
        return Array.prototype.slice.call(children);
    }

    /**
     * 从 wangeditor 内容构建分页数据
     * 完整实现：从编辑器DOM截图测高 -> 按分割线分组 -> 按高度分页 -> 生成staging HTML
     * @param {string} html - 编辑器HTML内容
     * @param {Array} blocks - parseHtmlToBlocks 解析后的块数组
     * @param {number} contentAreaHeight - 内容区可用高度(px)
     * @param {Object} sizeConfig - {width, height}
     * @returns {jQuery Deferred} resolves with contentPages array
     */
    function captureEditorBlocks(html, blocks, contentAreaHeight, sizeConfig) {
        var deferred = $.Deferred();

        // 按 page-break 分组
        var groups = [];
        var currentGroup = { blocks: [], domIndices: [] };
        var domIdx = 0;

        for (var i = 0; i < blocks.length; i++) {
            if (blocks[i].type === 'page-break') {
                if (currentGroup.blocks.length > 0) groups.push(currentGroup);
                currentGroup = { blocks: [], domIndices: [] };
                // page-break 对应 wangeditor 中的 divider(hr)，在 DOM 中也是一个子元素
                domIdx++;
                continue;
            }
            currentGroup.blocks.push(blocks[i]);
            currentGroup.domIndices.push(domIdx);
            domIdx++;
        }
        if (currentGroup.blocks.length > 0) groups.push(currentGroup);

        if (groups.length === 0) {
            deferred.resolve([]);
            return deferred.promise();
        }

        // 获取编辑器子元素
        var editorChildren = getEditorChildren();

        // 创建测量容器（500px = 540 - 20*2 padding，与内容区一致）
        var $mc = $('<div>').css({
            width: '500px',
            position: 'fixed',
            left: '-9999px',
            top: '0',
            visibility: 'hidden',
            background: '#ffffff',
            fontSize: '14px',
            lineHeight: '1.8',
            boxSizing: 'border-box'
        });
        $('body').append($mc);

        // 串行测高每组
        var gi = 0;

        function measureNext() {
            if (gi >= groups.length) {
                $mc.remove();
                // 给尚未设置高度的 block 设默认值
                for (var k = 0; k < blocks.length; k++) {
                    if (!blocks[k].estimatedHeight) {
                        blocks[k].estimatedHeight = 40;
                    }
                }
                // 用测量的实际高度后的 blocks 调用原有 paginateContent 分页
                var contentPages = paginateContent(blocks, contentAreaHeight, sizeConfig);
                deferred.resolve(contentPages);
                return;
            }

            var group = groups[gi];
            $mc.empty();

            for (var j = 0; j < group.domIndices.length; j++) {
                var di = group.domIndices[j];
                if (di < editorChildren.length) {
                    $mc.append(editorChildren[di].cloneNode(true));
                }
            }

            requestAnimationFrame(function () {
                var h = Math.round($mc[0].getBoundingClientRect().height);

                // 按比例分配测量的实际高度给组内各个 block
                var totalEstimated = 0;
                for (var k = 0; k < group.blocks.length; k++) {
                    totalEstimated += (group.blocks[k].estimatedHeight || 40);
                }
                for (var k = 0; k < group.blocks.length; k++) {
                    var ratio = (group.blocks[k].estimatedHeight || 40) / (totalEstimated || 1);
                    group.blocks[k].estimatedHeight = Math.round(h * ratio);
                }

                gi++;
                measureNext();
            });
        }

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

    // ===== 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];
        }

        // 代码块不拆分，保留原样
        if (block.type === 'pre') {
            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（兼容不支持 lookbehind 的浏览器）
        var effectiveFontSize = 14;
        var parts = text.split(/([。！？\n])/);
        var sentences = [];
        var current = '';
        for (var si = 0; si < parts.length; si++) {
            current += parts[si];
            if (/[。！？\n]/.test(parts[si]) && current.length > 0) {
                sentences.push(current);
                current = '';
            }
        }
        if (current) sentences.push(current);

        if (sentences.length <= 1) {
            // 无法按句子拆分，按固定字符数拆分
            sentences = [];
            var chunkSize = Math.floor(500 / effectiveFontSize) *
                Math.floor(pageHeight / (effectiveFontSize * 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 lineChars = Math.floor(500 / effectiveFontSize);
            if (lineChars < 1) lineChars = 1;
            var lines = Math.ceil(s.length / lineChars);
            var h = lines * effectiveFontSize * 1.8 + 10;
            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="' + escapeHtml(postData.poster) + '" alt="" onerror="this.style.display=\'none\'">';
            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>';
        }

        // 水印
        if (config.watermark) {
            html += '<div class="page-watermark">' + escapeHtml(config.watermark) + '</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>';

        // 水印
        if (config.watermark) {
            html += '<div class="page-watermark">' + escapeHtml(config.watermark) + '</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>';

        // 水印
        if (config.watermark) {
            html += '<div class="page-watermark">' + escapeHtml(config.watermark) + '</div>';
        }

        html += '</div>';

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

    // ===== 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;

        // 跳过由表格/代码块转换而来的图片（不应被当作纯图片页处理）
        if ($imgs.first().attr('data-converted') === 'true') 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();
    }

    /**
     * 共享截图核心逻辑 - 将pages渲染到staging并逐页截图
     * @param {Object} opts - { scale, outputCanvas, quality, sizeConfig }
     *   scale: html2canvas缩放 (1=缩略图, 2=保存)
     *   outputCanvas: true=输出canvas对象, false=输出dataURL字符串
     *   quality: JPEG质量 (0-1)
     *   sizeConfig: 尺寸配置(用于纯图片页canvas渲染)
     * @returns {jQuery Deferred} resolves with array of dataURL strings or canvas objects
     */
    function doCapturePages(opts) {
        var deferred = $.Deferred();
        ensureStaging();

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

        // 渲染所有页面到隐藏区域
        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);

        // 等待字体和DOM就绪
        var fontsReady = (typeof document.fonts !== 'undefined' && document.fonts.ready)
            ? document.fonts.ready
            : $.Deferred().resolve().promise();

        fontsReady.catch(function () {
            // 字体加载失败不影响截图，继续执行
        }).then(function () {
            requestAnimationFrame(function () {
                // html2canvas会跳过visibility:hidden的元素，临时切换为可见
                $staging.css({ visibility: 'visible' });
                // 表格和代码块已在中间栏中转为图片，无需再次转换
                runCaptureLoop($staging, opts, deferred);
            });
        });

        return deferred.promise();
    }

    /**
     * 执行串行截图循环
     * @param {jQuery} $staging - staging元素
     * @param {Object} opts - 截图选项
     * @param {jQuery Deferred} deferred - 外部deferred
     */
    function runCaptureLoop($staging, opts, deferred) {
        var $pageElems = $staging.find('.phone-image-page');
        if ($pageElems.length === 0) {
            $staging.css({ visibility: 'hidden' });
            if (opts.outputCanvas) {
                deferred.reject('没有可渲染的页面');
            } else {
                deferred.resolve([]);
            }
            return;
        }

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

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

            var $elem = $pageElems.eq(idx);

            // 纯图片页优化
            if (isPureImagePage($elem)) {
                var pureSrc = getPureImageSrc($elem);
                if (pureSrc) {
                    if (opts.outputCanvas) {
                        // 保存模式: 高质量绘制原图到canvas
                        renderPureImageToCanvas(pureSrc, opts.sizeConfig.width, opts.sizeConfig.height).then(function (canvas) {
                            results.push(canvas);
                            idx++;
                            captureNext();
                        }).catch(function () {
                            // 加载失败，回退到html2canvas
                            capturePageViaHtml2Canvas($elem, $staging, opts, results, deferred, function () { idx++; captureNext(); });
                        });
                        return;
                    } else {
                        // 缩略图模式: 直接用src
                        results.push(pureSrc);
                        idx++;
                        captureNext();
                        return;
                    }
                }
            }

            capturePageViaHtml2Canvas($elem, $staging, opts, results, deferred, function () { idx++; captureNext(); });
        }

        captureNext();
    }

    /**
     * 用html2canvas截图单页
     */
    function capturePageViaHtml2Canvas($elem, $staging, opts, results, deferred, onDone) {
        html2canvas($elem[0], {
            scale: opts.scale,
            useCORS: true,
            backgroundColor: '#ffffff',
            width: $elem.outerWidth(),
            height: $elem.outerHeight(),
            logging: false
        }).then(function (canvas) {
            if (opts.outputCanvas) {
                results.push(canvas);
            } else {
                results.push(canvas.toDataURL('image/jpeg', opts.quality));
            }
            onDone();
        }).catch(function (err) {
            $staging.empty();
            $staging.css({ visibility: 'hidden' });
            deferred.reject('截图失败: ' + err);
        });
    }

    /**
     * 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();

        doCapturePages({
            scale: 1,
            outputCanvas: false,
            quality: 0.85,
            sizeConfig: sizeConfig
        }).then(function (dataUrls) {
            displayThumbnails(dataUrls, sizeConfig);
            deferred.resolve(pages);
        }).catch(function (err) {
            deferred.reject(err);
        });

        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 sizeConfig = config.sizes[config.size] || config.sizes.xiaohongshu;
        return doCapturePages({
            scale: 2,
            outputCanvas: true,
            quality: 0.92,
            sizeConfig: sizeConfig
        });
    }

    // ===== 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));
            }

            // 检查数据总大小，防止超大文章导致请求失败
            var totalSize = 0;
            for (var i = 0; i < pagesData.length; i++) {
                if (pagesData[i]) {
                    totalSize += pagesData[i].length;
                }
            }
            if (totalSize > 16 * 1024 * 1024) {
                layer.msg('数据量过大（超过16MB），请减少内容或联系管理员');
                deferred.reject('数据量过大（超过16MB）');
                return;
            }

            $.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();
    }

    /**
     * 保存排版配置到服务端（不生成图片）
     * @param {number} postId 文章ID
     * @param {Object} saveConfig 配置信息 {size, fontSize, watermark, content_html}
     * @param {string} url 保存接口URL
     * @returns {Promise} jQuery Deferred, resolves with {output_id}
     */
    function saveConfig(postId, saveConfig, url) {
        var deferred = $.Deferred();

        var payload = {
            post_id: postId,
            output_type: 'phone_image',
            config: {
                size: saveConfig.size || config.size,
                watermark: saveConfig.watermark || config.watermark,
                pageAlignments: config.pageAlignments || {}
            },
            content_html: saveConfig.content_html || postData.content_html
        };

        $.ajax({
            url: url || '',
            type: 'POST',
            data: JSON.stringify(payload),
            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);
            }
        });

        return deferred.promise();
    }

    // ===== 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;
    }

    // ===== 导出长图 =====

    /**
     * 导出长图：从 wangeditor DOM 截取完整长图
     * @returns {jQuery Deferred} resolves with canvas
     */
    function exportLongImage() {
        var deferred = $.Deferred();

        if (render._locked) {
            deferred.reject('rendering');
            return deferred.promise();
        }

        var editorChildren = getEditorChildren();
        if (editorChildren.length === 0) {
            deferred.reject('编辑器内容为空');
            return deferred.promise();
        }

        // 创建临时容器，宽度540px与编辑器一致
        var $container = $('<div>').css({
            width: '540px',
            position: 'fixed',
            left: '-9999px',
            top: '0',
            visibility: 'visible',
            background: '#ffffff',
            padding: '20px',
            boxSizing: 'border-box',
            fontSize: '14px',
            lineHeight: '1.8'
        });

        // 克隆所有非 divider 的子元素
        for (var i = 0; i < editorChildren.length; i++) {
            var el = editorChildren[i];
            var isDivider = el.getAttribute('data-w-e-type') === 'divider' ||
                el.tagName.toLowerCase() === 'hr';
            if (!isDivider) {
                $container.append(el.cloneNode(true));
            }
        }

        $('body').append($container);

        requestAnimationFrame(function () {
            var width = $container.outerWidth();
            var height = $container[0].scrollHeight;

            html2canvas($container[0], {
                scale: 2,
                useCORS: true,
                backgroundColor: '#ffffff',
                width: width,
                height: height,
                logging: false
            }).then(function (canvas) {
                $container.remove();
                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) {
                $container.remove();
                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;
    }

    // ===== 公开API =====
    return {
        init: init,
        render: render,
        generateImages: generateImages,
        saveImages: saveImages,
        saveConfig: saveConfig,
        setPageAlignment: setPageAlignment,
        exportLongImage: exportLongImage,
        getContentHtml: function () {
            if (window.phoneImageEditor) {
                return window.phoneImageEditor.getHtml();
            }
            return postData.content_html;
        },
        updateConfig: function (newConfig) {
            if (newConfig) {
                $.extend(config, newConfig);
            }
        }
    };
})();