/**
 * 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 = [];

    /**
     * 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
     * 两遍遍历: 先算总页数, 再带页码生成
     * @returns {Array} 页面数组，每项是 { type, html, pageNum }
     */
    function render() {
        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>'
                );
            }
        }

        // 渲染到DOM
        renderToDOM(sizeConfig);

        return pages;
    }

    /**
     * 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, $el.text());
                    break;
                case 'img':
                    block.estimatedHeight = estimateImageHeight($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;
    }

    // ===== 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];
        }

        // 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 =====

    /**
     * 全尺寸平铺渲染到 #paginated-preview
     */
    function renderToDOM(sizeConfig) {
        var $preview = $('#paginated-preview');
        if (!$preview.length) return;

        $preview.empty();
        for (var i = 0; i < pages.length; i++) {
            $preview.append(pages[i].html);
        }
    }

    // ===== 图片生成 =====

    /**
     * 逐页截图生成图片（简化版：所有页面已在DOM中可见）
     * @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();
        var canvases = [];
        var $pages = $('#paginated-preview .phone-image-page');

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

        var index = 0;
        var total = $pages.length;

        function captureNext() {
            if (index >= total) {
                if (onProgress) onProgress(total, total, null);
                deferred.resolve(canvases);
                return;
            }

            html2canvas($pages.eq(index)[0], {
                scale: 2,
                useCORS: true,
                backgroundColor: '#ffffff',
                width: $pages.eq(index).outerWidth(),
                height: $pages.eq(index).outerHeight(),
                logging: false
            }).then(function (canvas) {
                canvases.push(canvas);
                index++;
                if (onProgress) onProgress(index, total, canvas);
                captureNext();
            }).catch(function (err) {
                deferred.reject('截图失败(第' + (index + 1) + '页): ' + err);
            });
        }

        if (onProgress) onProgress(0, total, null);
        captureNext();
        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();

        generateImages(onProgress).then(function (canvases) {
            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,
                    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;
    }

    // ===== 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
    };
})();