const express = require('express');
const cors = require('cors');
const { createCanvas, registerFont } = require('@napi-rs/canvas');
const echarts = require('echarts');
const path = require('path');

// 注册中文字体
try {
    registerFont('/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc', { family: 'Noto Sans CJK SC' });
    registerFont('/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc', { family: 'Noto Sans CJK SC', weight: 'bold' });
} catch (e) {
    console.warn('中文字体注册失败，将使用系统默认字体:', e.message);
}

const app = express();
const PORT = process.env.PORT || 16016;

// 中间件
app.use(cors());
app.use(express.json({ limit: '10mb' }));
app.use(express.urlencoded({ extended: true, limit: '10mb' }));

// 静态文件（前端页面）
app.use(express.static(path.join(__dirname)));

// ===== 预设颜色方案 =====
const colorPalettes = {
    default: ['#5470c6', '#91cc75', '#fac858', '#ee6666', '#73c0de', '#3ba272', '#fc8452', '#9a60b4', '#ea7ccc'],
    dark: ['#4fc3f7', '#81c784', '#fff176', '#ff8a65', '#ba68c8', '#4dd0e1', '#ffab91', '#aed581', '#f48fb1'],
    macarons: ['#2ec7c9', '#b6a2de', '#5ab1ef', '#ffb980', '#d87a80', '#8d98b3', '#e5cf0d', '#97b552', '#95706d'],
    gradient: ['#7f7fd5', '#86a8e7', '#91eae4', '#ff6b6b', '#feca57', '#48dbfb', '#ff9ff3', '#54a0ff', '#5f27cd'],
    retro: ['#d4a5a5', '#95b9c7', '#f6e8c3', '#dfceb4', '#a4c3b5', '#c9b1ff', '#f5c7b8', '#b8d4e3', '#e8c8a0'],
    ocean: ['#0077b6', '#00b4d8', '#90e0ef', '#caf0f8', '#023e8a', '#48cae4', '#ade8f4', '#0096c7', '#03045e'],
    forest: ['#2d6a4f', '#40916c', '#52b788', '#74c69d', '#95d5b2', '#b7e4c7', '#d8f3dc', '#1b4332', '#344e41'],
    sunset: ['#e85d04', '#f48c06', '#faa307', '#ffba08', '#dc2f02', '#d00000', '#9d0208', '#6a040f', '#370617'],
    lavender: ['#7c3aed', '#8b5cf6', '#a78bfa', '#c4b5fd', '#ddd6fe', '#ede9fe', '#5b21b6', '#4c1d95', '#6d28d9'],
    minimal: ['#111827', '#374151', '#6b7280', '#9ca3af', '#d1d5db', '#e5e7eb', '#f3f4f6', '#4b5563', '#1f2937'],
    cherry: ['#e91e63', '#f06292', '#f48fb1', '#f8bbd0', '#fce4ec', '#c2185b', '#ad1457', '#880e4f', '#d81b60'],
    midnight: ['#6c63ff', '#5a52d5', '#483fb5', '#7c79ff', '#3d3d5c', '#8b89ff', '#9d9bff', '#2c2c4a', '#b3b2ff'],
    gold: ['#b8860b', '#daa520', '#f0c040', '#ffd700', '#ffe066', '#996515', '#cc9900', '#e6b800', '#8b6914'],
    coral: ['#ff6f61', '#ff8a70', '#ffa07a', '#ffab91', '#ffccbc', '#e64a19', '#f4511e', '#ff5722', '#d84315'],
    mint: ['#00bfa5', '#26a69a', '#4db6ac', '#80cbc4', '#b2dfdb', '#00897b', '#00796b', '#004d40', '#009688']
};

// ===== 数据解析（与前端一致） =====
function parseData(rawText) {
    const lines = rawText.trim().split('\n').filter(l => l.trim());
    if (lines.length < 2) {
        throw new Error('数据至少需要包含表头和一行数据');
    }

    // 自动检测分隔符
    let delimiter = ',';
    if (lines[0].includes('\t')) {
        delimiter = '\t';
    } else if (lines[0].split('|').length > lines[0].split(',').length) {
        delimiter = '|';
    }

    const rows = lines.map(line => {
        return line.split(delimiter).map(cell => cell.trim());
    });

    const headers = rows[0];
    const categories = [];
    const seriesData = {};

    for (let i = 1; i < headers.length; i++) {
        seriesData[headers[i]] = [];
    }

    for (let i = 1; i < rows.length; i++) {
        categories.push(rows[i][0]);
        for (let j = 1; j < rows[i].length && j < headers.length; j++) {
            const val = parseFloat(rows[i][j]);
            seriesData[headers[j]].push(isNaN(val) ? 0 : val);
        }
    }

    return {
        categories,
        seriesNames: headers.slice(1),
        seriesData
    };
}

// ===== 颜色工具 =====
function adjustColor(hex, amount) {
    hex = hex.replace('#', '');
    const num = parseInt(hex, 16);
    let r = Math.min(255, ((num >> 16) & 0xff) + amount);
    let g = Math.min(255, ((num >> 8) & 0xff) + amount);
    let b = Math.min(255, (num & 0xff) + amount);
    return `rgb(${r},${g},${b})`;
}

// ===== 构建 ECharts option =====
function buildChartOption(params) {
    const {
        data,
        chartType = 'bar',
        title = '',
        theme = 'default',
        showLegend = true,
        showGrid = true,
        showLabel = false,
        stackMode = false,
        smoothLine = true,
        enableSplit = false,
        splitIndex = 3,
        leftLabel = '左侧',
        rightLabel = '右侧',
        splitStyle = 'solid',
        seriesColors: customColors = null
    } = params;

    const parsedData = parseData(data);
    const palette = colorPalettes[theme] || colorPalettes.default;
    const seriesColorsArr = customColors || parsedData.seriesNames.map((_, i) => palette[i % palette.length]);

    // 背景色和文字色
    const bgColor = theme === 'dark' ? '#1a1a2e' : '#ffffff';
    const textColor = theme === 'dark' ? '#e0e0e0' : '#333333';
    const axisLineColor = theme === 'dark' ? '#444' : '#ddd';

    // 构建系列
    const series = parsedData.seriesNames.map((name, idx) => {
        const dataArr = parsedData.seriesData[name];
        const color = seriesColorsArr[idx] || palette[idx % palette.length];

        let type = chartType === 'bar-line'
            ? (idx % 2 === 0 ? 'bar' : 'line')
            : chartType;

        const seriesItem = {
            name: name,
            type: type,
            data: [...dataArr],
            itemStyle: { color: color },
            emphasis: {
                focus: 'series',
                itemStyle: {
                    shadowBlur: 10,
                    shadowColor: 'rgba(0,0,0,0.3)'
                }
            }
        };

        if (stackMode) {
            seriesItem.stack = 'total';
        }

        if (type === 'line') {
            seriesItem.smooth = smoothLine;
            seriesItem.lineStyle = { width: 3 };
            seriesItem.symbolSize = 8;
            seriesItem.areaStyle = theme === 'gradient' ? { opacity: 0.15 } : undefined;
        }

        if (type === 'bar') {
            seriesItem.barMaxWidth = 40;
            seriesItem.itemStyle.borderRadius = stackMode ? [0, 0, 0, 0] : [4, 4, 0, 0];
        }

        if (showLabel) {
            seriesItem.label = {
                show: true,
                position: 'top',
                fontSize: 11,
                color: textColor,
                formatter: (p) => {
                    if (p.value >= 10000) return (p.value / 10000).toFixed(1) + 'w';
                    if (p.value >= 1000) return (p.value / 1000).toFixed(1) + 'k';
                    return p.value;
                }
            };
        }

        return seriesItem;
    });

    // 区域分割
    if (enableSplit && splitIndex < parsedData.categories.length && series.length > 0) {
        const splitLineColor = theme === 'dark' ? '#ff6b6b' : '#e74c3c';
        series[0].markArea = {
            silent: true,
            data: [
                [
                    {
                        name: leftLabel,
                        xAxis: parsedData.categories[0],
                        itemStyle: {
                            color: theme === 'dark' ? 'rgba(79,195,247,0.06)' : 'rgba(79,70,229,0.05)',
                            borderWidth: 0
                        },
                        label: {
                            show: true,
                            position: 'insideTop',
                            fontSize: 13,
                            fontWeight: 'bold',
                            color: theme === 'dark' ? '#4fc3f7' : '#4f46e5',
                            offset: [0, 10]
                        }
                    },
                    { xAxis: parsedData.categories[splitIndex - 1] }
                ],
                [
                    {
                        name: rightLabel,
                        xAxis: parsedData.categories[splitIndex],
                        itemStyle: {
                            color: theme === 'dark' ? 'rgba(255,107,107,0.06)' : 'rgba(239,68,68,0.05)',
                            borderWidth: 0
                        },
                        label: {
                            show: true,
                            position: 'insideTop',
                            fontSize: 13,
                            fontWeight: 'bold',
                            color: theme === 'dark' ? '#ff6b6b' : '#ef4444',
                            offset: [0, 10]
                        }
                    },
                    { xAxis: parsedData.categories[parsedData.categories.length - 1] }
                ]
            ]
        };
    }

    // 完整 option
    const option = {
        backgroundColor: bgColor,
        title: title ? {
            text: title,
            left: 'center',
            top: 15,
            textStyle: {
                color: textColor,
                fontSize: 18,
                fontWeight: 600
            }
        } : undefined,
        tooltip: { show: false },
        legend: showLegend ? {
            show: true,
            top: title ? 50 : 15,
            textStyle: { color: textColor, fontSize: 12 },
            itemGap: 20,
            icon: 'roundRect'
        } : { show: false },
        grid: {
            left: '3%',
            right: '4%',
            bottom: '3%',
            top: showLegend ? (title ? 90 : 60) : (title ? 60 : 30),
            containLabel: true
        },
        xAxis: {
            type: 'category',
            data: parsedData.categories,
            axisLine: { lineStyle: { color: axisLineColor } },
            axisLabel: {
                color: textColor,
                fontSize: 12,
                interval: 0,
                rotate: parsedData.categories.length > 10 ? 30 : 0
            },
            axisTick: { show: false }
        },
        yAxis: {
            type: 'value',
            axisLine: { show: false },
            axisTick: { show: false },
            axisLabel: { color: textColor, fontSize: 11 },
            splitLine: {
                show: showGrid,
                lineStyle: {
                    color: theme === 'dark' ? '#333' : '#f0f0f0',
                    type: 'dashed'
                }
            }
        },
        series: series,
        animation: false  // 服务端渲染关闭动画
    };

    return option;
}

// ===== API: 生成图表图片 =====
app.post('/api/chart', (req, res) => {
    try {
        const params = req.body;

        if (!params.data) {
            return res.status(400).json({ error: '缺少 data 参数（CSV 格式数据）' });
        }

        const width = parseInt(params.width) || 800;
        const height = parseInt(params.height) || 500;
        const format = params.format || 'png';
        const pixelRatio = parseInt(params.pixelRatio) || 2;

        // 构建图表配置
        const option = buildChartOption(params);

        // 创建 canvas 并渲染
        const canvas = createCanvas(width * pixelRatio, height * pixelRatio);
        const chart = echarts.init(canvas, null, {
            renderer: 'canvas',
            width: width,
            height: height,
            devicePixelRatio: pixelRatio
        });

        chart.setOption(option);

        // 输出图片
        if (format === 'svg') {
            // SVG 需要用 SVG 渲染器重新渲染
            // node-canvas 不支持 SVG，返回 PNG 并提示
            const buffer = canvas.toBuffer('image/png');
            res.set({
                'Content-Type': 'image/png',
                'Content-Length': buffer.length,
                'X-Chart-Format': 'png',
                'X-Chart-Note': 'SVG format not supported in server-side rendering, returned PNG instead'
            });
            res.send(buffer);
        } else {
            const buffer = canvas.toBuffer('image/png');
            res.set({
                'Content-Type': 'image/png',
                'Content-Length': buffer.length,
                'X-Chart-Width': width,
                'X-Chart-Height': height,
                'X-Chart-Pixel-Ratio': pixelRatio
            });
            res.send(buffer);
        }

        chart.dispose();
    } catch (err) {
        console.error('Chart generation error:', err);
        res.status(500).json({ error: '图表生成失败: ' + err.message });
    }
});

// ===== API: 生成图表（GET 方式，方便 URL 直接调用） =====
app.get('/api/chart', (req, res) => {
    try {
        const params = {
            data: req.query.data,
            chartType: req.query.chartType || req.query.type || 'bar',
            title: req.query.title || '',
            theme: req.query.theme || 'default',
            showLegend: req.query.showLegend !== 'false',
            showGrid: req.query.showGrid !== 'false',
            showLabel: req.query.showLabel === 'true',
            stackMode: req.query.stackMode === 'true',
            smoothLine: req.query.smoothLine !== 'false',
            enableSplit: req.query.enableSplit === 'true',
            splitIndex: parseInt(req.query.splitIndex) || 3,
            leftLabel: req.query.leftLabel || '左侧',
            rightLabel: req.query.rightLabel || '右侧',
            splitStyle: req.query.splitStyle || 'solid',
            width: parseInt(req.query.width) || 800,
            height: parseInt(req.query.height) || 500,
            format: req.query.format || 'png',
            pixelRatio: parseInt(req.query.pixelRatio) || 2
        };

        if (!params.data) {
            return res.status(400).json({ error: '缺少 data 参数' });
        }

        // 解码 data（支持 URL 编码的换行符）
        params.data = params.data.replace(/\\n/g, '\n');

        const option = buildChartOption(params);

        const width = params.width;
        const height = params.height;
        const pixelRatio = params.pixelRatio;

        const canvas = createCanvas(width * pixelRatio, height * pixelRatio);
        const chart = echarts.init(canvas, null, {
            renderer: 'canvas',
            width: width,
            height: height,
            devicePixelRatio: pixelRatio
        });

        chart.setOption(option);

        const buffer = canvas.toBuffer('image/png');
        res.set({
            'Content-Type': 'image/png',
            'Content-Length': buffer.length,
            'X-Chart-Width': width,
            'X-Chart-Height': height
        });
        res.send(buffer);

        chart.dispose();
    } catch (err) {
        console.error('Chart generation error:', err);
        res.status(500).json({ error: '图表生成失败: ' + err.message });
    }
});

// ===== 表格数据解析（保留原始文本） =====
function parseTableData(rawText) {
    const lines = rawText.trim().split('\n').filter(l => l.trim());
    if (lines.length < 2) {
        throw new Error('数据至少需要包含表头和一行数据');
    }

    // 自动检测分隔符
    let delimiter = ',';
    if (lines[0].includes('\t')) {
        delimiter = '\t';
    } else if (lines[0].split('|').length > lines[0].split(',').length) {
        delimiter = '|';
    }

    const rows = lines.map(line => {
        return line.split(delimiter).map(cell => cell.trim());
    });

    return {
        headers: rows[0],
        rows: rows.slice(1)
    };
}

// ===== 表格主题配置 =====
const tableThemes = {
    default: {
        bgColor: '#ffffff',
        headerBg: '#5470c6',
        headerColor: '#ffffff',
        cellColor: '#333333',
        borderColor: '#e0e0e0',
        stripeColor: '#f8f9fa',
        titleColor: '#333333'
    },
    dark: {
        bgColor: '#1a1a2e',
        headerBg: '#4fc3f7',
        headerColor: '#1a1a2e',
        cellColor: '#e0e0e0',
        borderColor: '#444444',
        stripeColor: '#252540',
        titleColor: '#e0e0e0'
    },
    macarons: {
        bgColor: '#ffffff',
        headerBg: '#2ec7c9',
        headerColor: '#ffffff',
        cellColor: '#333333',
        borderColor: '#e8e8e8',
        stripeColor: '#f0fafb',
        titleColor: '#333333'
    },
    gradient: {
        bgColor: '#ffffff',
        headerBg: '#7f7fd5',
        headerColor: '#ffffff',
        cellColor: '#333333',
        borderColor: '#e8e8e8',
        stripeColor: '#f5f5ff',
        titleColor: '#333333'
    },
    retro: {
        bgColor: '#fefefe',
        headerBg: '#95b9c7',
        headerColor: '#ffffff',
        cellColor: '#444444',
        borderColor: '#d4a5a5',
        stripeColor: '#f6e8c3',
        titleColor: '#444444'
    },
    ocean: {
        bgColor: '#f0f8ff',
        headerBg: '#0077b6',
        headerColor: '#ffffff',
        cellColor: '#023e58',
        borderColor: '#90e0ef',
        stripeColor: '#caf0f8',
        titleColor: '#023e58'
    },
    forest: {
        bgColor: '#f5faf5',
        headerBg: '#2d6a4f',
        headerColor: '#ffffff',
        cellColor: '#1b4332',
        borderColor: '#95d5b2',
        stripeColor: '#d8f3dc',
        titleColor: '#1b4332'
    },
    sunset: {
        bgColor: '#fff8f0',
        headerBg: '#e85d04',
        headerColor: '#ffffff',
        cellColor: '#6a040f',
        borderColor: '#ffba08',
        stripeColor: '#fff3e0',
        titleColor: '#6a040f'
    },
    lavender: {
        bgColor: '#faf5ff',
        headerBg: '#7c3aed',
        headerColor: '#ffffff',
        cellColor: '#4c1d95',
        borderColor: '#c4b5fd',
        stripeColor: '#ede9fe',
        titleColor: '#4c1d95'
    },
    minimal: {
        bgColor: '#ffffff',
        headerBg: '#f8f9fa',
        headerColor: '#212529',
        cellColor: '#495057',
        borderColor: '#dee2e6',
        stripeColor: '#f8f9fa',
        titleColor: '#212529'
    },
    cherry: {
        bgColor: '#fff5f7',
        headerBg: '#e91e63',
        headerColor: '#ffffff',
        cellColor: '#880e4f',
        borderColor: '#f48fb1',
        stripeColor: '#fce4ec',
        titleColor: '#880e4f'
    },
    midnight: {
        bgColor: '#1a1a2e',
        headerBg: '#6c63ff',
        headerColor: '#ffffff',
        cellColor: '#e0e0e0',
        borderColor: '#3d3d5c',
        stripeColor: '#22223a',
        titleColor: '#e0e0e0'
    },
    gold: {
        bgColor: '#fffef5',
        headerBg: '#b8860b',
        headerColor: '#ffffff',
        cellColor: '#5c4a00',
        borderColor: '#daa520',
        stripeColor: '#fdf6e3',
        titleColor: '#5c4a00'
    },
    coral: {
        bgColor: '#fff5f2',
        headerBg: '#ff6f61',
        headerColor: '#ffffff',
        cellColor: '#5d2b1f',
        borderColor: '#ffab91',
        stripeColor: '#fff0ed',
        titleColor: '#5d2b1f'
    },
    mint: {
        bgColor: '#f0fff8',
        headerBg: '#00bfa5',
        headerColor: '#ffffff',
        cellColor: '#004d40',
        borderColor: '#80cbc4',
        stripeColor: '#e0f2f1',
        titleColor: '#004d40'
    },
    // 简约纯色风格
    slate: {
        bgColor: '#ffffff',
        headerBg: '#475569',
        headerColor: '#ffffff',
        cellColor: '#334155',
        borderColor: '#cbd5e1',
        stripeColor: '#f8fafc',
        titleColor: '#1e293b'
    },
    sky: {
        bgColor: '#ffffff',
        headerBg: '#0ea5e9',
        headerColor: '#ffffff',
        cellColor: '#0c4a6e',
        borderColor: '#bae6fd',
        stripeColor: '#f0f9ff',
        titleColor: '#0c4a6e'
    },
    rose: {
        bgColor: '#ffffff',
        headerBg: '#e11d48',
        headerColor: '#ffffff',
        cellColor: '#881337',
        borderColor: '#fecdd3',
        stripeColor: '#fff1f2',
        titleColor: '#881337'
    },
    amber: {
        bgColor: '#ffffff',
        headerBg: '#f59e0b',
        headerColor: '#ffffff',
        cellColor: '#78350f',
        borderColor: '#fde68a',
        stripeColor: '#fffbeb',
        titleColor: '#78350f'
    },
    emerald: {
        bgColor: '#ffffff',
        headerBg: '#10b981',
        headerColor: '#ffffff',
        cellColor: '#064e3b',
        borderColor: '#a7f3d0',
        stripeColor: '#ecfdf5',
        titleColor: '#064e3b'
    },
    indigo: {
        bgColor: '#ffffff',
        headerBg: '#6366f1',
        headerColor: '#ffffff',
        cellColor: '#312e81',
        borderColor: '#c7d2fe',
        stripeColor: '#eef2ff',
        titleColor: '#312e81'
    },
    stone: {
        bgColor: '#ffffff',
        headerBg: '#78716c',
        headerColor: '#ffffff',
        cellColor: '#44403c',
        borderColor: '#d6d3d1',
        stripeColor: '#fafaf9',
        titleColor: '#292524'
    }
};

// ===== 测量文字宽度 =====
function measureTextWidth(ctx, text, fontSize) {
    ctx.font = `${fontSize}px "Noto Sans CJK SC", sans-serif`;
    const metrics = ctx.measureText(text);
    return metrics.width;
}

// ===== 生成表格图片 =====
function generateTableImage(params) {
    const {
        data,
        title = '',
        theme = 'default',
        fontSize = 14,
        cellPadding = 12,
        borderWidth = 1,
        stripeRows = true,
        pixelRatio = 2,
        maxWidth = 1200
    } = params;

    const tableData = parseTableData(data);
    const { headers, rows } = tableData;
    const themeConfig = tableThemes[theme] || tableThemes.default;

    // 创建临时 canvas 用于测量文字
    const tempCanvas = createCanvas(100, 100);
    const tempCtx = tempCanvas.getContext('2d');

    // 计算每列最大宽度
    const colWidths = headers.map((header, colIdx) => {
        let maxW = measureTextWidth(tempCtx, header, fontSize) + cellPadding * 2;
        
        rows.forEach(row => {
            if (row[colIdx]) {
                const cellW = measureTextWidth(tempCtx, row[colIdx], fontSize) + cellPadding * 2;
                if (cellW > maxW) maxW = cellW;
            }
        });
        
        return Math.min(maxW, 300); // 单列最大宽度 300px
    });

    // 计算表格总宽度
    const tableWidth = colWidths.reduce((sum, w) => sum + w, 0) + borderWidth * 2;
    const finalWidth = Math.min(tableWidth, maxWidth);
    
    // 如果超出最大宽度，按比例缩放列宽
    if (tableWidth > maxWidth) {
        const scale = maxWidth / tableWidth;
        colWidths.forEach((_, i) => colWidths[i] *= scale);
    }

    // 计算行高
    const headerHeight = fontSize * 2.5;
    const rowHeight = fontSize * 2.2;
    const titleHeight = title ? fontSize * 3 : 0;
    const tableHeight = headerHeight + rows.length * rowHeight;
    const finalHeight = tableHeight + titleHeight;

    // 创建正式 canvas
    const canvas = createCanvas(finalWidth * pixelRatio, finalHeight * pixelRatio);
    const ctx = canvas.getContext('2d');
    ctx.scale(pixelRatio, pixelRatio);

    // 绘制背景
    ctx.fillStyle = themeConfig.bgColor;
    ctx.fillRect(0, 0, finalWidth, finalHeight);

    let startY = 0;

    // 绘制标题
    if (title) {
        ctx.fillStyle = themeConfig.titleColor;
        ctx.font = `bold ${fontSize * 1.4}px "Noto Sans CJK SC", sans-serif`;
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(title, finalWidth / 2, titleHeight / 2);
        startY = titleHeight;
    }

    // 绘制表头背景
    ctx.fillStyle = themeConfig.headerBg;
    ctx.fillRect(0, startY, finalWidth, headerHeight);

    // 绘制表头文字
    ctx.fillStyle = themeConfig.headerColor;
    ctx.font = `bold ${fontSize}px "Noto Sans CJK SC", sans-serif`;
    ctx.textAlign = 'left';
    ctx.textBaseline = 'middle';

    let x = 0;
    headers.forEach((header, i) => {
        ctx.fillText(header, x + cellPadding, startY + headerHeight / 2, colWidths[i] - cellPadding * 2);
        x += colWidths[i];
    });

    // 绘制数据行
    rows.forEach((row, rowIdx) => {
        const y = startY + headerHeight + rowIdx * rowHeight;

        // 斑马纹背景
        if (stripeRows && rowIdx % 2 === 1) {
            ctx.fillStyle = themeConfig.stripeColor;
            ctx.fillRect(0, y, finalWidth, rowHeight);
        }

        // 绘制单元格文字
        ctx.fillStyle = themeConfig.cellColor;
        ctx.font = `${fontSize}px "Noto Sans CJK SC", sans-serif`;
        ctx.textAlign = 'left';
        ctx.textBaseline = 'middle';

        let cellX = 0;
        row.forEach((cell, colIdx) => {
            if (cell && colWidths[colIdx]) {
                ctx.fillText(cell, cellX + cellPadding, y + rowHeight / 2, colWidths[colIdx] - cellPadding * 2);
            }
            cellX += colWidths[colIdx];
        });
    });

    // 绘制边框
    ctx.strokeStyle = themeConfig.borderColor;
    ctx.lineWidth = borderWidth;

    // 外边框（向内偏移半个线宽，确保边框完全在画布内）
    const offset = borderWidth / 2;
    ctx.strokeRect(offset, startY + offset, finalWidth - borderWidth, tableHeight - borderWidth);

    // 横线
    ctx.beginPath();
    ctx.moveTo(0, startY + headerHeight);
    ctx.lineTo(finalWidth, startY + headerHeight);
    ctx.stroke();

    rows.forEach((_, rowIdx) => {
        const y = startY + headerHeight + (rowIdx + 1) * rowHeight;
        ctx.beginPath();
        ctx.moveTo(0, y);
        ctx.lineTo(finalWidth, y);
        ctx.stroke();
    });

    // 竖线
    x = 0;
    colWidths.forEach((width, i) => {
        if (i > 0) {
            ctx.beginPath();
            ctx.moveTo(x, startY);
            ctx.lineTo(x, startY + tableHeight);
            ctx.stroke();
        }
        x += width;
    });

    return canvas;
}

// ===== API: 生成表格图片 (POST) =====
app.post('/api/table', (req, res) => {
    try {
        const params = req.body;

        if (!params.data) {
            return res.status(400).json({ error: '缺少 data 参数（CSV 格式数据）' });
        }

        const pixelRatio = parseInt(params.pixelRatio) || 2;
        const canvas = generateTableImage(params);

        const buffer = canvas.toBuffer('image/png');
        res.set({
            'Content-Type': 'image/png',
            'Content-Length': buffer.length,
            'X-Table-Format': 'png'
        });
        res.send(buffer);
    } catch (err) {
        console.error('Table generation error:', err);
        res.status(500).json({ error: '表格生成失败: ' + err.message });
    }
});

// ===== API: 生成表格图片 (GET) =====
app.get('/api/table', (req, res) => {
    try {
        const params = {
            data: req.query.data,
            title: req.query.title || '',
            theme: req.query.theme || 'default',
            fontSize: parseInt(req.query.fontSize) || 14,
            cellPadding: parseInt(req.query.cellPadding) || 12,
            borderWidth: parseInt(req.query.borderWidth) || 1,
            stripeRows: req.query.stripeRows !== 'false',
            pixelRatio: parseInt(req.query.pixelRatio) || 2,
            maxWidth: parseInt(req.query.maxWidth) || 1200
        };

        if (!params.data) {
            return res.status(400).json({ error: '缺少 data 参数' });
        }

        // 解码 data（支持 URL 编码的换行符）
        params.data = params.data.replace(/\\n/g, '\n');

        const canvas = generateTableImage(params);
        const buffer = canvas.toBuffer('image/png');
        
        res.set({
            'Content-Type': 'image/png',
            'Content-Length': buffer.length,
            'X-Table-Format': 'png'
        });
        res.send(buffer);
    } catch (err) {
        console.error('Table generation error:', err);
        res.status(500).json({ error: '表格生成失败: ' + err.message });
    }
});

// ===== API: 健康检查 =====
app.get('/api/health', (req, res) => {
    res.json({
        status: 'ok',
        service: 'data-chart-tool',
        version: '1.2.0',
        endpoints: {
            'POST /api/chart': '生成图表图片（JSON body）',
            'GET /api/chart': '生成图表图片（URL 参数）',
            'POST /api/table': '生成表格图片（JSON body）',
            'GET /api/table': '生成表格图片（URL 参数）',
            'GET /api/health': '健康检查'
        }
    });
});

// ===== API: 文档/使用说明 =====
app.get('/api/docs', (req, res) => {
    res.json({
        name: '数据可视化图表生成器 API',
        version: '1.2.0',
        endpoints: [
            {
                method: 'POST',
                path: '/api/chart',
                description: '通过 JSON 请求体生成图表图片',
                'Content-Type': 'application/json',
                params: {
                    data: { type: 'string', required: true, description: 'CSV 格式数据（第一行表头，第一列横坐标）' },
                    chartType: { type: 'string', default: 'bar', options: ['bar', 'line', 'bar-line'], description: '图表类型' },
                    title: { type: 'string', default: '', description: '图表标题' },
                    theme: { type: 'string', default: 'default', options: ['default', 'dark', 'macarons', 'gradient', 'retro', 'ocean', 'forest', 'sunset', 'lavender', 'minimal', 'cherry', 'midnight', 'gold', 'coral', 'mint'], description: '主题风格' },
                    showLegend: { type: 'boolean', default: true, description: '是否显示图例' },
                    showGrid: { type: 'boolean', default: true, description: '是否显示网格线' },
                    showLabel: { type: 'boolean', default: false, description: '是否显示数据标签' },
                    stackMode: { type: 'boolean', default: false, description: '是否堆叠模式' },
                    smoothLine: { type: 'boolean', default: true, description: '折线图是否平滑' },
                    enableSplit: { type: 'boolean', default: false, description: '是否启用区域分割' },
                    splitIndex: { type: 'number', default: 3, description: '分割位置索引' },
                    leftLabel: { type: 'string', default: '左侧', description: '左侧区域标签' },
                    rightLabel: { type: 'string', default: '右侧', description: '右侧区域标签' },
                    splitStyle: { type: 'string', default: 'solid', options: ['solid', 'dashed', 'dotted'], description: '分割线样式' },
                    width: { type: 'number', default: 800, description: '图片宽度(px)' },
                    height: { type: 'number', default: 500, description: '图片高度(px)' },
                    format: { type: 'string', default: 'png', options: ['png'], description: '输出格式' },
                    pixelRatio: { type: 'number', default: 2, description: '像素倍率（清晰度）' }
                },
                returns: 'image/png',
                example: {
                    request: `curl -X POST http://localhost:16016/api/chart \\
  -H "Content-Type: application/json" \\
  -d '{
    "data": "产品, Q1, Q2, Q3, Q4\\n手机, 1200, 1800, 2100, 2500\\n平板, 800, 950, 1100, 1300",
    "chartType": "bar",
    "title": "季度销售对比",
    "theme": "default",
    "width": 800,
    "height": 500
  }' -o chart.png`,
                    response: 'PNG 图片二进制流'
                }
            },
            {
                method: 'GET',
                path: '/api/chart',
                description: '通过 URL 参数生成图表图片（适合简单场景）',
                params: {
                    data: { type: 'string', required: true, description: 'CSV 数据（换行用 \\n 分隔）' },
                    type: { type: 'string', default: 'bar', description: '图表类型' },
                    title: { type: 'string', description: '图表标题' },
                    theme: { type: 'string', default: 'default', description: '主题风格' },
                    width: { type: 'number', default: 800 },
                    height: { type: 'number', default: 500 }
                },
                returns: 'image/png',
                example: {
                    request: `curl "http://localhost:16016/api/chart?data=产品,Q1,Q2\\n手机,100,200\\n平板,150,250&type=bar&title=测试" -o chart.png`
                }
            },
            {
                method: 'POST',
                path: '/api/table',
                description: '通过 JSON 请求体生成表格图片',
                'Content-Type': 'application/json',
                params: {
                    data: { type: 'string', required: true, description: 'CSV 格式数据（第一行表头）' },
                    title: { type: 'string', default: '', description: '表格标题' },
                    theme: { type: 'string', default: 'default', options: ['default', 'dark', 'macarons', 'gradient', 'retro', 'ocean', 'forest', 'sunset', 'lavender', 'minimal', 'cherry', 'midnight', 'gold', 'coral', 'mint'], description: '主题风格' },
                    fontSize: { type: 'number', default: 14, description: '字体大小' },
                    cellPadding: { type: 'number', default: 12, description: '单元格内边距' },
                    borderWidth: { type: 'number', default: 1, description: '边框宽度' },
                    stripeRows: { type: 'boolean', default: true, description: '是否斑马纹' },
                    pixelRatio: { type: 'number', default: 2, description: '像素倍率（清晰度）' },
                    maxWidth: { type: 'number', default: 1200, description: '最大宽度(px)' }
                },
                returns: 'image/png',
                example: {
                    request: `curl -X POST http://localhost:16016/api/table \\
  -H "Content-Type: application/json" \\
  -d '{
    "data": "姓名, 部门, 职位, 薪资\\n张三, 技术部, 工程师, 15000\\n李四, 产品部, 产品经理, 18000\\n王五, 设计部, UI设计师, 16000",
    "title": "员工信息表",
    "theme": "default"
  }' -o table.png`,
                    response: 'PNG 图片二进制流'
                }
            },
            {
                method: 'GET',
                path: '/api/table',
                description: '通过 URL 参数生成表格图片',
                params: {
                    data: { type: 'string', required: true, description: 'CSV 数据（换行用 \\n 分隔）' },
                    title: { type: 'string', description: '表格标题' },
                    theme: { type: 'string', default: 'default', description: '主题风格' },
                    fontSize: { type: 'number', default: 14 },
                    stripeRows: { type: 'boolean', default: true }
                },
                returns: 'image/png',
                example: {
                    request: `curl "http://localhost:16016/api/table?data=产品,价格,库存\\n手机,2999,100\\n平板,1999,50&title=产品列表" -o table.png`
                }
            }
        ]
    });
});

// ===== 启动服务 =====
app.listen(PORT, '0.0.0.0', () => {
    console.log(`🚀 数据可视化图表生成器已启动`);
    console.log(`📊 Web UI:  http://0.0.0.0:${PORT}`);
    console.log(`📡 图表API: http://0.0.0.0:${PORT}/api/chart`);
    console.log(`📋 表格API: http://0.0.0.0:${PORT}/api/table`);
    console.log(`📖 文档:   http://0.0.0.0:${PORT}/api/docs`);
    console.log(`❤️  健康:   http://0.0.0.0:${PORT}/api/health`);
});