/**
 * 小红书封面 Playground
 * 用 node-canvas 画一张「截图风格」的封面，验证能否做出来。
 *
 * 运行：在 backend 目录下执行
 *   npm run playground:xhs-cover
 * 或
 *   npx ts-node scripts/xhs-cover-playground.ts
 *
 * 输出：backend/playground-xhs-cover.png（用系统看图打开即可）
 */

import { createCanvas, CanvasRenderingContext2D } from 'canvas';
import fs from 'fs/promises';
import path from 'path';

// 小红书常用比例 3:4，先用小尺寸快速验证（可改为 1080×1440 出高清）
const WIDTH = 540;
const HEIGHT = 720;

function wrapText(
  ctx: CanvasRenderingContext2D,
  text: string,
  maxWidth: number,
  fontSize: number,
  maxLines = 6
): string[] {
  const lines: string[] = [];
  let currentLine = '';
  for (const char of text.split('')) {
    const testLine = currentLine + char;
    const metrics = ctx.measureText(testLine);
    if (metrics.width > maxWidth && currentLine.length > 0) {
      lines.push(currentLine);
      currentLine = char;
      if (lines.length >= maxLines) break;
    } else {
      currentLine = testLine;
    }
  }
  if (currentLine.length > 0) lines.push(currentLine);
  return lines;
}

async function main() {
  const canvas = createCanvas(WIDTH, HEIGHT);
  const ctx = canvas.getContext('2d');

  // 1. 浅黄背景
  ctx.fillStyle = '#FFFDE7';
  ctx.fillRect(0, 0, WIDTH, HEIGHT);

  // 2. 网格（细线）
  const gridStep = 24;
  ctx.strokeStyle = 'rgba(0,0,0,0.06)';
  ctx.lineWidth = 0.5;
  for (let x = 0; x <= WIDTH; x += gridStep) {
    ctx.beginPath();
    ctx.moveTo(x, 0);
    ctx.lineTo(x, HEIGHT);
    ctx.stroke();
  }
  for (let y = 0; y <= HEIGHT; y += gridStep) {
    ctx.beginPath();
    ctx.moveTo(0, y);
    ctx.lineTo(WIDTH, y);
    ctx.stroke();
  }

  // 3. 白色圆角卡片（居中，留边距）
  const padding = 48;
  const cardX = padding;
  const cardY = 120;
  const cardW = WIDTH - padding * 2;
  const cardH = 380;
  const radius = 20;

  // 圆角矩形（兼容无 roundRect 的环境）
  function drawRoundRect(x: number, y: number, w: number, h: number, r: number) {
    ctx.beginPath();
    ctx.moveTo(x + r, y);
    ctx.lineTo(x + w - r, y);
    ctx.quadraticCurveTo(x + w, y, x + w, y + r);
    ctx.lineTo(x + w, y + h - r);
    ctx.quadraticCurveTo(x + w, y + h, x + w - r, y + h);
    ctx.lineTo(x + r, y + h);
    ctx.quadraticCurveTo(x, y + h, x, y + h - r);
    ctx.lineTo(x, y + r);
    ctx.quadraticCurveTo(x, y, x + r, y);
    ctx.closePath();
  }

  ctx.fillStyle = '#FFFFFF';
  drawRoundRect(cardX, cardY, cardW, cardH, radius);
  ctx.fill();

  ctx.strokeStyle = 'rgba(0,0,0,0.04)';
  ctx.lineWidth = 0.5;
  drawRoundRect(cardX, cardY, cardW, cardH, radius);
  ctx.stroke();

  // 4. 卡片顶部黄色小条（像截图里的 accent tab）
  const tabW = 60;
  const tabH = 12;
  const tabX = cardX + (cardW - tabW) / 2;
  const tabY = cardY - tabH / 2;
  ctx.fillStyle = '#FFD93D';
  drawRoundRect(tabX, tabY, tabW, tabH, 4);
  ctx.fill();

  // 5. 卡片内多行文字（加粗、黑色）
  const textX = cardX + 32;
  const textY = cardY + 44;
  const lineHeight = 38;
  const maxTextWidth = cardW - 64;

  // 尽量用系统里有的中文字体（Mac 有 PingFang SC）
  ctx.font = 'bold 26px "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif';
  ctx.fillStyle = '#000000';
  ctx.textAlign = 'left';

  const lines = [
    '谁懂!',
    '人生最好的事情',
    '不过是:',
    '拥有好朋友和',
    '幸福生活!',
  ];

  let y = textY;
  for (const line of lines) {
    const wrapped = wrapText(ctx, line, maxTextWidth, 26, 1);
    for (const seg of wrapped) {
      ctx.fillText(seg, textX, y);
      y += lineHeight;
    }
  }

  // 6. 卡片左下角装饰虚线（几条短横线）
  const dashY = cardY + cardH - 40;
  ctx.strokeStyle = '#FFD93D';
  ctx.lineWidth = 2;
  ctx.setLineDash([6, 6]);
  for (let i = 0; i < 4; i++) {
    ctx.beginPath();
    ctx.moveTo(textX + i * 36, dashY);
    ctx.lineTo(textX + i * 36 + 24, dashY);
    ctx.stroke();
  }
  ctx.setLineDash([]);

  // 7. 右下角「贴纸」占位（画一个圆 + 文字，模拟 emoji 位；真 emoji 可后续用图片贴）
  const stickerX = cardX + cardW - 72;
  const stickerY = cardY + cardH - 72;
  ctx.fillStyle = '#FFF3CD';
  ctx.beginPath();
  ctx.arc(stickerX, stickerY, 32, 0, Math.PI * 2);
  ctx.fill();
  ctx.strokeStyle = 'rgba(0,0,0,0.08)';
  ctx.lineWidth = 1;
  ctx.stroke();
  ctx.font = '20px "PingFang SC", sans-serif';
  ctx.fillStyle = '#333';
  ctx.textAlign = 'center';
  ctx.fillText('贴纸', stickerX, stickerY + 6);

  // 8. 导出 PNG
  const outPath = path.join(process.cwd(), 'playground-xhs-cover.png');
  const buffer = canvas.toBuffer('image/png');
  await fs.writeFile(outPath, buffer);

  console.log('✅ 已生成:', outPath);
  console.log('   用系统看图/预览打开即可查看效果。');
}

main().catch((e) => {
  console.error('生成失败:', e);
  process.exit(1);
});