Add TypeScript Express backend with love story APIs

.gitignore

@@ -1 +1,4 @@
-custom_order.class
+custom_order.class
+node_modules
+uploads
+npm-debug.log*

README.md

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 # Introduction to Java
 
 This your copy of the code for the java-course. The course itself is located in the issues of this repository.
+
+## Love Story Backend (Node + TypeScript)
+
+A lightweight Express API that powers the couple-themed front-end shown in the mockups. It includes photo uploads, chat history with playful bot replies, preset hero/banner text, love-letter storage, and simple game card metadata.
+
+### Getting started
+1. Install dependencies:
+   ```bash
+   npm install
+   ```
+2. Start the development server (watch mode with TypeScript):
+   ```bash
+   npm run dev
+   ```
+3. Or build and run the compiled server:
+   ```bash
+   npm run build
+   npm start
+   ```
+
+The API listens on `http://localhost:8080` by default and serves uploaded photos from `/uploads`.
+
+### Key endpoints
+- `GET /api/health` – health probe.
+- `GET /api/hero` – banner names, subtitle, and badge text.
+- `GET /api/stats` – summary counts for love days, photos, chats, and letter date.
+- `GET /api/game-cards` – metadata for the three game cards.
+- `GET /api/memories` – list of uploaded photos (in memory during runtime).
+- `POST /api/memories` – upload a photo (`photo` field) with optional `caption`.
+- `GET /api/chat/history` – conversation history.
+- `POST /api/chat/message` – send a message and receive a contextual bot reply.
+- `GET /api/love-letter` / `PUT /api/love-letter` – retrieve or update the shared letter.
+
+Uploads are stored on disk under `uploads/` (created automatically) and served as static files. The service keeps data in memory for simplicity; restart the server to reset state.

package.json

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+{
+  "name": "java-course-backend",
+  "version": "1.0.0",
+  "description": "Backend service to support the TypeScript front-end experience",
+  "main": "dist/server.js",
+  "scripts": {
+    "build": "tsc",
+    "start": "node dist/server.js",
+    "dev": "ts-node src/server.ts"
+  },
+  "dependencies": {
+    "cors": "^2.8.5",
+    "express": "^4.18.2",
+    "multer": "^1.4.5-lts.1"
+  },
+  "devDependencies": {
+    "@types/express": "^4.17.21",
+    "@types/multer": "^1.4.7",
+    "@types/node": "^20.10.5",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.3.3"
+  }
+}

src/server.ts

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+import cors from 'cors';
+import express, { Request, Response } from 'express';
+import fs from 'fs';
+import multer from 'multer';
+import path from 'path';
+
+// Simple in-memory stores that mimic persistent data.
+const memories: Memory[] = [];
+const chatHistory: ChatMessage[] = [];
+const loveLetter: LoveLetter = {
+  author: '宗睿',
+  recipient: '代琪',
+  title: '致 代琪',
+  content:
+    '亲爱的：\n\n感谢你成为我生活中的“专属温暖”。无论平静的午后，还是喧嚣的夜晚，我都想第一时间把喜悦和烦恼告诉你。\n\n这份网站想记录我们“回忆、美食、游戏、聊天”的每一个瞬间，它不只是一份作业，更是我们的数字小窝。希望未来有更多的故事被放进这里。\n\n愿你开心、健康，也愿我始终有勇气守护你。\n\n爱你的，宗睿',
+  date: new Date().toISOString()
+};
+
+interface Memory {
+  id: string;
+  fileName: string;
+  caption?: string;
+  createdAt: string;
+}
+
+interface ChatMessage {
+  id: string;
+  sender: 'user' | 'bot';
+  text: string;
+  createdAt: string;
+}
+
+interface LoveLetter {
+  author: string;
+  recipient: string;
+  title: string;
+  content: string;
+  date: string;
+}
+
+interface GameCard {
+  id: string;
+  title: string;
+  description: string;
+  action: string;
+}
+
+const app = express();
+const port = process.env.PORT || 8080;
+const uploadDir = path.join(__dirname, '..', 'uploads');
+
+if (!fs.existsSync(uploadDir)) {
+  fs.mkdirSync(uploadDir, { recursive: true });
+}
+
+const storage = multer.diskStorage({
+  destination: (_req, _file, cb) => cb(null, uploadDir),
+  filename: (_req, file, cb) => {
+    const uniqueSuffix = `${Date.now()}-${Math.round(Math.random() * 1e6)}`;
+    cb(null, `${uniqueSuffix}${path.extname(file.originalname)}`);
+  }
+});
+
+const upload = multer({ storage });
+
+app.use(cors());
+app.use(express.json());
+app.use('/uploads', express.static(uploadDir));
+
+app.get('/api/health', (_req: Request, res: Response) => {
+  res.json({ status: 'ok' });
+});
+
+app.get('/api/game-cards', (_req: Request, res: Response) => {
+  const cards: GameCard[] = [
+    {
+      id: 'hearts',
+      title: '爱情默契卡',
+      description: '10道甜蜜小问答，测试彼此的默契值并生成专属徽章。',
+      action: '开始'
+    },
+    {
+      id: 'puzzle',
+      title: '爱的拼图游戏',
+      description: '上传一张照片，自动生成 3x3 拼图，限时完成挑战。',
+      action: '组拼'
+    },
+    {
+      id: 'memory',
+      title: '甜蜜照片墙',
+      description: '把我们的照片、合影、旅行纪念都上传成相册墙。',
+      action: '看回忆'
+    }
+  ];
+
+  res.json(cards);
+});
+
+app.get('/api/memories', (_req: Request, res: Response) => {
+  res.json(memories);
+});
+
+app.post('/api/memories', upload.single('photo'), (req: Request, res: Response) => {
+  if (!req.file) {
+    return res.status(400).json({ error: '缺少图片文件' });
+  }
+
+  const memory: Memory = {
+    id: `${Date.now()}`,
+    fileName: `/uploads/${req.file.filename}`,
+    caption: req.body.caption,
+    createdAt: new Date().toISOString()
+  };
+
+  memories.unshift(memory);
+  res.status(201).json(memory);
+});
+
+app.get('/api/chat/history', (_req: Request, res: Response) => {
+  res.json(chatHistory);
+});
+
+app.post('/api/chat/message', (req: Request, res: Response) => {
+  const text: string | undefined = req.body?.text;
+
+  if (!text || !text.trim()) {
+    return res.status(400).json({ error: '消息内容不能为空' });
+  }
+
+  const userMessage: ChatMessage = {
+    id: `${Date.now()}-user`,
+    sender: 'user',
+    text: text.trim(),
+    createdAt: new Date().toISOString()
+  };
+
+  chatHistory.push(userMessage);
+
+  const botMessage: ChatMessage = {
+    id: `${Date.now()}-bot`,
+    sender: 'bot',
+    text: buildBotReply(text),
+    createdAt: new Date().toISOString()
+  };
+
+  chatHistory.push(botMessage);
+
+  res.status(201).json({ userMessage, botMessage });
+});
+
+app.get('/api/love-letter', (_req: Request, res: Response) => {
+  res.json(loveLetter);
+});
+
+app.put('/api/love-letter', (req: Request, res: Response) => {
+  const { author, recipient, title, content } = req.body;
+
+  if (!author || !recipient || !title || !content) {
+    return res.status(400).json({ error: '请填写完整的信件信息' });
+  }
+
+  loveLetter.author = author;
+  loveLetter.recipient = recipient;
+  loveLetter.title = title;
+  loveLetter.content = content;
+  loveLetter.date = new Date().toISOString();
+
+  res.json(loveLetter);
+});
+
+app.get('/api/hero', (_req: Request, res: Response) => {
+  res.json({
+    primaryName: '樊宗睿',
+    secondaryName: '代琪',
+    subtitle: '成为你的可爱，是我学会坚强的魔法',
+    badge: '恋爱日记'
+  });
+});
+
+app.get('/api/stats', (_req: Request, res: Response) => {
+  res.json({
+    loveDays: 288,
+    photosCount: memories.length,
+    chatCount: chatHistory.length,
+    letterDate: loveLetter.date
+  });
+});
+
+app.use((err: Error, _req: Request, res: Response, _next: () => void) => {
+  console.error(err);
+  res.status(500).json({ error: '服务器开小差了，请稍后再试' });
+});
+
+app.listen(port, () => {
+  console.log(`Love story backend is running on http://localhost:${port}`);
+});
+
+function buildBotReply(message: string): string {
+  const normalized = message.toLowerCase();
+
+  if (normalized.includes('开心') || normalized.includes('快乐')) {
+    return '听到你开心我也很开心，我们去吃好吃的庆祝一下吧！';
+  }
+
+  if (normalized.includes('难过') || normalized.includes('累')) {
+    return '抱抱你，累了就歇一会儿，我来给你煮奶茶，一起慢慢聊～';
+  }
+
+  if (normalized.includes('晚安')) {
+    return '晚安好梦，做个甜甜的梦，梦到我！';
+  }
+
+  return '收到！我一直在这儿陪你，告诉我更多细节，我们一起想办法。';
+}

tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "rootDir": "src",
+    "outDir": "dist",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true
+  },
+  "include": ["src/**/*"]
+}