import express from 'express'; import cors from 'cors'; import fs from 'fs'; import path from 'path'; import { fileURLToPath } from 'url'; import { v4 as uuidv4 } from 'uuid';

const __filename = fileURLToPath(import.meta.url); const __dirname = path.dirname(__filename); const rootDir = path.resolve(__dirname, '..'); const dataDir = path.join(rootDir, 'data'); const dataFile = path.join(dataDir, 'learning-data.json');

const app = express(); const PORT = process.env.PORT || 3001;

app.use(cors()); app.use(express.json());

const ensureDb = () => { if (!fs.existsSync(dataDir)) { fs.mkdirSync(dataDir, { recursive: true }); }

if (!fs.existsSync(dataFile)) { const defaultState = { user: { id: 'default-user', name: 'Learning Explorer', createdAt: new Date().toISOString() }, languages: [ { id: 'python-track', name: 'Python', totalTopics: 20, completedTopics: 8, hoursPerTopic: 1.5, color: '#4f46e5' }, { id: 'javascript-track', name: 'JavaScript', totalTopics: 18, completedTopics: 11, hoursPerTopic: 1.2, color: '#f59e0b' }, { id: 'c-track', name: 'C', totalTopics: 15, completedTopics: 6, hoursPerTopic: 1.8, color: '#22c55e' } ] };

fs.writeFileSync(dataFile, JSON.stringify(defaultState, null, 2));

} };

const readData = () => { ensureDb(); const raw = fs.readFileSync(dataFile, 'utf8'); return JSON.parse(raw); };

const saveData = (data) => { fs.writeFileSync(dataFile, JSON.stringify(data, null, 2)); };

const normalizeLanguage = (language) => { const totalTopics = Number(language.totalTopics) || 0; const completedTopics = Math.min(Math.max(Number(language.completedTopics || 0), 0), totalTopics); const hoursPerTopic = Number(language.hoursPerTopic) || 0.5;

return { id: language.id || uuidv4(), name: String(language.name || 'New Language').trim(), totalTopics, completedTopics, hoursPerTopic, color: language.color || '#6366f1' }; };

app.get('/api/health', (_, res) => { res.json({ ok: true, message: 'Learning tracker API is running' }); });

app.get('/api/dashboard', (_, res) => { const data = readData(); const languages = (data.languages || []).map((language) => { const totalTopics = Number(language.totalTopics || 0); const completedTopics = Math.min(Number(language.completedTopics || 0), totalTopics); const totalHours = totalTopics > 0 ? (totalTopics - completedTopics) * Number(language.hoursPerTopic || 0.5) : 0;

return {
  ...language,
  completedTopics,
  totalHours
};

});

res.json({ user: data.user, languages }); });

app.put('/api/profile', (req, res) => { const { name } = req.body || {}; if (!name || !String(name).trim()) { return res.status(400).json({ message: 'Profile name is required' }); }

const data = readData(); data.user = { ...data.user, name: String(name).trim() }; saveData(data);

res.json({ user: data.user, languages: data.languages }); });

app.post('/api/languages', (req, res) => { const { name, totalTopics, completedTopics, hoursPerTopic, color } = req.body || {};

if (!name || !String(name).trim()) { return res.status(400).json({ message: 'Language name is required' }); }

const data = readData(); const language = normalizeLanguage({ name, totalTopics, completedTopics, hoursPerTopic, color });

data.languages = [...(data.languages || []), language]; saveData(data);

res.status(201).json({ message: 'Language added successfully', languages: data.languages }); });

app.put('/api/languages/:id', (req, res) => { const { id } = req.params; const data = readData(); const index = data.languages.findIndex((language) => language.id === id);

if (index === -1) { return res.status(404).json({ message: 'Language not found' }); }

const merged = normalizeLanguage({ ...data.languages[index], ...req.body, totalTopics: req.body.totalTopics ?? data.languages[index].totalTopics, completedTopics: req.body.completedTopics ?? data.languages[index].completedTopics, hoursPerTopic: req.body.hoursPerTopic ?? data.languages[index].hoursPerTopic, color: req.body.color ?? data.languages[index].color });

data.languages[index] = merged; saveData(data);

res.json({ message: 'Language updated successfully', languages: data.languages }); });

app.delete('/api/languages/:id', (req, res) => { const { id } = req.params; const data = readData(); const filtered = (data.languages || []).filter((language) => language.id !== id);

if (filtered.length === data.languages.length) { return res.status(404).json({ message: 'Language not found' }); }

data.languages = filtered; saveData(data);

res.json({ message: 'Language deleted successfully', languages: data.languages }); });

app.use(express.static(path.join(rootDir, 'dist')));

app.get('*', (req, res) => { if (req.path.startsWith('/api/')) { return res.status(404).json({ message: 'API route not found' }); } res.sendFile(path.join(rootDir, 'dist', 'index.html')); });

ensureDb();

app.listen(PORT, () => { console.log(Learning tracker API running on port ${PORT}); });