Server.js

const express = require('express');
const cors = require('cors');

const app = express();
const PORT = 5000;

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

// All queues (you can add more)
const queues = {
  canteen: {
    name: 'Canteen',
    current: 0,
    last: 0,
    tokens: []
  },
  library: {
    name: 'Library',
    current: 0,
    last: 0,
    tokens: []
  },
  office: {
    name: 'Admin Office',
    current: 0,
    last: 0,
    tokens: []
  },

  // Extra services
  hostel: {
    name: 'Hostel Office',
    current: 0,
    last: 0,
    tokens: []
  },
  sports: {
    name: 'Sports Complex',
    current: 0,
    last: 0,
    tokens: []
  },
  labroom: {
    name: 'Lab Equipment Room',
    current: 0,
    last: 0,
    tokens: []
  },
  transport: {
    name: 'Transport Office',
    current: 0,
    last: 0,
    tokens: []
  }
};

// Helper function to create token
function createToken(serviceKey, username) {
  const queue = queues[serviceKey];
  if (!queue) {
    throw new Error('Invalid service');
  }

  const newTokenNumber = queue.last + 1;
  const token = {
    tokenNumber: newTokenNumber,
    name: username || "Anonymous",
    status: "waiting",
    createdAt: new Date().toISOString()
  };

  queue.last = newTokenNumber;
  queue.tokens.push(token);

  const position = queue.tokens.filter(t => t.status === "waiting").length;

  return { token, position, current: queue.current };
}

// Get all services
app.get('/api/services', (req, res) => {
  const data = Object.keys(queues).map(key => ({
    key,
    name: queues[key].name
  }));
  res.json(data);
});

// Create token
app.post('/api/token', (req, res) => {
  try {
    const { service, name } = req.body;
    const { token, position, current } = createToken(service, name);

    res.status(201).json({
      message: "Token generated successfully",
      tokenNumber: token.tokenNumber,
      service,
      position,
      current
    });

  } catch (error) {
    res.status(400).json({ message: error.message });
  }
});

// Get queue status
app.get('/api/queue/:service', (req, res) => {
  const serviceKey = req.params.service;
  const queue = queues[serviceKey];

  if (!queue) return res.status(404).json({ message: "Service not found" });

  const waitingTokens = queue.tokens.filter(t => t.status === "waiting");
  const servedTokens = queue.tokens.filter(t => t.status === "served");

  res.json({
    service: serviceKey,
    name: queue.name,
    current: queue.current,
    last: queue.last,
    waitingCount: waitingTokens.length,
    servedCount: servedTokens.length,
    waitingTokens,
    servedTokens
  });
});

// Admin: Next token
app.post('/api/queue/:service/next', (req, res) => {
  const serviceKey = req.params.service;
  const queue = queues[serviceKey];

  if (!queue) return res.status(404).json({ message: "Service not found" });

  const nextToken = queue.tokens.find(t => t.status === "waiting");
  if (!nextToken) {
    return res.json({ message: "No more tokens", current: queue.current });
  }

  nextToken.status = "served";
  queue.current = nextToken.tokenNumber;

  res.json({
    message: "Next token served",
    current: queue.current,
    servedToken: nextToken
  });
});

// Admin: Reset queue
app.post('/api/queue/:service/reset', (req, res) => {
  const serviceKey = req.params.service;
  const queue = queues[serviceKey];

  if (!queue) return res.status(404).json({ message: "Service not found" });

  queue.current = 0;
  queue.last = 0;
  queue.tokens = [];

  res.json({ message: "Queue reset successfully" });
});

// Root test
app.get('/', (req, res) => {
  res.send("Smart Queue Backend is Running Successfully");
});

app.listen(PORT, () => {
  console.log(`Smart Queue backend running on http://localhost:${PORT}`);
});