import express from 'express'
import cors from 'cors'
import { Parser } from 'json2csv'
import { v4 as uuidv4 } from 'uuid'

const app = express()
const port = 3000

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

// --- In-memory database for MVP ---
const users = [
  { id: 1, username: 'worker', password: 'password', role: 'worker', fullName: 'John Doe' },
  { id: 2, username: 'worker2', password: 'password', role: 'worker', fullName: 'Jane Smith' },
  { id: 3, username: 'manager', password: 'password', role: 'manager', fullName: 'Manager Bob' },
]

let qrCodes = [
  {
    id: 'FACTORY-MAIN-ENTRANCE',
    name: 'Factory Main Entrance',
    isActive: true,
    createdAt: new Date().toISOString(),
  },
  {
    id: 'WAREHOUSE-SECTION-A',
    name: 'Warehouse Section A',
    isActive: true,
    createdAt: new Date().toISOString(),
  },
  {
    id: 'ASSEMBLY-LINE-1',
    name: 'Assembly Line 1',
    isActive: false,
    createdAt: new Date().toISOString(),
  },
]

let clockEvents = [
  // Sample data for testing reports
  {
    id: 1,
    userId: 1,
    eventType: 'clock_in',
    timestamp: '2025-06-10T09:00:00.000Z',
    qrCodeUsedId: 'FACTORY-MAIN-ENTRANCE',
    qrCodeUsedName: 'Factory Main Entrance',
  },
  {
    id: 2,
    userId: 1,
    eventType: 'clock_out',
    timestamp: '2025-06-10T17:30:00.000Z',
    qrCodeUsedId: 'FACTORY-MAIN-ENTRANCE',
    qrCodeUsedName: 'Factory Main Entrance',
  },
  {
    id: 3,
    userId: 2,
    eventType: 'clock_in',
    timestamp: '2025-06-10T09:05:00.000Z',
    qrCodeUsedId: 'WAREHOUSE-SECTION-A',
    qrCodeUsedName: 'Warehouse Section A',
  },
  {
    id: 4,
    userId: 2,
    eventType: 'clock_out',
    timestamp: '2025-06-10T17:35:00.000Z',
    qrCodeUsedId: 'WAREHOUSE-SECTION-A',
    qrCodeUsedName: 'Warehouse Section A',
  },
  {
    id: 5,
    userId: 1,
    eventType: 'clock_in',
    timestamp: '2025-06-11T08:58:00.000Z',
    qrCodeUsedId: 'FACTORY-MAIN-ENTRANCE',
    qrCodeUsedName: 'Factory Main Entrance',
  }, // Missing clock out
]

let eventId = clockEvents.length + 1

// --- Helper Functions ---
const calculateHours = (events) => {
  const userHours = {}
  const pairedEvents = {}

  // Group events by user
  events.forEach((event) => {
    if (!pairedEvents[event.userId]) {
      pairedEvents[event.userId] = []
    }
    pairedEvents[event.userId].push(event)
  })

  for (const userId in pairedEvents) {
    const userEvents = pairedEvents[userId].sort(
      (a, b) => new Date(a.timestamp) - new Date(b.timestamp),
    )
    let totalHours = 0
    let clockInTime = null

    userEvents.forEach((event) => {
      if (event.eventType === 'clock_in' && !clockInTime) {
        clockInTime = new Date(event.timestamp)
      } else if (event.eventType === 'clock_out' && clockInTime) {
        const clockOutTime = new Date(event.timestamp)
        const diffMs = clockOutTime - clockInTime
        totalHours += diffMs / (1000 * 60 * 60)
        clockInTime = null // Reset for next pair
      }
    })

    const worker = users.find((u) => u.id === parseInt(userId))
    userHours[userId] = {
      userId,
      fullName: worker ? worker.fullName : `User ${userId}`,
      totalHours: parseFloat(totalHours.toFixed(2)),
      hasIncomplete: clockInTime !== null, // Mark if there's a pending clock-in
    }
  }
  return Object.values(userHours)
}

// --- API Endpoints ---

// Auth Endpoint
app.post('/api/auth/login', (req, res) => {
  const { username, password } = req.body
  const user = users.find((u) => u.username === username && u.password === password)
  if (user) {
    res.json({ message: 'Login successful', role: user.role, userId: user.id })
  } else {
    res.status(401).json({ message: 'Invalid credentials' })
  }
})

// Worker Clock In/Out Endpoint
app.post('/api/clock', (req, res) => {
  const { userId, eventType, qrCodeValue, latitude, longitude } = req.body
  const validQrCode = qrCodes.find((qr) => qr.id === qrCodeValue && qr.isActive)
  if (!validQrCode) return res.status(400).json({ message: 'Invalid or inactive QR Code.' })

  const lastEvent = clockEvents.filter((e) => e.userId === userId).pop()
  if (lastEvent && lastEvent.eventType === eventType)
    return res
      .status(400)
      .json({ message: `You are already clocked ${eventType === 'clock_in' ? 'in' : 'out'}.` })

  const newEvent = {
    id: eventId++,
    userId,
    eventType,
    timestamp: new Date().toISOString(),
    qrCodeUsedId: qrCodeValue,
    qrCodeUsedName: validQrCode.name, // Add human-readable name
    latitude,
    longitude,
  }
  clockEvents.push(newEvent)
  res.status(201).json(newEvent)
})

// Worker Status Endpoint
app.get('/api/worker/status/:userId', (req, res) => {
  const userId = parseInt(req.params.userId, 10)
  const lastEvent = clockEvents.filter((event) => event.userId === userId).pop()
  if (lastEvent) {
    res.json(lastEvent)
  } else {
    res.json({ eventType: 'clock_out' })
  }
})

// Worker History Endpoint
app.get('/api/worker/clock-history/:userId', (req, res) => {
  const userId = parseInt(req.params.userId, 10)
  const userEvents = clockEvents.filter((event) => event.userId === userId)
  res.json(userEvents)
})

// --- Manager Endpoints ---

// Reporting Endpoint
app.get('/api/managers/hours-report', (req, res) => {
  const { startDate, endDate, format } = req.query

  let filteredEvents = clockEvents
  if (startDate && endDate) {
    const endOfDay = new Date(endDate)
    endOfDay.setHours(23, 59, 59, 999) // Include the whole end day
    filteredEvents = clockEvents.filter((event) => {
      const eventDate = new Date(event.timestamp)
      return eventDate >= new Date(startDate) && eventDate <= endOfDay
    })
  }

  const reportData = calculateHours(filteredEvents)

  if (format === 'csv') {
    const json2csvParser = new Parser({
      fields: ['userId', 'fullName', 'totalHours', 'hasIncomplete'],
    })
    const csv = json2csvParser.parse(reportData)
    res.header('Content-Type', 'text/csv')
    res.attachment(`hours-report-${new Date().toISOString().split('T')[0]}.csv`)
    return res.send(csv)
  }

  res.json(reportData)
})

// GET QR Codes Endpoint
app.get('/api/managers/qr-codes', (req, res) => {
  res.json(qrCodes.sort((a, b) => new Date(b.createdAt) - new Date(a.createdAt)))
})

// POST (Add new) QR Code Endpoint
app.post('/api/managers/qr-codes', (req, res) => {
  const { name } = req.body
  if (!name) {
    return res.status(400).json({ message: 'QR Code name is required.' })
  }
  const newQrCode = {
    id: uuidv4(),
    name,
    isActive: true,
    createdAt: new Date().toISOString(),
  }
  qrCodes.push(newQrCode)
  res.status(201).json(newQrCode)
})

// PUT (Update) QR Code Endpoint
app.put('/api/managers/qr-codes/:id', (req, res) => {
  const { id } = req.params
  const { isActive } = req.body
  const qrCodeIndex = qrCodes.findIndex((qr) => qr.id === id)

  if (qrCodeIndex === -1) {
    return res.status(404).json({ message: 'QR Code not found.' })
  }
  if (typeof isActive !== 'boolean') {
    return res.status(400).json({ message: 'isActive must be a boolean.' })
  }

  qrCodes[qrCodeIndex].isActive = isActive
  res.json(qrCodes[qrCodeIndex])
})

// DELETE QR Code Endpoint
app.delete('/api/managers/qr-codes/:id', (req, res) => {
  const { id } = req.params
  const initialLength = qrCodes.length
  qrCodes = qrCodes.filter((qr) => qr.id !== id)

  if (qrCodes.length === initialLength) {
    return res.status(404).json({ message: 'QR Code not found.' })
  }

  res.status(204).send()
})

// --- Server Start ---
app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`)
})