import express from 'express'
import cors from 'cors'
import dotenv from 'dotenv'
import { pool } from './db.js'

dotenv.config()

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

// Simple health
app.get('/api/health', (req, res) => res.json({ ok: true }))

// List available cargobikes
app.get('/api/bikes', async (req, res) => {
  // fixed bike types
  const bikes = [1000, 2000, 3000, 4000, 5000]
  res.json({ bikes })
})

// Create a booking (supports single bike_type or multiple bike_types)
app.post('/api/bookings', async (req, res) => {
  try {
    const { bike_type, bike_types, start_date, end_date, start_time, end_time, name, email } = req.body

    const multi = Array.isArray(bike_types) ? bike_types.filter((v) => Number.isFinite(Number(v))).map(Number) : []
    const single = Number.isFinite(Number(bike_type)) ? Number(bike_type) : null

    if ((!single && multi.length === 0) || !start_date || !end_date || !name || !email) {
      return res.status(400).json({ error: 'Missing fields' })
    }

    // Explicitly set status to 'pending' to avoid relying solely on DB defaults
    const text = `INSERT INTO bookings(bike_type, bike_types, start_date, start_time, end_date, end_time, name, email, status)
                  VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9) RETURNING *`
    const values = [single, multi.length ? multi.join(',') : null, start_date, start_time || null, end_date, end_time || null, name, email, 'pending']
    const result = await pool.query(text, values)
    res.status(201).json({ booking: result.rows[0] })
  } catch (err) {
    console.error(err)
    res.status(500).json({ error: 'Server error' })
  }
})

// List bookings (simple)
app.get('/api/bookings', async (req, res) => {
  try {
    const result = await pool.query('SELECT * FROM bookings ORDER BY created_at DESC LIMIT 100')
    res.json({ bookings: result.rows })
  } catch (err) {
    console.error(err)
    res.status(500).json({ error: 'Server error' })
  }
})

// Update booking status
app.patch('/api/bookings/:id/status', async (req, res) => {
  try {
    const id = Number(req.params.id)
    if (!Number.isFinite(id)) return res.status(400).json({ error: 'Invalid id' })

    const { status } = req.body || {}
    const allowed = ['pending', 'accepted', 'refused']
    if (!allowed.includes(status)) return res.status(400).json({ error: 'Invalid status' })

    // Read current status to enforce immutability once accepted
    const current = await pool.query('SELECT status FROM bookings WHERE id = $1', [id])
    if (current.rowCount === 0) return res.status(404).json({ error: 'Booking not found' })
    const curr = current.rows[0].status
    if (curr === 'accepted' && status !== 'accepted') {
      return res.status(400).json({ error: 'Accepted bookings cannot change status' })
    }

    const result = await pool.query('UPDATE bookings SET status = $1 WHERE id = $2 RETURNING *', [status, id])
    if (result.rowCount === 0) return res.status(404).json({ error: 'Booking not found' })

    res.json({ booking: result.rows[0] })
  } catch (err) {
    console.error(err)
    res.status(500).json({ error: 'Server error' })
  }
})

// Update booking fields (non-status)
app.patch('/api/bookings/:id', async (req, res) => {
  try {
    const id = Number(req.params.id)
    if (!Number.isFinite(id)) return res.status(400).json({ error: 'Invalid id' })

    const allowed = ['bike_type', 'bike_types', 'start_date', 'start_time', 'end_date', 'end_time', 'name', 'email']
    const entries = Object.entries(req.body || {}).filter(([k, v]) => allowed.includes(k))

    if (entries.length === 0) return res.status(400).json({ error: 'No valid fields to update' })

    // Build dynamic update
    const sets = []
    const values = []
    for (let i = 0; i < entries.length; i++) {
      const [k, v] = entries[i]
      sets.push(`${k} = $${i + 1}`)
      values.push(v)
    }
    values.push(id)

    const sql = `UPDATE bookings SET ${sets.join(', ')} WHERE id = $${values.length} RETURNING *`
    const result = await pool.query(sql, values)
    if (result.rowCount === 0) return res.status(404).json({ error: 'Booking not found' })

    res.json({ booking: result.rows[0] })
  } catch (err) {
    console.error(err)
    res.status(500).json({ error: 'Server error' })
  }
})

// Delete a booking by id
app.delete('/api/bookings/:id', async (req, res) => {
  try {
    const id = Number(req.params.id)
    if (!Number.isFinite(id)) return res.status(400).json({ error: 'Invalid id' })

    const result = await pool.query('DELETE FROM bookings WHERE id = $1 RETURNING *', [id])
    if (result.rowCount === 0) return res.status(404).json({ error: 'Booking not found' })

    res.json({ ok: true, booking: result.rows[0] })
  } catch (err) {
    console.error(err)
    res.status(500).json({ error: 'Server error' })
  }
})

// --- ensure DB tables exist (auto-migration for dev) ---
async function ensureTables() {
  const createSql = `
    CREATE TABLE IF NOT EXISTS bookings (
      id SERIAL PRIMARY KEY,
      bike_type INTEGER,
      bike_types TEXT,
      start_date DATE NOT NULL,
      start_time TIME,
      end_date DATE NOT NULL,
      end_time TIME,
      name TEXT NOT NULL,
      email TEXT NOT NULL,
      status TEXT NOT NULL DEFAULT 'pending',
      created_at TIMESTAMP WITH TIME ZONE DEFAULT now()
    );
  `

  try {
    await pool.query(createSql)
    // Ensure columns and constraints for backward compatibility
    await pool.query(`ALTER TABLE bookings ADD COLUMN IF NOT EXISTS start_time TIME;`)
    await pool.query(`ALTER TABLE bookings ADD COLUMN IF NOT EXISTS end_time TIME;`)
    await pool.query(`ALTER TABLE bookings ADD COLUMN IF NOT EXISTS bike_types TEXT;`)
    await pool.query(`ALTER TABLE bookings ADD COLUMN IF NOT EXISTS status TEXT;`)
    // Ensure default and not-null for status
    await pool.query(`ALTER TABLE bookings ALTER COLUMN status SET DEFAULT 'pending';`)
    await pool.query(`UPDATE bookings SET status = 'pending' WHERE status IS NULL;`)
    await pool.query(`ALTER TABLE bookings ALTER COLUMN status SET NOT NULL;`)
    // bike_type nullable for multi-type support
    await pool.query(`ALTER TABLE bookings ALTER COLUMN bike_type DROP NOT NULL;`)
    console.log('Database: bookings table is present (created/migrated if needed)')
  } catch (err) {
    console.warn('Warning: could not ensure bookings table (DB may be unavailable).', err.message)
  }
}

const port = process.env.PORT || 3000

// Run migrations (if possible) then start server
;(async () => {
  await ensureTables()
  app.listen(port, () => console.log(`Backend listening on port ${port}`))
})()