import webPush from 'web-push'
import { pool } from '../db.js'

let _publicKey = null

// VAPID keys: prefer env vars; fall back to auto-generated keys stored in config table.
// Keys are generated once on first boot and persist — regenerating would invalidate all
// existing subscriptions.
export async function ensureVapid() {
  if (_publicKey) return _publicKey

  let publicKey = process.env.VAPID_PUBLIC_KEY
  let privateKey = process.env.VAPID_PRIVATE_KEY
  const subject = process.env.VAPID_SUBJECT || 'mailto:noreply@localhost'

  if (!publicKey || !privateKey) {
    const { rows } = await pool.query("SELECT value FROM config WHERE key = 'vapid_keys'")
    if (rows.length && rows[0].value?.publicKey) {
      publicKey = rows[0].value.publicKey
      privateKey = rows[0].value.privateKey
    } else {
      const keys = webPush.generateVAPIDKeys()
      publicKey = keys.publicKey
      privateKey = keys.privateKey
      await pool.query(
        "INSERT INTO config (key, value) VALUES ('vapid_keys', $1) ON CONFLICT (key) DO UPDATE SET value = $1",
        [JSON.stringify({ publicKey, privateKey })]
      )
    }
  }

  webPush.setVapidDetails(subject, publicKey, privateKey)
  _publicKey = publicKey
  return publicKey
}

export async function sendPushToUser(userEmail, payload) {
  await ensureVapid()
  const { rows } = await pool.query(
    'SELECT * FROM push_subscriptions WHERE user_email = $1',
    [userEmail]
  )
  if (!rows.length) return

  const results = await Promise.allSettled(
    rows.map(sub =>
      webPush.sendNotification(
        { endpoint: sub.endpoint, keys: { p256dh: sub.p256dh, auth: sub.auth } },
        JSON.stringify(payload)
      )
    )
  )

  // Clean up expired or invalid subscriptions
  for (let i = 0; i < results.length; i++) {
    const r = results[i]
    if (r.status === 'rejected' && [404, 410].includes(r.reason?.statusCode)) {
      await pool.query('DELETE FROM push_subscriptions WHERE id = $1', [rows[i].id]).catch(() => {})
    }
  }
}

// targetEmail overrides task.assigned_to (used when reassigning via PATCH before DB update)
export function notifyAssignmentPush(task, locationName, targetEmail = null) {
  const email = targetEmail || (task.assigned_type === 'staff' ? task.assigned_to : null)
  if (!email) return Promise.resolve()
  return sendPushToUser(email, {
    title: `New task: ${task.title}`,
    body: `${locationName} — ${task.priority} priority`,
    url: '/maintenance/',
    tag: `maint-task-${task.id}`,
  }).catch(err => console.error('[push] notify failed:', err.message))
}