import * as functions from 'firebase-functions'
import * as admin from 'firebase-admin'
import { recipientInQuietHours } from '../notifications/quietHours'

const CHANNEL = 'partner_activity'
// Suppress duplicate "was this you?" pushes when a request doc is rapidly deleted+recreated (a compromised
// account could loop that to spam both partners). The in-app queue entry is still written every time.
export const SELF_ALERT_DEDUPE_MS = 60 * 1000

/** Pure dedupe decision: allow a self-alert push only if none was sent within the window. */
export function selfAlertAllowed(lastAlertAt: unknown, now: number): boolean {
  if (typeof lastAlertAt !== 'number') return true
  return now - lastAlertAt >= SELF_ALERT_DEDUPE_MS
}

/** Pure guard: fire the completion alert only on the single REQUESTED→READY status transition. */
export function isRestoreReadyTransition(beforeStatus: unknown, afterStatus: unknown): boolean {
  return afterStatus === 'READY' && beforeStatus !== 'READY'
}

/** All FCM tokens for a user: the legacy single field + the multi-device `fcmTokens` subcollection. */
async function gatherTokens(db: admin.firestore.Firestore, uid: string): Promise<string[]> {
  const tokens: string[] = []
  const userDoc = await db.collection('users').doc(uid).get()
  const legacy = userDoc.data()?.fcmToken
  if (typeof legacy === 'string' && legacy.length > 0) tokens.push(legacy)
  const tokenSnap = await db.collection('users').doc(uid).collection('fcmTokens').get()
  tokenSnap.docs.forEach((d) => {
    const t = d.data()?.token
    if (typeof t === 'string' && t.length > 0 && !tokens.includes(t)) tokens.push(t)
  })
  return tokens
}

/**
 * Write the durable in-app queue entry (always) and — unless quiet hours suppress it — push to every device.
 * `bypassQuietHours` is for security signals (the "was this you?" self-alert) that must not be silenced.
 */
async function queueAndPush(
  db: admin.firestore.Firestore,
  uid: string,
  opts: { type: string; title: string; body: string; coupleId: string; bypassQuietHours?: boolean }
): Promise<void> {
  const { type, title, body, coupleId, bypassQuietHours } = opts
  await db.collection('users').doc(uid).collection('notification_queue').add({
    type, title, body, read: false, createdAt: admin.firestore.FieldValue.serverTimestamp(),
  })

  const userDoc = await db.collection('users').doc(uid).get()
  if (!userDoc.exists) return
  if (!bypassQuietHours && recipientInQuietHours(userDoc.data())) return

  const tokens = await gatherTokens(db, uid)
  if (tokens.length === 0) return
  const results = await Promise.allSettled(
    tokens.map((token) =>
      admin.messaging().send({
        notification: { title, body },
        data: { type, couple_id: coupleId },
        token,
        android: { notification: { channelId: CHANNEL } },
      } as admin.messaging.Message)
    )
  )
  results.forEach((r, i) => {
    if (r.status === 'rejected') console.warn(`[restore] FCM failed for ${tokens[i]}:`, r.reason)
  })
}

/**
 * Fires when a member starts a partner-assisted restore
 * (`couples/{coupleId}/restore_requests/{recipientUid}` created on a new/wiped device). Sends TWO
 * notifications, isolated so one failing never blocks the other:
 *   1. To the OTHER partner — "help them restore" (high-signal; only quiet hours suppress it).
 *   2. To the RECIPIENT'S OWN devices — a security "was this you?" alert. If the real owner still holds a
 *      device (a phished password without device loss), this is how they learn a restore is happening.
 * No key material is read or logged — the request carries only a public key + a nonce.
 */
export const onRestoreRequested = functions.firestore
  .document('couples/{coupleId}/restore_requests/{recipientUid}')
  .onCreate(async (_snap, context) => {
    const { coupleId, recipientUid } = context.params as { coupleId: string; recipientUid: string }
    const db = admin.firestore()

    const coupleRef = db.collection('couples').doc(coupleId)
    const coupleDoc = await coupleRef.get()
    if (!coupleDoc.exists) return
    const userIds = (coupleDoc.data()?.userIds ?? []) as string[]
    // The recipient must be a member; notify the OTHER member (the partner who can help).
    if (!userIds.includes(recipientUid)) return
    const partnerId = userIds.find((u) => u !== recipientUid)
    if (!partnerId) return

    // Audit trail (no key material — actor/recipient/timestamp only).
    console.log(`[onRestoreRequested] couple=${coupleId} recipient=${recipientUid} partner=${partnerId}`)

    // 1) Partner "help them restore" — routine quiet hours apply.
    try {
      await queueAndPush(db, partnerId, {
        type: 'restore_requested',
        title: 'Help your partner restore 💜',
        body: 'They’re setting up on a new device. Tap to help.',
        coupleId,
      })
    } catch (e) {
      console.warn('[onRestoreRequested] partner notify failed:', e)
    }

    // 2) Recipient self-alert — security signal, bypasses quiet hours, deduped against create-loops.
    try {
      const now = Date.now()
      if (selfAlertAllowed(coupleDoc.data()?.lastRestoreSelfAlertAt, now)) {
        await coupleRef.set({ lastRestoreSelfAlertAt: now }, { merge: true })
        await queueAndPush(db, recipientUid, {
          type: 'restore_self_alert',
          title: 'New device is restoring your history',
          body: 'If this wasn’t you, secure your account now.',
          coupleId,
          bypassQuietHours: true,
        })
      }
    } catch (e) {
      console.warn('[onRestoreRequested] self-alert failed:', e)
    }
  })

/**
 * Fires when the partner writes the keybox (status flips to READY) — the moment the couple key actually
 * transfers. Alerts the RECIPIENT'S OWN devices that a restore just completed, the strongest "it happened"
 * signal for the real owner. Guarded to the single REQUESTED→READY transition (ignores decline/expire).
 */
export const onRestoreFulfilled = functions.firestore
  .document('couples/{coupleId}/restore_requests/{recipientUid}')
  .onUpdate(async (change, context) => {
    const before = change.before.data()
    const after = change.after.data()
    if (!isRestoreReadyTransition(before?.status, after?.status)) return

    const { coupleId, recipientUid } = context.params as { coupleId: string; recipientUid: string }
    const db = admin.firestore()

    const coupleDoc = await db.collection('couples').doc(coupleId).get()
    const userIds = (coupleDoc.data()?.userIds ?? []) as string[]
    if (!userIds.includes(recipientUid)) return

    console.log(`[onRestoreFulfilled] couple=${coupleId} recipient=${recipientUid}`)
    try {
      await queueAndPush(db, recipientUid, {
        type: 'restore_self_alert',
        title: 'Your history was just restored',
        body: 'A new device now has access. If this wasn’t you, secure your account now.',
        coupleId,
        bypassQuietHours: true,
      })
    } catch (e) {
      console.warn('[onRestoreFulfilled] self-alert failed:', e)
    }
  })