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

const THINKING_OF_YOU_MAX_PER_DAY = 10
const THINKING_OF_YOU_WINDOW_MS = 24 * 60 * 60 * 1000 // rolling 24h

/**
 * "Thinking of you 💜" — a one-tap affectionate nudge from the partner sheet.
 *
 * Partner-initiated (like the gentle reminder), so it is guarded by a rate limit + quiet hours rather
 * than a per-type opt-out:
 *  - Per-user rolling 24h cap (transaction on `rate_limits/{uid}_thinking_of_you`) so it can't be looped.
 *  - Quiet hours: during the recipient's window the FCM push is suppressed, but the in-app record is
 *    still written so the love is waiting when they wake. (Improvement over the gentle reminder.)
 *
 * Writes a partner-safe `notification_queue` entry (in-app + the "Together" feed) and an FCM push.
 */
export const sendThinkingOfYouCallable = functions.https.onCall(async (_data, context) => {
  const callerId = context.auth?.uid
  if (!callerId) {
    throw new functions.https.HttpsError('unauthenticated', 'Must be signed in.')
  }
  if (!context.app) {
    throw new functions.https.HttpsError('failed-precondition', 'App Check verification required.')
  }

  const db = admin.firestore()

  // ── Resolve couple + partner ─────────────────────────────────────────────
  const userDoc = await db.collection('users').doc(callerId).get()
  const coupleId = userDoc.data()?.coupleId as string | undefined
  if (!coupleId) {
    throw new functions.https.HttpsError('failed-precondition', 'Not in a couple.')
  }
  const coupleDoc = await db.collection('couples').doc(coupleId).get()
  if (!coupleDoc.exists) {
    throw new functions.https.HttpsError('not-found', 'Couple not found.')
  }
  const userIds = (coupleDoc.data()?.userIds ?? []) as string[]
  const partnerId = userIds.find((id) => id !== callerId)
  if (!partnerId) {
    throw new functions.https.HttpsError('failed-precondition', 'No partner found.')
  }

  // ── Per-user rolling rate limit (transactional) ──────────────────────────
  const now = admin.firestore.Timestamp.now()
  const rateLimitRef = db.collection('rate_limits').doc(`${callerId}_thinking_of_you`)
  const throttle = await db.runTransaction(async (tx) => {
    const snap = await tx.get(rateLimitRef)
    const data = snap.data()
    let windowStart = now
    let count = 0
    if (snap.exists && data) {
      windowStart = data.windowStart as admin.firestore.Timestamp
      count = typeof data.count === 'number' ? data.count : 0
      if (now.toMillis() - windowStart.toMillis() >= THINKING_OF_YOU_WINDOW_MS) {
        windowStart = now
        count = 0
      }
    }
    if (count >= THINKING_OF_YOU_MAX_PER_DAY) {
      return { allowed: false }
    }
    tx.set(rateLimitRef, { count: count + 1, windowStart, updatedAt: now }, { merge: true })
    return { allowed: true }
  })
  if (!throttle.allowed) {
    throw new functions.https.HttpsError(
      'resource-exhausted',
      "You've sent a few already — give it a moment."
    )
  }

  // ── In-app record (always — shows in-app + the Together feed) ────────────
  await db.collection('users').doc(partnerId).collection('notification_queue').add({
    type: 'thinking_of_you',
    title: 'Your partner is thinking of you 💜',
    body: 'Tap to send one back.',
    read: false,
    createdAt: admin.firestore.FieldValue.serverTimestamp(),
  })

  // ── Quiet hours: keep the in-app record, suppress the disruptive push ─────
  const partnerDoc = await db.collection('users').doc(partnerId).get()
  if (recipientInQuietHours(partnerDoc.data())) {
    console.log(`[sendThinkingOfYouCallable] ${partnerId} in quiet hours — push suppressed (in-app kept)`)
    return { sent: true }
  }

  // ── FCM push ─────────────────────────────────────────────────────────────
  const tokens: string[] = []
  const legacy = partnerDoc.data()?.fcmToken
  if (typeof legacy === 'string' && legacy.length > 0) tokens.push(legacy)
  const tokenSnap = await db.collection('users').doc(partnerId).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)
  })

  if (tokens.length > 0) {
    const results = await Promise.allSettled(
      tokens.map((token) =>
        admin.messaging().send({
          token,
          notification: { title: 'Your partner is thinking of you 💜', body: 'Tap to send one back.' },
          android: { notification: { channelId: 'partner_activity' } }, // E-OBS
          data: { type: 'thinking_of_you', couple_id: coupleId },
        })
      )
    )
    results.forEach((r, i) => {
      if (r.status === 'rejected') {
        console.warn(`[sendThinkingOfYouCallable] FCM failed for token ${tokens[i]}:`, r.reason)
      }
    })
    await pruneDeadTokens(db, partnerId, tokens, results)
  }

  console.log(`[sendThinkingOfYouCallable] sent from ${callerId} to ${partnerId} in couple ${coupleId}`)
  return { sent: true }
})