import * as admin from 'firebase-admin'
import { onCall, HttpsError } from 'firebase-functions/v2/https'
import { recipientInQuietHours } from './quietHours'
import { sendPushToUser } from './push'
import { logger } from '../log'

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 = onCall(async (request) => {
  const callerId = request.auth?.uid
  if (!callerId) {
    throw new HttpsError('unauthenticated', 'Must be signed in.')
  }
  if (!request.app) {
    throw new 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 HttpsError('failed-precondition', 'Not in a couple.')
  }
  const coupleDoc = await db.collection('couples').doc(coupleId).get()
  if (!coupleDoc.exists) {
    throw new HttpsError('not-found', 'Couple not found.')
  }
  const userIds = (coupleDoc.data()?.userIds ?? []) as string[]
  const partnerId = userIds.find((id) => id !== callerId)
  if (!partnerId) {
    throw new HttpsError('failed-precondition', 'No partner found.')
  }

  try {
    // ── 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 as const }
      }
      tx.set(rateLimitRef, { count: count + 1, windowStart, updatedAt: now }, { merge: true })
      return { allowed: true as const }
    })
    if (!throttle.allowed) {
      throw new 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()
    const partnerData = partnerDoc.data()
    if (recipientInQuietHours(partnerData)) {
      logger.log(`[sendThinkingOfYouCallable] ${partnerId} in quiet hours — push suppressed (in-app kept)`)
      return { sent: true }
    }

    // ── FCM push ─────────────────────────────────────────────────────────────
    await sendPushToUser(
      db,
      admin.messaging(),
      partnerId,
      {
        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 },
      },
      partnerData,
    )

    logger.log(`[sendThinkingOfYouCallable] sent from ${callerId} to ${partnerId} in couple ${coupleId}`)
    return { sent: true }
  } catch (e) {
    if (e instanceof HttpsError) throw e
    logger.error('[sendThinkingOfYouCallable] failed', { error: String(e) })
    throw new HttpsError('internal', 'Failed to send. Please try again.')
  }
})