package com.aistudio.bonjuteri.jwlry.data

import android.content.Context
import android.util.Log
import com.google.firebase.Timestamp
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.firestore.FirebaseFirestore
import kotlinx.coroutines.channels.awaitClose
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.callbackFlow
import kotlinx.coroutines.tasks.await

class FavoriteRepository(
    private val firestore: FirebaseFirestore,
    private val auth: FirebaseAuth
) {
    companion object {
        private const val TAG = "FavoriteRepository"

        @Volatile
        private var INSTANCE: FavoriteRepository? = null

        fun getInstance(context: Context): FavoriteRepository {
            return INSTANCE ?: synchronized(this) {
                INSTANCE ?: FavoriteRepository(
                    FirestoreHelper.getFirestore(context),
                    FirebaseAuth.getInstance()
                ).also { INSTANCE = it }
            }
        }
    }

    private fun requireUserId(): String {
        return auth.currentUser?.uid ?: throw IllegalStateException("Favori işlemleri için lütfen giriş yapınız.")
    }

    fun observeFavoriteProductIds(): Flow<Set<String>> = callbackFlow {
        val uid = auth.currentUser?.uid
        if (uid == null) {
            trySend(emptySet())
            close()
            return@callbackFlow
        }

        val favRef = firestore.collection("users").document(uid).collection("favorites")
        val listener = favRef.addSnapshotListener { snapshot, error ->
            if (error != null) {
                FirestoreHelper.handleFirestoreError(error, "observeFavoriteProductIds", favRef.path)
                trySend(emptySet())
                return@addSnapshotListener
            }
            val ids = snapshot?.documents?.map { it.id }?.toSet() ?: emptySet()
            trySend(ids)
        }
        awaitClose { listener.remove() }
    }

    suspend fun toggleFavorite(productId: String): Result<Boolean> {
        return try {
            val uid = requireUserId()
            val docRef = firestore.collection("users").document(uid)
                .collection("favorites").document(productId)

            val snapshot = docRef.get().await()
            val isNowFavorite = if (snapshot.exists()) {
                docRef.delete().await()
                false
            } else {
                docRef.set(mapOf("productId" to productId, "addedAt" to Timestamp.now())).await()
                true
            }
            Result.success(isNowFavorite)
        } catch (e: Throwable) {
            Log.e(TAG, "Favori değiştirme hatası: ${e.message}", e)
            Result.failure(Exception(e.localizedMessage ?: "Favori işlemi başarısız."))
        }
    }
}