package com.taf.attendance.sync

import android.content.Context
import android.net.ConnectivityManager
import android.net.NetworkCapabilities
import android.util.Log
import androidx.work.CoroutineWorker
import androidx.work.WorkerParameters
import com.taf.attendance.data.AttendanceRepository

/**
 * Background worker that syncs pending attendance records when device comes online.
 * Runs periodically to check for unsynced records and attempt to upload them.
 */
class SyncWorker(
    context: Context,
    params: WorkerParameters
) : CoroutineWorker(context, params) {

    private val repository = AttendanceRepository(applicationContext)

    override suspend fun doWork(): Result {
        Log.d("SyncWorker", "Starting sync work")
        
        return try {
            // Check if device is online
            if (!isNetworkAvailable()) {
                Log.d("SyncWorker", "No network available, skipping sync")
                return Result.success()
            }

            // Check if there are unsynced records
            val unsyncedCount = repository.getUnsyncedCount()
            Log.d("SyncWorker", "Found $unsyncedCount unsynced records")
            
            if (unsyncedCount > 0) {
                // Attempt to sync pending records
                repository.sync()
                Log.d("SyncWorker", "Sync completed successfully")
            }
            
            Result.success()
        } catch (e: Exception) {
            Log.e("SyncWorker", "Sync failed", e)
            // Retry on network errors, fail permanently on auth errors
            if (e.message?.contains("401") == true || e.message?.contains("403") == true) {
                Result.failure()
            } else {
                Result.retry()
            }
        }
    }

    private fun isNetworkAvailable(): Boolean {
        val connectivityManager = applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val network = connectivityManager.activeNetwork ?: return false
        val networkCapabilities = connectivityManager.getNetworkCapabilities(network) ?: return false
        
        return networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) ||
               networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) ||
               networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET)
    }
}