labs-mobile-applications/app/src/main/java/com/example/myapplication/MainActivity.kt

package com.example.myapplication

import android.net.ConnectivityManager
import android.net.Network
import android.net.NetworkCapabilities
import android.os.Bundle
import android.widget.TextView
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.core.content.getSystemService

class MainActivity : ComponentActivity() {

    private lateinit var tvStatus: TextView
    private lateinit var connectivityManager: ConnectivityManager

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        tvStatus = findViewById(R.id.tvNetworkStatus)
        connectivityManager = getSystemService()!!

        // Проверяем сеть при старте
        updateNetworkStatus()

        // Подписываемся на изменения сети
        connectivityManager.registerDefaultNetworkCallback(object : ConnectivityManager.NetworkCallback() {
            override fun onAvailable(network: Network) {
                runOnUiThread {
                    tvStatus.text = "Сеть доступна"
                    Toast.makeText(this@MainActivity, "Подключение появилось", Toast.LENGTH_SHORT).show()
                }
            }

            override fun onLost(network: Network) {
                runOnUiThread {
                    tvStatus.text = "Сеть недоступна"
                    Toast.makeText(this@MainActivity, "Подключение потеряно", Toast.LENGTH_SHORT).show()
                }
            }
        })
    }

    // Проверка текущего состояния сети
    private fun updateNetworkStatus() {
        val network = connectivityManager.activeNetwork
        val caps = connectivityManager.getNetworkCapabilities(network)
        val connected = caps?.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET) == true

        tvStatus.text = if (connected) "Сеть доступна" else "Сеть недоступна"
    }
}