using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.Networking;

public class NetworkManager : MonoBehaviour
{

    [SerializeField]
    private float responseTimeThreshold = 1.0f;
    [SerializeField]
    private string checkUrl = "https://www.google.com";
    private float responseTime;
    private Coroutine checkInternetConnectivityCoroutine;
    private bool isOnline = false;
    public bool IsOnline
    {
        get
        {
            return isOnline;
        }
    }

    public UnityAction<bool> OnNetworkOnline;

    void Awake()
    {
        responseTime = 0.0f;
        checkInternetConnectivityCoroutine = null;
        isOnline = false;

        CheckNetwork();
    }

    void Update()
    {
        CheckNetwork();
    }

    private void CheckNetwork()
    {
        if (Application.internetReachability != NetworkReachability.NotReachable)
        {
            if (isOnline == false && checkInternetConnectivityCoroutine == null)
            {
                checkInternetConnectivityCoroutine = StartCoroutine(CheckInternetConnectivity());
            }
        }
        else
        {
            if (isOnline)
            {
                OnNetworkOnline?.Invoke(false);
            }
            isOnline = false;
        }
    }

    IEnumerator CheckInternetConnectivity()
    {
        float startTime = Time.time;

        using (UnityWebRequest www = UnityWebRequest.Get(checkUrl))
        {
            yield return www.SendWebRequest();

            responseTime = Time.time - startTime;
            if (www.result == UnityWebRequest.Result.Success && responseTime < responseTimeThreshold)
            {
                isOnline = true;
            }
            else
            {
                isOnline = false;
            }

            checkInternetConnectivityCoroutine = null;
            OnNetworkOnline?.Invoke(isOnline);
        }

        if (Time.time - startTime > responseTimeThreshold)
        {
            checkInternetConnectivityCoroutine = null;
            isOnline = false;
            OnNetworkOnline?.Invoke(false);

            yield break;
        }
    }
}