/*
  # ============================================
  # code is placed under the MIT license
  #  Copyright (c) 2024 J-M-L
  #  For the Arduino Forum : https://forum.arduino.cc/u/j-m-l
  #
  #  Permission is hereby granted, free of charge, to any person obtaining a copy
  #  of this software and associated documentation files (the "Software"), to deal
  #  in the Software without restriction, including without limitation the rights
  #  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  #  copies of the Software, and to permit persons to whom the Software is
  #  furnished to do so, subject to the following conditions:
  #
  #  The above copyright notice and this permission notice shall be included in
  #  all copies or substantial portions of the Software.
  #
  #  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  #  IMPLIED, INCLUDING BUT NOT

  LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  #  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  #  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  #  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  #  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  #  THE SOFTWARE.
  #  ===============================================
*/

#include <WiFi.h>
#include <esp_sntp.h>

const char *ssid = "Wokwi-GUEST";
const char *wifiPassword = "";

// Array of NTP servers
const char *ntpServers[] = {
  "time.apple.com",         // Apple
  "time.google.com",        // Google
  "time.windows.com",       // Microsoft
  "pool.ntp.org",           // NTP Pool Project
  "time.nist.gov",          // NIST
  "time.cloudflare.com",    // Cloudflare
  "ntp.ubuntu.com",         // Ubuntu
};


const size_t numNtpServers = sizeof ntpServers / sizeof *ntpServers;
bool syncCompleted = false;
bool wifiConnected = false;
size_t currentServerIndex = 0;
unsigned long syncStartTime = 0;
const unsigned long maxSyncWait = 10000; // Max time to wait for each server in ms

void onNTPTimeSync(struct timeval *tv) {
  syncCompleted = true;
  time_t lastNtpSync = time(NULL);
  struct tm *pTime = localtime(&lastNtpSync);
  Serial.print("NTP synchronized with ");
  Serial.println(ntpServers[currentServerIndex]);
  Serial.println(pTime, "%d/%m/%Y %H:%M:%S");
}


void onWiFiStationConnected(WiFiEvent_t event, WiFiEventInfo_t info) {
  Serial.println("...Network connection established");
}

void syncWithCurrentServer() {
  Serial.print("Trying NTP server: ");
  Serial.println(ntpServers[currentServerIndex]);

  // Configure NTP server and timezone (here configigured for France)
  configTzTime("CET-1CEST-2,M3.5.0/02:00:00,M10.5.0/03:00:00", ntpServers[currentServerIndex]);

  // Set the NTP time sync callback
  sntp_set_time_sync_notification_cb(onNTPTimeSync);
  syncCompleted = false;
  syncStartTime = millis();
}

void onWiFiStationGotIP(WiFiEvent_t event, WiFiEventInfo_t info) {
  Serial.print("Obtained IP address = ");
  Serial.println(WiFi.localIP());
  wifiConnected = true;
  syncWithCurrentServer(); // Start syncing with the first server
}

void onWiFiStationDisconnected(WiFiEvent_t event, WiFiEventInfo_t info) {
  wifiConnected = false;
  Serial.print("Network disconnected. (reason: ");
  Serial.println(info.wifi_sta_disconnected.reason);
  Serial.println(")\nAttempting to reconnect.");
  WiFi.begin(ssid, wifiPassword, 6); // use 6 for wokwi, not needed on physical hardware
}

void requestFromNextServer() {
  if (++currentServerIndex >= numNtpServers) {
    Serial.println("All NTP servers have been tried. Cycling through.");
    currentServerIndex = 0;
  }
  syncWithCurrentServer();
}

void setup() {
  Serial.begin(115200);
  Serial.println("NTP time management demonstration");

  Serial.println("Connecting to WiFi network");
  WiFi.onEvent(onWiFiStationConnected, WiFiEvent_t::ARDUINO_EVENT_WIFI_STA_CONNECTED);
  WiFi.onEvent(onWiFiStationGotIP, WiFiEvent_t::ARDUINO_EVENT_WIFI_STA_GOT_IP);
  WiFi.onEvent(onWiFiStationDisconnected, WiFiEvent_t::ARDUINO_EVENT_WIFI_STA_DISCONNECTED);

  WiFi.begin(ssid, wifiPassword, 6);
}

void loop() {
  if (wifiConnected) {
    if (syncCompleted) {
      delay(1000); // Wait for 1 second before trying the next server
      requestFromNextServer();
    }
  } else {
    // Check if we have timed out waiting for sync
    if (millis() - syncStartTime >= maxSyncWait) {
      Serial.print("Failed to sync with ");
      Serial.println(ntpServers[currentServerIndex]);
      requestFromNextServer();
    }
  }
}