// https://randomnerdtutorials.com/esp32-useful-wi-fi-functions-arduino/


#include "WiFi.h"

// function declarations
void wlan_scan (void);
void initWiFi (void);
void reconnecting (void);


// Replace with your network credentials - WiFi credentials
const char* ssid = "Wokwi-GUEST";
const char* password = "";


// Set your Static IP address - place outside loop() / setup()
IPAddress local_IP(10, 10, 0, 10);
IPAddress gateway(10, 10, 0, 138);
IPAddress subnet(255, 255, 255, 0);
IPAddress primaryDNS(8, 8, 8, 8);       // optional
IPAddress secondaryDNS(8, 8, 4, 4);     // optional


//  ------------------- setup  ---------------------------
void setup() {
  Serial.begin(115200);
  // Set WiFi to station mode and disconnect from an AP if it was previously connected
  // WIFI_STA	station mode: the ESP32 connects to an access point
  // WIFI_AP	access point mode: stations can connect to the ESP32
  // WIFI_AP_STA	access point and a station connected to another access point

  WiFi.mode(WIFI_STA);              // WiFi-Modus festlegen
                                    // WiFi.mode() & WiFi.config() können auch Platz tauschen!
                                    // OPTIONAL, -> Wifi-Beginn == WiFi.begin(ssid, password);
  // Configures static IP address           // static IP-Config
  if (!WiFi.config(local_IP, gateway, subnet, primaryDNS, secondaryDNS)) {
    Serial.println("STA Failed to configure");
  }
  // WiFi.disconnect();
  delay(100);
   
  // initial WiFi-Scan & Start command
  wlan_scan();
  initWiFi();
}



// *********************  main /  loop()  ******************************
void loop() {
  // wlan_scan();
  delay (1000);

  // initWiFi();
   
  reconnecting();
  // WiFi.disconnect();          // am Ende der Verbindung
}



// ***********************  Connect to a Wi-Fi Network  ******************
// const char* ssid = "REPLACE_WITH_YOUR_SSID";          -> VOR setup()
// const char* password = "REPLACE_WITH_YOUR_PASSWORD";

// IPAddress local_IP(10, 10, 0, 10);                    -> VOR setup()
// IPAddress gateway(10, 10, 0, 138);
// IPAddress subnet(255, 255, 255, 0);

void initWiFi() {                          // 1. ssid & password als Variable bestimmen
  WiFi.mode(WIFI_STA);                     // 2. Modus des WLANs -> ?? optional ?? WIFI_STA
  WiFi.begin(ssid, password);              // 3. WiFi.begin mit "ssid" / "password"
  Serial.print("Connecting to WiFi ..");   
  while (WiFi.status() != WL_CONNECTED) {  // 4. Abfrage: verbunden?
    Serial.print('.');
    /*
    0 -	WL_IDLE_STATUS	temporary status assigned when WiFi.begin() is called
    1 -	WL_NO_SSID_AVAIL	 when no SSID are available
    2 -	WL_SCAN_COMPLETED	scan networks is completed
    3 -	WL_CONNECTED	when connected to a WiFi network  **********
    4 -	WL_CONNECT_FAILED	when the connection fails for all the attempts
    5 -	WL_CONNECTION_LOST	when the connection is lost
    6 -	WL_DISCONNECTED	when disconnected from a network
    */
    delay(1000);
  }
  Serial.print(WiFi.localIP());            // Ausgabe der erhaltenen IP
  Serial.print("  Stärke: ");
  Serial.println(WiFi.RSSI(WiFi.scanNetworks()));   // Received Signal Strength Indicator in --dB--
}



// ***********************  wlan - scan  *********************************
void wlan_scan (void)
{
  Serial.println("scan start");

  int n = WiFi.scanNetworks();           // WiFi.scanNetworks returns the number of networks found
  Serial.println("scan done");
  if (n == 0) {
      Serial.println("no networks found");
  } else {
    Serial.print(n);
    Serial.println(" networks found");
    for (int i = 0; i < n; ++i) {
      // Print SSID and RSSI for each network found
      Serial.print(i + 1);
      Serial.print(": ");
      Serial.print(WiFi.SSID(i));       // WiFi.SSID() - Ausgabe des Names
      Serial.print(" (");
      Serial.print(WiFi.RSSI(i));       // Received Signal Strength Indicator in --dB--
      Serial.print(")");
      Serial.println((WiFi.encryptionType(i) == WIFI_AUTH_OPEN)?" ":"*");
      // WIFI_AUTH_OPEN        WIFI_AUTH_WEP    WIFI_AUTH_WPA_PSK  
      // WIFI_AUTH_WPA2_PSK    WIFI_AUTH_WPA_WPA2_PSK
      delay(10);
    }
  }
  Serial.println("");
  delay(5000);
}



// ***********************  WiFi - reconnect / disconnect  ***************
void reconnecting (void)
{
  unsigned long previousMillis = 0;
  unsigned long interval = 30000;

  unsigned long currentMillis = millis();

  // if WiFi is down, try reconnecting every 30 sec
  if ((WiFi.status() != WL_CONNECTED) && (currentMillis - previousMillis >=interval)) {
    Serial.print(millis());
    Serial.println("  Reconnecting to WiFi...  ");
    // WiFi.disconnect();
    WiFi.reconnect();
    previousMillis = currentMillis;
  }
  /*
  WiFi.reconnect();              // in case of lost connection
  WiFi.disconnect();             // equivalent to WiFi.reconnect()
  WiFi.begin(ssid, password);
  */
}