/*************************************************************************************************
                                      PROGRAMMINFO
**************************************************************************************************
Funktion: Funktion: ESP32 ntp Datum und Zeit Digitalanzeite
**************************************************************************************************
Version: 19.03.2022
**************************************************************************************************
Board: ESP32vn IoT UNO V1.0.4

**************************************************************************************************
C++ Arduino IDE V1.8.19
**************************************************************************************************
Einstellungen:
https://dl.espressif.com/dl/package_esp32_index.json
http://dan.drown.org/stm32duino/package_STM32duino_index.json
https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json
**************************************************************************************************
Librarys
- WiFi.h V0.16.1
**************************************************************************************************
OLED Schriftarten:
https://arduino-projekte.info/schriftarten-fuer-oled-display/#torussansbold8_8r

 **************************************************************************************************/

#include                              <time.h>                              // for time calculations
#include                              <WiFi.h>                              // for wifi
#include                              <WiFiUdp.h>                           // for udp via wifi
#include                              <U8g2lib.h>                           // see https://github.com/olikraus/u8g2/wiki/u8g2reference
//#include "SH1106.h"
#include <U8g2lib.h>
#include <Wire.h>

//////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Constants
//
//////////////////////////////////////////////////////////////////////////////////////////////////////////////

#define   FONT_ONE_HEIGHT               8                                   // font one height in pixels
#define   FONT_TWO_HEIGHT               20                                  // font two height in pixels
#define   NTP_DELAY_COUNT               20                                  // delay count for ntp update
#define   NTP_PACKET_LENGTH             48                                  // ntp packet length
#define   TIME_ZONE                     (+2)                                // offset from utc BERLIN
#define   UDP_PORT                      4000                                // UDP listen port

//////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Variables
//
//////////////////////////////////////////////////////////////////////////////////////////////////////////////

char      chBuffer[128];                                                    // general purpose character buffer

char      chSSID[] =                      "xxx";                   // your network SSID
char      chPassword[] =                  "xxx";               // your network password


bool      bTimeReceived =                 false;                            // time has not been received
//U8G2_SSD1306_128X64_NONAME_F_HW_I2C       u8g2(U8G2_R0, 16, 15, 4);         // OLED graphics
//SH1106  display(0x3C, 21,22);   //1,3"
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
int       nWifiStatus =                   WL_IDLE_STATUS;                   // wifi status
WiFiUDP   Udp;

//////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Setup
//
//////////////////////////////////////////////////////////////////////////////////////////////////////////////

void setup()
{
  // Serial.

  Serial.begin(115200);
  while(!Serial)
  {
    Serial.print('.');
  }

  // OLED graphics.

  u8g2.begin();
  u8g2.setFont(u8g2_font_6x10_tr);
  u8g2.setFontRefHeightExtendedText();
  u8g2.setDrawColor(1);
  u8g2.setFontPosTop();
  u8g2.setFontDirection(0);

  // Wifi.

    // Display title.

    u8g2.clearBuffer();
    sprintf(chBuffer, "%s", "Connecting to:");
    u8g2.drawStr(64 - (u8g2.getStrWidth(chBuffer) / 2), 0, chBuffer);
    sprintf(chBuffer, "%s", chSSID);
    u8g2.drawStr(64 - (u8g2.getStrWidth(chBuffer) / 2), 31 - (FONT_ONE_HEIGHT / 2), chBuffer);
    u8g2.sendBuffer();

    // Connect to wifi.

    Serial.print("NTP clock: connecting to wifi");
    WiFi.begin(chSSID, chPassword);
    while(WiFi.status() != WL_CONNECTED)
    {
        Serial.print(".");
        delay(500);
    }

    Serial.println();
    sprintf(chBuffer, "NTP clock: WiFi connected to %s.", chSSID);
    Serial.println(chBuffer);

    // Display connection stats.

      // Clean the display buffer.

      u8g2.clearBuffer();

      // Display the title.

      sprintf(chBuffer, "%s", "WiFi Stats:");
      u8g2.drawStr(64 - (u8g2.getStrWidth(chBuffer) / 2), 0, chBuffer);

      // Display the ip address assigned by the wifi router.

      char  chIp[81];
      WiFi.localIP().toString().toCharArray(chIp, sizeof(chIp) - 1);
      sprintf(chBuffer, "IP  : %s", chIp);
      u8g2.drawStr(0, FONT_ONE_HEIGHT * 2, chBuffer);

      // Display the ssid of the wifi router.

      sprintf(chBuffer, "SSID: %s", chSSID);
      u8g2.drawStr(0, FONT_ONE_HEIGHT * 3, chBuffer);

      // Display the rssi.

      sprintf(chBuffer, "RSSI: %d", WiFi.RSSI());
      u8g2.drawStr(0, FONT_ONE_HEIGHT * 4, chBuffer);

      // Display waiting for ntp message.

      u8g2.drawStr(0, FONT_ONE_HEIGHT * 6, "Awaiting NTP time...");

      // Now send the display buffer to the OLED.

      u8g2.sendBuffer();

  // Udp.

  Udp.begin(UDP_PORT);
}