// https://randomnerdtutorials.com/esp32-date-time-ntp-client-server-arduino/
// https://lastminuteengineers.com/esp32-i2c-lcd-tutorial/


#include <WiFi.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "time.h"

LiquidCrystal_I2C LCD = LiquidCrystal_I2C(0x27, 16, 2); 
// 0x27hex = default, je nach Chipsatz 0x3Fhex möglich


#define NTP_SERVER     "pool.ntp.org"
#define UTC_OFFSET     3600             // Zeitkorrektur mit Vielfachem von +/-3600
#define UTC_OFFSET_DST 3600             // Sommerzeit, sonst 0, Daylight Saving Time


void printLocalTime(void);
void i2c_scanner (void);
void special_char (void);


void setup() {
  Serial.begin(115200);

  LCD.init();                    // initialisation            - 1)
  LCD.backlight();               // Make sure backlight is on - 2)
  // LCD.clear();                // clears the display        - 3)  -> in setup
  LCD.setCursor(0, 0);           // x / y,   x=0-15,  y=0-1
  LCD.print("Connecting to ");
  LCD.setCursor(0, 1);
  LCD.print("WiFi ");

  WiFi.begin("Wokwi-GUEST", "", 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  delay (1000);

  LCD.clear();
  LCD.setCursor(0, 0);
  LCD.println("Online");
  LCD.setCursor(0, 1);
  LCD.println("Updating time...");

  configTime(UTC_OFFSET, UTC_OFFSET_DST, NTP_SERVER);

  i2c_scanner();
}

/*
lcd.home();   position cursor in the upper-left of the LCD without clearing display.
lcd.blink();  displays a blinking block of 5×8 pixels at the position of cursor
lcd.cursor(); displays an underscore (line) at the position of cursor.
lcd.noBlink(); function turns off the blinking LCD cursor.
lcd.noCursor(); hides the LCD cursor.
*/


void loop() {
  printLocalTime();
  
  delay(250);
}




void printLocalTime() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    LCD.setCursor(0, 1);
    LCD.println("Connection Error");
    return;
  }
  LCD.setCursor(8, 0);
  LCD.println(&timeinfo, "%H:%M:%S");
  LCD.setCursor(0, 1);
  LCD.println(&timeinfo, "%d/%m/%Y   %Z");
  Serial.println(&timeinfo, " %A %a %B %b  month  %d %Y  year  %H %M %S ");
  special_char ();
}


/*
struct tm
---------
%A	Full weekday name
%a  abbreviated weekday name
%B	Full month name
%b  abbreviated month name
%d	Day of the month
%Y	Year
%H	Hour in 24h format
%I	Hour in 12h format
%M	Minute
%S	Second

store data into variable:
char timeHour[3];                       // must be 3 char long, 2 char data & terminating char
strftime(timeHour,3, "%H", &timeinfo);
Serial.println(timeHour);

char timeWeekDay[10];
strftime(timeWeekDay,10, "%A", &timeinfo);
Serial.println(timeWeekDay);
*/



void i2c_scanner (void) {
  byte error, address;
  int nDevices = 0;

  Serial.println("Scanning for i2c devices . . .");
  // Wire.begin();         // ev. nicht nötig

  for(address = 1; address < 127; address++ ) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address<16) {
        Serial.print("0");
      }
      Serial.println(address,HEX);
      nDevices++;
    }
    else if (error==4) {
      Serial.print("Unknow error at address 0x");
      if (address<16) {
        Serial.print("0");
      }
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0) {
    Serial.println("No I2C devices found\n");
  }
  else {
    Serial.println("done\n");
  }
  delay(3000);       
}



void special_char (void) {
byte Alien[8] = {
0b11111,
0b10101,
0b11111,
0b11111,
0b01110,
0b01010,
0b11011,
0b00000
};
  // create a new characters, Skull[8] wird "0" zugeteilt -> ausgeschrieben
  LCD.createChar(0, Alien);
  LCD.setCursor(11, 1);
  LCD.write(0);
}


/*
createChar();
each character is made up of a 5×8 pixel matrix
https://lastminuteengineers.com/esp32-i2c-lcd-tutorial/  --> für binär-Struktur-Generierung

byte Heart[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000
};

byte Bell[8] = {
0b00100,
0b01110,
0b01110,
0b01110,
0b11111,
0b00000,
0b00100,
0b00000
};


byte Alien[8] = {
0b11111,
0b10101,
0b11111,
0b11111,
0b01110,
0b01010,
0b11011,
0b00000
};

byte Check[8] = {
0b00000,
0b00001,
0b00011,
0b10110,
0b11100,
0b01000,
0b00000,
0b00000
};

byte Speaker[8] = {
0b00001,
0b00011,
0b01111,
0b01111,
0b01111,
0b00011,
0b00001,
0b00000
};


byte Sound[8] = {
0b00001,
0b00011,
0b00101,
0b01001,
0b01001,
0b01011,
0b11011,
0b11000
};


byte Skull[8] = {
0b00000,
0b01110,
0b10101,
0b11011,
0b01110,
0b01110,
0b00000,
0b00000
};

byte Lock[8] = {
0b01110,
0b10001,
0b10001,
0b11111,
0b11011,
0b11011,
0b11111,
0b00000
};


*/