/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com
  Based on the NTP Client library example
*********/
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <WiFi.h>
#include <NTPClient.h>
#include <WiFiUdp.h>

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

// Define NTP Client to get time
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP);

// Variables to save date and time
String formattedDate;
String dayStamp;
String timeStamp;

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define NUMFLAKES     10 // Number of snowflakes in the animation example

void setup() {
  // Initialize Serial Monitor
  Serial.begin(115200);
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }
  display.display();
  delay(500); // Pause for 2 seconds
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  // Print local IP address and start web server
  Serial.println("");
    display.clearDisplay();
    display.setTextSize(1);             // Normal 1:1 pixel scale
    display.setTextColor(WHITE);        // Draw white text
    display.setCursor(0,0);             // Start at top-left corner
    display.println(WiFi.localIP());
    display.display();
  Serial.println("WiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
 delay(2000);
// Initialize a NTPClient to get time
  
  // Set offset time in seconds to adjust for your timezone, for example:
  // GMT +1 = 3600
  // GMT +8 = 28800
  // GMT -1 = -3600
  // GMT 0 = 0
  timeClient.setTimeOffset(10800);
  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  
}
void loop() {
    timeClient.forceUpdate();
  // The formattedDate comes with the following format:
  // 2018-05-28T16:00:13Z
  // We need to extract date and time
  formattedDate = timeClient.getFormattedTime();
  Serial.println(formattedDate);

  // Extract date
  int splitT = formattedDate.indexOf("T");
  dayStamp = formattedDate.substring(0, splitT);
  Serial.print("DATE: ");
  Serial.println(dayStamp);
  // Extract time
  timeStamp = formattedDate.substring(splitT+1, formattedDate.length()-1);
  Serial.print("HOUR: ");
  Serial.println(timeStamp);
  display.clearDisplay();
  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(WHITE);        // Draw white text
  display.setCursor(80,2);             // Start at top-left corner
  display.print(dayStamp);
  display.display();
  delay(200);
}