#include <LiquidCrystal_I2C.h>
#include <WiFi.h>      // Defines WiFi variable
#include "time.h"      // Defines configTime, getLocalTime, asctime, time_t
#include "sntp.h"      // For sntp_set_sync_interval (may vary based on ESP32 core version, sometimes implicitly available)

LiquidCrystal_I2C lcd(0x27, 20, 4);
uint8_t dot[] = {0x0E, 0x0A, 0x0E, 0x00, 0x00, 0x00, 0x00, 0x00};

// --- NTP Settings ---
const char* ntpServer = "pool.ntp.org";
const long gmtOffset_sec = 8 * 3600; // Your GMT offset (e.g., +8 hours for Singapore)
const int daylightOffset_sec = 0;    // Daylight saving offset in seconds (0 if not applicable)
const unsigned long ntpSyncIntervalMs = 5 * 60 * 1000; // 5 minutes in milliseconds

// Function to get current date and time as a formatted string
String getCurrentDateTimeString() {
  struct tm timeinfo;
  if (getLocalTime(&timeinfo)) {
    char timeString[20]; // Buffer for "%d/%m/%Y %H:%M:%S" (19 chars) + null terminator
    strftime(timeString, sizeof(timeString), "%d/%m/%Y %H:%M:%S", &timeinfo);
    return String(timeString);
  } else {
    return "Time not synced"; // Or any other placeholder
  }
}

void syncTimeWithNTP() {
  lcd.setCursor(0, 0);
  lcd.print("Configuring time... ");
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);

  // Set the SNTP synchronization interval (e.g., every 5 minutes)
  // This function tells the underlying SNTP service how often to resync.
  sntp_set_sync_interval(ntpSyncIntervalMs);

  struct tm timeinfo;
  lcd.setCursor(0, 1);
  lcd.print("Syncing time......."); // 20 chars wide
  int attempts = 0;
  // getLocalTime will wait for sync for its default timeout (or specified one)
  // after configTime has started the process.
  while (!getLocalTime(&timeinfo, 1000)) { // Check every 1 second, with a small timeout for getLocalTime itself
    Serial.println("Waiting for NTP time sync...");
    lcd.print(".");
    attempts++;
    if (attempts > 30) { // Give up after about 30 seconds of trying to get initial sync
        lcd.setCursor(0,1);
        lcd.print("Time sync FAILED!   ");
        Serial.println("Failed to obtain time after multiple attempts.");
        return; // Exit if sync fails
    }
    delay(500); // Wait a bit before retrying getLocalTime check
  }
  Serial.println("Time synchronized successfully.");
  lcd.setCursor(0, 0); // Clear "Configuring time..." and "Syncing time..." area
  lcd.print("WiFi & Time OK      ");
  lcd.setCursor(0, 1);
  lcd.print("                    "); // Clear sync status line
}

void connectToWiFi() {
  bool flag = true;
  WiFi.begin("Wokwi-GUEST", "", 6); // Replace with your credentials if not using Wokwi
  lcd.clear();
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    lcd.setCursor(0, 0);
    lcd.print(flag ? "Connecting to WiFi++" : "Connecting to WiFi--");
    flag = !flag;
    Serial.print(".");
  }
  Serial.println("\nWiFi connected!");
  lcd.setCursor(0, 0);
  lcd.print("WiFi connected!     ");
  lcd.setCursor(0, 1);
  lcd.print(WiFi.localIP());
  delay(2000); // Show IP for a couple of seconds

  syncTimeWithNTP(); // Configure and synchronize time
}

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, dot);  // Use slot 0 for degree symbol
  connectToWiFi();
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("WiFi Disconnected!");
    lcd.setCursor(0, 1);
    lcd.print("Attempting reconnect");
    Serial.println("WiFi Disconnected! Attempting reconnect...");
    delay(2000);
    connectToWiFi(); // This will re-attempt WiFi and time sync
  }

  // Get the formatted date and time string
  String dateTimeStr = getCurrentDateTimeString();

  lcd.setCursor(0, 1); // Display time on the second row
  lcd.print(dateTimeStr);

  // Example sensor data
  float h = 80.5;  // Relative humidity
  float c = 27.0;  // Celsius

  // Display humidity
  char buffer[21]; // Max 20 chars for LCD line + null
  snprintf(buffer, sizeof(buffer), "Humidity:    %4.1f%%", h); // Format to ensure clearing
  lcd.setCursor(0, 2);
  lcd.print(buffer);
  // Ensure any remaining characters from previous longer strings are cleared
  for (int i = strlen(buffer); i < 20; ++i) {
    lcd.print(" ");
  }


  // Display temperature
  snprintf(buffer, sizeof(buffer), "Temperature: %4.1f C", c);
  lcd.setCursor(0, 3);
  lcd.print(buffer);
  lcd.setCursor(18,3); // Position for degree symbol if not in snprintf
  lcd.write(0); // Custom degree symbol. Make sure it's "°C" if using write(0)
  // Or include degree symbol directly in snprintf if your LCD supports it well
  // For example: snprintf(buffer, sizeof(buffer), "Temperature: %4.1f%cC", c, (char)223); // 223 is often degree symbol
  // Using the custom char is safer:
  // snprintf(buffer, sizeof(buffer), "Temperature: %4.1f", c);
  // lcd.print(buffer); lcd.write(0); lcd.print("C");
  // Let's stick to your original way for temperature to keep it simple with the custom char
  lcd.setCursor(0, 3);
  lcd.print("Temperature: "); lcd.print(c, 1); lcd.write(0); lcd.print("C");
  // Clear remaining part of the line
  for (int i = (13 + String(c,1).length() + 2); i < 20; ++i) { // "Temperature: " is 13 chars
      lcd.print(" ");
  }


  // Your MQTT publishing logic would go here
  // Example:
  // if (client.connected()) {
  //   client.publish("esp32/datetime", dateTimeStr.c_str());
  //   client.publish("esp32/humidity", String(h).c_str());
  //   client.publish("esp32/temperature", String(c).c_str());
  // }

  delay(1000); // Update LCD (and potentially MQTT) every second
}