// =====================================
// LCD1602 (PARALLEL) + ESP32 NTP CLOCK
// =====================================

#include <WiFi.h>
#include <LiquidCrystal.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

// ===============================
// LCD CONFIG (YOUR PINOUT)
// RS, E, D4, D5, D6, D7
// ===============================
LiquidCrystal lcd(0, 4, 16, 17, 5, 18);

// ===============================
// WIFI + NTP CONFIG
// ===============================
#define NTP_SERVER     "pool.ntp.org"
#define UTC_OFFSET     6 * 3600
#define UTC_OFFSET_DST 0

// ===============================
// WEATHER API
// ===============================
const char* tempApiUrl = "http://api.open-meteo.com/v1/forecast?latitude=23.81&longitude=90.41&current_weather=true";
const unsigned long TEMP_UPDATE_INTERVAL = 5 * 60 * 1000;

// ===============================
// GLOBAL VARIABLES
// ===============================
float lastTemp = -1000.0;
unsigned long lastTempUpdate = 0;

const char* daysOfWeek[] = {"SUN","MON","TUE","WED","THU","FRI","SAT"};
const char* months[] = {"JAN","FEB","MAR","APR","MAY","JUN",
                        "JUL","AUG","SEP","OCT","NOV","DEC"};

// Display cache (avoid flicker)
struct DispCache {
  char weekDay[4];
  uint8_t hour, minute, second;
  uint8_t mon, day;
  float temperature;
} lastDisplay = {"", 99, 99, 99, 99, 99, -1000.0};

// ===============================
// FUNCTIONS
// ===============================

// Fetch temperature
void fetchTemperature() {
  HTTPClient http;
  http.begin(tempApiUrl);

  int httpCode = http.GET();
  if (httpCode == HTTP_CODE_OK) {
    String payload = http.getString();

    StaticJsonDocument<512> doc;
    if (deserializeJson(doc, payload) == DeserializationError::Ok) {
      if (doc["current_weather"]["temperature"]) {
        lastTemp = doc["current_weather"]["temperature"];
      }
    }
  }
  http.end();
  lastTempUpdate = millis();
}

// Print static part (HH:MM)
void printTimeStatic(const struct tm &timeinfo) {
  char line1[14];
  snprintf(line1, sizeof(line1), "%s - %02d:%02d:",
           daysOfWeek[timeinfo.tm_wday],
           timeinfo.tm_hour,
           timeinfo.tm_min);

  lcd.setCursor(0, 0);
  lcd.print(line1);
}

// Print seconds only
void printSeconds(uint8_t sec) {
  lcd.setCursor(12, 0);

  char secStr[3];
  snprintf(secStr, sizeof(secStr), "%02d", sec);
  lcd.print(secStr);
}

// Print date + temperature
void printDateTemp(const struct tm &timeinfo, float temp) {
  char dateStr[9];
  snprintf(dateStr, sizeof(dateStr), "%s %2d   ",
           months[timeinfo.tm_mon],
           timeinfo.tm_mday);

  char tempStr[8];
  if (temp > -100) {
    snprintf(tempStr, sizeof(tempStr), "%5.1fC", temp);
  } else {
    snprintf(tempStr, sizeof(tempStr), "  --.-C");
  }

  lcd.setCursor(0, 1);
  lcd.print(dateStr);

  lcd.setCursor(8, 1);
  lcd.print(tempStr);
}

// ===============================
// SETUP
// ===============================
void setup() {
  Serial.begin(115200);

  lcd.begin(16, 2);

  // Boot message
  lcd.setCursor(0, 0);
  lcd.print("Connecting WiFi");
  lcd.setCursor(0, 1);
  lcd.print("Please wait... ");

  // WiFi connect
  WiFi.begin("Wokwi-GUEST", "", 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(300);
  }

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("WiFi Connected ");
  lcd.setCursor(0, 1);
  lcd.print("Syncing Time...");

  // NTP setup
  configTime(UTC_OFFSET, UTC_OFFSET_DST, NTP_SERVER);

  // Initial temp fetch
  fetchTemperature();
  lastTempUpdate = millis() - TEMP_UPDATE_INTERVAL;
}

// ===============================
// LOOP
// ===============================
void loop() {

  struct tm timeinfo;

  // Get time
  if (!getLocalTime(&timeinfo)) {
    lcd.setCursor(0, 0);
    lcd.print("NTP Error      ");
    lcd.setCursor(0, 1);
    lcd.print("Retrying...    ");
    delay(1000);
    return;
  }

  // Update temperature periodically
  if (millis() - lastTempUpdate >= TEMP_UPDATE_INTERVAL) {
    fetchTemperature();
  }

  // Update hour/min/day only when changed
  if (strcmp(daysOfWeek[timeinfo.tm_wday], lastDisplay.weekDay) != 0 ||
      timeinfo.tm_hour != lastDisplay.hour ||
      timeinfo.tm_min != lastDisplay.minute) {

    printTimeStatic(timeinfo);

    strncpy(lastDisplay.weekDay, daysOfWeek[timeinfo.tm_wday], 4);
    lastDisplay.hour = timeinfo.tm_hour;
    lastDisplay.minute = timeinfo.tm_min;
  }

  // Update seconds only
  if (timeinfo.tm_sec != lastDisplay.second) {
    printSeconds(timeinfo.tm_sec);
    lastDisplay.second = timeinfo.tm_sec;
  }

  // Update date/temp only when needed
  if (timeinfo.tm_mon != lastDisplay.mon ||
      timeinfo.tm_mday != lastDisplay.day ||
      abs(lastTemp - lastDisplay.temperature) > 0.1) {

    printDateTemp(timeinfo, lastTemp);

    lastDisplay.mon = timeinfo.tm_mon;
    lastDisplay.day = timeinfo.tm_mday;
    lastDisplay.temperature = lastTemp;
  }

  delay(50);
}