#include <EEPROM.h>
#include "DHT.h"

#define DHTPIN 4
#define DHTTYPE DHT22
#define EEPROM_SIZE 512

DHT dht(DHTPIN, DHTTYPE);

int logCount = 0;

float prevTemp = -100;
float prevHum  = -100;


// Display all logs
void displayLogs() {

  Serial.println("----- COMPLETE LOG -----");

  int count = EEPROM.read(0);

  for(int i=0;i<count;i++) {

    int base = 1 + i*4;

    int16_t tempStored;
    int16_t humStored;

    EEPROM.get(base, tempStored);
    EEPROM.get(base+2, humStored);

    float temp = tempStored / 10.0;
    float hum  = humStored / 10.0;

    Serial.print("Log ");
    Serial.print(i+1);
    Serial.print(" → Temp: ");
    Serial.print(temp,1);
    Serial.print(" C  Humidity: ");
    Serial.print(hum,1);
    Serial.println(" %");
  }

  Serial.println("------------------------");
}


void setup() {

  Serial.begin(115200);
  EEPROM.begin(EEPROM_SIZE);

  dht.begin();

  Serial.println("ESP32 Sensor Logging Started");
  delay(5000);
  // Reset logs
  EEPROM.write(0,0);
  EEPROM.commit();

  logCount = 0;
}


void loop() {

  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  if(isnan(temperature) || isnan(humidity)) {
    Serial.println("DHT Read Failed");
    delay(2000);
    return;
  }

  Serial.print("Temperature: ");
  Serial.print(temperature,1);
  Serial.print(" C  Humidity: ");
  Serial.print(humidity,1);
  Serial.println(" %");


  // Log only if value changes
  if(temperature != prevTemp || humidity != prevHum) {

    Serial.println("Change detected → Logging data");

    int16_t tempStore = temperature * 10;
    int16_t humStore  = humidity * 10;

    int base = 1 + logCount * 4;

    EEPROM.put(base, tempStore);
    EEPROM.put(base+2, humStore);

    logCount++;

    EEPROM.write(0, logCount);

    EEPROM.commit();

    prevTemp = temperature;
    prevHum  = humidity;

    Serial.print("Total Logs = ");
    Serial.println(logCount);
  }
  else {
    Serial.println("No change → Log skipped");
  }


  // Show logs if user types L
  if(Serial.available()) {

    char c = Serial.read();

    if(c=='L' || c=='l') {
      displayLogs();
    }
  }

  delay(3000);
}