#include <ESP8266WiFi.h>
#include <ThingSpeak.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>

#define DHTPIN D5     // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11 // DHT 11

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const char *ssid = "ssid";
const char *password = "12345";
const char *host = "api.thingspeak.com";
const String apiKey = "TDZ3FM3REZWWM9IG";

const int postingInterval = 15 * 1000; // Post data every 15 seconds
unsigned long lastConnectionTime = 0;

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  delay(100);

  WiFi.begin(ssid, password);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Address 0x3C for 128x64

  dht.begin();

  ThingSpeak.begin(client);
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();

    if (isnan(temperature) || isnan(humidity)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }

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

    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.print("Temp: ");
    display.println(temperature);
    display.print("Humidity: ");
    display.println(humidity);
    display.display();

    if (millis() - lastConnectionTime > postingInterval) {
      updateThingspeak(temperature, humidity);
    }
  } else {
    Serial.println("WiFi Disconnected");
  }
}

void updateThingspeak(float temperature, float humidity) {
  WiFiClient client;

  String postStr = apiKey;
  postStr += "&field1=";
  postStr += String(temperature);
  postStr += "&field2=";
  postStr += String(humidity);

  if (client.connect(host, 80)) {
    client.println("POST /update HTTP/1.1");
    client.println("Host: " + String(host));
    client.println("Connection: close");
    client.println("Content-Type: application/x-www-form-urlencoded");
    client.println("Content-Length: " + String(postStr.length()));
    client.println();
    client.print(postStr);

    lastConnectionTime = millis();
  } else {
    Serial.println("Failed to connect to Thingspeak");
  }
}