#include <Arduino.h>
#include <Wire.h>
#include <DHT.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Sensor pins
#define DHT_PIN PA1
#define DHT_TYPE DHT22
#define GAS_PIN PA0

// Alert output pins
#define BUZZER_PIN PB0
#define LED_PIN PB1

// Threshold values
#define TEMP_LIMIT 30.0
#define HUM_LIMIT 75.0
#define GAS_LIMIT 800

// OLED settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDRESS 0x3C

DHT dht(DHT_PIN, DHT_TYPE);

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

        void setup() {
          Serial.begin(115200);

            // Initialize sensors and outputs
              dht.begin();

                pinMode(GAS_PIN, INPUT);
                  pinMode(LED_PIN, OUTPUT);
                    pinMode(BUZZER_PIN, OUTPUT);

                      digitalWrite(LED_PIN, LOW);
                        noTone(BUZZER_PIN);

                          // Initialize OLED I2C
                            Wire.setSDA(PB7);
                              Wire.setSCL(PB6);
                                Wire.begin();

                                  if (display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
                                      display.clearDisplay();
                                          display.setTextSize(1);
                                              display.setTextColor(SSD1306_WHITE);
                                                  display.setCursor(0, 0);
                                                      display.println("MULTI-SENSOR LOGGER");
                                                          display.println("Starting...");
                                                              display.display();
                                                                } else {
                                                                    Serial.println("OLED initialization failed!");
                                                                      }

                                                                        Serial.println("MULTI-SENSOR MONITOR");
                                                                          Serial.println("System ready.");
                                                                            delay(1000);
                                                                            }

                                                                            void loop() {
                                                                              // Read sensor values
                                                                                float temperature = dht.readTemperature();
                                                                                  float humidity = dht.readHumidity();
                                                                                    int gasValue = analogRead(GAS_PIN);

                                                                                      // Check whether DHT readings are valid
                                                                                        bool validDHT = !isnan(temperature) && !isnan(humidity);

                                                                                          // Check thresholds
                                                                                            bool highTemperature =
                                                                                                validDHT && temperature >= TEMP_LIMIT;

                                                                                                  bool highHumidity =
                                                                                                      validDHT && humidity >= HUM_LIMIT;

                                                                                                        bool highGas =
                                                                                                            gasValue >= GAS_LIMIT;

                                                                                                              bool alert =
                                                                                                                  highTemperature || highHumidity || highGas;

                                                                                                                    // Print readings to Serial Monitor
                                                                                                                      Serial.println("------------------------");

                                                                                                                        Serial.print("Temperature: ");
                                                                                                                          if (validDHT) {
                                                                                                                              Serial.print(temperature, 1);
                                                                                                                                  Serial.println(" C");
                                                                                                                                    } else {
                                                                                                                                        Serial.println("Sensor error");
                                                                                                                                          }

                                                                                                                                            Serial.print("Humidity: ");
                                                                                                                                              if (validDHT) {
                                                                                                                                                  Serial.print(humidity, 1);
                                                                                                                                                      Serial.println(" %");
                                                                                                                                                        } else {
                                                                                                                                                            Serial.println("Sensor error");
                                                                                                                                                              }

                                                                                                                                                                Serial.print("Gas reading: ");
                                                                                                                                                                  Serial.println(gasValue);

                                                                                                                                                                    // Update OLED display
                                                                                                                                                                      display.clearDisplay();
                                                                                                                                                                        display.setTextSize(1);
                                                                                                                                                                          display.setTextColor(SSD1306_WHITE);
                                                                                                                                                                            display.setCursor(0, 0);

                                                                                                                                                                              display.println("MULTI-SENSOR LOGGER");
                                                                                                                                                                                display.println("--------------------");

                                                                                                                                                                                  display.print("Temp: ");
                                                                                                                                                                                    if (validDHT) {
                                                                                                                                                                                        display.print(temperature, 1);
                                                                                                                                                                                            display.println(" C");
                                                                                                                                                                                              } else {
                                                                                                                                                                                                  display.println("Error");
                                                                                                                                                                                                    }

                                                                                                                                                                                                      display.print("Humidity: ");
                                                                                                                                                                                                        if (validDHT) {
                                                                                                                                                                                                            display.print(humidity, 1);
                                                                                                                                                                                                                display.println(" %");
                                                                                                                                                                                                                  } else {
                                                                                                                                                                                                                      display.println("Error");
                                                                                                                                                                                                                        }

                                                                                                                                                                                                                          display.print("Gas: ");
                                                                                                                                                                                                                            display.println(gasValue);

                                                                                                                                                                                                                              // Activate or deactivate the alert
                                                                                                                                                                                                                                if (alert) {
                                                                                                                                                                                                                                    digitalWrite(LED_PIN, HIGH);
                                                                                                                                                                                                                                        tone(BUZZER_PIN, 1000);

                                                                                                                                                                                                                                            display.println();
                                                                                                                                                                                                                                                display.println("!! THRESHOLD ALERT !!");

                                                                                                                                                                                                                                                    Serial.println("WARNING: THRESHOLD EXCEEDED!");

                                                                                                                                                                                                                                                        if (highTemperature) {
                                                                                                                                                                                                                                                              Serial.println("High temperature!");
                                                                                                                                                                                                                                                                  }

                                                                                                                                                                                                                                                                      if (highHumidity) {
                                                                                                                                                                                                                                                                            Serial.println("High humidity!");
                                                                                                                                                                                                                                                                                }

                                                                                                                                                                                                                                                                                    if (highGas) {
                                                                                                                                                                                                                                                                                          Serial.println("High gas reading!");
                                                                                                                                                                                                                                                                                              }
                                                                                                                                                                                                                                                                                                } else {
                                                                                                                                                                                                                                                                                                    digitalWrite(LED_PIN, LOW);
                                                                                                                                                                                                                                                                                                        noTone(BUZZER_PIN);

                                                                                                                                                                                                                                                                                                            display.println();
                                                                                                                                                                                                                                                                                                                display.println("Status: NORMAL");

                                                                                                                                                                                                                                                                                                                    Serial.println("Status: NORMAL");
                                                                                                                                                                                                                                                                                                                      }

                                                                                                                                                                                                                                                                                                                        display.display();

                                                                                                                                                                                                                                                                                                                          delay(2000);
                                                                                                                                                                                                                                                                                                                          }