#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
#include <Stepper.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define DHTPIN 4
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

#define LDR_PIN 34
#define MQ2_PIN 35
#define PIR_PIN 5

#define STEPPER_STEPS 2048
Stepper stepper(STEPPER_STEPS, 12, 14, 13, 15);

float oxygenThreshold = 70.0;

// Array for pulse graph (stores previous values for scrolling effect)
int pulseData[SCREEN_WIDTH] = {0};

void setup() {
  Serial.begin(115200);
  dht.begin();
  pinMode(LDR_PIN, INPUT);
  pinMode(MQ2_PIN, INPUT);
  pinMode(PIR_PIN, INPUT);
  stepper.setSpeed(10);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  display.display();
}

void loop() {
  // Read sensors
  int ldrValue = analogRead(LDR_PIN);
  int mq2Value = analogRead(MQ2_PIN);
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();
  int motionDetected = digitalRead(PIR_PIN);

  // Convert MQ2 reading to oxygen % (simple scaling)
  float oxygenLevel = map(mq2Value, 0, 4095, 0, 100);

  // ----- Serial Monitor Output -----
  Serial.println("=== Sensor Readings ===");
  Serial.print("Temperature (C): "); Serial.println(temperature);
  Serial.print("Humidity (%): "); Serial.println(humidity);
  Serial.print("Oxygen Level (%): "); Serial.println(oxygenLevel);
  Serial.print("LDR Value: "); Serial.println(ldrValue);
  Serial.print("Motion Detected: "); Serial.println(motionDetected ? "Yes" : "No");
  Serial.println("========================\n");

  // Shift pulse data to left
  for (int i = 0; i < SCREEN_WIDTH - 1; i++) {
    pulseData[i] = pulseData[i + 1];
  }
  // Map new LDR value to screen height and store at end
  pulseData[SCREEN_WIDTH - 1] = map(ldrValue, 0, 4095, SCREEN_HEIGHT - 1, SCREEN_HEIGHT / 2);

  // Show data on OLED
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  // Text data
  display.setCursor(0,0);
  display.print("T:"); display.print(temperature); display.print("C ");
  display.print("H:"); display.print(humidity); display.println("%");
  display.print("O2:"); display.print(oxygenLevel); display.println("%");
  display.print("M:"); display.println(motionDetected ? "Yes" : "No");

  // Draw pulse waveform
  for (int x = 1; x < SCREEN_WIDTH; x++) {
    display.drawLine(x - 1, pulseData[x - 1], x, pulseData[x], SSD1306_WHITE);
  }

  display.display();

  // Control stepper motor if oxygen < threshold
  if (oxygenLevel < oxygenThreshold) {
    stepper.step(100);
  }

  delay(100); // Faster refresh for smooth graph
}