#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <MAX30105.h>
#include "spo2_algorithm.h"
#include "heartRate.h"

// Display OLED
Adafruit_SSD1306 display(128, 64, &Wire, -1);

// DHT22
#define DHTPIN 15
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

// MAX30102
MAX30105 particleSensor;
uint32_t irBuffer[100], redBuffer[100];
int32_t bufferLength, spo2, heartRate;
int8_t validSPO2, validHeartRate;

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22); // Explicitly define I2C pins

  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.display();
  delay(2000);
  display.clearDisplay();

  // Initialize DHT22
  dht.begin();

  // Initialize MAX30102
  if (!particleSensor.begin(Wire, I2C_SPEED_FAST, 0x57)) { 
    Serial.println(F("MAX30105 was not found. Please check wiring/power."));
    while (1);
  }

  particleSensor.setup(50, 4, 2, 100, 411, 4096);
}

void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  // Read MAX30102 data
  bufferLength = 100;
  for (byte i = 0; i < bufferLength; i++) {
    while (!particleSensor.available()) { 
      particleSensor.check();
    }
    redBuffer[i] = particleSensor.getRed();
    irBuffer[i] = particleSensor.getIR();
    particleSensor.nextSample();
  }

  // Compute SpO2 and heart rate
  maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

  // Display data on OLED
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.setTextColor(WHITE);

  display.print("Temp: "); display.print(t); display.println(" *C");
  display.print("Humidity: "); display.print(h); display.println(" %");

  if (validHeartRate) {
    display.print("Heart Rate: "); display.print(heartRate); display.println(" bpm");
  } else {
    display.println("Invalid Heart Rate");
  }

  if (validSPO2) {
    display.print("SpO2: "); display.print(spo2); display.println(" %");
  } else {
    display.println("Invalid SpO2");
  }

  display.display();
  delay(2000);
}