#include <Wire.h>
#include "MAX30105.h"
#include "spo2_algorithm.h"

MAX30105 particleSensor;

#define MAX_BRIGHTNESS 255

#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
uint16_t irBuffer[100]; // IR LED sensor data
uint16_t redBuffer[100]; // Red LED sensor data
#else
uint32_t irBuffer[100];
uint32_t redBuffer[100];
#endif

int32_t bufferLength;
int32_t spo2;
int8_t validSPO2;
int32_t heartRate;
int8_t validHeartRate;

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

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

  Serial.println(F("Attach sensor to finger and press any key to start..."));
  while (Serial.available() == 0);
  Serial.read();

  particleSensor.setup(60, 4, 2, 100, 411, 4096); // Sensor settings
}

void loop() {
  bufferLength = 100; // 4 seconds of samples

  for (byte i = 0; i < bufferLength; i++) {
    while (particleSensor.available() == false)
      particleSensor.check();

    redBuffer[i] = particleSensor.getRed();
    irBuffer[i] = particleSensor.getIR();
    particleSensor.nextSample();
  }

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

  while (1) {
    for (byte i = 25; i < 100; i++) {
      redBuffer[i - 25] = redBuffer[i];
      irBuffer[i - 25] = irBuffer[i];
    }

    for (byte i = 75; i < 100; i++) {
      while (particleSensor.available() == false)
        particleSensor.check();

      redBuffer[i] = particleSensor.getRed();
      irBuffer[i] = particleSensor.getIR();
      particleSensor.nextSample();
    }

    // Recalculate every second
    maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

    // Print heart rate, SpO2, and corresponding emoji
    if (validHeartRate && validSPO2) {
      Serial.print(F("Heart Rate: "));
      Serial.print(heartRate);
      Serial.print(F(" BPM "));
      Serial.print((heartRate >= 50 && heartRate <= 100) ? "\xF0\x9F\x98\x81" : "\xF0\x9F\x98\x9E"); // 😀 or 😞

      Serial.print(F(", SpO2: "));
      Serial.print(spo2);
      Serial.print(F("% "));
      Serial.println((spo2 >= 90) ? "\xF0\x9F\x98\x81" : "\xF0\x9F\x98\x9E"); // 😀 or 😞
    } else {
      Serial.println(F("Invalid reading. Please adjust finger placement."));
    }
  }
}