#define USE_ARDUINO_INTERRUPTS true

#include <PulseSensorPlayground.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <SD.h>

LiquidCrystal_I2C lcd(0x27,16,2);       // LCD initialization

int Signal;
int const PULSE_SENSOR_PIN = 0;
const int LED = 9;
int Threshold = 550;                    // Determine which Signal to "count as a beat" and which to ignore
File myFile;
const int chipSelect = 10;
                               
PulseSensorPlayground pulseSensor;      // Creates an object

// Heart character to be displayed on LCD screen
byte Heart[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000
};

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

  pinMode(LED, OUTPUT);

  // Configure the LCD screen
  lcd.init();
  lcd.clear();         
  lcd.backlight();
  lcd.createChar(0, Heart);

  // Configure the PulseSensor object
  pulseSensor.analogInput(PULSE_SENSOR_PIN);   
  pulseSensor.blinkOnPulse(LED);       
  pulseSensor.setThreshold(Threshold);   

  if (pulseSensor.begin()) {
    Serial.println("PulseSensor object created!");
  }

  // Open log file on the sd card in order to write to it
  myFile = SD.open("log.txt");
  if (myFile) {
    Serial.println("log.txt:");
    while (myFile.available()) {
      Serial.write(myFile.read());
    }
    myFile.close();
  } else {
    Serial.println("error opening log file on microSD card!");
  }
}

void loop() {
  int myBPM = 0;
  int currentBPM = 0;
  int count = 0;
  int failures = 0;

  // Instructuions for the user
  lcd.setCursor(0,0);
  lcd.print("To start, place");
  lcd.setCursor(0,1);
  lcd.print("finger on sensor.");
  delay(2000);

  if (pulseSensor.sawStartOfBeat()) {
    Serial.println("Measurement started");
    lcd.clear();
    lcd.setCursor(2,0);
    lcd.print("Measurement");
    lcd.setCursor(4,1);
    lcd.print("started");
    delay(2000);

    lcd.clear();
    lcd.setCursor(2,0);
    lcd.print("Measuring...");

    // Tries to take 30 measurements
    for (int i = 0; i < 30; i++) {
      // Take a measurement
      currentBPM = pulseSensor.getBeatsPerMinute();

      // If actual measurement failed
      if (currentBPM == 0) {
        Serial.println("Please hold your finger still on the sensor");
        failures++;
      // If 5 consecutive failures registered, then
      // current measurement is considered failed
      } else if (failures >= 5) {
        count = 0;
        break;
      } else {
        Serial.println(currentBPM);
        myBPM += currentBPM;
        currentBPM = 0;
        count++;
        failures = 0;
      }

      lcd.setCursor(7,1);
      lcd.print(i + 1);
      lcd.print("s");
      delay(1000);
    }

    // Enough data to extract a result has been recorded
    if (count > 5) {
      myBPM /= count;

      // Write to serial
      Serial.println("♥ Your heartrate measurement ♥\nBPM:\t ");
      Serial.println(myBPM);

      // Display result on LCD
      lcd.clear();
      lcd.setCursor(0,0);
      lcd.write(0);
      lcd.setCursor(4,0);
      lcd.print("your BPM");
      lcd.setCursor(15,0);
      lcd.write(0);
      lcd.setCursor(6,1);
      lcd.print(myBPM);
      delay(5000);

      // Write result to file
      /*
      if (myFile) {
        myFile = SD.open("test.txt", FILE_WRITE);
        // Write to sd card
        myFile.println("♥ Your heartrate measurement ♥");
        myFile.println(myBPM);
        myFile.close();
        Serial.println("success writing to log file on microSD card.");
        lcd.clear();
        lcd.setCursor(0,0);
        lcd.print("Writing to file");
        lcd.setCursor(6,0);
        lcd.print("<<<<");
        delay(1000);
        lcd.clear();
        lcd.setCursor(2,0);
        lcd.print("Measurement");
        lcd.setCursor(5,1);
        lcd.print("logged");
        delay(1000);
      } else {
        Serial.println("error opening log file on microSD card!");
      }
      */

      // Simulate writing to sd card (owned card not supported)
      lcd.clear();
      lcd.setCursor(0,0);
      lcd.print("Writing to file");
      lcd.setCursor(6,1);
      lcd.print("<<<<");
      delay(3000);
      lcd.clear();
      lcd.setCursor(2,0);
      lcd.print("Measurement");
      lcd.setCursor(5,1);
      lcd.print("logged");
      delay(3000);
      
    } else {
      Serial.println("Measurement failed, try again!");
      lcd.clear();
      lcd.setCursor(2,0);
      lcd.print("Measurement");
      lcd.setCursor(5,1);
      lcd.print("failed");
      delay(2000);
      lcd.clear();
      lcd.setCursor(3,0);
      lcd.print("Try again");
      delay(2000);
      lcd.clear();
    }
  } else {
    delay(1000);
  }

  delay(50);
}