#include <WiFi.h>
#include "PubSubClient.h"
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define PULSES_PER_BEAT     1
#define INTERRUPT_PIN       5
#define SAMPLING_INTERVAL   1000

#define SCREEN_WIDTH 16
#define SCREEN_HEIGHT 2

volatile uint16_t heartPulse;    // Count of heart pulses (volatile for use in interrupt)
uint16_t pulseCount;              // Current count of heart pulses

float heartRate;                  // Calculated heart rate
float lastHeartRate = -1.0;       // Last recorded heart rate

const int ledPin = 13;            // Pin connected to LED to indicate elevated heart rate

portMUX_TYPE mutex = portMUX_INITIALIZER_UNLOCKED;  // Mutex to protect critical section in ISR

const char *wifiSSID = "Wokwi-GUEST";
const char *wifiPassword = "";

// Flespi MQTT details
const char *mqttServer = "mqtt.flespi.io";
const char *mqttUser = "mmV7UcyWRMXkzvwEc96PimGo0hv9hm3ryOohQN3ynPGMa2ea1aN8kjmboH8tR1Jg";
const char *mqttPassword = "";
const int mqttPort = 1883;

const char *mqttTopic = "Tabasan/Tapongot/Banaynal/Naduma/HeartRate";

WiFiClient espClient;
PubSubClient client(espClient);

// Initialize LCD object
LiquidCrystal_I2C lcd(0x27, SCREEN_WIDTH, SCREEN_HEIGHT);

void IRAM_ATTR PulseInterrupt() {
  portENTER_CRITICAL_ISR(&mutex);
  heartPulse++;  // Increment the heartPulse variable safely within ISR
  portEXIT_CRITICAL_ISR(&mutex);
}

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

  pinMode(INTERRUPT_PIN, INPUT);
  attachInterrupt(digitalPinToInterrupt(INTERRUPT_PIN), PulseInterrupt, RISING);
  pinMode(ledPin, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.clear();

  connectToWiFi();   // Function to connect to WiFi
  connectToMqtt();   // Function to connect to MQTT
}

void connectToWiFi() {
  Serial.print("Connecting to WiFi");
  WiFi.begin(wifiSSID, wifiPassword);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void connectToMqtt() {
  client.setServer(mqttServer, mqttPort);

  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    long r = random(1000);
    String clientId = "clientId-" + String(r);
    if (client.connect(clientId.c_str(), mqttUser, mqttPassword)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void loop() {
  if (!client.connected()) {
    connectToMqtt();
  }
  client.loop();

  CalculateHeartRate();   // Function to calculate and publish heart rate data

  delay(500);
}

void CalculateHeartRate() {
  static unsigned long startTime;
  if (millis() - startTime < SAMPLING_INTERVAL) return;   // Sampling interval
  startTime = millis();

  portENTER_CRITICAL(&mutex);  // Enter a critical section
  pulseCount = heartPulse;     // Save the current value of heartPulse and reset heartPulse
  heartPulse = 0;
  portEXIT_CRITICAL(&mutex);   // Exit the critical section

  heartRate = map(pulseCount, 0, 220, 0, 220);  // Map the pulseCount to the desired range

  const int blinkDuration = 500;  // Blink duration in milliseconds

  if (heartRate < 60 || heartRate > 140) {
      // Blink the LED if heart rate is below 60 or above 140 BPM
      digitalWrite(ledPin, HIGH);
      delay(blinkDuration);
      digitalWrite(ledPin, LOW);
      delay(blinkDuration);
  } else {
      digitalWrite(ledPin, LOW);   // Turn off the LED otherwise
  }
  // if (heartRate > 80) {
  //   digitalWrite(ledPin, HIGH);  // Turn on the LED if heart rate is above 80 BPM
  // } else {
  //   digitalWrite(ledPin, LOW);   // Turn off the LED otherwise
  // }

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Heart Rate:");
  lcd.setCursor(0, 1);
  lcd.print(String(heartRate, 2) + " BPM");

  String heartRateStr = String(heartRate, 2);
  client.publish(mqttTopic, heartRateStr.c_str());  // Publish heart rate data to MQTT

  Serial.println("Heart Rate: " + String(heartRate, 2) + " BPM");
}