// Set up for GPS and Temperature sensing thing
#include "NMEA.h"
#include "DHT.h"

#define DHTPIN 12       // Temperature pin setup
#define DHTTYPE DHT22 

// Create Data Connections to GPS and Temp sensor
NMEA gps(GPRMC);                            
DHT dht(DHTPIN, DHTTYPE);

//define variables to hold GPS and temperature readings
float latitude;
float longitude;
float temperature;

// Set up for wearable control thing
#define SWITCH_PIN 5  
#define LED_PIN 13
// Tracks the previous state of the switch
bool wasSwitchOn = false; 

// Set up for Air Pollution Sensing thing
//define three variables to hold each pollutant value (NO2, pm2.5m pm10)
float pollution1; 
float pollution2; 
float pollution3; 

// Storing sensor readings from all things in a single data structure
#define MAX_READINGS 360 // 3 a minute, max 2 hour activity (3*2*60)
// Struct to hold a single set of sensor readings
struct SensorReadings {
  float temperature;
  float pollution1;
  float pollution2;
  float pollution3;
  float latitude;
  float longitude;
  int flag;
};
// Array to store all sensor readings
SensorReadings readings[MAX_READINGS]; 
// Counter to keep track of the current reading so list can be written to
int currentReading = 0;


void setup() {

  // GPS and temperature sensor thing
  Serial.begin(115200);
  Serial1.begin(9600); // Serial1 is connected to the custom GPS chip                 
  dht.begin();

  // LED and switch (wearable control thing)
  pinMode(SWITCH_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);

  // air pollution sensing thing
  // set up potentiometers simulating air pollution sensors
  pinMode(A0, INPUT);
  pinMode(A1, INPUT);
  pinMode(A2, INPUT);

}

void loop() {
  
  while (Serial1.available()) { // Waits for serial port data
    
    if (digitalRead(SWITCH_PIN) == LOW) { // Switch is ON
    
    // Turn on LED to indicate sampling
    digitalWrite(LED_PIN, HIGH); 

     // Receives data from GPS serial port
    char serialData = Serial1.read();      
    
    // Checks if the GPS sentence is valid then proceeds to read sensors
    if (gps.decode(serialData)) {           
      latitude  = gps.gprmc_latitude();
      longitude = gps.gprmc_longitude();

      // print Latitude
      Serial.print("Latitude: ");
      Serial.println(latitude, 8);

      // print Longitude
      Serial.print("Longitude: ");
      Serial.println(longitude, 8);

    // Read and print temperature
    if (!isnan(dht.readTemperature())) { 
      temperature = dht.readTemperature();
      Serial.print(F("Temperature: "));
      Serial.print(temperature);
      Serial.println(F("°C"));
    } else {
      Serial.println(F("Failed to read from DHT sensor!"));
    }

    // Read three potentiometers 

    pollution1 = analogRead(A0);
    Serial.print("PM2.5: ");
    Serial.println(pollution1);

    pollution2 = analogRead(A1);
    Serial.print("PM10: ");
    Serial.println(pollution2);

    pollution3 = analogRead(A2);
    Serial.print("NO2: ");
    Serial.println(pollution3);

    Serial.println(); // print blank line

    // add recorded data to an array to be sent to phone
    readings[currentReading].latitude = latitude;
    readings[currentReading].longitude = latitude;
    readings[currentReading].temperature = temperature;
    readings[currentReading].pollution1 = pollution1;
    readings[currentReading].pollution2 = pollution2;
    readings[currentReading].pollution3 = pollution3;

    //indicates vals have been assigned (0 by default)
    readings[currentReading].flag = 1; 

    // Update the counter, wrapping around if reach the maximum
    currentReading = (currentReading + 1) % MAX_READINGS;

    wasSwitchOn = true;
    // wait 20 seconds for next read
    delay(2000);
    }
    
    } else {

      // Turn off LED to indicate stop
      digitalWrite(LED_PIN, LOW); 

      // If the switch was on during the last iteration but is now off, print readings
      if (wasSwitchOn){
        printReadings();
        wasSwitchOn = false;
      }
      
      // Loop until the switch is turned on again.
      // Short delay to avoid bouncing or rapid switching issues
      delay(10);
    }
  }
}

void printReadings() {
  Serial.println(F("All Sensor Readings:"));
  for (int i = 0; i < MAX_READINGS; ++i) {
    // Only print valid readings
    if (readings[i].flag != 0) { 
      Serial.print(F("Reading "));
      Serial.print(i + 1);
      Serial.print(F(": Latitude: "));
      Serial.print(readings[i].latitude, 8);
      Serial.print(F(", Longitude: "));
      Serial.print(readings[i].longitude, 8);
      Serial.print(F(", Temperature: "));
      Serial.print(readings[i].temperature);
      Serial.print(F("°C, Pollution1: "));
      Serial.print(readings[i].pollution1);
      Serial.print(F(", Pollution2: "));
      Serial.print(readings[i].pollution2);
      Serial.print(F(", Pollution3: "));
      Serial.println(readings[i].pollution3);
    }
  }
}