#include <TinyGPSplus.h>
#include <SoftwareSerial.h>


//GPS stuff
const byte gps_RX = 7, gps_TX = 6;
TinyGPSPlus gps;
SoftwareSerial NEO6M(gps_RX, gps_TX);

//Sensor Stuff
const float BETA = 3950; // should match the Beta Coefficient of the thermistor
const byte motionPin = 13;
const byte buzzPin = 12;

//button stuff
const byte button_Vin = 9; 
const byte button_Vout = 11;

//bluetooth stuff
const byte bt_RX = 2, bt_TX = 3;
const byte bt_Vin = 4;
SoftwareSerial BTSerial(bt_RX, bt_TX);

//pressure resistor stuff
const byte pressurePin_Vin = 8; 


void setup() {
  Serial.begin(9600);// put your setup code here, to run once:
  NEO6M.begin(9600);
  BTSerial.begin(9600);

  //thermistor is connected to A0
  pinMode(motionPin, INPUT_PULLUP); //motion sensor
  pinMode(buzzPin, OUTPUT); //Buzzer

  pinMode(button_Vin, OUTPUT);
  pinMode(button_Vout, INPUT_PULLUP);

  //read pressure with pin A1;
  pinMode(pressurePin_Vin, OUTPUT);
  

  pinMode(bt_Vin, OUTPUT);
  digitalWrite(bt_Vin, HIGH); //powers bluetooth

}


void loop() {

  int analogValue = analogRead(A0); //thermistor uses analog pins
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  
  int motion = digitalRead(motionPin);
  int pressure = analogRead(A1);
  int buzzTime = 250; //buzzer rhythm
  static int trackingMode = 0; //remembers if someone was in the backseat
  static int trackingTime = 150;

  static String msg_to_bt = "";
  static String msg_from_bt = "";
  static String atm = "";
  static byte dByte = "";

  if (digitalRead(button_Vout) == 0) {
   Serial.println("Button Test Successful");
   BTSerial.write("->Hey!");
   tone(buzzPin,150,50);
   delay(buzzTime);
   tone(buzzPin,250,50);
}

  //GPS location and time
  while (NEO6M.available() > 0){
    if (gps.encode(NEO6M.read())) displayInfo();

    if (millis() > 5000 && gps.charsProcessed() < 10) {
      Serial.println(F("No GPS detected: check wiring."));
      while(true);
    }
  }

  //---------------------

  //pressure sensor 
  Serial.print(pressure); 
  Serial.print("   ");
  //motion sensor
  Serial.print(motion);
  Serial.print("   ");
  //thermistor
  Serial.print(celsius);
  Serial.print("   ");
  
  if (motion == 1 || pressure < 15){
    trackingMode = 1; //someone is in the backseat
    trackingTime = 10; //memory of someone in backseat
  }

if (trackingMode == 1) {
  Serial.print("Passenger?");
  Serial.print("   ");
}


//alert siren for heat stroke or hypothermia threat
if (trackingMode == 1 && (celsius >= 37.8 || celsius <= 0)) {
  Serial.print("DANGER!");
  Serial.print("   ");
  BTSerial.write("HELP!! ");
  tone(buzzPin,150,50);
  delay(buzzTime);
  tone(buzzPin,250,50);
} else delay(buzzTime); //delay compensates for buzzer usage

Serial.println();


if (trackingMode == 1) trackingTime--; //passenger memory fades

if (trackingTime == 0) trackingMode = 0;

//command line -> bluetooth module
  msg_to_bt = "";
  while(Serial.available()){
    dByte = Serial.read();
    if (dByte >= 97 && dByte <= 122) dByte -= 32; //capitalizes message
    Serial.print((char)dByte);
    if (dByte > 31 && dByte < 127) msg_to_bt += (char)dByte; //only stores printing bytes
  }
  if (msg_to_bt != "") BTSerial.println(msg_to_bt);

  //since HC-06 is always in slave mode when paired, Arduino must emulate AT functions
  if(msg_to_bt == "AT") BTSerial.write(" OK\n");
  if(msg_to_bt == "AT+NAME") BTSerial.write(" Backseat Guardian\n");
  if(msg_to_bt == "AT+VERSION") BTSerial.write(" LINVORV1.8\n");
  if(msg_to_bt == "AT+BAUD") BTSerial.write(" 9600\n");

  //bluetooth module -> serial monitor
  msg_from_bt = "";
  while(BTSerial.available()){
    dByte = BTSerial.read();
    if (dByte >= 97 && dByte <=122) dByte -= 32; //capitalizes message
    Serial.print((char)dByte);
    if (dByte > 31 && dByte < 127) msg_from_bt += (char)dByte; //only stores printing bytes
  }
  
  atm = "";
  delay(100);
  atm += msg_from_bt[0];
  atm += msg_from_bt[1];
  atm += msg_from_bt[2];

  if (msg_from_bt != "") {
  //since HC-06 is always in slave mode when paired, Arduino must emulate AT functions
    if (atm == "AT+") {
      if(msg_from_bt == "AT+NAME") BTSerial.write("+NAME:Backseat Guardian\n"); //"AT+NAME"
      if(msg_from_bt == "AT+VERSION") BTSerial.write("LINVORV1.8\n"); //"AT+VERSION"
      if(msg_from_bt == "AT+BAUD") BTSerial.write("9600\n"); //"AT+BAUD"
      Serial.print(".");
    }
    if(msg_from_bt == "AT") BTSerial.write("OK\n"); //"AT"
    if(msg_from_bt == "HELLO") BTSerial.write("Welcome!\n");
    if(msg_from_bt == "LOCATION") BTSerial.write("I'm right here: \n");
    if(msg_from_bt == "BYE") {
      digitalWrite(bt_Vin, LOW); //disconnects bluetooth
      delay(1000);
      BTSerial.read();
      digitalWrite(bt_Vin, HIGH);
      delay(1000);
    }
  }

} 

//--------end of the main loop----------

void displayInfo(){
  Serial.print(F("Location: ")); 
  if (gps.location.isValid())
  {
    Serial.print(gps.location.lat(), 6);
    Serial.print(F(","));
    Serial.print(gps.location.lng(), 6);
  } else Serial.print(F("INVALID"));

  Serial.print(F("  Date "));
  if (gps.date.isValid()) {
    Serial.print(gps.date.month());
    Serial.print(F("/"));
    Serial.print(gps.date.day());
    Serial.print(F("/"));
    Serial.print(gps.date.year());
  }
  else Serial.print(F("INVALID"));

  Serial.println();
}