#include <SoftwareSerial.h>

// Define pin numbers
const int lowTrigPin = 2;
const int lowEchoPin = 3;
const int highTrigPin = 12;
const int highEchoPin = 13;
const int buzzerPin = 8;
const int emergencyButtonPin = 4; // Emergency button pin

// Simulate GPS and GSM module pins
SoftwareSerial gpsSerial(7, 6); // RX, TX for GPS
SoftwareSerial gsmSerial(0, 1); // RX, TX for GSM (Using different pins to avoid conflict with Serial Monitor)

// Define duration and distance variables
long lowDuration, lowDistance;
long highDuration, highDistance;

void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);

  // Initialize pins for sensors and modules
  pinMode(lowTrigPin, OUTPUT);
  pinMode(lowEchoPin, INPUT);
  pinMode(highTrigPin, OUTPUT);
  pinMode(highEchoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(emergencyButtonPin, INPUT_PULLUP); // Use internal pull-up resistor

  // Initialize GPS and GSM modules
  gpsSerial.begin(9600);
  gsmSerial.begin(9600);
  sendGSMCommand("AT");
  sendGSMCommand("AT+CMGF=1"); // Set SMS to text mode
}

void loop() {
  // Read emergency button state
  bool emergencyButtonPressed = digitalRead(emergencyButtonPin) == LOW; // Button pressed

  // Low obstacle detection
  lowDistance = getDistance(lowTrigPin, lowEchoPin);

  // High obstacle detection
  highDistance = getDistance(highTrigPin, highEchoPin);

  // Handle emergency button press
  if (emergencyButtonPressed) {
    handleEmergency();
  } else if (lowDistance < 20) {
    tone(buzzerPin, 1000); // Low tone for low obstacle
    Serial.println("Low obstacle detected: " + String(lowDistance) + " cm");
  } else if (highDistance < 20) {
    tone(buzzerPin, 2000); // High tone for high obstacle
    Serial.println("High obstacle detected: " + String(highDistance) + " cm");
  } else {
    noTone(buzzerPin);
    Serial.println("No obstacles detected");
  }
  delay(500);
}

long getDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2;
}

String getGPSLocation() {
  // Simulate GPS location data
  return "Lat: 36.778259, Lon: -119.417931";
}

void sendEmergencySMS(String message, String location) {
  Serial.print("Sending SMS: ");
  Serial.println(message + ": " + location);
  gsmSerial.print("AT+CMGS=\"+21623574721\"\r"); // Replace with actual phone number
  delay(100);
  gsmSerial.print(message + ": " + location);
  delay(100);
  gsmSerial.write(26); // ASCII code for Ctrl+Z to send SMS
}

void sendGSMCommand(String command) {
  gsmSerial.println(command);
  delay(100);
  while (gsmSerial.available()) {
    char c = gsmSerial.read();
    Serial.print(c);
  }
  Serial.println();
}

void handleEmergency() {
  tone(buzzerPin, 4000); // High tone for emergency
  String location = getGPSLocation();
  Serial.println("Emergency button pressed, sending SMS...");
  sendEmergencySMS("Emergency button pressed", location);
}