#include <Wire.h>
#include <LiquidCrystal_I2C.h>

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

// ==============================
// PIN DEFINITIONS
// ==============================

#define BUZZER_PIN 26
#define LED_PIN 27
#define BUTTON_PIN 14

// ==============================
// VARIABLES
// ==============================

float acceleration;
int gasLevel;

float impactThreshold;
int gasThreshold;

void setup() {

  Serial.begin(115200);

  // LCD I2C
  Wire.begin(21, 22);

  // LCD initialize
  lcd.init();
  lcd.backlight();

  // Pin Modes
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // Startup Screen
  lcd.setCursor(0, 0);
  lcd.print("SMART HELMET");

  lcd.setCursor(0, 1);
  lcd.print("SYSTEM READY");

  delay(2000);

  lcd.clear();

  // ==============================
  // USER INPUT THRESHOLDS
  // ==============================

  Serial.println("===== SMART HELMET =====");

  Serial.println("Enter Accident Threshold:");
  while (Serial.available() == 0);

  impactThreshold = Serial.parseFloat();

  while (Serial.available() > 0) {
    Serial.read();
  }

  Serial.print("Impact Threshold = ");
  Serial.println(impactThreshold);

  delay(1000);

  Serial.println("Enter Gas Threshold:");
  while (Serial.available() == 0);

  gasThreshold = Serial.parseInt();

  while (Serial.available() > 0) {
    Serial.read();
  }

  Serial.print("Gas Threshold = ");
  Serial.println(gasThreshold);

  Serial.println("========================");
}

void loop() {

  // ==============================
  // USER ENTERS ACCELERATION VALUE
  // ==============================

  Serial.println("\nEnter Acceleration Value:");

  while (Serial.available() == 0);

  acceleration = Serial.parseFloat();

  while (Serial.available() > 0) {
    Serial.read();
  }

  Serial.print("Acceleration = ");
  Serial.println(acceleration);

  // ==============================
  // USER ENTERS GAS VALUE
  // ==============================

  Serial.println("Enter Gas Value:");

  while (Serial.available() == 0);

  gasLevel = Serial.parseInt();

  while (Serial.available() > 0) {
    Serial.read();
  }

  Serial.print("Gas Level = ");
  Serial.println(gasLevel);

  Serial.println("-----------------------");

  // ==============================
  // LCD DISPLAY
  // ==============================

  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Gas:");
  lcd.print(gasLevel);

  // ==============================
  // ACCIDENT DETECTION
  // ==============================

  if (acceleration > impactThreshold ||
      digitalRead(BUTTON_PIN) == LOW) {

    Serial.println("ACCIDENT DETECTED!");
    Serial.println("GPS LOCATION SENT");

    // Simulated GPS Coordinates
    float latitude = 17.3850;
    float longitude = 78.4867;

    Serial.print("Latitude: ");
    Serial.println(latitude, 6);

    Serial.print("Longitude: ");
    Serial.println(longitude, 6);

    // LCD Alert
    lcd.clear();

    lcd.setCursor(0, 0);
    lcd.print("ACCIDENT!");

    lcd.setCursor(0, 1);
    lcd.print("GPS SENT");

    // LED ON
    digitalWrite(LED_PIN, HIGH);

    // Buzzer ON
    tone(BUZZER_PIN, 1000);

    delay(5000);

    // OFF
    noTone(BUZZER_PIN);
    digitalWrite(LED_PIN, LOW);

    lcd.clear();
  }

  // ==============================
  // GAS DETECTION
  // ==============================

  else if (gasLevel > gasThreshold) {

    Serial.println("GAS/ALCOHOL DETECTED!");

    lcd.clear();

    lcd.setCursor(0, 0);
    lcd.print("GAS DETECTED");

    lcd.setCursor(0, 1);
    lcd.print("RIDE BLOCKED");

    // LED ON
    digitalWrite(LED_PIN, HIGH);

    // Buzzer ON
    tone(BUZZER_PIN, 1500);

    delay(3000);

    // OFF
    noTone(BUZZER_PIN);
    digitalWrite(LED_PIN, LOW);

    lcd.clear();
  }

  // ==============================
  // NORMAL CONDITION
  // ==============================

  else {

    lcd.setCursor(0, 1);
    lcd.print("Helmet Safe");

    digitalWrite(LED_PIN, LOW);

    noTone(BUZZER_PIN);

    Serial.println("Helmet Safe");
  }

  delay(1000);
}