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

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

// Pins
#define STRAIN_PIN A1
#define GREEN_LED D12
#define YELLOW_LED D11
#define RED_LED D13
#define BUZZER D10

// MPU6050
#define MPU_ADDR 0x68

void setup() {

  Serial.begin(115200);

  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  // All outputs OFF
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(RED_LED, LOW);
  digitalWrite(BUZZER, LOW);

  // I2C
  Wire.begin();

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

  lcd.setCursor(0, 0);
  lcd.print("BRIDGE HEALTH");

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

  // Start MPU6050
  Wire.beginTransmission(MPU_ADDR);
  Wire.write(0x6B);
  Wire.write(0x00);
  Wire.endTransmission();

  delay(2000);
}

void loop() {

  // Read strain simulation
  int strain = analogRead(STRAIN_PIN);

  Serial.print("Strain: ");
  Serial.println(strain);

  // Turn everything OFF
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(RED_LED, LOW);
  digitalWrite(BUZZER, LOW);

  lcd.clear();

  // NORMAL
  if (strain < 100) {

    digitalWrite(GREEN_LED, HIGH);

    lcd.setCursor(0, 0);
    lcd.print("BRIDGE NORMAL");

    lcd.setCursor(0, 1);
    lcd.print("SAFE");

    Serial.println("STATUS: NORMAL");
  }

  // WARNING
  else if (strain < 200) {

    digitalWrite(YELLOW_LED, HIGH);

    lcd.setCursor(0, 0);
    lcd.print("BRIDGE WARNING");

    lcd.setCursor(0, 1);
    lcd.print("CAUTION");

    Serial.println("STATUS: WARNING");
  }

  // CRITICAL
  else {

    digitalWrite(RED_LED, HIGH);

    // Buzzer ON ONLY during critical
    digitalWrite(BUZZER, HIGH);

    lcd.setCursor(0, 0);
    lcd.print("CRITICAL ALERT");

    lcd.setCursor(0, 1);
    lcd.print("ALERT PASSENGERS");

    Serial.println("STATUS: CRITICAL");
    Serial.println("BUZZER: ON");
  }

  delay(500);
}