// SmartBridgeX: Wokwi simulation for a bridge safety monitor.
// This code reads from a few sensors to check for overload, cracks, and environmental stress.

// Libraries
#include <DHT.h>
#include <Wire.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <math.h>

// Pin setup for all our sensors
// Potentiometer to act like a weight sensor
const int WEIGHT_PIN = 34; 
const float MAX_BRIDGE_LOAD_TONS = 100.0;     // Our bridge's max designed load
const float OVERLOAD_THRESHOLD_TONS = 80.0;   // Alert at 80% of max load

// Ultrasonic sensor to check for cracks or joint gaps
const int TRIG_PIN = 5;
const int ECHO_PIN = 18;
const float CRACK_ALERT_THRESHOLD_CM = 15.0;  // Alert if a gap is over 15cm

// Temp/Humidity sensor
const int DHT_PIN = 4;
#define DHTTYPE DHT22 // Using DHT22
DHT dht(DHT_PIN, DHTTYPE);
const float TEMP_STRESS_THRESHOLD_C = 40.0;   // Alert if it gets too hot

Adafruit_MPU6050 mpu;

// ----- Configuration -----
float vibrationAxisThreshold = 1.5;  // Max allowed spike in any axis (g units)
float tiltThreshold = 10.0;          // Max tilt allowed in degrees
float gravityBaseline = 9.8;         // Baseline Z acceleration (g)


// This runs once when the ESP32 starts up
void setup() {
  // Start the serial monitor so we can see the output
  Serial.begin(115200);
  Serial.println("--- SmartBridgeX System Online ---");

  // Setup the ultrasonic sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Get the DHT sensor ready
  dht.begin();
  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050 chip");
    while (1) delay(10);
  }

  Serial.println("MPU6050 Initialized.");
  mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
  mpu.setGyroRange(MPU6050_RANGE_500_DEG);
  mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);

  pinMode(32, OUTPUT); // Tilt warning
  pinMode(33, OUTPUT); // Vibration warning
  pinMode(25, OUTPUT); // Temperature warning
  pinMode(26, OUTPUT); // Weight warning
  pinMode(27, OUTPUT); // Crack warning


  delay(100);
}

// This part runs over and over again
void loop() {
  Serial.println("\n------------------------------------");
  // Just a simple timestamp to see when the reading was taken
  Serial.println("Reading at " + String(millis() / 1000) + " seconds");

  // Read the simulated weight from the potentiometer
  int weightValueRaw = analogRead(WEIGHT_PIN); 
  // Convert the pot's 0-4095 reading to a 0-100 ton scale for our bridge
  float currentLoadTons = map(weightValueRaw, 0, 4095, 0, (int)MAX_BRIDGE_LOAD_TONS); 

  Serial.print("[LOAD] ");
  Serial.print(currentLoadTons);
  Serial.println(" tons");

  // Check for overload
  if (currentLoadTons > OVERLOAD_THRESHOLD_TONS) {
    Serial.println("  >> ALERT: Bridge Overload!");
    digitalWrite(26, HIGH);
  } else {
    digitalWrite(26, LOW);
  }

  // Use the ultrasonic sensor to measure a gap
  // Send out a sound pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  // Listen for the echo and measure the time it took
  long duration = pulseIn(ECHO_PIN, HIGH);
  
  // Calculate distance from time
  float gapDistanceCm = duration * 0.034 / 2;

  Serial.print("[GAP] ");
  Serial.print(gapDistanceCm);
  Serial.println(" cm");

  // Check if the gap is too wide
  if (gapDistanceCm > CRACK_ALERT_THRESHOLD_CM) {
    Serial.println("  >> ALERT: Structural gap is too wide!");
    digitalWrite(27, HIGH);
  } else {
    digitalWrite(27, LOW);
  }

  // Read the temperature and humidity
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Sometimes the sensor fails, so check for that
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("[ENV] Couldn't read from DHT sensor");
  } else {
    Serial.print("[ENV] Temp: ");
    Serial.print(temperature);
    Serial.print("C, Humidity: ");
    Serial.print(humidity);
    Serial.println("%");

    // Check for extreme heat
    if (temperature > TEMP_STRESS_THRESHOLD_C) {
      Serial.println("  >> ALERT: High temperature stress!");
      digitalWrite(25, HIGH);
    } else {
      digitalWrite(25, LOW);
    }
  }
  
sensors_event_t acc, gyro, temp;
  mpu.getEvent(&acc, &gyro, &temp);

  float ax = acc.acceleration.x;
  float ay = acc.acceleration.y;
  float az = acc.acceleration.z;

  // Approximate tilt angle using accelerometer
  float tiltX = atan2(ay, az) * 180 / PI;
  float tiltY = atan2(ax, az) * 180 / PI;

  // Print current readings
  Serial.print("Tilt X: ");
  Serial.print(tiltX);
  Serial.print("°, Y: ");
  Serial.print(tiltY);
  Serial.print("° | Acc X: ");
  Serial.print(ax);
  Serial.print(" Y: ");
  Serial.print(ay);
  Serial.print(" Z: ");
  Serial.println(az);

  // Check tilt threshold
  if (abs(tiltX) > tiltThreshold || abs(tiltY) > tiltThreshold) {
    Serial.println("⚠️  WARNING: Bridge Tilt Detected!");
    digitalWrite(32, HIGH);
  } else {
    digitalWrite(32, LOW);
  }

  // Check vibration per-axis
  Serial.println(abs(az - gravityBaseline));
  bool excessiveVibration =
    abs(ax) > vibrationAxisThreshold ||
    abs(ay) > vibrationAxisThreshold ||
    abs(az - gravityBaseline) > vibrationAxisThreshold;

  if (excessiveVibration) {
    Serial.println("💥 WARNING: Excessive Bridge Vibration Detected!");
    digitalWrite(33, HIGH);
  } else {
    digitalWrite(33, LOW);
  }

  // Wait 2 seconds before the next loop
  delay(2000);








  
}