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

// ---------- Pin assignments ----------
const int GREEN_LED_PIN  = 25;   // Gate OPEN indicator
const int RED_LED_PIN    = 26;   // Gate CLOSED / booth busy indicator
const int BUZZER_PIN     = 27;   // Short beep when a vehicle finishes

// ---------- LCD setup (address, columns, rows) ----------
LiquidCrystal_I2C lcd(0x27, 16, 2);

// ---------- Time scaling ----------
const unsigned long TIME_UNIT_MS = 1000; // 1 unit = 1 second

// ---------- Vehicle model ----------
struct Vehicle {
  String id;
  int arrivalTime;
  int serviceTime;
  int startTime;
  int completionTime;
  int waitingTime;
  int turnaroundTime;
};

// ---------- Sample input data (edit these for your report) ----------
const int NUM_VEHICLES = 5;
Vehicle fleet[NUM_VEHICLES] = {
  {"V1", 0, 4, 0, 0, 0, 0},
  {"V2", 1, 3, 0, 0, 0, 0},
  {"V3", 2, 1, 0, 0, 0, 0},
  {"V4", 3, 2, 0, 0, 0, 0},
  {"V5", 5, 3, 0, 0, 0, 0}
};

void sortByArrivalTime(Vehicle arr[], int n) {
  for (int i = 0; i < n - 1; i++) {
    for (int j = 0; j < n - i - 1; j++) {
      if (arr[j].arrivalTime > arr[j + 1].arrivalTime) {
        Vehicle temp = arr[j];
        arr[j] = arr[j + 1];
        arr[j + 1] = temp;
      }
    }
  }
}

void computeSchedule(Vehicle arr[], int n) {
  int currentTime = 0;
  for (int i = 0; i < n; i++) {
    if (currentTime < arr[i].arrivalTime) {
      currentTime = arr[i].arrivalTime;
    }
    arr[i].startTime      = currentTime;
    arr[i].completionTime = currentTime + arr[i].serviceTime;
    arr[i].waitingTime    = arr[i].startTime - arr[i].arrivalTime;
    arr[i].turnaroundTime = arr[i].completionTime - arr[i].arrivalTime;
    currentTime = arr[i].completionTime;
  }
}

void gateOpen() {
  digitalWrite(GREEN_LED_PIN, HIGH);
  digitalWrite(RED_LED_PIN, LOW);
}

void gateClosed() {
  digitalWrite(GREEN_LED_PIN, LOW);
  digitalWrite(RED_LED_PIN, HIGH);
}

void beep() {
  digitalWrite(BUZZER_PIN, HIGH);
  delay(150);
  digitalWrite(BUZZER_PIN, LOW);
}

void simulateProcessing(Vehicle arr[], int n) {
  for (int i = 0; i < n; i++) {
    gateClosed();

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Processing ");
    lcd.print(arr[i].id);
    lcd.setCursor(0, 1);
    lcd.print("Wait:");
    lcd.print(arr[i].waitingTime);
    lcd.print(" Serv:");
    lcd.print(arr[i].serviceTime);

    Serial.println("----------------------------------------");
    Serial.print("Now serving: "); Serial.println(arr[i].id);
    Serial.print("  Arrival Time     : "); Serial.println(arr[i].arrivalTime);
    Serial.print("  Start Time       : "); Serial.println(arr[i].startTime);
    Serial.print("  Service Time     : "); Serial.println(arr[i].serviceTime);
    Serial.print("  Completion Time  : "); Serial.println(arr[i].completionTime);
    Serial.print("  Waiting Time     : "); Serial.println(arr[i].waitingTime);
    Serial.print("  Turnaround Time  : "); Serial.println(arr[i].turnaroundTime);

    delay(arr[i].serviceTime * TIME_UNIT_MS);

    gateOpen();
    beep();
    delay(300);
  }
}

void printSummary(Vehicle arr[], int n) {
  float totalWT = 0, totalTAT = 0;
  Serial.println("\n========== FCFS TOLL PLAZA - FINAL REPORT ==========");
  Serial.println("ID\tAT\tBT\tST\tCT\tWT\tTAT");
  for (int i = 0; i < n; i++) {
    Serial.print(arr[i].id);          Serial.print("\t");
    Serial.print(arr[i].arrivalTime); Serial.print("\t");
    Serial.print(arr[i].serviceTime); Serial.print("\t");
    Serial.print(arr[i].startTime);   Serial.print("\t");
    Serial.print(arr[i].completionTime); Serial.print("\t");
    Serial.print(arr[i].waitingTime); Serial.print("\t");
    Serial.println(arr[i].turnaroundTime);

    totalWT  += arr[i].waitingTime;
    totalTAT += arr[i].turnaroundTime;
  }
  Serial.print("Average Waiting Time    : "); Serial.println(totalWT / n);
  Serial.print("Average Turnaround Time : "); Serial.println(totalTAT / n);
  Serial.println("=====================================================");

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("AvgWT:");
  lcd.print(totalWT / n);
  lcd.setCursor(0, 1);
  lcd.print("AvgTAT:");
  lcd.print(totalTAT / n);
}

void setup() {
  Serial.begin(115200);

  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Toll Plaza FCFS");
  lcd.setCursor(0, 1);
  lcd.print("Simulator");
  delay(1500);

  sortByArrivalTime(fleet, NUM_VEHICLES);
  computeSchedule(fleet, NUM_VEHICLES);

  Serial.println("Vehicles sorted by arrival time (FCFS order):");
  for (int i = 0; i < NUM_VEHICLES; i++) {
    Serial.println(fleet[i].id);
  }

  simulateProcessing(fleet, NUM_VEHICLES);
  printSummary(fleet, NUM_VEHICLES);
}

void loop() {
  // Nothing repeating - this is a one-shot simulation for the demo video.
}