#include <SPI.h>
#include <MFRC522.h>
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <EEPROM.h>

#define SS_PIN    5
#define RST_PIN   4
#define TRIG      14
#define ECHO      12
#define SERVO_PIN 13
#define LED_G     26
#define LED_R     27
#define BUZZER    25
#define THRESHOLD 20

#define EEPROM_SIZE  250
#define MAX_VEHICLES 4
#define SLOT_SIZE    41
#define UID_LEN      8
#define NUMBER_LEN   12
#define INIT_FLAG    0xAB

MFRC522 rfid(SS_PIN, RST_PIN);
LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo barrier;

const char* ssid     = "Wokwi-GUEST";
const char* password = "";
const char* apiURL   = "https://httpbin.org/post";

int uidAddr(int i)     { return 1 + i * SLOT_SIZE; }
int numberAddr(int i)  { return 1 + i * SLOT_SIZE + UID_LEN; }
int balanceAddr(int i) { return 1 + i * SLOT_SIZE + UID_LEN + NUMBER_LEN; }
int tripAddr(int i)    { return 1 + i * SLOT_SIZE + UID_LEN + NUMBER_LEN + 4; }
int typeAddr(int i)    { return 1 + i * SLOT_SIZE + UID_LEN + NUMBER_LEN + 8; }

void eepromWriteStr(int addr, const char* s, int len) {
  for (int i = 0; i < len; i++)
    EEPROM.write(addr + i, i < (int)strlen(s) ? s[i] : 0);
}

String eepromReadStr(int addr, int len) {
  String s = "";
  for (int i = 0; i < len; i++) {
    char c = EEPROM.read(addr + i);
    if (c == 0) break;
    s += c;
  }
  return s;
}

void eepromWriteFloat(int addr, float val) { EEPROM.put(addr, val); }
float eepromReadFloat(int addr) { float v; EEPROM.get(addr, v); return v; }
void eepromWriteInt(int addr, int val) { EEPROM.put(addr, val); }
int eepromReadInt(int addr) { int v; EEPROM.get(addr, v); return v; }

String getTypeName(int type) {
  if (type == 0) return "Car";
  if (type == 1) return "Truck";
  return "Car";
}

float getToll(int type) {
  if (type == 0) return 50.0;
  if (type == 1) return 100.0;
  return 50.0;
}

void seedEEPROM() {
  if (EEPROM.read(0) == INIT_FLAG) return;

  struct { const char* uid; const char* number; float balance; int type; }
  defaults[] = {
    {"AABBCCDD", "TS09AB1234", 200.0, 0},
    {"55667788", "AP28XY5678", 300.0, 1},
    {"11223344", "KA01ZZ9999", 150.0, 0},
    {"01020304", "MH12CD3456", 400.0, 1}
  };

  for (int i = 0; i < MAX_VEHICLES; i++) {
    eepromWriteStr  (uidAddr(i),     defaults[i].uid,    UID_LEN);
    eepromWriteStr  (numberAddr(i),  defaults[i].number, NUMBER_LEN);
    eepromWriteFloat(balanceAddr(i), defaults[i].balance);
    eepromWriteInt  (tripAddr(i),    0);
    EEPROM.write    (typeAddr(i),    defaults[i].type);
  }

  EEPROM.write(0, INIT_FLAG);
  EEPROM.commit();
}

int findVehicle(String uid) {
  for (int i = 0; i < MAX_VEHICLES; i++)
    if (eepromReadStr(uidAddr(i), UID_LEN) == uid) return i;
  return -1;
}

bool chargePayment(int idx, float toll) {
  float bal = eepromReadFloat(balanceAddr(idx));
  if (bal >= toll) {
    bal -= toll;
    eepromWriteFloat(balanceAddr(idx), bal);
    int trips = eepromReadInt(tripAddr(idx)) + 1;
    eepromWriteInt(tripAddr(idx), trips);
    EEPROM.commit();
    return true;
  }
  return false;
}

void connectWiFi() {
  lcd.clear();
  lcd.print("Connecting WiFi");
  WiFi.begin(ssid, password);
  int tries = 0;
  while (WiFi.status() != WL_CONNECTED && tries < 20) {
    delay(300);
    Serial.print(".");
    tries++;
  }
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nWiFi Connected!");
    lcd.clear();
    lcd.print("WiFi Connected");
    delay(800);
  } else {
    Serial.println("\nWiFi Failed");
    lcd.clear();
    lcd.print("WiFi Failed");
    lcd.setCursor(0, 1);
    lcd.print("Offline Mode");
    delay(1000);
  }
}

void sendTransaction(String uid, String number, String type, float amount, float remainingBal, bool success, int trips) {
  if (WiFi.status() != WL_CONNECTED) return;
  HTTPClient http;
  http.begin(apiURL);
  http.addHeader("Content-Type", "application/json");
  String payload = "{";
  payload += "\"uid\":\"" + uid + "\",";
  payload += "\"vehicle\":\"" + number + "\",";
  payload += "\"type\":\"" + type + "\",";
  payload += "\"amount\":" + String(amount, 2) + ",";
  payload += "\"balance\":" + String(remainingBal, 2) + ",";
  payload += "\"status\":\"" + String(success ? "paid" : "denied") + "\",";
  payload += "\"trips\":" + String(trips) + ",";
  payload += "\"timestamp\":" + String(millis());
  payload += "}";
  Serial.println("Sending: " + payload);
  int code = http.POST(payload);
  Serial.println("HTTP: " + String(code));
  http.end();
}

long getDistance() {
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  long dur = pulseIn(ECHO, HIGH, 30000UL);
  if (dur == 0) return 999;
  return dur * 0.034 / 2;
}

String getUID() {
  String uid = "";
  for (byte i = 0; i < rfid.uid.size; i++) {
    if (rfid.uid.uidByte[i] < 0x10) uid += "0";
    uid += String(rfid.uid.uidByte[i], HEX);
  }
  uid.toUpperCase();
  return uid;
}

void openGate() {
  digitalWrite(LED_G, HIGH);
  barrier.write(90);
  lcd.clear();
  lcd.print("Gate Open");
}

void closeGate() {
  barrier.write(0);
  delay(800);
  digitalWrite(LED_G, LOW);
  lcd.clear();
  lcd.print("Gate Closed");
  delay(1000);
}

void deny() {
  digitalWrite(LED_R, HIGH);
  tone(BUZZER, 400, 800);
  lcd.clear();
  lcd.print("Low Balance");
  lcd.setCursor(0, 1);
  lcd.print("Recharge Req");
  delay(1500);
  digitalWrite(LED_R, LOW);
}

void setup() {
  Serial.begin(115200);
  EEPROM.begin(EEPROM_SIZE);
  seedEEPROM();

  SPI.begin();
  rfid.PCD_Init();

  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(LED_G, OUTPUT);
  pinMode(LED_R, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  barrier.setPeriodHertz(50);
  barrier.attach(SERVO_PIN, 500, 2400);
  barrier.write(0);

  lcd.init();
  lcd.backlight();
  lcd.print("Welcome to Toll");
  delay(1000);

  connectWiFi();

  lcd.clear();
  lcd.print("Waiting Vehicle");
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) connectWiFi();

  long dist = getDistance();

  if (dist < THRESHOLD) {
    lcd.clear();
    lcd.print("Vehicle Detected");
    delay(300);

    lcd.clear();
    lcd.print("Scan FASTag");

    unsigned long scanStart = millis();
    bool cardFound = false;
    while (millis() - scanStart < 6000) {
      if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {
        cardFound = true;
        break;
      }
      delay(50);
    }

    if (!cardFound) {
      lcd.clear();
      lcd.print("No Card Found");
      delay(1200);
      lcd.clear();
      lcd.print("Waiting Vehicle");
      return;
    }

    String uid = getUID();
    Serial.println("UID: " + uid);
    tone(BUZZER, 1000, 100);

    int idx = findVehicle(uid);

    if (idx == -1) {
      lcd.clear();
      lcd.print("Unknown Tag");
      lcd.setCursor(0, 1);
      lcd.print("Access Denied");
      digitalWrite(LED_R, HIGH);
      tone(BUZZER, 400, 1000);
      delay(2000);
      digitalWrite(LED_R, LOW);
      rfid.PICC_HaltA();
      rfid.PCD_StopCrypto1();
      lcd.clear();
      lcd.print("Waiting Vehicle");
      return;
    }

    String number   = eepromReadStr(numberAddr(idx), NUMBER_LEN);
    int    type     = EEPROM.read(typeAddr(idx));
    String typeName = getTypeName(type);
    float  toll     = getToll(type);
    float  bal      = eepromReadFloat(balanceAddr(idx));

    lcd.clear();
    lcd.print(number);
    lcd.setCursor(0, 1);
    lcd.print(typeName + " | Rs" + String((int)toll));
    delay(1200);

    lcd.clear();
    lcd.print("Processing...");
    delay(500);

    bool paid = chargePayment(idx, toll);
    float newBal = eepromReadFloat(balanceAddr(idx));
    int trips = eepromReadInt(tripAddr(idx));

    lcd.clear();
    lcd.print("Uploading...");
    sendTransaction(uid, number, typeName, toll, newBal, paid, trips);

    if (paid) {
      lcd.clear();
      lcd.print("Paid Rs" + String((int)toll));
      lcd.setCursor(0, 1);
      lcd.print("Bal:" + String(newBal, 1));
      delay(2000);

      lcd.clear();
      lcd.print("Trip No: " + String(trips));
      lcd.setCursor(0, 1);
      lcd.print(number);
      delay(1500);

      lcd.clear();
      lcd.print("Thank You!");
      lcd.setCursor(0, 1);
      lcd.print("Visit Again");
      delay(1500);

      openGate();

      lcd.clear();
      lcd.print("Waiting Exit...");
      unsigned long start = millis();
      while (getDistance() < THRESHOLD) {
        if (millis() - start > 5000) break;
        delay(100);
      }

      closeGate();

      lcd.clear();
      lcd.print("Waiting Vehicle");
      delay(800);

    } else {
      deny();
      rfid.PICC_HaltA();
      rfid.PCD_StopCrypto1();
      lcd.clear();
      lcd.print("Waiting Vehicle");
      return;
    }

    rfid.PICC_HaltA();
    rfid.PCD_StopCrypto1();
  }

  delay(50);
}