#include <SPI.h> 
#include <MFRC522.h> 
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>
#include <DFRobotDFPlayerMini.h>

#define  SS   5
#define  RST  14
#define  BUTTON_PIN 4
#define  servoPin 13

struct Product {
  String tag;
  String name;
  String expiry;
  float price;
};

Product products[10] = {
  {"A1B2C3", "Milk", "2025-08-01", 2500},
  {"D4E5F6", "Bread", "2025-07-15", 500},
  {"123ABC", "Sugar", "2026-01-01", 5000},
  {"456DEF", "Soap", "2027-03-10", 3000},
  {"789GHI", "Juice", "2025-12-12", 1500},
  {"JKL012", "Rice", "2026-05-20", 3500},
  {"MNO345", "Salt", "2025-09-09", 1000},
  {"PQR678", "Soda", "2024-12-25", 1200},
  {"STU901", "Water", "2026-06-06", 750},
  {"VWX234", "Oil", "2026-08-15", 8500}
};

float totalAmount = 0.0;
bool checkout = true;

LiquidCrystal_I2C lcd(0x27, 20, 4);
MFRC522 scanner(SS,RST);
DFRobotDFPlayerMini myDFPlayer;
Servo myServo;

void setup() {
  Serial.begin(9600);
  delay(500);
  Serial.println("initializing");
  pinMode(BUTTON_PIN, INPUT);
  lcd.init();
  lcd.backlight();
  welcomeDisplay();
  myServo.attach(servoPin);
  myServo.write(0);
  Serial.println("Type RFID Tag ID to scan a product...");
  lcd.clear();
}

void loop() 
{
  init_display();
  if (digitalRead(BUTTON_PIN) == HIGH) 
  {
    delay(1000);
    while(digitalRead(BUTTON_PIN) == LOW)
    {
      pickProduct();
    }
    delay(1000);
    while(digitalRead(BUTTON_PIN) == LOW)
    {
      if(checkout)
      {
        setBill();
        checkout=LOW;
      }
    }
    checkout=HIGH;
    Serial.println("Cart reset for next user.");
    delay(2000);
    lcd.clear();
  }
}

void pickProduct()
{
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("-TOTAL EXPENDITURE:-");
  lcd.setCursor(0, 1);
  lcd.print("Tsh.:");
  lcd.setCursor(7, 1);
  lcd.print(totalAmount, 2);
  lcd.setCursor(0, 2);
  lcd.print("SCAN NEXT PRODUCT OR");
  lcd.setCursor(0, 3);
  lcd.print("PRESS BUTTON TO END");
  if (Serial.available()) {
    String inputTag = Serial.readStringUntil('\n');
    inputTag.trim();
    bool found = false;
    for (int i = 0; i < 10; i++) {
      if (products[i].tag == inputTag) {
        found = true;
        Serial.println("Product found: " + products[i].name);
        Serial.println("Opening door... Product dropped.");
        totalAmount += products[i].price;
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("FOUND PRODUCT DETAIL");
        lcd.setCursor(0, 1);
        lcd.print("NAME:");
        lcd.setCursor(5, 1);
        lcd.print(products[i].name);
        lcd.setCursor(0, 2);
        lcd.print("Exp :");
        lcd.setCursor(5, 2);
        lcd.print(products[i].expiry);
        lcd.setCursor(0, 3);
        lcd.print("PRICE:");
        lcd.setCursor(6, 3);
        lcd.print(products[i].price);
        delay(3000);
        myServo.write(90);
        delay(3000);
        myServo.write(0);
        totalAmount += products[i].price;
        break;
      }
    }
    if (!found) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("UNKNOW/UNREGISTERED");
      lcd.setCursor(0, 1);
      lcd.print("    PRODUCT TAG    ");
      lcd.setCursor(0, 2);
      lcd.print("CONTACT SALES OFFICE");
      lcd.setCursor(0, 3);
      lcd.print(" FOR PRODUCT DETAIL ");
      Serial.println("Tag not recognized!");
      delay(2000);
    }
  }delay(500);
}

void setBill()
{
     lcd.clear();
     lcd.setCursor(0,0);
     lcd.print("GENERATING PAYMENT"); 
     lcd.setCursor(0,1);
     lcd.print("CONTROLL NUMBER FOR"); 
     lcd.setCursor(0,2);
     lcd.print("AMOUNT(Tsh):");
     lcd.setCursor(12,2);
     lcd.print(totalAmount);
     lcd.setCursor(0,3);
     lcd.print("PLEASE WAIT");
     for(uint8_t i=11;i<20;i++)
     {
      lcd.setCursor(i,3);
      lcd.print("_");
      delay(500);
     }
    
    int controlNum = random(100000, 999999);
    
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("===>- CHECKOUT -<==="); 
    lcd.setCursor(0,1);
    lcd.print("BILL(Tsh.):"); 
    lcd.setCursor(11,1);
    lcd.print(totalAmount); 
    lcd.setCursor(0,2);
    lcd.print("CONT. NO:");
    lcd.setCursor(10,2);
    lcd.print(controlNum);
    lcd.setCursor(0,3);
    lcd.print("=========<>=========");

    Serial.println("=== Checkout ===");
    Serial.print("Total Amount: ");
    Serial.println(totalAmount, 2);
    Serial.print("Payment Control #: ");
    Serial.println(controlNum);
}

void init_display()
{
  lcd.setCursor(0,0);
  lcd.print("--------<<>>--------");
  lcd.setCursor(0,1);
  lcd.print("   PRESS BUTTON    ");
  lcd.setCursor(0,2);
  lcd.print("TO START SHOPPING");
  lcd.setCursor(0,3);
  lcd.print("--------<<>>--------");
}

void welcomeDisplay()
{
     lcd.clear();
     lcd.setCursor(0,0);
     lcd.print("SMART SHOPPING CART"); 
     lcd.setCursor(0,1);
     lcd.print("   BY USING RFID   "); 
     lcd.setCursor(0,2);
     lcd.print("SYSTEM INITIALIZE");
     lcd.setCursor(0,3);
     lcd.print("PLEASE WAIT");
     for(uint8_t i=11;i<20;i++)
     {
      lcd.setCursor(i,3);
      lcd.print("_");
      delay(500);
     }
}

/*
void error_display()
{
  myDFPlayer.play(6);
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("--------<<>>--------");
  lcd.setCursor(0,1);
  lcd.print("Soory!,Locker Loaded");
  lcd.setCursor(0,2);
  lcd.print("Please Retry Later");
  lcd.setCursor(0,3);
  lcd.print("--------<<>>--------");
  delay(6000);
}

String readTag()
{
   if(!scanner.PICC_IsNewCardPresent())
    {
      //Serial.println("no card present");
      return "error";
    }
    if(!scanner.PICC_ReadCardSerial())
    {
      //Serial.println("card not readable");
      return "error";
    }
    //save data and return output
    String myTag;
    for (int i = 0; i < scanner.uid.size; i++) 
    {
      myTag += String(scanner.uid.uidByte[i],HEX);
    }
    //Serial.print("THE TAG DETECTED IS:");
    //Serial.println(myTag);
    return myTag; 
}*/