#include <iostream>
#include <limits>
#ifdef _WIN32
#include <Windows.h>
// Function to clear the console screen on Windows
void clearConsole() {
system("cls");
}
#else
#include <unistd.h>
// Function to clear the console screen on Unix-like systems
void clearConsole() {
system("clear");
}
#endif
using namespace std;

// Function to clear input buffer to prevent infinite loops from invalid input
void clearInput() {
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(), '\n');
}

int main() {
int choice;

// Main loop for the menu system
while (true) {
// Clear the console and display the enhanced menu with designs
clearConsole();
cout << "****************************************" << endl;
cout << "* *" << endl;
cout << "* MAIN MENU *" << endl;
cout << "* *" << endl;
cout << "****************************************" << endl;
cout << "* [1] Electric Bill *" << endl;
cout << "* [2] Water Bill *" << endl;
cout << "* [3] Calculator *" << endl;
cout << "* [4] Exit *" << endl;
cout << "* [0] Credits *" << endl;
cout << "****************************************" << endl;
cout << "Choose an option: ";

// Check if input is a valid integer
if (!(cin >> choice)) {
cout << "\n****************************************" << endl;
cout << "* Invalid input. Please enter a number *" << endl;
cout << "* between 0 and 4. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
clearInput();
continue;
}

// Handle menu choices with switch statement
switch (choice) {
case 1: {
// Electric bill calculation with enhanced interface
clearConsole();
cout << "****************************************" << endl;
cout << "* ELECTRIC BILL *" << endl;
cout << "****************************************" << endl;
double prevReading, presReading;
const double rate = 12.25;

cout << "Enter previous electric meter reading: ";
if (!(cin >> prevReading) || prevReading < 0) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for previous reading. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
clearInput();
break;
}

cout << "\nEnter present electric meter reading: ";
if (!(cin >> presReading) || presReading < prevReading) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for present reading. *" << endl;
cout << "* It must be >= previous reading. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.get();
clearInput();
break;
}

double bill = (presReading - prevReading) * rate;
cout << "\n****************************************" << endl;
cout << "* Electric Bill: " << bill << " *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
}
case 2: {
// Water bill calculation with tiered rates and enhanced interface
clearConsole();
cout << "****************************************" << endl;
cout << "* WATER BILL *" << endl;
cout << "****************************************" << endl;
double prevReading, presReading, rate;
cout << "\nEnter previous water meter reading (cu.m): ";
if (!(cin >> prevReading) || prevReading < 0) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for previous reading. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
clearInput();
break;
}

cout << "\nEnter present water meter reading (cu.m): ";
if (!(cin >> presReading) || presReading < prevReading) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for present reading. *" << endl;
cout << "* It must be >= previous reading. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.get();
clearInput();
break;
}

double consumption = presReading - prevReading;

// Determine rate based on consumption tiers
if (consumption >= 0 && consumption <= 10) {
rate = 10.00;
} else if (consumption >= 11 && consumption <= 20) {
rate = 20.00;
} else if (consumption >= 21) {
rate = 30.00;
} else {
cout << "\n****************************************" << endl;
cout << "* Invalid consumption value. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
}

double bill = consumption * rate;
cout << "\n****************************************" << endl;
cout << "* Water Bill: " << bill << " *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
}
case 3: {
// Simple calculator for basic operations with enhanced interface
clearConsole();
cout << "****************************************" << endl;
cout << "* CALCULATOR *" << endl;
cout << "****************************************" << endl;
double num1, num2;
char op;

cout << "Enter first number: ";
if (!(cin >> num1)) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for first number. *" << endl;
cout << "****************************************" << endl;
clearInput();
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
}

cout << "Enter operator (+, -, *, /): ";
cin >> op;
if (op != '+' && op != '-' && op != '*' && op != '/') {
cout << "\n****************************************" << endl;
cout << "* Invalid operator. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
clearInput();
break;
}

cout << "Enter second number: ";
if (!(cin >> num2)) {
cout << "\n****************************************" << endl;
cout << "* Invalid input for second number. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
clearInput();
break;
}

// Perform calculation based on operator
cout << "\n****************************************" << endl;
switch (op) {
case '+':
cout << "* Result: " << num1 + num2 << " *" << endl;
break;
case '-':
cout << "* Result: " << num1 - num2 << " *" << endl;
break;
case '*':
cout << "* Result: " << num1 * num2 << " *" << endl;
break;
case '/':
if (num2 == 0) {
cout << "* Error: Division by zero is not allowed.*" << endl;
} else {
cout << "* Result: " << num1 / num2 << " *" << endl;
}
break;
}
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
}
case 4:
// Exit the program with a design
cout << "****************************************" << endl;
cout << "* Goodbye! *" << endl;
cout << "****************************************" << endl;
return 0;

case 0:
// Display credits with enhanced design
clearConsole();
cout << "****************************************" << endl;
cout << "* CREDITS *" << endl;
cout << "****************************************" << endl;
cout << "* Made by: Regidor, Shokri Iam *" << endl;
cout << "* Source:https://pastebin.com/8Wb8ub3b *" << endl;
cout << "* Thanks to you! *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
break;
default:
// Handle invalid menu choices with design
cout << "****************************************" << endl;
cout << "* Invalid choice. Please select *" << endl;
cout << "* between 0 and 4. *" << endl;
cout << "****************************************" << endl;
cout << "Press Enter to continue!" << endl;
cin.ignore();
cin.get();
}
}
}