#include <iostream>
#include <ctime>
using namespace std;

// Class with constructor and variable
class HelloWorld {
private:
    string message;

public:
    // Default constructor
    HelloWorld() {
        message = "Hello, World!";
    }

    // Parameterized constructor
    HelloWorld(string msg) {
        message = msg;
    }

    // Function to get message length
    int getMessageLength() {
        return message.length();
    }

    // Static member function
    static void displayStaticMessage() {
        cout << "This is a static member function!" << endl;
    }

    // Virtual function
    virtual void displayMessage() {
        cout << message << endl;
    }

    // Function overloading
    void displayMessage(string extraMsg) {
        cout << message << " " << extraMsg << endl;
    }

    // Operator overloading
    bool operator==(HelloWorld &other) {
        return this->message == other.message;
    }

    // Friend function
    friend void friendFunction(HelloWorld &obj);

    // Exception handling
    void demonstrateExceptionHandling() {
        try {
            if (message.empty()) {
                throw runtime_error("Message is empty!");
            }
        } catch (const exception &e) {
            cerr << "Exception caught: " << e.what() << endl;
        }
    }
};

// Inheritance
class DerivedHelloWorld : public HelloWorld {
public:
    // Override virtual function
    void displayMessage() override {
        cout << "Derived: ";
        HelloWorld::displayMessage();
    }
};

// Function demonstrating call by value
void callByValue(int num) {
    num++;
    cout << "Inside callByValue: " << num << endl;
}

// Function demonstrating call by reference
void callByReference(int &num) {
    num++;
    cout << "Inside callByReference: " << num << endl;
}

// Friend function definition
void friendFunction(HelloWorld &obj) {
    cout << "Friend Function: " << obj.message << endl;
}

int main(int argc, char *argv[]) {
    // Taking input from command line arguments
    string filename;
    if (argc > 1) {
        filename = argv[1];
    } else {
        filename = "default.txt";
    }

    // Creating object using constructors
    HelloWorld obj1; // Using default constructor
    HelloWorld obj2("Hola, Mundo!"); // Using parameterized constructor

    // Displaying hello world messages using different methods
    obj1.displayMessage();
    obj2.displayMessage("Bonjour, Monde!");

    // Static member function call
    HelloWorld::displayStaticMessage();

    // Inheritance usage
    DerivedHelloWorld derivedObj;
    derivedObj.displayMessage();

    // Function overloading
    obj1.displayMessage("Welcome!");

    // Operator overloading
    if (obj1 == obj2) {
        cout << "Messages are the same!" << endl;
    } else {
        cout << "Messages are different!" << endl;
    }

    // Exception handling demonstration
    obj1.demonstrateExceptionHandling();

    // Has-a relationship
    int length = obj1.getMessageLength();

    // Current system time
    time_t now = time(0);
    char* timeStr = ctime(&now);

    // Outputting results
    cout << "Length of 'Hello, World!': " << length << endl;
    cout << "Current System Time: " << timeStr;
    cout << "File Name: " << filename << endl;

    return 0;
}