InventoryManager.cpp

#include "InventoryManager.h"
#include <iostream> // For std::cout, std::cin
#include <limits>   // For std::numeric_limits
#include <iomanip>  // For std::fixed, std::setprecision

// Constructor
InventoryManager::InventoryManager() {
    // Optionally initialize with some dummy data for testing
    // inventory.emplace_back("Laptop", 10, 15000.00);
    // inventory.emplace_back("Mouse", 50, 250.00);
    // inventory.emplace_back("Keyboard", 20, 750.00);
}

// Helper function to find an item by name
int InventoryManager::findItemIndex(const std::string& itemName) const {
    for (size_t i = 0; i < inventory.size(); ++i) {
        if (inventory[i].getName() == itemName) {
            return static_cast<int>(i); // Found
        }
    }
    return -1; // Not found
}

// Helper function for robust integer input
int InventoryManager::getIntInput(const std::string& prompt) {
    int value;
    while (true) {
        std::cout << prompt;
        std::cin >> value;
        if (std::cin.fail() || value < 0) { // Check for fail state or negative input
            std::cin.clear(); // Clear the error flag
            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Discard invalid input
            std::cout << "Invalid input. Please enter a non-negative whole number.\n";
        } else {
            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Discard remaining newline
            return value;
        }
    }
}

// Helper function for robust double input
double InventoryManager::getDoubleInput(const std::string& prompt) {
    double value;
    while (true) {
        std::cout << prompt;
        std::cin >> value;
        if (std::cin.fail() || value < 0.0) { // Check for fail state or negative input
            std::cin.clear(); // Clear the error flag
            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Discard invalid input
            std::cout << "Invalid input. Please enter a non-negative number.\n";
        } else {
            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Discard remaining newline
            return value;
        }
    }
}

void InventoryManager::addItem() {
    std::string name;
    int quantity;
    double price;

    std::cout << "\n--- Add New Item ---" << std::endl;
    std::cout << "Enter item name: ";
    std::getline(std::cin, name); // Use getline to read names with spaces

    // Check if item already exists
    if (findItemIndex(name) != -1) {
        std::cout << "Item with name '" << name << "' already exists. Use 'Update Item Quantity' to change it.\n";
        return;
    }

    quantity = getIntInput("Enter quantity: ");
    price = getDoubleInput("Enter price per unit: R");

    inventory.emplace_back(name, quantity, price);
    std::cout << "Item '" << name << "' added successfully!\n";
}

void InventoryManager::viewInventory() const {
    std::cout << "\n--- Current Inventory ---" << std::endl;
    if (inventory.empty()) {
        std::cout << "Inventory is empty." << std::endl;
        return;
    }

    // Print table header
    std::cout << std::left << std::setw(20) << "Name"
              << std::right << std::setw(10) << "Quantity"
              << std::right << std::setw(15) << "Price (R)"
              << std::right << std::setw(15) << "Total (R)" << std::endl;
    std::cout << std::string(60, '-') << std::endl;

    for (const auto& item : inventory) {
        std::cout << std::left << std::setw(20) << item.getName()
                  << std::right << std::setw(10) << item.getQuantity()
                  << std::right << std::setw(15) << std::fixed << std::setprecision(2) << item.getPrice()
                  << std::right << std::setw(15) << std::fixed << std::setprecision(2) << (item.getQuantity() * item.getPrice()) << std::endl;
    }
    std::cout << std::string(60, '-') << std::endl;
    std::cout << "Total Inventory Value: R" << std::fixed << std::setprecision(2) << calculateTotalValue() << std::endl;
}

void InventoryManager::updateItemQuantity() {
    std::string name;
    int newQuantity;

    std::cout << "\n--- Update Item Quantity ---" << std::endl;
    if (inventory.empty()) {
        std::cout << "Inventory is empty. Nothing to update." << std::endl;
        return;
    }
    std::cout << "Enter name of item to update: ";
    std::getline(std::cin, name);

    int index = findItemIndex(name);
    if (index != -1) {
        std::cout << "Current quantity for '" << name << "': " << inventory[index].getQuantity() << std::endl;
        newQuantity = getIntInput("Enter new quantity: ");
        inventory[index].setQuantity(newQuantity);
        std::cout << "Quantity for '" << name << "' updated successfully!\n";
    } else {
        std::cout << "Item '" << name << "' not found in inventory.\n";
    }
}

void InventoryManager::removeItem() {
    std::string name;
    std::cout << "\n--- Remove Item ---" << std::endl;
    if (inventory.empty()) {
        std::cout << "Inventory is empty. Nothing to remove." << std::endl;
        return;
    }
    std::cout << "Enter name of item to remove: ";
    std::getline(std::cin, name);

    int index = findItemIndex(name);
    if (index != -1) {
        inventory.erase(inventory.begin() + index);
        std::cout << "Item '" << name << "' removed successfully!\n";
    } else {
        std::cout << "Item '" << name << "' not found in inventory.\n";
    }
}

double InventoryManager::calculateTotalValue() const {
    double totalValue = 0.0;
    for (const auto& item : inventory) {
        totalValue += (item.getQuantity() * item.getPrice());
    }
    return totalValue;
}

void InventoryManager::displayMenu() const {
    std::cout << "\n--- Inventory System Menu ---" << std::endl;
    std::cout << "1. Add Item" << std::endl;
    std::cout << "2. View Inventory" << std::endl;
    std::cout << "3. Update Item Quantity" << std::endl;
    std::cout << "4. Remove Item" << std::endl;
    std::cout << "5. Calculate Total Inventory Value" << std::endl;
    std::cout << "6. Exit" << std::endl;
    std::cout << "Enter your choice: ";
}

void InventoryManager::run() {
    int choice;
    do {
        displayMenu();
        choice = getIntInput(""); // Use getIntInput for menu choice

        switch (choice) {
            case 1:
                addItem();
                break;
            case 2:
                viewInventory();
                break;
            case 3:
                updateItemQuantity();
                break;
            case 4:
                removeItem();
                break;
            case 5:
                std::cout << "\nTotal Inventory Value: R" << std::fixed << std::setprecision(2) << calculateTotalValue() << std::endl;
                break;
            case 6:
                std::cout << "Exiting Inventory System. Goodbye!\n";
                break;
            default:
                std::cout << "Invalid choice. Please try again.\n";
                break;
        }
        std::cout << "\nPress Enter to continue...";
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // Consume any leftover newline
        std::cin.get(); // Wait for user to press Enter
    } while (choice != 6);
}