请帮助重构此代码。我是 C 语言初学者，想学习干净的代码和最佳实践。这是一个具有以下功能的应用程序：

• 用户可以进行预订（年、月、日、公司名称）
• 预订信息存储在一个结构体中
• 如果日期不可用，则会通知用户
• 使用自定义排序机制更新预订结构

#include <stdio.h>
#include <string.h>

#define MAX_RESERVATIONS 100

// Structure for a reservation
typedef struct
{
    int year;
    int month;
    int day;
    char companyName[50];
} Reservation;

// Global variables
Reservation reservations[MAX_RESERVATIONS];
int reservationCount = 0;

// Function declarations
void showMenu();
void handleInput(int option);
void addReservation();
void inputReservation(Reservation *newReservation);
int isDateAvailable(int year, int month, int day);
void insertReservation(Reservation newReservation);
void printReservations();

// Main function - streamlined and clean
int main()
{
    int option;

    while (1)
    {
        showMenu();
        if (scanf("%d", &option) != 1 || option == 3)
        {
            printf("Exiting program.\n");
            break; // Exit the program
        }
        handleInput(option); // Delegate responsibility to handle user input
    }

    return 0;
}

// Show menu options
void showMenu()
{
    printf("\nMenu:\n");
    printf("1. New Reservation\n");
    printf("2. Print Reservations\n");
    printf("3. Exit\n");
    printf("Choose an option: ");
}

// Handle user input
void handleInput(int option)
{
    if (option == 1)
    {
        addReservation();
    }
    else if (option == 2)
    {
        printReservations();
    }
    else
    {
        printf("Invalid choice. Please try again.\n");
    }
}

// Add a new reservation (modular: only handles adding)
void addReservation()
{
    Reservation newReservation;

    // Input reservation details
    inputReservation(&newReservation);

    // Check if the date is available
    if (!isDateAvailable(newReservation.year, newReservation.month, newReservation.day))
    {
        printf("The room is already booked on that date.\n");
        return;
    }

    // Insert the reservation
    insertReservation(newReservation);
    printf("Reservation added successfully.\n");
}

// Input reservation details (year, month, day, company name)
void inputReservation(Reservation *newReservation)
{
    // Input: Date
    printf("Enter the reservation date (YYYY MM DD): ");
    scanf("%d %d %d", &newReservation->year, &newReservation->month, &newReservation->day);

    // Input: Company name
    printf("Enter the company name: ");
    scanf("%s", newReservation->companyName);
}

// Check if the date is available for booking
int isDateAvailable(int year, int month, int day)
{
    for (int i = 0; i < reservationCount; i++)
    {
        if (reservations[i].year == year &&
            reservations[i].month == month &&
            reservations[i].day == day)
        {
            return 0; // Date is not available
        }
    }
    return 1; // Date is available
}

// Insert the reservation in the correct position (sorted by date)
void insertReservation(Reservation newReservation)
{
    int i = reservationCount - 1;

    // Find the correct position and shift the elements back
    while (i >= 0 && (reservations[i].year > newReservation.year ||
                      (reservations[i].year == newReservation.year && reservations[i].month > newReservation.month) ||
                      (reservations[i].year == newReservation.year && reservations[i].month == newReservation.month && reservations[i].day > newReservation.day)))
    {
        reservations[i + 1] = reservations[i];
        i--;
    }

    // Insert the new reservation
    reservations[i + 1] = newReservation;
    reservationCount++;
}

// Print all reservations
void printReservations()
{
    if (reservationCount == 0)
    {
        printf("No reservations found.\n");
        return;
    }

    printf("Current reservations:\n");
    for (int i = 0; i < reservationCount; i++)
    {
        printf("%d-d-d: %s\n", reservations[i].year, reservations[i].month, reservations[i].day, reservations[i].companyName);
    }
}