C# Fundamentals - 03. SchoolLibrary - MidExam 10.12.2020

using System;
using System.Collections.Generic;
using System.Linq;

namespace _03._SchoolLibrary
{
    class SchoolLibrary
    {
        static void Main()
        {
            List<string> books = Console.ReadLine()
                                 .Split('&')
                                 .ToList();

            string command = Console.ReadLine();
            while (command != "Done")
            {
                string[] currentCommand = command.Split(" | ");
                string instruction = currentCommand[0];

                if (instruction == "Add Book")
                {
                    string bookName = currentCommand[1];
                    if (!books.Contains(bookName))
                    {
                        books.Insert(0, bookName);
                    }
                }

                else if (instruction == "Take Book")
                {
                    string bookName = currentCommand[1];

                    if (books.Contains(bookName))
                    {
                        books.Remove(bookName);
                    }
                }

                else if (instruction == "Swap Books")
                {
                    string firstBook = currentCommand[1];
                    string secondBook = currentCommand[2];

                    if (books.Contains(firstBook) && books.Contains(secondBook))
                    {
                        int firstIndex = books.IndexOf(firstBook);
                        int secondIndex = books.IndexOf(secondBook);

                        books.Remove(secondBook);
                        books.Insert(firstIndex, secondBook);
                        books.Remove(firstBook);
                        books.Insert(secondIndex, firstBook);
                    }
                }

                else if (instruction == "Insert Book")
                {
                    string bookName = currentCommand[1];

                    books.Add(bookName);
                }

                else if (instruction == "Check Book")
                {
                    int index = int.Parse(currentCommand[1]);

                    if (0 <= index && index < books.Count)
                    {
                        Console.WriteLine(books[index]);
                    }
                }

                command = Console.ReadLine();
            }

            Console.WriteLine(string.Join(", ", books));
        }
    }
}