KeyboardHandler.cs

using NShell.Shell.Commands;
using NShell.Shell.History;
using Spectre.Console;

namespace NShell.Shell.Keyboard
{
    public class KeyboardHandler
    {
        public static void Handler(HistoryManager history, ShellContext context, CommandParser parser)
        {
            ConsoleKeyInfo key;
            ConsoleKeyInfo promptKey;
            string inputBuffer = "";
            history.ResetIndex();

            while (true)
            {
                Environment.SetEnvironmentVariable("LS_COLORS", context.GetLsColors());
                context.SetTheme(context.CurrentTheme);
                AnsiConsole.Markup(context.GetPrompt());
                inputBuffer = "";
                history.ResetIndex();

                while (true)
                {
                    key = Console.ReadKey(intercept: true);

                    if (key.Key == ConsoleKey.Enter)
                    {
                        if (inputBuffer.Trim() != "")
                        {
                            history.Add(inputBuffer);
                            history.Save();
                        }
                        Console.WriteLine();
                        break;
                    }

                    if (key.Key == ConsoleKey.Backspace && inputBuffer.Length > 0)
                    {
                        inputBuffer = inputBuffer[..^1];
                        Console.Write("\b \b");
                    }
                    else if (key.Key == ConsoleKey.UpArrow)
                    {
                        var prev = history.GetPrevious();
                        if (prev != null)
                        {
                            Console.Write(new string('\b', inputBuffer.Length) + new string(' ', inputBuffer.Length) + new string('\b', inputBuffer.Length));
                            inputBuffer = prev;
                            Console.Write(inputBuffer);
                        }
                    }
                    else if (key.Key == ConsoleKey.DownArrow)
                    {
                        var next = history.GetNext();
                        Console.Write(new string('\b', inputBuffer.Length) + new string(' ', inputBuffer.Length) + new string('\b', inputBuffer.Length));
                        inputBuffer = next ?? "";
                        Console.Write(inputBuffer);
                    }
                    else if (key.Key == ConsoleKey.Tab)
                    {
                        if (inputBuffer.StartsWith("cd "))
                        {
                            string path = inputBuffer.Substring(3);
                            string currentDir = Directory.GetCurrentDirectory();
                            string fullPath = Path.Combine(currentDir, path);

                            if (Directory.Exists(fullPath))
                            {
                                inputBuffer += Path.DirectorySeparatorChar;

                                var directories = Directory.GetDirectories(fullPath);

                                if (directories.Length > 0)
                                {
                                    string directoryToSuggest = directories[0];
                                    Console.Write(new string('\b', inputBuffer.Length) + new string(' ', inputBuffer.Length) + new string('\b', inputBuffer.Length));
                                    inputBuffer = "cd " + directoryToSuggest;
                                    Console.Write(inputBuffer);
                                }
                                else
                                {
                                    Console.Write(new string('\b', inputBuffer.Length) + new string(' ', inputBuffer.Length) + new string('\b', inputBuffer.Length));
                                    Console.Write(inputBuffer);
                                }
                            }
                            else
                            {
                                Console.Write(new string('\b', inputBuffer.Length) + new string(' ', inputBuffer.Length) + new string('\b', inputBuffer.Length));
                                Console.Write(inputBuffer);
                            }
                        } else if (inputBuffer.Length > 0) {
                            HashSet<string> suggestCommands = new();
                            HashSet<string> allCommands = CommandParser.CustomCommands.Keys
                                .Concat(CommandParser.SystemCommands)
                                .ToHashSet();

                            foreach (var suggestion in allCommands)
                            {
                                if (suggestion.StartsWith(inputBuffer))
                                {
                                    suggestCommands.Add(suggestion);
                                }
                            }

                            if (suggestCommands.Count > 15)
                            {
                                bool showFullList = false;
                                AnsiConsole.MarkupLine($"[[[yellow]*[/]]] - Do you want to list all [yellow]{suggestCommands.Count}[/] commands ? ([yellow]y[/]/[yellow]n[/]) >> ");
                                while (true)
                                {
                                    promptKey = Console.ReadKey(intercept: true);
                                    if (promptKey.Key == ConsoleKey.Y || promptKey.Key == ConsoleKey.N)
                                    {
                                        if (promptKey.Key == ConsoleKey.Y)
                                        {
                                            showFullList = true;
                                        }
                                        break;
                                    }
                                }
                                if (showFullList)
                                {
                                    var sortedCommands = suggestCommands.OrderBy(c => c.Length).ToArray();
                                    int i = 0;

                                    foreach (var cmd in sortedCommands)
                                    {
                                        if (i == 7)
                                        {
                                            AnsiConsole.MarkupLine("");
                                            i = 0;
                                        }
                                        AnsiConsole.Markup($"{cmd}  ");
                                        i++;
                                    }

                                    inputBuffer = string.Empty;
                                    AnsiConsole.MarkupLine("");
                                    AnsiConsole.MarkupLine("[[[yellow]*[/]]] - Press enter to continue...");
                                }
                            }
                            else
                            {
                                var sortedCommands = suggestCommands.OrderBy(c => c.Length).ToArray();
                                List<string> commandsList = sortedCommands.ToList();

                                int currentIndex = 0;
                                
                                if (!string.IsNullOrEmpty(inputBuffer))
                                {
                                    for (int i = 0; i < commandsList.Count; i++)
                                    {
                                        if (commandsList[i].StartsWith(inputBuffer))
                                        {
                                            currentIndex = (i + 1) % commandsList.Count;
                                            inputBuffer = commandsList[currentIndex];
                                            break;
                                        }
                                    }
                                }
                                
                                Console.SetCursorPosition(0, Console.CursorTop - 1);
                                Console.SetCursorPosition(0, Console.CursorTop);
                                Console.Write(new string(' ', Console.WindowWidth));
                                Console.SetCursorPosition(0, Console.CursorTop);
                                
                                AnsiConsole.Markup(context.GetPrompt());
                                Console.Write(inputBuffer);
                            }
                        }
                    }
                    else if (!char.IsControl(key.KeyChar))
                    {
                        inputBuffer += key.KeyChar;
                        Console.Write(key.KeyChar);
                    }
                }

                if (string.IsNullOrWhiteSpace(inputBuffer)) continue;

                history.Add(inputBuffer);

                try
                {
                    parser.TryExecute(inputBuffer, context);
                }
                catch (Exception ex)
                {
                    AnsiConsole.MarkupLine($"[[[red]-[/]]] - Shell crash: [yellow]{ex.Message}[/]");
                }
            }
        }
    }
}