#33 Tapeti.Cmd confirm overwrite existing files when exporting

Also fixed issue with input remaining in buffer which can cause accidental confirms

Tapeti.Cmd/ConsoleHelper/ConsoleWrapper.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.Text;
 using System.Threading;
+using Console = System.Console;
 
 namespace Tapeti.Cmd.ConsoleHelper
 {
@@ -138,39 +140,79 @@ namespace Tapeti.Cmd.ConsoleHelper
 
             public abstract bool Enabled { get; }
 
+            public abstract void WriteCaptured(string value, Action processInput);
             public abstract void WriteLine(string value);
 
 
             public void Confirm(string message)
             {
                 WriteLine(message);
-                TryReadKey(false, out _);
+
+                // Clear any previous key entered before this confirmation
+                while (!Owner.Cancelled && Console.KeyAvailable)
+                    Console.ReadKey(true);
+
+                while (!Owner.Cancelled && !Console.KeyAvailable)
+                    Thread.Sleep(50);
+
+                if (Owner.Cancelled)
+                    return;
+
+                Console.ReadKey(true);
             }
 
 
             public bool ConfirmYesNo(string message)
             {
-                WriteLine($"{message} (Y/N) ");
-                if (!TryReadKey(true, out var key))
-                    return false;
+                var confirmed = false;
 
-                return key.KeyChar == 'y' || key.KeyChar == 'Y';
-            }
-
-
-            private bool TryReadKey(bool showKeyOutput, out ConsoleKeyInfo keyInfo)
+                WriteCaptured($"{message} (Y/N) ", () =>
+                {
+                    // Clear any previous key entered before this confirmation
+                    while (!Owner.Cancelled && Console.KeyAvailable)
+                        Console.ReadKey(true);
+
+                    var input = new StringBuilder();
+
+                    while (!Owner.Cancelled)
+                    {
+                        if (!Console.KeyAvailable)
                         {
-                while (!Owner.Cancelled && !Console.KeyAvailable)
                             Thread.Sleep(50);
-
-                if (Owner.Cancelled)
-                {
-                    keyInfo = default;
-                    return false;
+                            continue;
                         }
 
-                keyInfo = Console.ReadKey(!showKeyOutput);
-                return true;
+                        var keyInfo = Console.ReadKey(false);
+
+                        // ReSharper disable once SwitchStatementHandlesSomeKnownEnumValuesWithDefault - by design
+                        switch (keyInfo.Key)
+                        {
+                            case ConsoleKey.Enter:
+                                Console.WriteLine();
+                                confirmed = input.ToString().Equals("Y", StringComparison.CurrentCultureIgnoreCase);
+                                return;
+
+                            case ConsoleKey.Backspace:
+                                if (input.Length > 0)
+                                {
+                                    input.Remove(input.Length - 1, 1);
+
+                                    // We need to handle erasing the character ourselves, as we want to use ReadKey so that we can monitor Cancelled
+                                    Console.Write(" \b");
+                                }
+
+                                break;
+
+                            default:
+                                if (keyInfo.KeyChar != -1)
+                                    input.Append(keyInfo.KeyChar);
+
+                                break;
+                        }
+                    }
+                });
+
+                return confirmed;
             }
         }
 
@@ -185,6 +227,22 @@ namespace Tapeti.Cmd.ConsoleHelper
             public override bool Enabled => true;
 
 
+            
+            public override void WriteCaptured(string value, Action waitForInput)
+            {
+                Owner.AcquirePermanent();
+                try
+                {
+                    Console.Write(value);
+                    waitForInput();
+                }
+                finally
+                {
+                    Owner.ReleasePermanent();
+                }
+            }
+
+
             public override void WriteLine(string value)
             {
                 Owner.AcquirePermanent();
@@ -217,6 +275,13 @@ namespace Tapeti.Cmd.ConsoleHelper
             public override bool Enabled => !Console.IsOutputRedirected;
 
 
+            public override void WriteCaptured(string value, Action waitForInput)
+            {
+                WriteLine(value);
+                waitForInput();
+            }
+            
+
             public override void WriteLine(string value)
             {
                 if (!Enabled)

Tapeti.Cmd/Serialization/EasyNetQMessageSerializer.cs

@@ -31,6 +31,12 @@ namespace Tapeti.Cmd.Serialization
         }
 
 
+        public static bool OutputExists(string path)
+        {
+            return Directory.Exists(path) && Directory.GetFiles(path, "*.message.txt").Length > 0;
+        }
+
+
         public void Dispose()
         {
         }

Tapeti.Cmd/Verbs/ExportVerb.cs

@@ -2,7 +2,6 @@
 using System.IO;
 using System.Text;
 using CommandLine;
-using RabbitMQ.Client;
 using Tapeti.Cmd.ConsoleHelper;
 using Tapeti.Cmd.Serialization;
 
@@ -18,6 +17,9 @@ namespace Tapeti.Cmd.Verbs
         [Option('o', "output", Required = true, HelpText = "Path or filename (depending on the chosen serialization method) where the messages will be output to.")]
         public string OutputPath { get; set; }
         
+        [Option('y', "overwrite", HelpText = "If the output exists, do not ask to overwrite.")]
+        public bool Overwrite { get; set; }
+
         [Option('r', "remove", HelpText = "If specified messages are acknowledged and removed from the queue. If not messages are kept.")]
         public bool RemoveMessages { get; set; }
 
@@ -40,8 +42,12 @@ namespace Tapeti.Cmd.Verbs
         public void Execute(IConsole console)
         {
             var consoleWriter = console.GetPermanentWriter();
+            
+            using var messageSerializer = GetMessageSerializer(options, consoleWriter);
+            if (messageSerializer == null)
+                return;
+
             var factory = options.CreateConnectionFactory(console);
-            using var messageSerializer = GetMessageSerializer(options);
             using var connection = factory.CreateConnection();
             using var channel = connection.CreateModel();
 
@@ -86,16 +92,27 @@ namespace Tapeti.Cmd.Verbs
         }
 
 
-        private static IMessageSerializer GetMessageSerializer(ExportOptions options)
+        private static IMessageSerializer GetMessageSerializer(ExportOptions options, IConsoleWriter consoleWriter)
         {
             switch (options.SerializationMethod)
             {
                 case SerializationMethod.SingleFileJSON:
+                    // ReSharper disable once InvertIf - causes two lines of "new SingleFileJSONMessageSerializer". DRY ReSharper.
+                    if (!options.Overwrite && File.Exists(options.OutputPath))
+                    {
+                        if (!consoleWriter.ConfirmYesNo($"The output file '{options.OutputPath}' already exists, do you want to overwrite it?"))
+                            return null;
+                    }
+                    
                     return new SingleFileJSONMessageSerializer(new FileStream(options.OutputPath, FileMode.Create, FileAccess.Write, FileShare.Read), true, Encoding.UTF8);
 
                 case SerializationMethod.EasyNetQHosepipe:
-                    if (string.IsNullOrEmpty(options.OutputPath))
-                        throw new ArgumentException("An output path must be provided when using EasyNetQHosepipe serialization");
+                    // ReSharper disable once InvertIf - causes two lines of "new SingleFileJSONMessageSerializer". DRY ReSharper.
+                    if (!options.Overwrite && EasyNetQMessageSerializer.OutputExists(options.OutputPath))
+                    {
+                        if (!consoleWriter.ConfirmYesNo($"The output path '{options.OutputPath}' already contains a previous export, do you want to overwrite it?"))
+                            return null;
+                    }
 
                     return new EasyNetQMessageSerializer(options.OutputPath);
 

docs/tapeticmd.rst

@@ -45,6 +45,9 @@ Fetches messages from a queue and writes them to disk.
 -o <target>, --output <target>
   *Required*. Path or filename (depending on the chosen serialization method) where the messages will be output to.
 
+-y, --overwrite
+  If the output exists, do not ask to overwrite.
+
 -r, --remove
   If specified messages are acknowledged and removed from the queue. If not messages are kept.