From 1082ac1efc7407c0c40d546afe44d9785bc6b8e2 Mon Sep 17 00:00:00 2001
From: nkochnev <n.kochnev@gmail.com>
Date: Fri, 12 Aug 2022 09:10:42 +0500
Subject: [PATCH] Backward direction of autocomplete with Tab + Shift

---
 .../Extensions/AnsiConsoleExtensions.Input.cs | 44 +++++++++++++++----
 1 file changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/Spectre.Console/Extensions/AnsiConsoleExtensions.Input.cs b/src/Spectre.Console/Extensions/AnsiConsoleExtensions.Input.cs
index 30c493e..c56e060 100644
--- a/src/Spectre.Console/Extensions/AnsiConsoleExtensions.Input.cs
+++ b/src/Spectre.Console/Extensions/AnsiConsoleExtensions.Input.cs
@@ -33,7 +33,10 @@ public static partial class AnsiConsoleExtensions
 
             if (key.Key == ConsoleKey.Tab && autocomplete.Count > 0)
             {
-                var replace = AutoComplete(autocomplete, text);
+                var autoCompleteDirection = key.Modifiers.HasFlag(ConsoleModifiers.Shift)
+                    ? AutoCompleteDirection.Backward
+                    : AutoCompleteDirection.Forward;
+                var replace = AutoComplete(autocomplete, text, autoCompleteDirection);
                 if (!string.IsNullOrEmpty(replace))
                 {
                     // Render the suggestion
@@ -63,7 +66,7 @@ public static partial class AnsiConsoleExtensions
         }
     }
 
-    private static string AutoComplete(List<string> autocomplete, string text)
+    private static string AutoComplete(List<string> autocomplete, string text, AutoCompleteDirection autoCompleteDirection)
     {
         var found = autocomplete.Find(i => i == text);
         var replace = string.Empty;
@@ -85,15 +88,38 @@ public static partial class AnsiConsoleExtensions
         else
         {
             // Get the next match
-            var index = autocomplete.IndexOf(found) + 1;
-            if (index >= autocomplete.Count)
-            {
-                index = 0;
-            }
-
-            replace = autocomplete[index];
+            replace = GetAutocompleteValue(autoCompleteDirection, autocomplete, found);
         }
 
         return replace;
     }
+
+    private static string GetAutocompleteValue(AutoCompleteDirection autoCompleteDirection, IList<string> autocomplete, string found)
+    {
+        var foundAutocompleteIndex = autocomplete.IndexOf(found);
+        var index = autoCompleteDirection switch
+        {
+            AutoCompleteDirection.Forward => foundAutocompleteIndex + 1,
+            AutoCompleteDirection.Backward => foundAutocompleteIndex - 1,
+            _ => throw new ArgumentOutOfRangeException(nameof(autoCompleteDirection), autoCompleteDirection, null),
+        };
+
+        if (index >= autocomplete.Count)
+        {
+            index = 0;
+        }
+
+        if (index < 0)
+        {
+            index = autocomplete.Count - 1;
+        }
+
+        return autocomplete[index];
+    }
+
+    private enum AutoCompleteDirection
+    {
+        Forward,
+        Backward,
+    }
 }
\ No newline at end of file