Use the history as the suggestion source

Author: daxian-dbw

PSReadLine/BasicEditing.cs

@@ -79,6 +79,8 @@ public static void CancelLine(ConsoleKeyInfo? key = null, object arg = null)
         {
             _singleton.ClearStatusMessage(false);
             _singleton._current = _singleton._buffer.Length;
+
+            using var _ = _singleton.ChangeSuggestionMode(showSuggestion: false);
             _singleton.ForceRender();
 
             _singleton._console.Write("\x1b[91m^C\x1b[0m");

PSReadLine/Completion.cs

@@ -217,6 +217,9 @@ private void CompleteImpl(bool menuSelect)
                 ViInsertWithAppend();
             }
 
+            // Do not show suggestion text during tab completion.
+            using var _ = ChangeSuggestionMode(showSuggestion: false);
+
             var completions = GetCompletions();
             if (completions == null || completions.CompletionMatches.Count == 0)
                 return;

PSReadLine/History.cs

@@ -679,6 +679,20 @@ private void HistorySearch(int direction)
             }
         }
 
+        private string GetHistorySuggestion(string text)
+        {
+            for (int index = _history.Count - 1; index > 0; index --)
+            {
+                var line = _history[index].CommandLine;
+                if (line.Length > text.Length && !LineIsMultiLine(line) && line.StartsWith(text, Options.HistoryStringComparison))
+                {
+                    return line;
+                }
+            }
+
+            return null;
+        }
+
         /// <summary>
         /// Move to the first item in the history.
         /// </summary>

PSReadLine/PublicAPI.cs

@@ -243,6 +243,7 @@ public static void AcceptSuggestion()
         {
             if (_singleton._suggestionText != null)
             {
+                using var _ = _singleton.ChangeSuggestionMode(showSuggestion: false);
                 Replace(0, _singleton._buffer.Length, _singleton._suggestionText);
             }
         }

PSReadLine/ReadLine.vi.cs

@@ -522,6 +522,9 @@ internal static IDisposable UseViInsertModeTables()
 
         private void ViIndicateCommandMode()
         {
+            // Show suggestion in 'InsertMode' but not 'CommandMode'.
+            _showSuggestion = false;
+
             if (_options.ViModeIndicator == ViModeStyle.Cursor)
             {
                 _console.CursorSize = _normalCursorSize < 50 ? 100 : 25;
@@ -541,6 +544,9 @@ private void ViIndicateCommandMode()
 
         private void ViIndicateInsertMode()
         {
+            // Show suggestion in 'InsertMode' but not 'CommandMode'.
+            _showSuggestion = true;
+
             if (_options.ViModeIndicator == ViModeStyle.Cursor)
             {
                 _console.CursorSize = _normalCursorSize;

PSReadLine/Render.cs

@@ -110,7 +110,7 @@ private string GetSuggestion(string text)
                 _lastRenderedTextHash = FNV1a32Hash.ComputeHash(text);
                 if (textHash != _lastRenderedTextHash)
                 {
-                    _suggestionText = DummySuggestion.GetCommandLineSuggestion(text);
+                    _suggestionText = GetHistorySuggestion(text);
                 }
             }
             catch
@@ -1257,6 +1257,16 @@ private bool LineIsMultiLine()
             return false;
         }
 
+        private bool LineIsMultiLine(string text)
+        {
+            for (int i = 0; i < text.Length; i++)
+            {
+                if (text[i] == '\n')
+                    return true;
+            }
+            return false;
+        }
+
         private int GetStatusLineCount()
         {
             if (_statusLinePrompt == null)

PSReadLine/Suggestion.cs

@@ -3,43 +3,6 @@
 
 namespace Microsoft.PowerShell
 {
-    internal class DummySuggestion
-    {
-        private static readonly List<string> s_suggestions;
-
-        static DummySuggestion()
-        {
-            s_suggestions = new List<string>()
-            {
-                "ildasm",
-                "git",
-                "git branch -r",
-                "git checkout -b",
-                "git checkout master",
-                "git fetch --all -p",
-                "git status",
-                "git diff",
-                "git diff --cached",
-                "git add -u",
-                "git add -A",
-                "start",
-            };
-        }
-
-        internal static string GetCommandLineSuggestion(string text)
-        {
-            foreach (string candidate in s_suggestions)
-            {
-                if (candidate.Length > text.Length && candidate.StartsWith(text, StringComparison.OrdinalIgnoreCase))
-                {
-                    return candidate;
-                }
-            }
-
-            return null;
-        }
-    }
-
     public partial class PSConsoleReadLine
     {
         private class SuggestionModeRestore : IDisposable