[PTRun][UnitConverter]Fix "feet" and "gal" (#16618)

* Update InputInterpreter.cs

* Update InputInterpreter.cs

src/modules/launcher/Plugins/Community.PowerToys.Run.Plugin.UnitConverter/InputInterpreter.cs

@@ -1,7 +1,8 @@
-// Copyright (c) Microsoft Corporation
+// Copyright (c) Microsoft Corporation
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
 using System.Text.RegularExpressions;
@@ -151,6 +152,53 @@ namespace Community.PowerToys.Run.Plugin.UnitConverter
             }
         }
 
+        /// <summary>
+        /// The plural form "feet" is not recognized by UniteNets. Replace it with "ft".
+        /// </summary>
+        public static void FeetToFt(ref string[] split)
+        {
+            if (split[1].ToLower() == "feet")
+            {
+                split[1] = "ft";
+            }
+
+            if (split[3].ToLower() == "feet")
+            {
+                split[3] = "ft";
+            }
+        }
+
+        /// <summary>
+        /// Choose "UsGallon" or "ImperialGallon" according to current culture when the input contains "gal" or "gallon".
+        /// </summary>
+        public static void GallonHandler(ref string[] split, CultureInfo culture)
+        {
+            HashSet<string> britishCultureNames = new HashSet<string>() { "en-AI", "en-VG", "en-GB", "en-KY", "en-MS", "en-AG", "en-DM", "en-GD", "en-KN", "en-LC", "en-VC", "en-IE", "en-GY", "en-AE" };
+            if (split[1].ToLower() == "gal" || split[1].ToLower() == "gallon")
+            {
+                if (britishCultureNames.Contains(culture.Name))
+                {
+                    split[1] = "ImperialGallon";
+                }
+                else
+                {
+                    split[1] = "UsGallon";
+                }
+            }
+
+            if (split[3].ToLower() == "gal" || split[3].ToLower() == "gallon")
+            {
+                if (britishCultureNames.Contains(culture.Name))
+                {
+                    split[3] = "ImperialGallon";
+                }
+                else
+                {
+                    split[3] = "UsGallon";
+                }
+            }
+        }
+
         public static ConvertModel Parse(Query query)
         {
             string[] split = query.Search.Split(' ');
@@ -167,6 +215,8 @@ namespace Community.PowerToys.Run.Plugin.UnitConverter
             }
 
             InputInterpreter.DegreePrefixer(ref split);
+            InputInterpreter.FeetToFt(ref split);
+            InputInterpreter.GallonHandler(ref split, CultureInfo.CurrentCulture);
             if (!double.TryParse(split[0], out double value))
             {
                 return null;