Fill with initial codebase

Base64.cs

@@ -0,0 +1,58 @@
+using System.Management.Automation;
+using System;
+
+namespace Base64
+{
+    [Cmdlet(VerbsData.ConvertTo, "Base64String")]
+    [OutputType(typeof(string))]
+    public class ConvertToBase64Command : Cmdlet
+    {
+        // Declare the parameters for the cmdlet.
+        [Parameter(Position = 0, Mandatory = true, ValueFromPipeline = true)]
+        [Alias("InputString","String","Text")]
+        public string InputObject { get; set; }
+
+
+        [Parameter]
+        [ArgumentCompleter(typeof(EncodingCompleter))]
+        [EncodingTransform]
+        public System.Text.Encoding Encoding { get; set; } = EncodingTransformAttribute.StandardEncoding["UTF8"];
+
+
+        //This is the "Process {}" block of a Powershell script
+        protected override void ProcessRecord()
+        {
+            //WriteObject("Hello " + name + "!");
+
+            byte[] bytes = Encoding.GetBytes(InputObject);
+            WriteObject(Convert.ToBase64String(bytes), true);
+
+        }
+    } //class
+
+    [Cmdlet(VerbsData.ConvertFrom, "Base64String")]
+    [OutputType(typeof(string))]
+    public class ConvertFromBase64Command : Cmdlet
+    {
+        // Declare the parameters for the cmdlet.
+        [Parameter(Position = 0, Mandatory = true, ValueFromPipeline = true)]
+        [Alias("InputString","String","Text")]
+        public string InputObject { get; set; }
+
+
+        [Parameter]
+        [ArgumentCompleter(typeof(EncodingCompleter))]
+        [EncodingTransform]
+        public System.Text.Encoding Encoding { get; set; } = EncodingTransformAttribute.StandardEncoding["UTF8"];
+
+
+        //This is the "Process {}" block of a Powershell script
+        protected override void ProcessRecord()
+        {
+            //WriteObject("Hello " + name + "!");
+            // $Encoding.GetString([System.Convert]::FromBase64String($Base64String))
+            byte[] bytes = Convert.FromBase64String(InputObject);
+            WriteObject(Encoding.GetString(bytes), true);
+        }
+    } //class
+} //namespace

Base64.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="PowerShellStandard.Library" Version="5.1.0" />
+  </ItemGroup>
+
+</Project>

EncodingTransformAttribute.cs

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+using System.Management.Automation;
+using System.Management.Automation.Language;
+using System.Collections;
+using System.Collections.Generic;
+using System.Text;
+using System;
+
+namespace Base64
+{
+    class EncodingTransformAttribute : ArgumentTransformationAttribute
+    {
+        public EncodingTransformAttribute() { }
+        internal static Dictionary<string, Encoding> StandardEncoding = new Dictionary<string, Encoding>()
+        {
+            { "ASCII", Encoding.ASCII },
+            { "UnicodeBE", Encoding.BigEndianUnicode },
+            { "Unicode", Encoding.Unicode },
+            { "UTF32", Encoding.UTF32 },
+            { "UTF7", Encoding.UTF7 },
+            { "UTF8", new UTF8Encoding(encoderShouldEmitUTF8Identifier: false) },
+            { "UTF8BOM", Encoding.UTF8 }
+        };
+
+        public override object Transform(EngineIntrinsics engineIntrinsics, object inputData)
+        {
+            switch (inputData)
+            {
+                case Encoding e:
+                    return e;
+                case string s:
+                    if (StandardEncoding.ContainsKey(s))
+                    {
+                        return StandardEncoding[s];
+                    }
+                    else
+                    {
+                        return Encoding.GetEncoding(s);
+                    }
+                default:
+                    throw new ArgumentTransformationMetadataException();
+            }
+        }
+
+        public override string ToString() 
+        {
+            return "[EncodingTransformAttribute]";
+        }
+    }
+
+    class EncodingCompleter : IArgumentCompleter
+    {
+        public EncodingCompleter() { }
+        public IEnumerable<CompletionResult> CompleteArgument(
+            string commandName,
+            string parameterName,
+            string wordToComplete,
+            CommandAst commandAst,
+            IDictionary fakeBoundParameters)
+        {
+            List<string> encodingValues = new List<string>(EncodingTransformAttribute.StandardEncoding.Keys);
+
+            if (!string.IsNullOrEmpty(wordToComplete))
+            {
+                foreach (string encoding in encodingValues)
+                {
+                    yield return new CompletionResult(
+                        completionText: encoding,
+                        listItemText: encoding,
+                        resultType: CompletionResultType.ParameterValue,
+                        toolTip: string.Format("{0} {1}", "[Encoding]", encoding));
+                }
+            }
+            else
+            {
+                var filteredList = encodingValues.FindAll(x => x.StartsWith(wordToComplete, StringComparison.OrdinalIgnoreCase));
+                foreach (string result in filteredList)
+                {
+                    yield return new CompletionResult(
+                        completionText: result,
+                        listItemText: result,
+                        resultType: CompletionResultType.ParameterValue,
+                        toolTip: string.Format("{0} {1}", "[Encoding]", result));
+                }
+            }
+        }
+    }
+}