Decode APLCart TSV and show in Out-Gridview (C# decoder)

decode-aplcart-tsv-csharp.ps1

# Imports the table.tsv file from APLCart
# Decodes the TIO.run links
# Shows in Out-Gridview

$tablePath = "c:\sc\aplcart\table.tsv"

$csharp = @'
using System;
using System.IO;
using System.Net;
using System.Text;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public class TIOAssist
{
	public static string decodeTIO(string TIOLink)
	{
		// remove domain parts from URL
		string hash = (new Uri(TIOLink)).Fragment.Trim('#');
		
		// convert hash to base64, pad length to multipe of 4 with =, decode to bytes
		string b64 = WebUtility.UrlDecode(hash).Replace('@', '+').Replace('-', '+').Replace('_', '/');
	    byte[] deflatedBytes = Convert.FromBase64String(b64 + (new string('=', ((4 - (b64.Length % 4)) % 4))));

		// inflate() (decompress) bytes
		MemoryStream inflatedStream = new System.IO.MemoryStream();
		(new System.IO.Compression.DeflateStream(
				(new MemoryStream(deflatedBytes)),
				System.IO.Compression.CompressionMode.Decompress
			)).CopyTo(inflatedStream);

		Regex rIndent = new System.Text.RegularExpressions.Regex("^", RegexOptions.Compiled | RegexOptions.Multiline);
		List<string> fields = new List<string>();

		byte[] bytes = inflatedStream.ToArray();
		int last = 0;
		int i = 0;
		while (i < bytes.Length) {
			if (bytes[i] == (byte)0xff) {
				fields.Add(Encoding.UTF8.GetString(bytes, last, i-last));
				last = i+1;
			}
			i++;
		}
		fields.Add(Encoding.UTF8.GetString(bytes, last, bytes.Length - last));

		List<string> result = new List<string>();
		if ("" != fields[1]) { result.Add("HEADER:\n" + rIndent.Replace(fields[1], "    ")); }
		if ("" != fields[2]) { result.Add("CODE:\n"   + rIndent.Replace(fields[2], "    ")); }
		if ("" != fields[3]) { result.Add("FOOTER:\n" + rIndent.Replace(fields[3], "    ")); }
		if ("" != fields[4]) { result.Add("INPUT:\n"  + rIndent.Replace(fields[4], "    ")); }
 
		return String.Join("\n", result);
	}
}
'@

Add-Type -TypeDefinition $csharp

Import-Csv -Path $tablePath -Delimiter "`t" |
    Select-Object -Property Syntax, TIO, @{Label="TIOCode";Expression={[TIOAssist]::decodeTIO($_.TIO)}} |
    Out-GridView -OutputMode Multiple |
    Format-List -Property *