encode-base64-url.ps1

<#
	.SYNOPSIS
	Adds a Base64 encoded string to CSV file

	.DESCRIPTION
	Looks for URL/URI/PATH column in CSV file.
	Encodes the image in URI to Base64 string.
	Creates a new column 'Encoded' with Base64 string
  
  	Column values can be http/https url or path to local file
	
	Encode functions adapted from https://gist.github.com/brunolm/ceefbf4ee61da63fad5f004db96c5c82

	.EXAMPLE encode-base64-url.ps1 "C:\data\imageUrls.csv"
#>



function Get-ImageBase64([string]$file) {
    if ($file -like 'http*') {
        return Get-ImageBase64FromUrl($file);
    }

    return Get-ImageBase64FromFile($file);
}

function Get-ImageBase64FromFile(
    [string]
    [ValidateScript( { Test-Path $_ })]
    $file
) {
    $type = Get-MimeType $file;
    $base64 = [convert]::ToBase64String((Get-Content $file -Encoding byte));

    return "data:$type;base64,$base64";
}

function Get-ImageBase64FromUrl([Uri]$url) {
    $b = Invoke-WebRequest $url;

    $type = $b.Headers["Content-Type"];
    $base64 = [convert]::ToBase64String($b.Content);

    return "data:$type;base64,$base64";
}

function Get-MimeType($CheckFile) {
    Add-Type -AssemblyName "System.Web"

    [System.IO.FileInfo]$checkFile = $CheckFile
    $mime_type = ''

    if ($checkFile.Exists) {
        $mime_type = [System.Web.MimeMapping]::GetMimeMapping($checkFile.FullName);
    }

    return $mime_type;
}

function Write-Red {
	process { Write-Host $_ -ForegroundColor Red }
}

function Encode-Csv($csvPath) {
	$csvFile = Get-Item -Path $csvPath
	$csvEncodedPath = Join-Path $csvFile.DirectoryName "$($csvFile.BaseName)_encoded.csv"

	$csv = Import-Csv -Path $csvPath
	$headers = ($csv | Get-Member -MemberType NoteProperty).Name

	if('uri' -in $headers -Or 'url' -in $headers -Or 'path' -in $headers){
		ForEach ($row in $csv)
		{
			# Pick first non-null value
			$uri = (@($row.url, $row.uri, $row.path) -ne $null)[0]

			try{
				$encoded = Get-ImageBase64($uri)
				$row | Add-Member -MemberType NoteProperty -Name 'Encoded' -Value $encoded
			}
			catch {
				Write-Output "Error processing URI: $uri" | Write-Red
			}
		}
		
		$csv | Export-Csv -Path $csvEncodedPath -NoTypeInformation
	}
	else {
		Write-Output "uri/url/path column missing" | Write-Red
	}	
}

if ($args.count -eq 0) {
	Write-Output "File path missing" | Write-Red
}
else {
	Encode-Csv($args[0])
}