param (
    [Parameter(Mandatory = $true, Position = 0)]
    [string]$InputFile
)

if (-not (Test-Path $InputFile)) {
    Write-Error "Bestand niet gevonden: $InputFile"
    exit 1
}

$raw = Get-Content $InputFile -Raw

if ($raw -notmatch "Content-Type:\s*text/html") {
    Write-Error "Geen HTML-part gevonden in dit EML-bestand."
    exit 1
}

# Pak alles NA Content-Type: text/html
$htmlPart = ($raw -split "Content-Type:\s*text/html", 2)[1]

# Verwijder headers van de MIME-part
$htmlBody = ($htmlPart -split "\r?\n\r?\n", 2)[1]

# --- Quoted-printable decoding ---
# 1) line continuations (= aan einde regel)
$htmlBody = $htmlBody -replace "=\r?\n", ""

# 2) =XX hex decoding
$bytes = [System.Text.Encoding]::ASCII.GetBytes($htmlBody)
$decodedBytes = New-Object System.Collections.Generic.List[byte]

for ($i = 0; $i -lt $bytes.Length; $i++) {
    if ($bytes[$i] -eq 61 -and $i + 2 -lt $bytes.Length) { # '='
        $hex = [char]$bytes[$i + 1] + [char]$bytes[$i + 2]
        if ($hex -match '^[0-9A-Fa-f]{2}$') {
            $decodedBytes.Add([Convert]::ToByte($hex, 16))
            $i += 2
            continue
        }
    }
    $decodedBytes.Add($bytes[$i])
}

# Charset (default utf-8)
$encoding = [System.Text.Encoding]::UTF8
$decodedHtml = $encoding.GetString($decodedBytes.ToArray())

$outputFile = [System.IO.Path]::ChangeExtension($InputFile, ".html")
$decodedHtml | Out-File $outputFile -Encoding UTF8

Write-Host "HTML geëxtraheerd naar:"
Write-Host "  $outputFile"