param(
    [string]$SourceDir,
    [string]$OutputDir,
    [string]$Prefix = "ARC_x64_part",
    [long]$MaxSize = 48000000
)

$SourceDir = $SourceDir.Trim('"', "'", ' ')
$OutputDir = $OutputDir.Trim('"', "'", ' ')

$part = 1
$currentSize = 0
$currentFiles = @()
$allItems = Get-ChildItem -Path $SourceDir -Recurse -File | Sort-Object Length

function Flush-Part {
    param($files, $partNum, $size)
    $zipName = Join-Path $OutputDir "$Prefix$partNum.zip"
    Write-Host "Creating part $partNum ($([math]::Round($size/1MB,1)) MB, $($files.Count) files)"
    $tempDir = Join-Path $env:TEMP "arc_split_$partNum"
    if (Test-Path $tempDir) { Remove-Item $tempDir -Recurse -Force }
    foreach ($cf in $files) {
        $dest = Join-Path $tempDir $cf.Rel
        $destDir = Split-Path $dest -Parent
        if (!(Test-Path $destDir)) { New-Item -ItemType Directory -Path $destDir -Force | Out-Null }
        Copy-Item $cf.Full $dest
    }
    Compress-Archive -Path (Join-Path $tempDir '*') -DestinationPath $zipName -Force
    Remove-Item $tempDir -Recurse -Force
}

foreach ($f in $allItems) {
    $rel = $f.FullName.Substring($SourceDir.TrimEnd('\').Length)
    if ($currentSize + $f.Length -gt $MaxSize -and $currentFiles.Count -gt 0) {
        Flush-Part $currentFiles $part $currentSize
        $part++
        $currentSize = 0
        $currentFiles = @()
    }
    $currentFiles += @{ Full = $f.FullName; Rel = $rel }
    $currentSize += $f.Length
}

if ($currentFiles.Count -gt 0) {
    Flush-Part $currentFiles $part $currentSize
}

Write-Host "Done: $part part(s) created."