param (
    [Parameter(Mandatory = $true, Position = 0)]
    [string]$Ext1,

    [Parameter(Mandatory = $true, Position = 1)]
    [string]$Ext2,

    [int]$Jobs = 4  # Number of simultaneous conversions
)

$sourceExt = $Ext1.TrimStart('.')
$targetExt = $Ext2.TrimStart('.')
$audioExts = @('opus', 'ogg', 'flac', 'wav')

$files = Get-ChildItem -File -Recurse -Filter "*.$sourceExt"

if ($files.Count -eq 0) {
    Write-Host "No files matching *.$sourceExt found." -ForegroundColor Yellow
    return
}

Write-Host "Starting conversion using $Jobs parallel jobs..." -ForegroundColor Green

$files | ForEach-Object -Parallel {
    $file = $_
    $targetExt = $using:targetExt
    $audioExts = $using:audioExts

    $outputPath = Join-Path -Path $file.DirectoryName -ChildPath "$($file.BaseName).$targetExt"
    $relativePath = Resolve-Path -Path $file.FullName -Relative

    Write-Host "Processing: $relativePath" -ForegroundColor Cyan

    if ($audioExts -contains $targetExt.ToLower()) {
        ffmpeg -y -i $file.FullName -c:a libopus -b:a 128k -vbr on $outputPath 2>$null
    } else {
        # -preset 8 drastically speeds up SVT-AV1 while maintaining high quality
        ffmpeg -y -i $file.FullName -c:v libsvtav1 -crf 26 -preset 8 -c:a libopus -b:a 128k $outputPath 2>$null
    }
} -ThrottleLimit $Jobs

Write-Host "Finished processing $($files.Count) file(s)." -ForegroundColor Green

# -------------------------------------------------------------------------
# Step 1: Recursively delete all existing .sha256 files
# -------------------------------------------------------------------------
Write-Host "Deleting existing .sha256 files recursively..." -ForegroundColor Yellow
Get-ChildItem -Path . -Recurse -Filter "*.sha256" -File | Remove-Item -Force

# -------------------------------------------------------------------------
# Step 2: Run checksums in current directory and every subdirectory
# -------------------------------------------------------------------------
Write-Host "Generating checksums in each subfolder..." -ForegroundColor Cyan

# Gather current working directory and all child directories
$allDirs = @((Get-Item .).FullName) + (Get-ChildItem -Path . -Recurse -Directory | Select-Object -ExpandProperty FullName)

foreach ($dir in $allDirs) {
    Push-Location $dir
    try {
        Write-Host "Updating checksums in: $dir" -ForegroundColor Gray
        checksum * -o
    } finally {
        Pop-Location
    }
}

# -------------------------------------------------------------------------
# Step 3: Recursively verify checksums in each directory
# -------------------------------------------------------------------------
Write-Host "Verifying checksums in each subfolder..." -ForegroundColor Cyan

foreach ($dir in $allDirs) {
    Push-Location $dir
    try {
        if (Test-Path "checksums.sha256") {
            Write-Host "Verifying: $dir" -ForegroundColor Gray
            checksum -c checksums.sha256
        }
    } finally {
        Pop-Location
    }
}

Write-Host "All conversions, checksum creations, and verifications completed successfully." -ForegroundColor Green