combine multiple PDFS into one using powershell and qpdf on win11

combinepdf.ps1

# PDF Merger Script using QPDF
# This script allows user to select order of PDFs and combines them into a single PDF file
# Requirements: QPDF must be installed on the system

function Get-PdfPageCount {
    param (
        [string]$pdfPath
    )
    try {
        $pageCount = & qpdf --show-npages $pdfPath 2>&1
        if ($LASTEXITCODE -eq 0) {
            return [int]$pageCount
        }
        return -1
    } catch {
        return -1
    }
}

# Display script purpose
Write-Host "`nPDF Merger Script" -ForegroundColor Cyan
Write-Host "This script will combine PDF files in your specified order.`n"
Write-Host "Requirements: QPDF must be installed on your system.`n"

# Check if QPDF is installed
try {
    $qpdfVersion = & qpdf --version 2>&1
    if ($LASTEXITCODE -ne 0) {
        throw "QPDF not found"
    }
} catch {
    Write-Host "Error: QPDF is not installed or not accessible. Please install QPDF first." -ForegroundColor Red
    exit 1
}

# Get all PDF files in the current directory
$pdfFiles = Get-ChildItem -Filter *.pdf | Sort-Object Name

# Check if any PDF files exist
if ($pdfFiles.Count -eq 0) {
    Write-Host "No PDF files found in the current directory." -ForegroundColor Red
    exit 1
}

# Display available PDF files with numbers
Write-Host "Available PDF files:" -ForegroundColor Green
$pdfDict = @{}
for ($i = 1; $i -le $pdfFiles.Count; $i++) {
    $pdf = $pdfFiles[$i-1]
    $pageCount = Get-PdfPageCount -pdfPath $pdf.FullName
    if ($pageCount -eq -1) {
        Write-Host "Error: Unable to read page count for $($pdf.Name)" -ForegroundColor Red
        exit 1
    }
    Write-Host "$i. $($pdf.Name) ($pageCount pages)"
    $pdfDict[$i] = @{
        File = $pdf
        Pages = $pageCount
    }
}
Write-Host ""

# Create ordered list based on user input
$orderedPdfs = @()
$totalPages = 0
$usedNumbers = @()

while ($orderedPdfs.Count -lt $pdfFiles.Count) {
    $remaining = $pdfFiles.Count - $orderedPdfs.Count
    $nextPosition = $orderedPdfs.Count + 1
    
    Write-Host "Select PDF #$nextPosition of $($pdfFiles.Count) ($(($pdfFiles.Count - $usedNumbers.Count)) remaining)"
    $selection = Read-Host "Enter number (1-2)"
    
    # Validate input
    try {
        $num = [int]$selection
        if ($num -lt 1 -or $num -gt $pdfFiles.Count) {
            Write-Host "Invalid number. Please enter a number between 1 and $($pdfFiles.Count)" -ForegroundColor Yellow
            continue
        }
        if ($usedNumbers -contains $num) {
            Write-Host "You've already selected this PDF. Please choose a different one." -ForegroundColor Yellow
            continue
        }
        
        $orderedPdfs += $pdfDict[$num].File
        $totalPages += $pdfDict[$num].Pages
        $usedNumbers += $num
        
        Write-Host "Added $($pdfDict[$num].File.Name) to position $nextPosition`n" -ForegroundColor Green
    } catch {
        Write-Host "Invalid input. Please enter a number." -ForegroundColor Yellow
        continue
    }
}

# Final confirmation
Write-Host "`nSelected PDF order:" -ForegroundColor Cyan
for ($i = 0; $i -lt $orderedPdfs.Count; $i++) {
    Write-Host "$($i+1). $($orderedPdfs[$i].Name)"
}
Write-Host "`nTotal pages: $totalPages"

$confirmation = Read-Host "`nDo you want to merge these PDF files in this order? (y/n)"

if ($confirmation -ne 'y') {
    Write-Host "`nOperation cancelled by user." -ForegroundColor Yellow
    exit 0
}

# Create output filename with timestamp
$timestamp = Get-Date -Format "yyyyMMdd_HHmmss"
$outputFile = "merged_${timestamp}.pdf"

try {
    # Build command string directly
    $command = "qpdf --empty --pages"
    
    # Add all PDF files to the command
    foreach ($pdf in $orderedPdfs) {
        $command += " `"$($pdf.FullName)`" 1-z"
    }
    
    # Add output file
    $command += " -- `"$outputFile`""

    # Execute QPDF command
    Write-Host "`nMerging PDF files..." -ForegroundColor Yellow
    $output = Invoke-Expression $command 2>&1
    
    if ($LASTEXITCODE -ne 0) {
        throw "QPDF error: $output"
    }

    # Verify the output file
    if (Test-Path $outputFile) {
        $finalPageCount = Get-PdfPageCount -pdfPath $outputFile
        if ($finalPageCount -eq $totalPages) {
            Write-Host "`nPDF files successfully merged into: $outputFile" -ForegroundColor Green
            Write-Host "Verified page count: $finalPageCount pages" -ForegroundColor Green
        } else {
            Write-Host "`nWarning: Page count mismatch. Expected $totalPages pages, got $finalPageCount pages" -ForegroundColor Yellow
            Write-Host "The file was still created successfully as: $outputFile" -ForegroundColor Green
        }
    } else {
        throw "Output file was not created"
    }
} catch {
    Write-Host "`nError occurred while merging PDF files: $($_.Exception.Message)" -ForegroundColor Red
    if (Test-Path $outputFile) {
        Remove-Item $outputFile -Force
        Write-Host "Cleaned up incomplete output file." -ForegroundColor Yellow
    }
    exit 1
}