allow configuring cache directory

Public/ConvertTo-ExcelXlsx.ps1

@@ -3,64 +3,109 @@ function ConvertTo-ExcelXlsx {
     param
     (
         [parameter(Mandatory = $true, ValueFromPipeline)]
-        [string]$Path,
+        [string[]]$Path,
         [parameter(Mandatory = $false)]
-        [switch]$Force
+        [switch]$Force,
+        [parameter(Mandatory = $false)]
+        [switch]$CacheToTemp,
+        [parameter(Mandatory = $false)]
+        [string]$CacheDirectory
     )
     process {
-        if (-Not ($Path | Test-Path) ) {
-            throw "File not found"
-        }
-        if (-Not ($Path | Test-Path -PathType Leaf) ) {
-            throw "Folder paths are not allowed"
-        }
+        try {
+            foreach ($singlePath in $Path) {
+                if (-Not ($singlePath | Test-Path) ) {
+                    throw "File not found"
+                }
+                if (-Not ($singlePath | Test-Path -PathType Leaf) ) {
+                    throw "Folder paths are not allowed"
+                }
 
-        $xlFixedFormat = 51 #Constant for XLSX Workbook
-        $xlsFile = Get-Item -Path $Path
-        $xlsxPath = "{0}x" -f $xlsFile.FullName
+                $xlFixedFormat = 51 #Constant for XLSX Workbook
+                $xlsFile = Get-Item -Path $singlePath
+                $destinationXlsxPath = [System.IO.Path]::ChangeExtension($xlsFile.FullName, ".xlsx")
 
-        if ($xlsFile.Extension -ne ".xls") {
-            throw "Expected .xls extension"
-        }
+                if ($xlsFile.Extension -ne ".xls") {
+                    throw "Expected .xls extension"
+                }
 
-        if (Test-Path -Path $xlsxPath) {
-            if ($Force) {
-                try {
-                    Remove-Item $xlsxPath -Force
+                if (Test-Path -Path $destinationXlsxPath) {
+                    if ($Force) {
+                        try {
+                            Remove-Item $destinationXlsxPath -Force
+                        }
+                        catch {
+                            throw "{0} already exists and cannot be removed. The file may be locked by another application." -f $destinationXlsxPath
+                        }
+                        Write-Verbose $("Removed {0}" -f $destinationXlsxPath)
+                    }
+                    else {
+                        throw "{0} already exists!" -f $destinationXlsxPath
+                    }
+                }
+
+                if ($null -eq $Excel)
+                {
+                    try {
+                        $Excel = New-Object -ComObject "Excel.Application"
+                    }
+                    catch {
+                        throw "Could not create Excel.Application ComObject. Please verify that Excel is installed."
+                    }
+                }
+
+                if ($CacheToTemp) {
+                    if (-not $CacheDirectory) {
+                        $CacheDirectory = [System.IO.Path]::GetTempPath()
+                    }
+                    $tempPath = [System.IO.Path]::Combine($CacheDirectory, [System.IO.Path]::GetFileName($xlsFile.FullName))
+                    Write-Host ("Using Temp path: {0}" -f $tempPath)
+                    Copy-Item -Path $xlsFile.FullName -Destination $tempPath -Force
+                    $fileToProcess = $tempPath
+                }
+                else {
+                    $fileToProcess = $xlsFile.FullName
+                }
+
+                $xlsxPath = [System.IO.Path]::ChangeExtension($fileToProcess, ".xlsx")
+
+                try {  
+                    $Excel.Visible = $false
+                    $workbook = $Excel.Workbooks.Open($fileToProcess, $null, $true)
+                    if ($null -eq $workbook) {
+                        Write-Host "Failed to open workbook"
+                    } else {
+                        $workbook.SaveAs($xlsxPath, $xlFixedFormat)
+                        
+                        if ($CacheToTemp) {
+                            Copy-Item -Path $xlsxPath -Destination $destinationXlsxPath -Force
+                        }
+                    }
                 }
                 catch {
-                    throw "{0} already exists and cannot be removed. The file may be locked by another application." -f $xlsxPath
+                    Write-Error ("Failed to convert {0} to XLSX." -f $xlsFile.FullName)
+                    throw
                 }
-                Write-Verbose $("Removed {0}" -f $xlsxPath)
-            }
-            else {
-                throw "{0} already exists!" -f $xlsxPath
-            }
-        }
+                finally {
+                    if ($null -ne $workbook) {
+                        $workbook.Close()
+                        [System.Runtime.InteropServices.Marshal]::ReleaseComObject($workbook) | Out-Null
+                        $workbook = $null
+                    }
 
-        try {
-            $Excel = New-Object -ComObject "Excel.Application"
-        }
-        catch {
-            throw "Could not create Excel.Application ComObject. Please verify that Excel is installed."
-        }
-
-        try {  
-            $Excel.Visible = $false
-            $workbook = $Excel.Workbooks.Open($xlsFile.FullName, $null, $true)
-            if ($null -eq $workbook) {
-                Write-Host "Failed to open workbook"
-            } else {
-                $workbook.SaveAs($xlsxPath, $xlFixedFormat)
+                    if ($CacheToTemp) {
+                        Remove-Item -Path $tempPath -Force
+                        Remove-Item -Path $xlsxPath -Force
+                    }
+                }
             }
         }
         finally {
-            if ($null -ne $workbook) {
-                $workbook.Close()
+            if ($null -ne $Excel) {
+                $Excel.Quit()
+                [System.Runtime.InteropServices.Marshal]::ReleaseComObject($Excel) | Out-Null
+                $Excel = $null
             }
-            
-            $Excel.Quit()
         }
     }
 }
-