<#
.SYNOPSIS
	Checks the swap space
.DESCRIPTION
	This PowerShell script queries the current status of the swap space and prints it.
.PARAMETER minLevel
	Specifies the minimum level in MB (10 MB by default)
.EXAMPLE
	PS> ./check-swap-space.ps1
	✅ Swap space uses 21% of 1GB - 1005MB free
.LINK
	https://github.com/fleschutz/PowerShell
.NOTES
	Author: Markus Fleschutz | License: CC0
#>

param([int]$minLevel = 10)

function MB2String { param([int64]$bytes)
        if ($bytes -lt 1024) { return "$($bytes)MB" }
        $bytes /= 1024
        if ($bytes -lt 1024) { return "$($bytes)GB" }
        $bytes /= 1024
        if ($bytes -lt 1024) { return "$($bytes)TB" }
        $bytes /= 1024
        if ($bytes -lt 1024) { return "$($bytes)PB" }
        $bytes /= 1024
        if ($bytes -lt 1024) { return "$($bytes)EB" }
}

try {
	
	if ($IsLinux) {
		$Result = $(free --mega | grep Swap:)
		[int64]$total = $Result.subString(5,14)
		[int64]$used = $Result.substring(20,13)
		[int64]$free = $Result.substring(32,11)
	} else {
		$items = Get-WmiObject -class "Win32_PageFileUsage" -namespace "root\CIMV2" -computername localhost 
		[int64]$total = [int64]$used = 0
		foreach ($item in $items) { 
			$total += $item.AllocatedBaseSize
			$used += $item.CurrentUsage
			
		}
		[int64]$free = ($total - $used)
	}
	if ($total -eq 0) {
        	Write-Output "⚠️ No swap space configured"
	} elseif ($free -eq 0) {
		Write-Output "⚠️ Swap space of $(MB2String $total) is full"
	} elseif ($free -lt $minLevel) {
		Write-Output "⚠️ Swap space has only $(MB2String $free) of $(MB2String $total) free"
	} elseif ($used -lt 3) {
		Write-Output "✅ Swap space unused - full $(MB2String $free) free"
	} else {
		[int64]$percent = ($used * 100) / $total
		Write-Output "✅ Swap space at $percent% of $(MB2String $total) - $(MB2String $free) free"
	}
	exit 0 # success
} catch {
	"⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
	exit 1
}
