# PRTG-WordPress
#
# Collect version information from an installed WordPress instance and compare it with most recent version
#
# 20210910 frank@carius.de  initial version
# 20210921 Version 2 with other way to parse versions.
# 20220415 Adding wpurl to output

[CmdletBinding()]
param (
    [string]$wpurl = "https://www.netatwork.de",       # zu testende öffentliche Wordpress Webseite
    [long]$maxage  = 7,                                # maximales Alter einer neueren Version zum Warn-Status
    [ValidateSet("","simple","xml")][string]$prtg =""  # Der Code enthält eine AutoDetectFunktion, wenn der Scriptpfad auf EXEXML endet
)

if ($PSScriptRoot.EndsWith("EXEXML")) {
    Write-Verbose "PRTG EXEXML-Mode enabled"
    [string]$prtg="xml"
}
elseif ($PSScriptRoot.EndsWith("EXE")) {
    Write-Verbose "PRTG Simple-Mode enabled"
    [string]$prtg="simple"
}
else {
    Set-PSDEBUG -strict  # enable strict variable checking. Not usable with PRTG
}

$error.clear()

[string]$publicversion="unknown"
[datetime]$releasedate = get-date "1.1.1900"
[long]$releaseage=1
[string]$installedversion="unknown"
[long]$updateavailable=-1
[string]$finalstatus = "NoStatus"
[int]$finalstatuscode = -1

Write-Verbose "GET installed Version at $($wpurl)"
$htmlanswer = Invoke-WebRequest -Uri $wpurl -Method GET -UseBasicParsing
$generatorvalid = $htmlanswer.Content -match "<meta name=""generator"".* content=""WordPress (.*)""?.*"".*/>"
if ($generatorvalid) {
    Write-Verbose "GET Get newest public version Age"
    $installedversion = $($matches[1])
    $historyrest = Invoke-RestMethod https://wordpress.org/news/feed/
    $currentversion = $historyrest `
        | Where-Object {     ($_.category."#cdata-section" -contains "releases") `
                -and ($_.category."#cdata-section" -notcontains "development")} `
        | Select-Object -first 1
    $releasedate = (get-date $currentversion.pubDate)
    $releaseage=[int]((get-date) - $releasedate).totaldays
    Write-Verbose " Release Date          : $($currentversion.pubDate)"
    Write-Verbose " Age of Public Version : $($releaseage)"

    Write-Verbose "GET Get newest public version Build"
    $wpversioncheck=Invoke-RestMethod http://api.wordpress.org/core/version-check/1.7/
    $publicversion = $wpversioncheck.offers.current
    Write-Verbose " Latest Public Version : $($publicversion)"

    Write-Verbose " Installed WP Version  : $($installedversion)"
    if ($installedversion -eq $publicversion) {
        Write-Verbose "OK WP Installation is uptodate"
        $updateavailable = 0
        $finalstatus = "OK UpToDate"
        $finalstatuscode = 0  # OK
    }
    else {
        Write-Verbose " WP Installation outdated"
        $updateavailable = 1  
        if ($releaseage -lt $maxage) {
            Write-Warning "WARN WPInstallation should be updated"
            $finalstatus = "WARN Update Pending from $($installedversion) to $($publicversion)"
            $finalstatuscode = 1 # Warning
        }
        else {
            Write-Warning "  ALERT Please update Wordpress Installation"
            $finalstatus = "ALERT Update Required from $($installedversion) to $($publicversion)"
            $finalstatuscode = 2  # Critical
        }
    }
}
else {
    Write-Verbose "No WPVersion found"
    $finalstatus = "ERROR NoWPVersionFound"
    $updateavailable = 3
    $finalstatuscode = "3"    # Protocol/Unknown
}

if ($prtg -eq "xml") {
    Write-Verbose "Generating PRTG XML"
    $prtgresult="<prtg>`r`n"
    $prtgresult+="    <result>`r`n"
    $prtgresult+="        <channel>ReleaseAge</channel>`r`n"
    $prtgresult+="        <customunit>Days</customunit>`r`n"
    $prtgresult+="        <float>0</float>`r`n"
    $prtgresult+="        <mode>absolut</mode>`r`n"
    $prtgresult+="        <value>$($releaseage)</value>`r`n"
    $prtgresult+="    </result>`r`n"
    $prtgresult+="    <result>`r`n"
    $prtgresult+="        <channel>UpdateAvailable</channel>`r`n"
    $prtgresult+="        <customunit></customunit>`r`n"
    $prtgresult+="        <float>0</float>`r`n"
    $prtgresult+="        <mode>absolut</mode>`r`n"
    $prtgresult+="        <warning>$($updateavailable)</warning>`r`n"
    $prtgresult+="        <value>$($updateavailable)</value>`r`n"
    $prtgresult+="    </result>`r`n"
    $prtgresult+="   <text>$($Finalstatus) for URL $($wpurl)</text>`r`n"
    $prtgresult+="   <error>$(if ($finalstatuscode -eq 0) {"0"} else {"1"})</error>`r`n"
    $prtgresult+="</prtg>"
    $prtgresult
}
elseif ($prtg -eq "simple") {
    Write-Verbose "Generating PRTG Simple"
    "$($updateavailable):$($Finalstatus)"
}
else {
    [pscustomobject][ordered]@{
        wpurl                 = $wpurl
        LatestPublicVersion   = $publicversion
        LatestReleaseDate     = $releasedate
        Releaseage            = $releaseage
        InstalledWPVersion    = $installedversion
        updateavailable       = $updateavailable
        Finalstatus           = $finalstatus 
        finalstatuscode       = $finalstatuscode
    }
}

Write-Verbose "END WP-Versioncheck  Exitcode $($finalstatuscode)"
exit $finalstatuscode