##########################################
#   CheckMK Agent Registrierung
#   Author: Marius Gielnik
#   E-Mail: marius.gielnik@gc-gruppe.de
##########################################


# Farben fuer bessere Lesbarkeit
$ColorInfo = "Cyan"
$ColorSuccess = "Green"
$ColorError = "Red"
$ColorWarning = "Yellow"


# Fester API-Server
$API_SERVER = "monitoring.gc-gruppe.net"


# Funktion fuer formatierte Ausgaben
function Write-Header {
    Write-Host ""
    Write-Host "============================================================" -ForegroundColor Cyan
    Write-Host "  CheckMK Agent - TLS & Updater Registrierung             " -ForegroundColor Cyan
    Write-Host "============================================================" -ForegroundColor Cyan
    Write-Host ""
}


function Write-Success {
    param([string]$Message)
    Write-Host "[OK] $Message" -ForegroundColor Green
}


function Write-ErrorMsg {
    param([string]$Message)
    Write-Host "[FEHLER] $Message" -ForegroundColor Red
}


function Write-Info {
    param([string]$Message)
    Write-Host "[INFO] $Message" -ForegroundColor Cyan
}


function Write-Warning {
    param([string]$Message)
    Write-Host "[WARNUNG] $Message" -ForegroundColor Yellow
}


function Write-SectionHeader {
    param([string]$Message)
    Write-Host ""
    Write-Host "--- $Message ---" -ForegroundColor Cyan
    Write-Host ""
}


# Funktion zur Ueberpruefung ob Dateien existieren
function Test-Dependencies {
    $agentCtlPath = "C:\Program Files (x86)\checkmk\service\cmk-agent-ctl.exe"
    $updaterPath = "C:\Program Files (x86)\checkmk\service\check_mk_agent.exe"
   
    $missingDeps = 0
   
    if (-not (Test-Path $agentCtlPath)) {
        Write-ErrorMsg "cmk-agent-ctl.exe nicht gefunden: $agentCtlPath"
        $missingDeps++
    }
   
    if (-not (Test-Path $updaterPath)) {
        Write-ErrorMsg "check_mk_agent.exe nicht gefunden: $updaterPath"
        $missingDeps++
    }
   
    if ($missingDeps -gt 0) {
        Write-ErrorMsg "Bitte installieren Sie den CheckMK Agent"
        exit 1
    }
   
    return $true
}


# Funktion zur Eingabevalidierung
function Get-ValidatedInput {
    param(
        [string]$Prompt,
        [switch]$IsSecure,
        [string]$DefaultValue = ""
    )
   
    while ($true) {
        if ($IsSecure) {
            $value = Read-Host -AsSecureString $Prompt
            $plainValue = [Runtime.InteropServices.Marshal]::PtrToStringAuto(
                [Runtime.InteropServices.Marshal]::SecureStringToBSTR($value)
            )
        } else {
            if ($DefaultValue) {
                $value = Read-Host "$Prompt [$DefaultValue]"
                if ([string]::IsNullOrWhiteSpace($value)) {
                    $plainValue = $DefaultValue
                } else {
                    $plainValue = $value
                }
            } else {
                $value = Read-Host $Prompt
                $plainValue = $value
            }
        }
       
        if (-not [string]::IsNullOrWhiteSpace($plainValue)) {
            return $plainValue
        }
       
        Write-ErrorMsg "Eingabe darf nicht leer sein"
    }
}


# Funktion zum Suchen des Hosts in CheckMK via API (fest ueber monitoring.gc-gruppe.net)
function Get-CheckMKHostname {
    param(
        [string]$Site,
        [string]$Username,
        [string]$Password,
        [string]$SearchHostname
    )
   
    try {
        Write-Info "Suche Host in CheckMK (via $API_SERVER)..."
       
        # TLS 1.2 erzwingen
        [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
       
        # Automation User Format: "username password" als Bearer Token
        $authString = "$Username $Password"
       
        $headers = @{
            "Authorization" = "Bearer $authString"
            "Accept" = "application/json"
        }
       
        $url = "https://$API_SERVER/$Site/check_mk/api/1.0/domain-types/host_config/collections/all"
       
        $response = Invoke-RestMethod -Uri $url -Headers $headers -Method Get -ErrorAction Stop
       
        # Suche nach dem Host (case-insensitive)
        $searchLower = $SearchHostname.ToLower()
       
        if ($response.value) {
            foreach ($hostItem in $response.value) {
                if ($hostItem.id.ToLower() -eq $searchLower) {
                    Write-Success "Host gefunden in CheckMK: $($hostItem.id)"
                    return $hostItem.id
                }
            }
        }
       
        Write-Warning "Host '$SearchHostname' nicht in CheckMK gefunden"
        return $null
       
    } catch {
        Write-Warning "Konnte nicht auf CheckMK API zugreifen ($API_SERVER)"
        Write-Info "Fehler: $($_.Exception.Message)"
        return $null
    }
}


# Header anzeigen
Clear-Host
Write-Header


# Abhaengigkeiten pruefen
Write-Info "Pruefe Systemvoraussetzungen..."
Test-Dependencies | Out-Null
Write-Success "Alle benoetigten Dateien gefunden"


# Benutzereingaben sammeln
Write-SectionHeader "Schritt 1: Server-Informationen"


$server = Get-ValidatedInput -Prompt "Server"
$site = Get-ValidatedInput -Prompt "Site"


Write-SectionHeader "Schritt 2: Anmeldedaten"


$username = Get-ValidatedInput -Prompt "Benutzername"
$passwordPlain = Get-ValidatedInput -Prompt "Passwort" -IsSecure


Write-SectionHeader "Schritt 3: Hostname"


$defaultHostname = "$env:COMPUTERNAME.ad.ghnit.net".ToLower()
$hostname = Get-ValidatedInput -Prompt "Hostname" -DefaultValue $defaultHostname


# Versuche den Host in CheckMK zu finden (API-Call ueber monitoring.gc-gruppe.net)
Write-Host ""
$checkmkHostname = Get-CheckMKHostname -Site $site -Username $username -Password $passwordPlain -SearchHostname $hostname


if ($checkmkHostname) {
    # Host in CheckMK gefunden - verwende exakte Schreibweise
    $hostname = $checkmkHostname
} else {
    # Host nicht gefunden - verwende Kleinschreibung als Fallback
    $hostname = $hostname.ToLower()
    Write-Warning "Verwende Fallback-Hostname: $hostname"
    Write-Host ""
    $continue = Read-Host "Trotzdem fortfahren? (j/n)"
    if ($continue -notmatch "^[jJ]$") {
        Write-Warning "Abbruch durch Benutzer"
        exit 0
    }
}


# Zusammenfassung anzeigen
Write-SectionHeader "Zusammenfassung"


Write-Host "Server:    " -NoNewline
Write-Host "$server" -ForegroundColor Green
Write-Host "Site:      " -NoNewline
Write-Host "$site" -ForegroundColor Green
Write-Host "Username:  " -NoNewline
Write-Host "$username" -ForegroundColor Green
Write-Host "Hostname:  " -NoNewline
Write-Host "$hostname" -ForegroundColor Green
Write-Host "API-Server:" -NoNewline
Write-Host " $API_SERVER" -ForegroundColor Cyan
Write-Host ""


$confirm = Read-Host "Fortfahren? (j/n)"
if ($confirm -notmatch "^[jJ]$") {
    Write-Warning "Abbruch durch Benutzer"
    exit 0
}


# TLS-Registrierung durchfuehren
Write-SectionHeader "Schritt 4: TLS-Registrierung"
Write-Info "Registriere Agent mit TLS..."


$cmdPathAgentCtl = "C:\Program Files (x86)\checkmk\service\cmk-agent-ctl.exe"
$cmdArgsAgentCtl = @(
    "register",
    "--trust-cert",
    "--hostname", $hostname,
    "--server", $server,
    "--site", $site,
    "--user", $username,
    "--password", $passwordPlain
)


try {
    $output = & $cmdPathAgentCtl @cmdArgsAgentCtl 2>&1
    if ($LASTEXITCODE -eq 0) {
        Write-Success "TLS-Registrierung erfolgreich abgeschlossen"
    } else {
        Write-ErrorMsg "TLS-Registrierung fehlgeschlagen (Exit-Code: $LASTEXITCODE)"
        Write-Host ""
        Write-Host "Fehlermeldung:" -ForegroundColor Yellow
        Write-Host $output -ForegroundColor Yellow
        Write-Host ""
        exit 1
    }
} catch {
    Write-ErrorMsg "Fehler bei der TLS-Registrierung: $_"
    exit 1
}


# Updater registrieren
Write-SectionHeader "Schritt 5: Updater-Registrierung"
Write-Info "Registriere Agent-Updater..."


$cmdPathUpdater = "C:\Program Files (x86)\checkmk\service\check_mk_agent.exe"
$cmdArgsUpdater = @(
    "updater",
    "register",
    "--hostname", $hostname,
    "--server", $server,
    "--site", $site,
    "--user", $username,
    "--password", $passwordPlain
)


try {
    $output = & $cmdPathUpdater @cmdArgsUpdater 2>&1
    if ($LASTEXITCODE -eq 0) {
        Write-Success "Updater-Registrierung erfolgreich abgeschlossen"
    } else {
        Write-ErrorMsg "Updater-Registrierung fehlgeschlagen (Exit-Code: $LASTEXITCODE)"
        Write-Host ""
        Write-Host "Fehlermeldung:" -ForegroundColor Yellow
        Write-Host $output -ForegroundColor Yellow
        Write-Host ""
        exit 1
    }
} catch {
    Write-ErrorMsg "Fehler bei der Updater-Registrierung: $_"
    exit 1
}


# Erfolgsmeldung
Write-Host ""
Write-Host "============================================================" -ForegroundColor Green
Write-Host "  Registrierung erfolgreich abgeschlossen!               " -ForegroundColor Green
Write-Host "============================================================" -ForegroundColor Green
Write-Host ""
Write-Info "Der CheckMK Agent ist nun registriert und einsatzbereit"
Write-Host ""


# Warten auf Benutzereingabe vor dem Schliessen
Read-Host "Druecken Sie Enter zum Beenden"
exit 0