#Requires -RunAsAdministrator
# =============================================================================
# Zabbix Agent 2 – Windows Installer / Updater (Version 7.4)
#
# Aufruf:
#   PowerShell -ExecutionPolicy Bypass -File install-update-zabbix-agent.ps1
#
# Interaktiv: Proxy-Auswahl, Hostname-Eingabe, automatische Install/Update-Erkennung
# =============================================================================

# ── Konfiguration (manuell anpassen) ─────────────────────────────────────────

$ZabbixServer  = "zabbix.server-nb.de"     # Zabbix-Server-Adresse
$ZabbixVersion = "7.4.2"                  # Zabbix-Version (bei neuen Releases anpassen)

# Proxy-Liste – hier manuell pflegen
$ProxyList = @(
    "http://proxy01.example.com:3128"
    "http://proxy02.example.com:3128"
    # weitere Proxys einfach hier eintragen
)

# Installationspfade (normalerweise nicht ändern nötig)
$InstallDir  = "C:\Program Files\Zabbix Agent 2"
$ConfigFile  = "$InstallDir\zabbix_agent2.conf"
$ServiceName = "Zabbix Agent 2"
$TempDir     = $env:TEMP

# ── Hilfsfunktionen ───────────────────────────────────────────────────────────

function Write-Info  { param($msg) Write-Host "[INFO]  $msg" -ForegroundColor Green }
function Write-Warn  { param($msg) Write-Host "[WARN]  $msg" -ForegroundColor Yellow }
function Write-Err   { param($msg) Write-Host "[ERROR] $msg" -ForegroundColor Red }

function Show-Header {
    Write-Host ""
    Write-Host "=============================================" -ForegroundColor Cyan
    Write-Host "  Zabbix Agent 2 $ZabbixVersion – Windows Setup" -ForegroundColor Cyan
    Write-Host "=============================================" -ForegroundColor Cyan
    Write-Host ""
}

# ── Installierte Version prüfen ───────────────────────────────────────────────

function Get-InstalledVersion {
    $reg = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*" `
           -ErrorAction SilentlyContinue |
           Where-Object { $_.DisplayName -like "Zabbix Agent 2*" } |
           Select-Object -First 1
    return $reg?.DisplayVersion
}

# ── Proxy-Auswahl ─────────────────────────────────────────────────────────────

function Select-Proxy {
    Write-Host "Proxy-Einstellungen:" -ForegroundColor Cyan
    Write-Host "  [0] Kein Proxy (direkte Verbindung)"
    for ($i = 0; $i -lt $ProxyList.Count; $i++) {
        Write-Host "  [$($i+1)] $($ProxyList[$i])"
    }
    Write-Host ""

    do {
        $choice = Read-Host "Auswahl [0-$($ProxyList.Count)]"
    } while ($choice -notmatch "^\d+$" -or [int]$choice -gt $ProxyList.Count)

    if ($choice -eq "0") {
        return $null
    } else {
        return $ProxyList[[int]$choice - 1]
    }
}

# ── Download ──────────────────────────────────────────────────────────────────

function Get-ZabbixMsi {
    param(
        [string]$Url,
        [string]$Destination,
        [string]$ProxyUrl
    )

    Write-Info "Lade MSI herunter ..."
    Write-Info "URL: $Url"

    try {
        $webClient = New-Object System.Net.WebClient

        if ($ProxyUrl) {
            Write-Info "Verwende Proxy: $ProxyUrl"
            $proxy = New-Object System.Net.WebProxy($ProxyUrl, $true)
            $proxy.Credentials = [System.Net.CredentialCache]::DefaultNetworkCredentials
            $webClient.Proxy = $proxy
        } else {
            $webClient.Proxy = $null
            Write-Info "Direktverbindung (kein Proxy)"
        }

        $webClient.DownloadFile($Url, $Destination)
        Write-Info "Download abgeschlossen: $Destination"
    } catch {
        Write-Err "Download fehlgeschlagen: $_"
        exit 1
    } finally {
        $webClient.Dispose()
    }
}

# ── MSI Install / Update ──────────────────────────────────────────────────────

function Install-ZabbixMsi {
    param(
        [string]$MsiPath,
        [string]$Hostname,
        [bool]$IsUpdate
    )

    $action = if ($IsUpdate) { "Update" } else { "Installation" }
    Write-Info "Starte $action ..."

    # Bei Update: Dienst stoppen
    if ($IsUpdate) {
        $svc = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue
        if ($svc -and $svc.Status -eq "Running") {
            Write-Info "Stoppe Dienst '$ServiceName' ..."
            Stop-Service -Name $ServiceName -Force
            Start-Sleep -Seconds 2
        }
    }

    $msiArgs = @(
        "/i", $MsiPath,
        "/qn",                              # Silent
        "/l*v", "$TempDir\zabbix-install.log",
        "SERVER=$ZabbixServer",
        "SERVERACTIVE=$ZabbixServer",
        "HOSTNAME=$Hostname",
        "LISTENPORT=10050"
    )

    $proc = Start-Process -FilePath "msiexec.exe" -ArgumentList $msiArgs -Wait -PassThru

    if ($proc.ExitCode -ne 0) {
        Write-Err "MSI $action fehlgeschlagen (ExitCode: $($proc.ExitCode))"
        Write-Err "Details: $TempDir\zabbix-install.log"
        exit 1
    }

    Write-Info "MSI $action erfolgreich."
}

# ── Dienst starten ────────────────────────────────────────────────────────────

function Start-ZabbixService {
    $svc = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue
    if (-not $svc) {
        Write-Err "Dienst '$ServiceName' nicht gefunden."
        exit 1
    }

    Set-Service -Name $ServiceName -StartupType Automatic
    Start-Service -Name $ServiceName
    Start-Sleep -Seconds 2

    $svc.Refresh()
    return $svc.Status
}

# ── Hauptprogramm ─────────────────────────────────────────────────────────────

Show-Header

# Installierte Version ermitteln
$installedVersion = Get-InstalledVersion
$isUpdate = $null -ne $installedVersion

if ($isUpdate) {
    Write-Info "Installierte Version gefunden: $installedVersion"
    Write-Info "Modus: UPDATE auf $ZabbixVersion"
} else {
    Write-Info "Kein Zabbix Agent gefunden."
    Write-Info "Modus: NEUINSTALLATION von $ZabbixVersion"
}
Write-Host ""

# Hostname abfragen
$defaultHostname = $env:COMPUTERNAME
$inputHostname = Read-Host "Zabbix-Hostname eingeben [Standard: $defaultHostname]"
$agentHostname = if ($inputHostname.Trim() -eq "") { $defaultHostname } else { $inputHostname.Trim() }
Write-Info "Verwende Hostname: $agentHostname"
Write-Host ""

# Proxy-Auswahl
$selectedProxy = Select-Proxy
Write-Host ""

# MSI-Download-URL zusammenbauen
$arch    = "amd64"
$msiFile = "zabbix_agent2-$ZabbixVersion-windows-$arch-openssl.msi"
$msiUrl  = "https://cdn.zabbix.com/zabbix/binaries/stable/" +
           "$($ZabbixVersion.Split('.')[0..1] -join '.')/$ZabbixVersion/$msiFile"
$msiDest = "$TempDir\$msiFile"

# Download
Get-ZabbixMsi -Url $msiUrl -Destination $msiDest -ProxyUrl $selectedProxy

# Installation / Update
Install-ZabbixMsi -MsiPath $msiDest -Hostname $agentHostname -IsUpdate $isUpdate

# Temporäre Datei aufräumen
Remove-Item -Path $msiDest -Force -ErrorAction SilentlyContinue

# Dienst starten
Write-Info "Starte Zabbix-Dienst ..."
$status = Start-ZabbixService

# Ergebnis
Write-Host ""
Write-Host "=============================================" -ForegroundColor Cyan
Write-Info " Zabbix Agent 2 erfolgreich eingerichtet!"
Write-Info "  Hostname  : $agentHostname"
Write-Info "  Server    : $ZabbixServer"
Write-Info "  Version   : $ZabbixVersion"
Write-Info "  Modus     : Aktiv"
Write-Info "  Dienst    : $status"
Write-Host "=============================================" -ForegroundColor Cyan
Write-Host ""
Write-Warn "Denk daran: Den Host '$agentHostname' im Zabbix-Frontend anlegen,"
Write-Warn "falls er noch nicht existiert (Configuration -> Hosts -> Create host)."
Write-Host ""