<#
SCRIPT 23 –, step-by-step, production-ready SCRIPT 23 – SHAREPOINT CU INSTALL SCRIPT

Purpose:
- Install SharePoint CU across a server
- Apply patch safely using controlled sequence
- Execute PSConfig to complete upgrade

IMPORTANT:
- RUN ON EACH SERVER INDIVIDUALLY
- RUN AS ADMIN IN SHAREPOINT MANAGEMENT SHELL
- EXPECT SERVICE INTERRUPTION
#>

[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [string]$CULocation,

    [Parameter(Mandatory = $true)]
    [string]$LogPath,

    [switch]$SkipPrompt
)

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"

Write-Host "SCRIPT 23 - SHAREPOINT CU INSTALL" -ForegroundColor Cyan
Write-Host "THIS SCRIPT INSTALLS SHAREPOINT PATCHES" -ForegroundColor Yellow

# --------------------------------------------------
# STEP 1 – VALIDATION
# --------------------------------------------------
if (-not (Test-Path $CULocation)) {
    throw "CU location not found: $CULocation"
}

if (-not (Test-Path $LogPath)) {
    New-Item -Path $LogPath -ItemType Directory -Force | Out-Null
}

if (-not $SkipPrompt) {
    $resp = Read-Host "Type YES to proceed with CU install"
    if ($resp -ne "YES") {
        Write-Host "Cancelled by user" -ForegroundColor Yellow
        return
    }
}

# --------------------------------------------------
# STEP 2 – LOAD SHAREPOINT SNAP-IN
# --------------------------------------------------
try {
    if (-not (Get-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue)) {
        Add-PSSnapin Microsoft.SharePoint.PowerShell
    }
}
catch {
    throw "Failed to load SharePoint snap-in"
}

# --------------------------------------------------
# STEP 3 – STOP SHAREPOINT SERVICES
# --------------------------------------------------
function Stop-SPServices {
    Write-Host "Stopping SharePoint services..." -ForegroundColor Yellow

    $services = @(
        "SPTimerV4",      # Timer Service
        "SPAdminV4",      # Admin Service
        "SPTraceV4",      # Logging
        "W3SVC",          # IIS
        "OSearch16",      # Search
        "SPSearchHostController",
        "SPCache"         # Distributed Cache
    )

    foreach ($svc in $services) {
        $service = Get-Service -Name $svc -ErrorAction SilentlyContinue
        if ($service -and $service.Status -ne "Stopped") {
            Stop-Service $svc -Force
            Write-Host "Stopped: $svc"
        }
    }
}

# --------------------------------------------------
# STEP 4 – INSTALL CU
# --------------------------------------------------
function Install-CU {
    Write-Host "Installing CU from: $CULocation" -ForegroundColor Yellow

    $installers = Get-ChildItem $CULocation -Filter *.exe

    if ($installers.Count -eq 0) {
        throw "No CU installers found"
    }

    foreach ($exe in $installers) {
        Write-Host "Running: $($exe.Name)"
        Start-Process -FilePath $exe.FullName -ArgumentList "/quiet /norestart" -Wait
    }
}

# --------------------------------------------------
# STEP 5 – RUN PSCONFIG
# --------------------------------------------------
function Run-PSConfig {
    Write-Host "Running SharePoint configuration update..." -ForegroundColor Yellow

    $psconfig = "$env:COMMONPROGRAMFILES\Microsoft Shared\Web Server Extensions\16\BIN\psconfig.exe"

    if (-not (Test-Path $psconfig)) {
        throw "PSConfig not found"
    }

    Start-Process -FilePath $psconfig `
        -ArgumentList "-cmd upgrade -inplace b2b -wait -force -cmd applicationcontent -install -cmd installfeatures" `
        -Wait
}

# --------------------------------------------------
# STEP 6 – START SERVICES
# --------------------------------------------------
function Start-SPServices {
    Write-Host "Starting SharePoint services..." -ForegroundColor Yellow

    $services = @(
        "SPTimerV4",
        "SPAdminV4",
        "SPTraceV4",
        "W3SVC",
        "OSearch16",
        "SPSearchHostController",
        "SPCache"
    )

    foreach ($svc in $services) {
        $service = Get-Service -Name $svc -ErrorAction SilentlyContinue
        if ($service -and $service.Status -ne "Running") {
            Start-Service $svc
            Write-Host "Started: $svc"
        }
    }
}

# --------------------------------------------------
# EXECUTION FLOW
# --------------------------------------------------
try {
    Stop-SPServices
    Install-CU
    Run-PSConfig
    Start-SPServices

    Write-Host "CU INSTALL COMPLETED SUCCESSFULLY" -ForegroundColor Green
}
catch {
    Write-Host "INSTALL FAILED: $($_.Exception.Message)" -ForegroundColor Red
    throw
}