#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : DFS Namespace clients get the wrong target or no target at all
    Fix   : Make referrals follow the site topology
    Source: https://jbtecwiz.com/support/srv-sto-dfs-referral

    Run as     : Elevated PowerShell
    Expect     : 40 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Clients are being sent across the wide area link.

    HOW TO UNDO IT
    Set-DfsnRoot -EnableSiteCosting $false returns to the previous
    behaviour.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 6"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  DFS Namespace clients get the wrong target or no target at all' -ForegroundColor White
Write-Host '  Make referrals follow the site topology' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   40 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'See what a client is actually being told.' -Command {
    dfsutil /pktinfo
    dfsutil cache referral flush
}

Invoke-Step -Number 2 -Do 'Check site costing is enabled on the namespace.' -Command {
    Get-DfsnRoot | Format-List Path,State,Flags,TimeToLiveSec
}

Invoke-Step -Number 3 -Do 'Enable it. Without costing, a client picks a target at random from those with equal priority.' -Why 'Site costing makes referrals follow the Active Directory sites and services topology, so a client is offered its local server first. Without it, half the clients at a branch office will work over the wide area link and nobody will know why some are slow.' -Command {
    Set-DfsnRoot -Path '\\example.local\Shares' -EnableSiteCosting $true
}

Invoke-Step -Number 4 -Do 'Confirm the subnets are actually mapped to sites -- costing depends entirely on that being right.' -Command {
    Get-ADReplicationSubnet -Filter * | Format-Table Name,Site
    nltest /dsgetsite
}

Invoke-Step -Number 5 -Do 'Set target priority explicitly where a particular server should be preferred.' -Command {
    Set-DfsnServerConfiguration -TargetPath '\\fs01\share' -ReferralPriorityClass GlobalHigh
}

Invoke-Step -Number 6 -Do 'Flush the client cache and re-test.' -Command {
    dfsutil cache referral flush
    dfsutil /pktinfo
}

Write-Rule "  Confirm it worked"
Show-Prose 'A client at each site is referred to its local server.' 'White'
Write-Host ''
if (-not $DryRun) {
    dfsutil /pktinfo
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-sto-dfs-referral' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Set-DfsnRoot -EnableSiteCosting $false returns to the previous behaviour.' 'DarkGray'
Write-Rule