#requires -Version 5.1
<#
.SYNOPSIS
    Write the ShopDB server public key pins to HKLM:\SOFTWARE\GE\ShopDB
    ServerPins, so the endpoint agent and the SYSTEM reporters trust only this
    site's server key.

.DESCRIPTION
    Each pin is the lowercase hex SHA-256 of the server leaf certificate's
    SubjectPublicKeyInfo. The ShopDB Server Certificate settings page shows the
    current one, and Get-ShopDBServerPin.ps1 computes one from a URL or a
    certificate file.

    Written as REG_MULTI_SZ in BOTH registry views (64-bit and WOW6432Node),
    the same way CollectorKey is, so a 32-bit reader sees the same set.

    Meant to run as a GE-Enforce PS1 entry under the SYSTEM task, before agent
    1.20 reaches the PC. Idempotent: the set on the PC is compared with the
    requested set first, and nothing is written when they already match, so it
    is safe every cycle.

    ROTATING THE SERVER KEY: pass the old pin AND the new pin until every PC has
    both, switch the server certificate, then drop the old pin. A PC holding
    only the old pin refuses the new certificate.

.PARAMETER Pins
    One or more pins separated by commas, semicolons or spaces. Colons and case
    are ignored. Every value must be 64 hex characters or nothing is written.

.PARAMETER Clear
    Remove ServerPins from both views. Pinning is then off and the normal
    Windows certificate checks apply.

.PARAMETER LogPath
    Append a transcript here as well as writing to the pipeline.

.EXAMPLE
    .\Set-ShopDBServerPins.ps1 -Pins <pin>
    Pin one server key.

.EXAMPLE
    .\Set-ShopDBServerPins.ps1 -Pins "<oldpin>,<newpin>" -WhatIf
    Show what a key rotation would write without touching the registry.

.NOTES
    Exit codes:
      0  written, or already correct
      1  bad input or an error stopped the write
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param(
    [string]$Pins,
    [switch]$Clear,
    [string]$LogPath
)

Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

$SubKey    = 'SOFTWARE\GE\ShopDB'
$ValueName = 'ServerPins'

function Log {
    param([string]$Message)
    $line = "{0} [Set-ShopDBServerPins] {1}" -f (Get-Date -Format 'yyyy-MM-dd HH:mm:ss'), $Message
    Write-Output $line
    if ($LogPath) {
        try { Add-Content -LiteralPath $LogPath -Value $line -ErrorAction Stop } catch { }
    }
}

function Get-CurrentPins {
    param([Microsoft.Win32.RegistryView]$View)
    $base = [Microsoft.Win32.RegistryKey]::OpenBaseKey([Microsoft.Win32.RegistryHive]::LocalMachine, $View)
    try {
        $key = $base.OpenSubKey($SubKey)
        if (-not $key) { return @() }
        try {
            $value = $key.GetValue($ValueName)
            if ($null -eq $value) { return @() }
            return @(@($value) | ForEach-Object { ([string]$_).Trim().ToLowerInvariant() } | Where-Object { $_ })
        } finally { $key.Dispose() }
    } finally { $base.Dispose() }
}

function Test-SamePins {
    param([string[]]$Left, [string[]]$Right)
    $a = @($Left | Sort-Object -Unique)
    $b = @($Right | Sort-Object -Unique)
    if ($a.Count -ne $b.Count) { return $false }
    for ($i = 0; $i -lt $a.Count; $i++) {
        if ($a[$i] -ne $b[$i]) { return $false }
    }
    return $true
}

# --- 1. validate the request ------------------------------------------------

$requested = @()
if (-not $Clear) {
    if (-not $Pins -or -not $Pins.Trim()) {
        Log 'ERROR no -Pins given (use -Clear to remove pinning)'
        exit 1
    }
    foreach ($raw in ($Pins -split '[,;\s]+')) {
        if (-not $raw) { continue }
        $pin = ($raw -replace ':', '').ToLowerInvariant()
        if ($pin -notmatch '^[0-9a-f]{64}$') {
            Log "ERROR '$raw' is not a SHA-256 pin (64 hex characters); nothing written"
            exit 1
        }
        if ($requested -notcontains $pin) { $requested += $pin }
    }
    if ($requested.Count -eq 0) {
        Log 'ERROR -Pins held no values; nothing written'
        exit 1
    }
    Log "requested $($requested.Count) pin(s): $($requested -join ', ')"
}

# --- 2. write each view -----------------------------------------------------

$views = @(
    @{ Name = '64-bit'; View = [Microsoft.Win32.RegistryView]::Registry64 },
    @{ Name = '32-bit'; View = [Microsoft.Win32.RegistryView]::Registry32 }
)

$failed = $false
foreach ($entry in $views) {
    try {
        $current = @(Get-CurrentPins -View $entry.View)

        if ($Clear) {
            if ($current.Count -eq 0) {
                Log "$($entry.Name): no ServerPins; nothing to do"
                continue
            }
            if ($PSCmdlet.ShouldProcess("HKLM\$SubKey ($($entry.Name))", "Remove $ValueName")) {
                $base = [Microsoft.Win32.RegistryKey]::OpenBaseKey([Microsoft.Win32.RegistryHive]::LocalMachine, $entry.View)
                try {
                    $key = $base.OpenSubKey($SubKey, $true)
                    if ($key) {
                        try { $key.DeleteValue($ValueName, $false) } finally { $key.Dispose() }
                    }
                } finally { $base.Dispose() }
                Log "$($entry.Name): removed ServerPins"
            }
            continue
        }

        if (Test-SamePins -Left $current -Right $requested) {
            Log "$($entry.Name): ServerPins already correct; nothing to do"
            continue
        }

        $action = "Set $ValueName to $($requested.Count) pin(s) (was $($current.Count))"
        if ($PSCmdlet.ShouldProcess("HKLM\$SubKey ($($entry.Name))", $action)) {
            $base = [Microsoft.Win32.RegistryKey]::OpenBaseKey([Microsoft.Win32.RegistryHive]::LocalMachine, $entry.View)
            try {
                $key = $base.CreateSubKey($SubKey)
                try {
                    $key.SetValue($ValueName, [string[]]$requested, [Microsoft.Win32.RegistryValueKind]::MultiString)
                } finally { $key.Dispose() }
            } finally { $base.Dispose() }

            # Read back rather than trust SetValue.
            $after = @(Get-CurrentPins -View $entry.View)
            if (-not (Test-SamePins -Left $after -Right $requested)) {
                Log "ERROR $($entry.Name): ServerPins did not read back as written"
                $failed = $true
                continue
            }
            Log "$($entry.Name): wrote ServerPins ($($requested.Count) pin(s), was $($current.Count))"
        }
    } catch {
        Log "ERROR $($entry.Name): $($_.Exception.Message)"
        $failed = $true
    }
}

if ($failed) { exit 1 }
exit 0