<#
.SYNOPSIS
  Verify an DezhNebesht release is authentic and unmodified BEFORE installing (AFTA §6 / FPT_TUD_EXT.1).

.DESCRIPTION
  1. Verifies the RSA signature of RELEASE.manifest with the trusted PUBLIC certificate
     (proves the manifest was produced by the holder of the release key — authenticity).
  2. Re-hashes every file in -ReleaseDir and compares against the manifest
     (proves no file was added, removed, or altered — integrity).
  Exits non-zero on ANY failure, so it can gate an installer/deploy step. Runs on Windows
  PowerShell 5.1 and PowerShell 7.

.PARAMETER ReleaseDir
  Folder containing the artifacts plus RELEASE.manifest and RELEASE.manifest.sig.

.PARAMETER CerPath
  Path to the trusted PUBLIC certificate (.cer/.crt) exported from the release cert.
  Pin this with the deployer, NOT alongside the release it verifies.

.EXAMPLE
  ./verify-release.ps1 -ReleaseDir ./publish -CerPath ./release.cer
#>
[CmdletBinding()]
param(
    [Parameter(Mandatory)] [string]$ReleaseDir,
    [Parameter(Mandatory)] [string]$CerPath
)
$ErrorActionPreference = 'Stop'

$tab          = [char]9
$manifestPath = Join-Path $ReleaseDir 'RELEASE.manifest'
$sigPath      = Join-Path $ReleaseDir 'RELEASE.manifest.sig'
# release-public.cer is the (public) verification material shipped with the package, not part of the
# signed payload — it is written AFTER the manifest, so exclude it from the "unexpected file" check.
$skip         = @('RELEASE.manifest','RELEASE.manifest.sig','release-public.cer')
foreach ($p in @($ReleaseDir, $CerPath, $manifestPath, $sigPath)) {
    if (-not (Test-Path $p)) { Write-Error "Missing: $p"; exit 2 }
}

# 1) Verify the manifest signature with the trusted public certificate.
$manifestBytes = [System.IO.File]::ReadAllBytes($manifestPath)
$sig  = [Convert]::FromBase64String((Get-Content -Raw $sigPath).Trim())
$cert = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2($CerPath)
$rsa  = [System.Security.Cryptography.X509Certificates.RSACertificateExtensions]::GetRSAPublicKey($cert)
$sigOk = $rsa.VerifyData($manifestBytes, $sig,
        [System.Security.Cryptography.HashAlgorithmName]::SHA256,
        [System.Security.Cryptography.RSASignaturePadding]::Pkcs1)
if (-not $sigOk) {
    Write-Error "SIGNATURE INVALID - manifest is not signed by the trusted release key. Do NOT install."
    exit 1
}
Write-Host "Manifest signature: VALID (cert: $($cert.Subject))" -ForegroundColor Green

# 2) Re-hash every file and compare against the manifest.
$root = (Resolve-Path $ReleaseDir).Path
$expected = @{}
Get-Content $manifestPath | Where-Object { $_ -notmatch '^#' -and $_.Trim() } | ForEach-Object {
    $parts = $_ -split $tab, 2
    $expected[$parts[1]] = $parts[0].ToLower()
}

$problems = 0
foreach ($rel in $expected.Keys) {
    $full = Join-Path $root $rel
    if (-not (Test-Path $full)) { Write-Warning "MISSING: $rel"; $problems++; continue }
    $actual = (Get-FileHash -Algorithm SHA256 -Path $full).Hash.ToLower()
    if ($actual -ne $expected[$rel]) { Write-Warning "ALTERED: $rel"; $problems++ }
}
Get-ChildItem -Path $root -Recurse -File |
    Where-Object { $skip -notcontains $_.Name } |
    ForEach-Object {
        $rel = $_.FullName.Substring($root.Length).TrimStart('\','/').Replace('\','/')
        if (-not $expected.ContainsKey($rel)) { Write-Warning "UNEXPECTED: $rel"; $problems++ }
    }

if ($problems -gt 0) {
    Write-Error "$problems integrity problem(s) - release does NOT match the signed manifest. Do NOT install."
    exit 1
}
Write-Host "Integrity: all $($expected.Count) files match the signed manifest." -ForegroundColor Green
Write-Host "Release is AUTHENTIC and UNMODIFIED - safe to install." -ForegroundColor Green
exit 0