<#
.SYNOPSIS
  Restore ODBC DSNs and registry keys, and identify missing drivers.

.DESCRIPTION
  - Extracts ODBC_Backup.zip into C:\ODBC_Migration\restore
  - Imports all .reg and .xml files
  - Recreates DSNs
  - Compares exported vs installed ODBC drivers
  - Displays missing drivers with official vendor download links
  - Logs all operations
#>

# ===========================
# CONFIGURATION
# ===========================
$BaseDir    = "C:\ODBC_Migration"
$ZipFile    = Join-Path $BaseDir "ODBC_Backup.zip"
$ExtractDir = Join-Path $BaseDir "restore"
$LogFile    = Join-Path $BaseDir ("restore_log_" + (Get-Date -Format "yyyyMMdd_HHmm") + ".txt")

# ===========================
# PREP
# ===========================
New-Item -ItemType Directory -Path $ExtractDir -Force | Out-Null
Start-Transcript -Path $LogFile -Append
Write-Host "`n=== ODBC RESTORE STARTED ===`n" -ForegroundColor Cyan

# ===========================
# STEP 1: EXTRACT ZIP PACKAGE
# ===========================
if (-not (Test-Path $ZipFile)) {
    Write-Error "Cannot find ODBC_Backup.zip in $BaseDir"
    Stop-Transcript
    exit 1
}
Write-Host "Extracting archive..."
Expand-Archive -Path $ZipFile -DestinationPath $ExtractDir -Force

# ===========================
# STEP 2: IMPORT REGISTRY KEYS
# ===========================
Write-Host "Importing registry keys..."
$regFiles = Get-ChildItem $ExtractDir -Filter *.reg
foreach ($reg in $regFiles) {
    Write-Host "  -> $($reg.Name)"
    reg import $reg.FullName | Out-Null
}

# ===========================
# STEP 3: RESTORE DSNs
# ===========================
$xmlPath = Join-Path $ExtractDir "odbc_dsns.xml"
if (Test-Path $xmlPath) {
    Write-Host "Recreating DSNs from XML..."
    $dsns = Import-Clixml $xmlPath
    foreach ($dsn in $dsns) {
        try {
            Add-OdbcDsn @dsn -ErrorAction Stop
            Write-Host "  + Added DSN: $($dsn.Name)" -ForegroundColor Green
        } catch {
            Write-Warning "  ! Failed to add DSN: $($dsn.Name) - $_"
        }
    }
} else {
    Write-Warning "No odbc_dsns.xml found in package."
}

# ===========================
# STEP 4: VERIFY DRIVER PRESENCE
# ===========================
Write-Host "`nChecking for missing ODBC drivers..." -ForegroundColor Yellow
$exportCsv = Join-Path $ExtractDir "odbc_driver_product_map.csv"
if (-not (Test-Path $exportCsv)) {
    Write-Warning "No driver map CSV found — skipping driver comparison."
} else {
    $needed = Import-Csv $exportCsv
    $installed = Get-OdbcDriver | Select-Object -ExpandProperty Name

    $missing = @()
    foreach ($n in $needed) {
        if ($n.OdbcDriverName -and ($installed -notcontains $n.OdbcDriverName)) {
            $missing += $n
        }
    }

    if ($missing.Count -gt 0) {
        Write-Host "`n=== Missing ODBC Drivers Detected ===`n" -ForegroundColor Red
        foreach ($m in $missing) {
            $dl = $m.DownloadURL
            if ($dl -match '^https?') {
                Write-Host ("  - {0} ({1})`n    Download: {2}" -f $m.OdbcDriverName, $m.Platform, $dl) -ForegroundColor Yellow
            } else {
                Write-Host ("  - {0} ({1})`n    Download: [Manual search required]" -f $m.OdbcDriverName, $m.Platform) -ForegroundColor DarkYellow
            }
        }
        Write-Host "`nSee the detailed Markdown report for clickable links:" -ForegroundColor Cyan
        Write-Host "  $($ExtractDir)\ODBC_Migration_Report.md`n" -ForegroundColor White
    } else {
        Write-Host "All previously detected drivers are installed." -ForegroundColor Green
    }
}

# ===========================
# STEP 5: SUMMARY
# ===========================
Write-Host "`n=== RESTORE COMPLETE ===`n" -ForegroundColor Cyan
Write-Host "✔ Registry and DSNs restored"
Write-Host "✔ Logs saved to: $LogFile"
Write-Host "✔ Extracted files in: $ExtractDir"
Write-Host "`nNext Steps:"
Write-Host "1️⃣ Verify DSNs in ODBC Administrator (32-bit and 64-bit)."
Write-Host "2️⃣ Install any missing drivers listed above."
Write-Host "3️⃣ Re-run this script if needed after driver installation.`n"
Stop-Transcript