<#
.SYNOPSIS
    Set Windows Time Zone based on IP address and sync time via NTP

.DESCRIPTION
timesync.osdcloud.ch

.NOTES
    Version:		0.1
    Creation Date:  25.11.2025
    Author:			Akos Bakos
    Company:        SmartCon GmbH
    Contact:		akos.bakos@smartcon.ch

    Copyright (c) 2025 SmartCon GmbH

HISTORY:
Date			By			Comments
----------		---			----------------------------------------------------------
25.11.2025		Akos Bakos	Script created

#>

$Global:Transcript = "$((Get-Date).ToString('yyyy-MM-dd-HHmmss'))-TimeSync.log"
Start-Transcript -Path (Join-Path "$env:ProgramData\Microsoft\IntuneManagementExtension\Logs\OSD\" $Global:Transcript) -ErrorAction Ignore | Out-Null

#region Helper Functions
function Write-DarkGrayDate {
    [CmdletBinding()]
    param (
        [Parameter(Position=0)]
        [System.String]
        $Message
    )
    if ($Message) {
        Write-Host -ForegroundColor DarkGray "$((Get-Date).ToString('yyyy-MM-dd-HHmmss')) $Message"
    }
    else {
        Write-Host -ForegroundColor DarkGray "$((Get-Date).ToString('yyyy-MM-dd-HHmmss')) " -NoNewline
    }
}
function Write-DarkGrayHost {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [System.String]
        $Message
    )
    Write-Host -ForegroundColor DarkGray $Message
}
function Write-DarkGrayLine {
    [CmdletBinding()]
    param ()
    Write-Host -ForegroundColor DarkGray "========================================================================="
}
function Write-SectionHeader {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [System.String]
        $Message
    )
    Write-DarkGrayLine
    Write-DarkGrayDate
    Write-Host -ForegroundColor Cyan $Message
}
function Write-SectionSuccess {
    [CmdletBinding()]
    param (
        [Parameter(Position=0)]
        [System.String]
        $Message = 'Success!'
    )
    Write-DarkGrayDate
    Write-Host -ForegroundColor Green $Message
}
#endregion

Write-SectionHeader "Set Windows Time Zone based on IP address and sync time via NTP"

# DNS readiness
function Wait-Network {
    param([int]$TimeoutSec = 45)
    $deadline = (Get-Date).AddSeconds($TimeoutSec)
    do {
        try { [void][System.Net.Dns]::GetHostEntry('time.windows.com'); return $true } catch { Start-Sleep 2 }
    } while ((Get-Date) -lt $deadline)
    return $false
}

# Robust NTP (returns UTC)
function Get-NtpUtc {
    param([string]$Server = 'time.windows.com', [int]$TimeoutMs = 4000)
    $addrs = [System.Net.Dns]::GetHostAddresses($Server)
    $addr  = $addrs | Where-Object { $_.AddressFamily -eq 'InterNetwork' } | Select-Object -First 1
    if (-not $addr) { $addr = $addrs | Where-Object { $_.AddressFamily -eq 'InterNetworkV6' } | Select-Object -First 1 }
    if (-not $addr) { throw "DNS failed for $Server" }

    $ep  = [System.Net.IPEndPoint]::new($addr,123)
    $udp = [System.Net.Sockets.UdpClient]::new()
    $udp.Client.ReceiveTimeout = $TimeoutMs
    $udp.Connect($ep)

    $req = New-Object byte[] 48; $req[0] = 0x1B
    [void]$udp.Send($req,$req.Length)
    $remote = $ep
    $resp = $udp.Receive([ref]$remote)
    $udp.Close()

    if ($resp.Length -lt 48) { throw "Bad NTP response" }
    $int  = [System.BitConverter]::ToUInt32(($resp[43],$resp[42],$resp[41],$resp[40]),0)
    $frac = [System.BitConverter]::ToUInt32(($resp[47],$resp[46],$resp[45],$resp[44]),0)
    $seconds = $int + ($frac / [math]::Pow(2,32))
    $epoch = [DateTime]::SpecifyKind([datetime]'1900-01-01T00:00:00Z','Utc')
    return $epoch.AddSeconds($seconds) # UTC
}

# Set UTC directly (fallback when TZ tools missing)
function Set-UTCSystemTime {
    param([Parameter(Mandatory)][DateTime]$Utc)
    Add-Type -Namespace Win32 -Name NativeMethods -MemberDefinition @"
using System;
using System.Runtime.InteropServices;
public class NativeMethods {
    [StructLayout(LayoutKind.Sequential)]
    public struct SYSTEMTIME {
        public ushort Year; public ushort Month; public ushort DayOfWeek; public ushort Day;
        public ushort Hour; public ushort Minute; public ushort Second; public ushort Milliseconds;
    }
    [DllImport("kernel32.dll", SetLastError=true)]
    public static extern bool SetSystemTime(ref SYSTEMTIME st);
}
"@ -ErrorAction SilentlyContinue
    $u = $Utc.ToUniversalTime()
    $st = New-Object Win32.NativeMethods+SYSTEMTIME
    $st.Year=[uint16]$u.Year; $st.Month=[uint16]$u.Month; $st.Day=[uint16]$u.Day
    $st.Hour=[uint16]$u.Hour; $st.Minute=[uint16]$u.Minute; $st.Second=[uint16]$u.Second
    $st.Milliseconds=[uint16]$u.Millisecond
    [void][Win32.NativeMethods]::SetSystemTime([ref]$st)
}

# TZ helpers
function Resolve-TzUtilPath {
    $candidates = @(
        (Join-Path $env:SystemRoot 'System32\tzutil.exe'),
        (Join-Path $env:WINDIR      'Sysnative\tzutil.exe')
    ) | Select-Object -Unique
    foreach ($p in $candidates) { if (Test-Path $p) { return $p } }
    $null
}
function Set-SystemTimeZone {
    param([Parameter(Mandatory)][string]$Id)
    try {
        if (Get-Command Set-TimeZone -ErrorAction SilentlyContinue) {
            Set-TimeZone -Id $Id -ErrorAction Stop
            return $true
        }
    } catch {}
    $tz = Resolve-TzUtilPath
    if ($tz) {
        $p = Start-Process -FilePath $tz -ArgumentList @('/s', $Id) -WindowStyle Hidden -Wait -PassThru
        return ($p.ExitCode -eq 0)
    }
    Write-Warning "No Set-TimeZone or tzutil.exe (likely specialize/WinPE)."
    $false
}

# IANA TZ detection and mapping
function Get-IanaTimeZone {
    try { return (Invoke-RestMethod -Uri "https://ipinfo.io/json" -TimeoutSec 6 -UseBasicParsing).timezone } catch { return $null }
}
function Map-IanaToWindowsTz {
    param([Parameter(Mandatory)][string]$Iana)
    $xmlUrl = "https://raw.githubusercontent.com/FlorianSLZ/scloud/main/scripts/Set-TimeZoneByIPAddress/windowsZones.xml"
    [xml]$windowsZones = Invoke-RestMethod -Uri $xmlUrl -TimeoutSec 10 -UseBasicParsing
    $mapping = $windowsZones.supplementalData.windowsZones.mapTimezones.mapZone | Where-Object {
        ($_.type -split '\s+') -contains $Iana
    }
    if (-not $mapping) { throw "No mapping for IANA: $Iana" }
    $mapping.other | Select-Object -First 1
}

# Orchestration
if (-not (Wait-Network -TimeoutSec 60)) {
    Write-Warning "Network/DNS not ready; skipping time/TZ operations."
    return
}

# 1) Detect and set Windows TZ (best effort)
$tzSet = $false
try {
    Write-DarkGrayHost "Fetching IANA time zone..."
    $iana = Get-IanaTimeZone
    if ($iana) {
        Write-DarkGrayHost "Detected IANA TZ: $iana"
        $winTz = Map-IanaToWindowsTz -Iana $iana
        Write-DarkGrayHost "Mapped Windows TZ: $winTz"
        $tzSet = Set-SystemTimeZone -Id $winTz
        if ($tzSet) { Write-Host -ForegroundColor Yellow "Windows Time Zone set: $winTz" }
        else { Write-Warning "Could not set Windows Time Zone in this phase." }
    } else {
        Write-Warning "Could not detect IANA time zone."
    }
} catch { Write-Warning "TZ step skipped: $($_.Exception.Message)" }

# 2) NTP sync (UTC) then set clock
try {
    Write-DarkGrayHost "Synchronizing system time with NTP..."
    $servers = @('time.windows.com','time.nist.gov','pool.ntp.org')
    $utc = $null
    foreach ($s in $servers) {
        try { $utc = Get-NtpUtc -Server $s -TimeoutMs 4000; break } catch { Write-DarkGrayHost "NTP failed ($s): $($_.Exception.Message)" }
    }
    if (-not $utc) { throw "All NTP servers failed." }

    if ($tzSet) {
        $local = $utc.ToLocalTime()
        Set-Date -Date $local -ErrorAction Stop | Out-Null
        Write-DarkGrayHost "Time synced. UTC=$($utc.ToString('u')) Local=$([DateTime]::Now.ToString('u'))"
    } else {
        Set-UTCSystemTime -Utc $utc
        Write-DarkGrayHost "Time synced (UTC set directly). UTC=$([DateTime]::UtcNow.ToString('u'))"
    }

    $skewSec = [math]::Abs(([DateTime]::UtcNow - $utc).TotalSeconds)
    Write-DarkGrayHost "Residual UTC skew: $([math]::Round($skewSec,2)) s"
    Write-SectionSuccess "Time/TZ completed"
} catch {
    Write-Warning "Failed to sync time: $($_.Exception.Message)"
}

Stop-Transcript | Out-Null