# Windows Update module
$VERSION = 0.0 # There is no manifest

# This is version 20220513 of the module. Like any other piece of
# software (and information generally), this module comes with NO WARRANTY.

# Use with:
#  Import-Module -Force:$True -Name:"C:\Path\to\WU.psm1"

# Better than:
# <URL:https://github.com/keithga/DeploySharedLibrary/blob/master/DeployShared/Update/Find-LatestCumulativeUpdate.ps1>

New-Variable -Option:ReadOnly -Name:ascii -Value:(New-Object System.Text.ASCIIEncoding)
New-Variable -Option:ReadOnly -Name:date_format_str -Value:'MMMM d, yyyy'
New-Variable -Option:ReadOnly -Name:ms_catalog_url -Value:'https://www.catalog.update.microsoft.com'
New-Variable -Option:ReadOnly -Name:os_build_str -Value:'(OS Build'

# <URL:https://support.microsoft.com/en-us/rss-feed-picker>
New-Variable -Option:ReadOnly -Name:RSSInfo -Value:@{
  '10' = @{
      'Feed' = 'https://support.microsoft.com/en-us/feed/rss/6ae59d69-36fc-8e4d-23dd-631d98bf74a9';
  }
  '11' = @{
      'Feed' = 'https://support.microsoft.com/en-us/feed/rss/4ec863cc-2ecd-e187-6cb3-b50c6545db92';
  }
}

New-Variable -Option:ReadOnly -Name:WindowsOSBuildMap -Value:@{
  # <URL:https://en.wikipedia.org/wiki/Windows_11_version_history>
  '22000' = @{ 'Id' = '5006099'; 'Name' = '21H2'; EndOfLife = '2023-10-10'; }

  # <URL:https://en.wikipedia.org/wiki/Windows_10_version_history>
  '19044' = @{ 'Id' = '5008339'; 'Name' = '21H2'; EndOfLife = '2023-06-13'; }
  '19043' = @{ 'Id' = '5003498'; 'Name' = '21H1'; EndOfLife = '2022-12-13'; }
  '19042' = @{ 'Id' = '4581839'; 'Name' = '20H2'; EndOfLife = '2023-05-09'; }
  '19041' = @{ 'Id' = '4557957'; 'Name' = '2004'; EndOfLife = '2021-12-14'; }

  '18363' = @{ 'Id' = '4529964'; 'Name' = '1909'; EndOfLife = '2022-05-10'; }
  '18362' = @{ 'Id' = '4498140'; 'Name' = '1903'; EndOfLife = '2020-12-08'; }

  '17763' = @{ 'Id' = '4464619'; 'Name' = '1809'; EndOfLife = '2029-01-09'; }
  '17134' = @{ 'Id' = '4099479'; 'Name' = '1803'; EndOfLife = '2021-05-11'; }
  '16299' = @{ 'Id' = '4043454'; 'Name' = '1709'; EndOfLife = '2020-10-13'; }
  '15063' = @{ 'Id' = '4018124'; 'Name' = '1703'; EndOfLife = '2019-10-08'; }
  '14393' = @{ 'Id' = '4000825'; 'Name' = '1607'; EndOfLife = '2026-10-13'; }
  '10586' = @{ 'Id' = '4000824'; 'Name' = '1511'; EndOfLife = '2018-04-10'; }
  '10240' = @{ 'Id' = '4000823'; 'Name' = '1507'; EndOfLife = '2025-10-14'; }
}

Function Get-CurrentKBUpdateList {
  Param(
    [Parameter(Mandatory=$False)] [ValidateNotNullOrEmpty()] [String] $WindowsVersion = '10',
    [Parameter(Mandatory=$False)] [ValidateNotNullOrEmpty()] [UInt16] $CacheTime = 3600
  )

  $out                = @()
  $updates            = @()
  $now                = Get-Date
  $t                  = Get-SecondTuesday
  $fetch_flag         = $True
  $request_properties = @{
    'Uri'     = $RSSInfo[$WindowsVersion].Feed;
    'OutFile' = [System.IO.Path]::Combine(${Env:UserProfile}, 'Desktop', ("win{0}_rss.xml" -f ($WindowsVersion)));
  };

  if ($now -lt $t) {
    $t = $now.AddMonths(-1)
    $t = Get-SecondTuesday -Date:([System.DateTime]::new($t.Year,$t.Month,1))
  }

  if (Test-Path -Path:$request_properties.OutFile) {
    $ts = $now.ToUniversalTime() - (Get-Item -Path:$request_properties.OutFile).LastWriteTimeUtc
    if ($CacheTime -ge $ts.TotalSeconds) {
      $fetch_flag = $False
    }
  }

  if ($fetch_flag) {
    Invoke-WebRequest @request_properties
  }

  [XML] $xml = Get-Content -Path:$request_properties.OutFile

  $xml.rss.channel.item | foreach {
    $date_pub = Get-Date $_.pubDate
    if ($date_pub.Date -ge $t.Date) {
      if ($_.title.StartsWith($t.ToString($date_format_str))) {
        $updates += New-Object -TypeName:PSObject -Property:@{
          'PublicationDate' = $date_pub.Date;
          'Title'           = $_.title;
        }
      }
    }
  }

  foreach ($update in $updates) {
    $line = $update.Title

    # parse date
    $d    = $t.ToString($date_format_str)
    $ch1  = $line.IndexOf($d)
    if ((0 -gt $ch1) -or (1 -lt $ch1)) { Write-Error 'parse error' }

    # parse KB
    $ch1 = $line.IndexOf('KB')
    if (1 -gt $ch1) { Write-Error 'parse error' }
    $ch2 = $line.IndexOf(' ', $ch1)
    if ($ch1 -gt $ch2) { Write-Error 'parse error' }
    $kb = $line.Substring($ch1, ($ch2 - $ch1))

    # parse "(OS Build" string
    $ch1 = $line.IndexOf($os_build_str)
    if (1 -gt $ch1) { Write-Error 'parse error' }
    $ch2 = $os_build_str.Length + $ch1
    $ch1 = $line.IndexOf(' ', $ch2)
    if ($ch1 -lt $ch2) { Write-Error 'parse error' }
    $builds = $line.Substring(1 + $ch1)

    # parse version strings
    $version = ''
    for ($i = 0; $i -lt $builds.Length; $i++) {
      $ch1 = $ascii.GetBytes($builds[$i])[0]
      if ((46 -eq $ch1) -or ((47 -lt $ch1) -and (58 -gt $ch1))) {
        $version += $builds[$i]
      } else {
        if (-not ([String]::IsNullOrEmpty($version))) {
          $ch1 = $version.IndexOf('.')
          if (1 -gt $ch1) { Write-Error 'parse error' }
          $build = $version.Substring(0, $ch1)
          $out += New-Object -TypeName:PSObject -Property:@{
            'PublicationDate' = $update.PublicationDate.ToString('yyyy-MM-dd');
            'KB'              = $kb;
            'OSBuild'         = $version;
            'OSName'          = $WindowsOSBuildMap[$build].Name;
            'SupportId'       = $WindowsOSBuildMap[$build].Id;
            'EndOfLife'       = $WindowsOSBuildMap[$build].EndOfLife;
          }
          $version = ''
        }
      }
    }
  }

  Return $out
}

Function Get-KBSource {
  Param(
    [Parameter(Mandatory=$True)]  [ValidateNotNullOrEmpty()] [String] $KB,
    [Parameter(Mandatory=$False)] [ValidateNotNullOrEmpty()] [String] $Filter = 'x64'
  )

  $uri_search   = "{0}/Search.aspx?q={1}" -f ($ms_catalog_url, $KB)
  $uri_download = "{0}/DownloadDialog.aspx" -f ($ms_catalog_url)
  $wr           = Invoke-WebRequest -Uri:$uri_search

  Set-StrictMode -Version:1 # some of these things won't exist
    $ids = $wr.InputFields | Where-Object { $_.type -eq 'Button' -and $_.Value -eq 'Download' } | Select-Object -ExpandProperty:ID

    $guids = $wr.Links | 
      Where-Object ID -match '_link' |
      Where-Object { $_.OuterHTML -match $Filter } |
      ForEach-Object { $_.id.replace('_link','') } |
      Where-Object { $_ -in $ids }
  Set-StrictMode -Version:2

  $links = @()
  foreach ( $guid in $guids ) {
    $post_json = @{ size = 0; updateID = $guid; uidInfo = $guid } | ConvertTo-Json -Compress
    $request_properties = @{
      'Uri'    = $uri_download;
      'Method' = 'POST';
      'Body'   = @{ updateIDs = '[' + $post_json + ']' };
    }
    $links += Invoke-WebRequest @request_properties |
      Select-Object -ExpandProperty:Content |
      Select-String -AllMatches -Pattern:"(http[s]?\://catalog\.s\.download\.windowsupdate\.com\/[^\'\""]*)" | 
      ForEach-Object { $_.matches.value }
  }

  Return ($links | Select-Object -Unique | ForEach-Object { [PSCustomObject] @{ Source = $_ } })
}

Function Get-SecondTuesday {
  Param([Parameter(Mandatory=$False)] [ValidateNotNullOrEmpty()] [DateTime] $DateTime = (Get-Date))

  $tz_redmond = [System.TimeZoneInfo]::FindSystemTimeZoneById('Pacific Standard Time')
  $d          = New-Object -TypeName:System.DateTimeOffset $DateTime.Year,$DateTime.Month,8,10,0,0,0,$tz_redmond.BaseUtcOffset
  $num        = [Byte] $d.DayOfWeek # 0 = Sun, 1 = Mon, 2 = Tue, etc.
  $delta      = (9 - $num) % 7 # 9 = 7 + 2 (2 = Tue)
  $d          = $d.AddDays($delta)

  Return $d.DateTime
}

Export-ModuleMember -Function Get-CurrentKBUpdateList
Export-ModuleMember -Function Get-KBSource
Export-ModuleMember -Function Get-SecondTuesday

# END