#Requires -RunAsAdministrator
<#
Sets Windows language system-wide on Windows 11.

Menu:
1 = English (en-US)
2 = Svenska (sv-SE)
3 = Norsk Bokmål (nb-NO)

What it does:
- Installs language capabilities if available
- Sets current user's language list
- Sets current user's UI language override
- Sets current user's culture/format
- Sets computer system locale
- Copies current user's international settings to:
  - Welcome screen and system accounts
  - New user accounts

Notes:
- Requires internet access to Windows Update (or internal FoD / WSUS source)
- Requires Administrator
- Restart is recommended after completion
- Designed to avoid collection method calls such as .Insert(), .RemoveAt(), .IndexOf()
#>

param(
    [string]$Choice
)

$ErrorActionPreference = "Stop"

if (-not $Choice) {
    Write-Host ""
    Write-Host "Choose language:"
    Write-Host "1 = English"
    Write-Host "2 = Svenska"
    Write-Host "3 = Norsk Bokmål"
    Write-Host ""

    $Choice = Read-Host "Enter 1, 2, or 3"
}

switch ($Choice) {
    '1' {
        $LanguageTag  = 'en-US'
        $LanguageName = 'English (United States)'
    }
    '2' {
        $LanguageTag  = 'sv-SE'
        $LanguageName = 'Svenska (Sverige)'
    }
    '3' {
        $LanguageTag  = 'nb-NO'
        $LanguageName = 'Norsk Bokmål (Norge)'
    }
    default {
        Write-Host "Invalid choice: $Choice"
        Write-Host "Use 1, 2, or 3."
        exit 1
    }
}

Write-Host ""
Write-Host "Selected language: $LanguageName [$LanguageTag]"
Write-Host ""

Write-Host "== Installing language capabilities for $LanguageTag =="

$capabilityPrefixes = @(
    "Language.Basic",
    "Language.OCR",
    "Language.Speech",
    "Language.TextToSpeech",
    "Language.Handwriting"
)

$allCaps = Get-WindowsCapability -Online

foreach ($prefix in $capabilityPrefixes) {
    $caps = $allCaps | Where-Object { $_.Name -like "$prefix*~~~$LanguageTag~*" }

    if (-not $caps) {
        Write-Host " - ${prefix}: not available for $LanguageTag on this system (skipping)"
        continue
    }

    foreach ($cap in $caps) {
        if ($cap.State -eq "Installed") {
            Write-Host " - $($cap.Name): already installed"
        }
        else {
            Write-Host " - Installing: $($cap.Name)"
            Add-WindowsCapability -Online -Name $cap.Name | Out-Null
        }
    }
}

Write-Host ""
Write-Host "== Configuring current user =="

# Build new user language list with selected language first
$currentList = Get-WinUserLanguageList
$newList = New-WinUserLanguageList -Language $LanguageTag

foreach ($item in $currentList) {
    if ($item.LanguageTag -ne $LanguageTag) {
        $newList += $item
    }
}

Set-WinUserLanguageList -LanguageList $newList -Force | Out-Null
Set-WinUILanguageOverride -Language $LanguageTag
Set-Culture -CultureInfo $LanguageTag

Write-Host " - User language list set"
Write-Host " - UI language override set"
Write-Host " - User culture set"

Write-Host ""
Write-Host "== Configuring computer-wide settings =="

# Computer-wide system locale (mainly for legacy/non-Unicode apps)
Set-WinSystemLocale -SystemLocale $LanguageTag
Write-Host " - System locale set"

# Windows 11+: copy current user's display/input/region settings
# to welcome screen, system accounts, and new users
Copy-UserInternationalSettingsToSystem -WelcomeScreen $True -NewUser $True
Write-Host " - Copied settings to Welcome screen, system accounts, and new users"

Write-Host ""
Write-Host "Done."
Write-Host "Language set to $LanguageName [$LanguageTag] system-wide."
Write-Host "Restart the computer to fully apply the change."