function Test-AdminPrivileges {
    <#
    .SYNOPSIS
    Verifies script is running with administrator privileges.
    #>
    $currentPrincipal = New-Object Security.Principal.WindowsPrincipal([Security.Principal.WindowsIdentity]::GetCurrent())
    return $currentPrincipal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
}

function Test-WindowsADK {
    <#
    .SYNOPSIS
    Checks if Windows ADK and WinPE add-on are installed.
    #>
    try {
        $adkPath = "C:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit"
        $deploymentToolsPath = Join-Path $adkPath "Deployment Tools"
        $winPEPath = Join-Path $adkPath "Windows Preinstallation Environment"

        $registryPath = "HKLM:\SOFTWARE\Microsoft\Windows Kits\Installed Roots"
        $registryExists = Test-Path $registryPath

        if (-not $registryExists) {
            Write-Verbose "ADK registry key not found"
            return $false
        }

        if (-not (Test-Path $deploymentToolsPath)) {
            Write-Verbose "Deployment Tools not found at: $deploymentToolsPath"
            return $false
        }

        if (-not (Test-Path $winPEPath)) {
            Write-Verbose "WinPE add-on not found at: $winPEPath"
            return $false
        }

        $dismPath = Join-Path $deploymentToolsPath "DISM\dism.exe"
        $copypePath = Join-Path $winPEPath "copype.cmd"

        if (-not (Test-Path $dismPath)) {
            Write-Verbose "DISM executable not found"
            return $false
        }

        if (-not (Test-Path $copypePath)) {
            Write-Verbose "copype.cmd not found"
            return $false
        }

        Write-Verbose "Windows ADK and WinPE add-on are installed"
        return $true
    }
    catch {
        Write-Verbose "Error checking ADK: $_"
        return $false
    }
}

function Install-WindowsADK {
    <#
    .SYNOPSIS
    Downloads and installs Windows ADK and WinPE add-on silently.
    #>
    [CmdletBinding()]
    param()

    Write-Host "`n=== Windows ADK Installation ===" -ForegroundColor Cyan
    Write-Host "This will download and install:"
    Write-Host "  - Windows ADK (~150MB download)"
    Write-Host "  - WinPE Add-on (~5GB download)"
    Write-Host "  - Total time: ~20-30 minutes depending on connection`n"

    $downloadsDir = ".\downloads"
    if (-not (Test-Path $downloadsDir)) {
        New-Item -ItemType Directory -Path $downloadsDir | Out-Null
    }

    $adkInstallerPath = Join-Path $downloadsDir "adksetup.exe"
    $winpeInstallerPath = Join-Path $downloadsDir "adkwinpesetup.exe"

    $adkUrl = "https://go.microsoft.com/fwlink/?linkid=2271337"
    $winpeUrl = "https://go.microsoft.com/fwlink/?linkid=2271338"

    try {
        Write-Host "[1/4] Downloading Windows ADK installer..." -ForegroundColor Yellow
        if (-not (Test-Path $adkInstallerPath)) {
            $ProgressPreference = 'SilentlyContinue'
            Invoke-WebRequest -Uri $adkUrl -OutFile $adkInstallerPath -UseBasicParsing
            $ProgressPreference = 'Continue'
            Write-Host "  ✓ ADK installer downloaded" -ForegroundColor Green
        } else {
            Write-Host "  ✓ ADK installer already exists" -ForegroundColor Green
        }

        Write-Host "[2/4] Installing Windows ADK (this may take 5-10 minutes)..." -ForegroundColor Yellow
        $adkProcess = Start-Process -FilePath $adkInstallerPath `
            -ArgumentList "/quiet", "/norestart", "/features", "OptionId.DeploymentTools" `
            -Wait -PassThru -NoNewWindow

        if ($adkProcess.ExitCode -ne 0) {
            throw "ADK installation failed with exit code: $($adkProcess.ExitCode)"
        }
        Write-Host "  ✓ Windows ADK installed successfully" -ForegroundColor Green

        Write-Host "[3/4] Downloading WinPE add-on installer (large download)..." -ForegroundColor Yellow
        if (-not (Test-Path $winpeInstallerPath)) {
            $ProgressPreference = 'SilentlyContinue'
            Invoke-WebRequest -Uri $winpeUrl -OutFile $winpeInstallerPath -UseBasicParsing
            $ProgressPreference = 'Continue'
            Write-Host "  ✓ WinPE installer downloaded" -ForegroundColor Green
        } else {
            Write-Host "  ✓ WinPE installer already exists" -ForegroundColor Green
        }

        Write-Host "[4/4] Installing WinPE add-on (this may take 10-15 minutes)..." -ForegroundColor Yellow
        $winpeProcess = Start-Process -FilePath $winpeInstallerPath `
            -ArgumentList "/quiet", "/norestart", "/features", "OptionId.WindowsPreinstallationEnvironment" `
            -Wait -PassThru -NoNewWindow

        if ($winpeProcess.ExitCode -ne 0) {
            throw "WinPE add-on installation failed with exit code: $($winpeProcess.ExitCode)"
        }
        Write-Host "  ✓ WinPE add-on installed successfully" -ForegroundColor Green

        Write-Host "`n✓ Windows ADK and WinPE add-on installation complete!`n" -ForegroundColor Green
    }
    catch {
        Write-Error "Failed to install Windows ADK: $_"
        throw
    }
}

function Test-PowerShell7Archive {
    <#
    .SYNOPSIS
    Verifies PowerShell 7 zip archive exists locally.
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $true)]
        [PSCustomObject]$Config
    )

    $ps7FileName = "PowerShell-$($Config.powershell7Version)-win-x64.zip"
    $ps7Path = Join-Path (Get-Location) $ps7FileName

    if (Test-Path $ps7Path) {
        Write-Verbose "PowerShell 7 archive found: $ps7Path"
        return $true
    }

    Write-Verbose "PowerShell 7 archive not found: $ps7Path"
    return $false
}

function Get-PowerShell7Archive {
    <#
    .SYNOPSIS
    Downloads PowerShell 7 zip archive from GitHub.
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $true)]
        [PSCustomObject]$Config
    )

    $ps7FileName = "PowerShell-$($Config.powershell7Version)-win-x64.zip"
    $ps7Path = Join-Path (Get-Location) $ps7FileName

    Write-Host "Downloading PowerShell $($Config.powershell7Version)..." -ForegroundColor Yellow

    try {
        $ProgressPreference = 'SilentlyContinue'
        Invoke-WebRequest -Uri $Config.powershell7ZipUrl -OutFile $ps7Path -UseBasicParsing
        $ProgressPreference = 'Continue'

        if (Test-Path $ps7Path) {
            Write-Host "  ✓ PowerShell 7 downloaded successfully" -ForegroundColor Green
        } else {
            throw "Download completed but file not found"
        }
    }
    catch {
        Write-Error "Failed to download PowerShell 7: $_"
        throw
    }
}

Export-ModuleMember -Function @(
    'Test-AdminPrivileges',
    'Test-WindowsADK',
    'Install-WindowsADK',
    'Test-PowerShell7Archive',
    'Get-PowerShell7Archive'
)