Add-Type -AssemblyName System.IO.Compression.FileSystem

function Main {
    if ($PSVersionTable.PSEdition -ne 'Desktop' -and $env:OS -ne 'Windows_NT') {
        Write-Warning "Please run it on Windows. "
        return 1
    }

    $procArch = $Env:PROCESSOR_ARCHITECTURE
    if ($procArch -eq 'ARM') {
        Write-Warning "This script does not support Windows RT. Exiting..."
        return 1
    }
    elseif ($procArch -eq 'ia64') {
        Write-Warning "This script does not support Itanium. Exiting..."
        return 1
    }

    $flagPath = "$env:TEMP\elevation_success.flag"
    if (Test-Path $flagPath) { Remove-Item $flagPath -ErrorAction SilentlyContinue }

    # --- Elevation check ---
    $IsAdmin = ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole(
        [Security.Principal.WindowsBuiltInRole]::Administrator)

    if (-not $IsAdmin) {
        Write-Host "Elevation required. Relaunching..."
        $tempScript = [IO.Path]::ChangeExtension([IO.Path]::GetTempFileName(), ".ps1")
        Invoke-WebRequest -Uri "https://get.msvc.win/dx" -OutFile $tempScript
        Start-Process powershell -Verb RunAs -ArgumentList "-NoProfile -ExecutionPolicy Bypass -File `"$tempScript`""
        Start-Sleep -Seconds 10
        if (-Not (Test-Path $flagPath)) {
            Write-Warning "User did not confirm UAC prompt or something went wrong."
            return 1
        }
        else {
            Remove-Item $flagPath -ErrorAction SilentlyContinue
            Write-Host "Setup ran successfully."
            return 0
        }
    }

    # --- Elevated section ---
    New-Item -Path $flagPath -ItemType File -Force | Out-Null
    Write-Host "Running with elevated privileges..."

    $tempDir = New-Item -ItemType Directory -Path ([IO.Path]::Combine($env:TEMP, [guid]::NewGuid().ToString()))
    $aria2Dir = Join-Path $tempDir "aria2"
    $aria2Exe = Join-Path $aria2Dir "aria2c.exe"

    # --- Check User IP location ---

    $geoInfo = Invoke-RestMethod -Uri 'https://ipapi.co/json/'
    $countryCode = $geoInfo.country

    # --- Check Proxy Settings ---
    $webProxy = [System.Net.WebRequest]::GetSystemWebProxy()
    $uri = New-Object Uri("http://example.com")
    $proxyUri = $webProxy.GetProxy($uri)

    $useProxy = $proxyUri.Host -ne "example.com"
    if ($useProxy) {
        $proxyAddress = $proxyUri.Authority
        Write-Host "Detected system proxy: $proxyAddress"
    }

    # --- Ensure aria2c is available ---
    if (-not (Test-Path $aria2Exe)) {
        Write-Host "Downloading aria2c..."
        $aria2Zip = Join-Path $tempDir "aria2.zip"
        if ($countryCode -eq 'CN') {
            $aria2Url = "https://gitee.com/HikariCalyx/OSTRemote/releases/download/v1.0/aria2-1.37.0-win-32bit-build1.zip"
            # Workaround for specific Chinese ISPs that would not resolve domains properly like aka.ms
            $regionalWorkaround = "--async-dns-server=223.5.5.5"
        }
        else {
            $aria2Url = "https://github.com/aria2/aria2/releases/download/release-1.37.0/aria2-1.37.0-win-64bit-build1.zip"
            $regionalWorkaround = ""
        }
        if ($useProxy) {
            $regionalWorkaround = "--all-proxy=$proxyAddress"
        }
        if ($procArch -ne "AMD64") {
            $aria2Url = $aria2Url.Replace("64bit", "32bit")
        }
        Invoke-WebRequest -Uri $aria2Url -OutFile $aria2Zip
        Expand-Archive -Path $aria2Zip -DestinationPath $aria2Dir -Force
        $found = Get-ChildItem -Path $aria2Dir -Recurse -Filter "aria2c.exe" | Select-Object -First 1
        if ($found) { Copy-Item $found.FullName -Destination $aria2Exe -Force }
    }

    # --- Define all downloads ---
    $downloads = @(
        @{ Name = "directx_redist.exe"; Url = "https://download.microsoft.com/download/8/4/a/84a35bf1-dafe-4ae8-82af-ad2ae20b6b14/directx_jun2010_redist.exe" }
    )

    # --- Download everything up front ---
    foreach ($item in $downloads) {
        $outFile = Join-Path $tempDir $item.Name
        Write-Host "Downloading $($item.Name)..."
        $argumentList = @(
            "--dir=`"$($outFile | Split-Path)`"",
            "--out=`"$(Split-Path -Leaf $outFile)`"",
            "--allow-overwrite=true",
            "--retry-wait=5",
            "--max-connection-per-server=8",
            "--split=8",
            "--min-split-size=1M",
            "`"$($item.Url)`""
        )
        if (![string]::IsNullOrEmpty($regionalWorkaround)) {
            $argumentList += $regionalWorkaround
        }
        $proc = Start-Process -FilePath $aria2Exe -ArgumentList $argumentList -NoNewWindow -PassThru -Wait
        if ($proc.ExitCode -ne 0) {
            Write-Warning "aria2c failed (exit code $($proc.ExitCode)). Retrying with --check-certificate=false..."
            $argsRetry = $argumentList + "--check-certificate=false"
            Start-Process -FilePath $aria2Exe -ArgumentList $argsRetry -NoNewWindow -Wait
        }
    }

    # --- Check Signature ---
    foreach ($item in $downloads) {
        $outFile = Join-Path $tempDir $item.Name
        Write-Host "Verifying signature of $($item.Name)..."
        $signature = Get-AuthenticodeSignature $outFile
        if ($signature.SignerCertificate.Subject -like "*CN=Microsoft Corporation*" -and $signature.Status -eq "Valid") {
            if ($env:WT_SESSION) {
                Write-Host "✅ Valid Microsoft signature found from $($item.Name)."
            }
            else {
                Write-Host "[OKAY] Valid Microsoft signature found from $($item.Name)."
            }
        }
        else {
            if ($env:WT_SESSION) {
                Write-Warning "⚠️ $($item.Name) is not signed by Microsoft. The download may get corrupted or your PC is infected with virus."
            }
            else {
                Write-Warning "[WARN] $($item.Name) is not signed by Microsoft. The download may get corrupted or your PC is infected with virus."
            }
            $response = Read-Host -Prompt "Would you like to proceed anyway? (Y/N)"
            if ($response -eq 'Y' -or $response -eq 'y') {
                continue
            }
            elseif ($response -eq 'N' -or $response -eq 'n') {
                return 1
            }
            else {
                Write-Host "Invalid input. Please enter Y or N."
            }
        }
    }

    # --- Install DirectX ---
    Write-Host "Installing DirectX..."
    Start-Process -FilePath "$tempDir\directx_redist.exe" -ArgumentList "/Q /T:`"$tempDir`"" -Wait
    Start-Process -FilePath "$tempDir\DXSETUP.exe" -ArgumentList "/silent" -Wait

    # --- Cleanup ---
    Write-Host "Cleaning up temporary files..."
    Start-Sleep -Seconds 2
    Remove-Item -Path $tempDir -Recurse -Force -ErrorAction SilentlyContinue
    Remove-Item -Path $flagPath -Force -ErrorAction SilentlyContinue
}

Main
Write-Host "Press any key to exit."
$null = [System.Console]::ReadKey($true)