param(
  [switch]$NoPause,
  [string]$IndexUrl = "https://pypi.org/simple"
)

$ErrorActionPreference = "Stop"
$Root = Split-Path -Parent $PSScriptRoot
$WheelDir = Join-Path $Root "vendor\wheels"
$Req = Join-Path $Root "requirements.txt"

function Wait-BeforeExit {
  if (-not $NoPause) {
    Write-Host ""
    Read-Host "Press Enter to exit"
  }
}

function Get-PythonCommand {
  foreach ($name in @("py", "python", "python3")) {
    if (Get-Command $name -ErrorAction SilentlyContinue) {
      return $name
    }
  }
  throw "Python was not found. Install Python 3.10+ before downloading wheels."
}

function Invoke-PipDownload {
  param(
    [string]$PythonCommand,
    [string[]]$PythonArgs
  )

  $pipArgs = @(
    "-m", "pip", "download",
    "--index-url", $IndexUrl,
    "--trusted-host", "pypi.org",
    "--trusted-host", "files.pythonhosted.org",
    "--disable-pip-version-check",
    "--retries", "3",
    "--timeout", "60",
    "-r", $Req,
    "-d", $WheelDir
  )

  & $PythonCommand @PythonArgs @pipArgs
}

try {
  Set-Location $Root
  if (-not (Test-Path $Req)) {
    throw "requirements.txt was not found: $Req"
  }

  $python = Get-PythonCommand
  New-Item -ItemType Directory -Force -Path $WheelDir | Out-Null

  Write-Host "Downloading offline wheels to: $WheelDir" -ForegroundColor Cyan
  if ($python -eq "py") {
    Invoke-PipDownload -PythonCommand "py" -PythonArgs @("-3")
  } else {
    Invoke-PipDownload -PythonCommand $python -PythonArgs @()
  }

  if ($LASTEXITCODE -ne 0) {
    throw "Wheel download failed. Check network access to $IndexUrl. If your environment uses a private PyPI mirror, pass -IndexUrl with the mirror address."
  }

  Write-Host ""
  Write-Host "Offline wheels downloaded. Copy the whole project folder to the server and run scripts\install_offline.ps1." -ForegroundColor Green
} catch {
  Write-Host ""
  Write-Host "Download failed:" -ForegroundColor Red
  Write-Host $_.Exception.Message -ForegroundColor Red
  exit 1
} finally {
  Wait-BeforeExit
}