# Installs the latest XTermium release from GitHub on Windows (x64), for the current user:
#
#   irm https://xtermium.com/install.ps1 | iex
#
# Runs the installer (.exe) silently; $env:XTERMIUM_PACKAGE = 'msi' takes the .msi instead, which
# installs for every user and asks for admin. The download is checked against the sha256 GitHub
# publishes for it before it runs. Everything sits in one script block, so nothing leaks into
# the session that ran it.
& {
  $ErrorActionPreference = 'Stop'
  $ProgressPreference = 'SilentlyContinue' # Invoke-WebRequest is far slower with its progress bar
  [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12

  $repo = 'xtermium/xtermium'
  try {
    $release = Invoke-RestMethod "https://api.github.com/repos/$repo/releases/latest" -Headers @{ Accept = 'application/vnd.github+json' }
  } catch {
    throw 'xtermium: no public release yet; see https://xtermium.com/#downloads'
  }

  $msi = $env:XTERMIUM_PACKAGE -eq 'msi'
  $like = if ($msi) { '*_x64_*.msi' } else { '*_x64-setup.exe' }
  $asset = $release.assets | Where-Object { $_.name -like $like } | Select-Object -First 1
  if (-not $asset) { throw "xtermium: this release has no $like" }
  if ($asset.digest -notlike 'sha256:*') { throw "xtermium: GitHub publishes no sha256 for $($asset.name); not installing it unchecked" }

  $file = Join-Path ([IO.Path]::GetTempPath()) $asset.name
  Write-Host "xtermium: downloading $($asset.name)"
  Invoke-WebRequest $asset.browser_download_url -OutFile $file -UseBasicParsing
  if ((Get-FileHash $file -Algorithm SHA256).Hash -ne $asset.digest.Substring(7)) {
    Remove-Item $file
    throw "xtermium: sha256 mismatch for $($asset.name); not installing it"
  }
  Write-Host 'xtermium: sha256 checked; installing'
  $run = if ($msi) {
    Start-Process msiexec.exe -ArgumentList '/i', "`"$file`"", '/passive' -Wait -PassThru
  } else {
    Start-Process $file -ArgumentList '/S' -Wait -PassThru
  }
  Remove-Item $file -ErrorAction SilentlyContinue
  if ($run.ExitCode -ne 0) { throw "xtermium: the installer stopped with code $($run.ExitCode)" }
  Write-Host 'xtermium: done; open XTermium from the Start menu'
}