<#
  diffweb installer — Windows (PowerShell 5.1+ / 7+).
    powershell -c "irm https://diffweb.pages.dev/install.ps1|iex"
    & ([scriptblock]::Create((irm https://diffweb.pages.dev/install.ps1))) -Uninstall
#>
param([switch] $Uninstall)

$ErrorActionPreference = 'Stop'

# Release tarball from `npm run build:version`. Update this once it is hosted.
$Url = if ($env:DIFFWEB_URL)  { $env:DIFFWEB_URL }  else { 'https://raw.githubusercontent.com/acharyarupak391/diffweb/main/bin/diffweb.tar.gz' }
$Dir = if ($env:DIFFWEB_HOME) { $env:DIFFWEB_HOME } else { Join-Path $env:LOCALAPPDATA 'diffweb' }
$Bin = if ($env:DIFFWEB_BIN)  { $env:DIFFWEB_BIN }  else { Join-Path $Dir 'bin' }

if ($Uninstall -or $env:DIFFWEB_UNINSTALL -eq '1') {
  if (Test-Path (Join-Path $Bin 'diffweb.cmd')) { Remove-Item (Join-Path $Bin 'diffweb.cmd') -Force }
  if (Test-Path $Dir) { Remove-Item $Dir -Recurse -Force }
  Write-Host "  diffweb removed" -ForegroundColor Green
  exit 0
}

if (-not (Get-Command node -ErrorAction SilentlyContinue)) {
  throw "Node.js 16+ is required. Install it from https://nodejs.org and re-run."
}
if (-not (Get-Command tar -ErrorAction SilentlyContinue)) {
  throw "tar is required (built in to Windows 10 1803+)."
}

Write-Host "`n  diffweb installer`n" -ForegroundColor DarkGray
Write-Host "  downloading $Url"

$tmp = Join-Path $env:TEMP 'diffweb.tar.gz'
$ProgressPreference = 'SilentlyContinue'
Invoke-WebRequest -Uri $Url -OutFile $tmp -UseBasicParsing

New-Item -ItemType Directory -Path $Dir -Force | Out-Null
tar -xzf $tmp -C $Dir --strip-components=1
Remove-Item $tmp -Force

$entry = Join-Path $Dir 'server.js'
if (-not (Test-Path $entry)) { throw "the archive is missing server.js" }

New-Item -ItemType Directory -Path $Bin -Force | Out-Null
Set-Content -Path (Join-Path $Bin 'diffweb.cmd') -Encoding ASCII -Value "@echo off`r`nnode `"$entry`" %*"

$version = (& node $entry --version)
Write-Host "  diffweb $version installed to $Dir" -ForegroundColor Green
Write-Host "  launcher $Bin\diffweb.cmd" -ForegroundColor Green

$userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
if (($userPath -split ';') -notcontains $Bin) {
  [Environment]::SetEnvironmentVariable('Path', "$userPath;$Bin", 'User')
  $env:Path = "$env:Path;$Bin"
  Write-Host "  added $Bin to your PATH — open a new terminal to pick it up" -ForegroundColor Yellow
}

Write-Host "`n  Try it:  diffweb old.txt new.txt`n" -ForegroundColor Cyan