param(
  [string]$Source
)

$ErrorActionPreference = 'Stop'
if ($Source -and -not (Test-Path -LiteralPath $Source -PathType Leaf)) {
  throw "Client file not found: $Source"
}
$nodeCommand = Get-Command node -ErrorAction SilentlyContinue
if (-not $nodeCommand) {
  throw 'Install Node.js 22 or newer on this laptop, then rerun this installer.'
}
$nodeVersion = (& node --version).Trim()
if ($nodeVersion -notmatch '^v(\d+)\.') {
  throw "Could not read Node.js version: $nodeVersion"
}
$nodeMajor = [int]$Matches[1]
if ($nodeMajor -lt 22) {
  throw "Whisper terminal needs Node.js 22 or newer (found $nodeMajor)."
}

$appDir = Join-Path $env:LOCALAPPDATA 'WhisperTerminal'
$binDir = Join-Path $appDir 'bin'
$target = Join-Path $binDir 'whisper.cmd'
$existing = Get-Command whisper -ErrorAction SilentlyContinue
if ((Test-Path -LiteralPath $target) -and
    -not ((Get-Content -LiteralPath $target -TotalCount 2) -contains 'rem Whisper terminal launcher v1')) {
  throw "Another command already exists at $target. Nothing was overwritten."
}
if ($existing -and $existing.Source -ne $target) {
  Write-Host "An existing whisper command was found at $($existing.Source)."
  Write-Host 'The other command and its files will stay intact.'
  $answer = Read-Host 'Install this Whisper launcher and give it PATH priority? [y/N]'
  if ($answer -notmatch '^(y|yes)$') {
    Write-Host 'Installation cancelled.'
    exit 0
  }
}

$downloaded = $null
try {
  if ($Source) {
    $client = $Source
  } else {
    $downloaded = Join-Path $env:TEMP ("whisper-terminal-$([guid]::NewGuid().ToString('N')).mjs")
    Invoke-WebRequest -Uri 'https://whisper.rachida.dev/downloads/whisper.mjs' `
      -OutFile $downloaded -UseBasicParsing
    $client = $downloaded
  }
  $firstLine = Get-Content -LiteralPath $client -TotalCount 1
  if ($firstLine -ne '#!/usr/bin/env node') {
    throw 'The downloaded file is not the Whisper terminal client.'
  }

  New-Item -ItemType Directory -Path $binDir -Force | Out-Null
  Copy-Item -LiteralPath $client -Destination (Join-Path $appDir 'whisper.mjs') -Force
  $launcher = @'
@echo off
rem Whisper terminal launcher v1
node "%LOCALAPPDATA%\WhisperTerminal\whisper.mjs" %*
'@
  $temporary = "$target.tmp"
  [IO.File]::WriteAllText($temporary, $launcher)
  Move-Item -LiteralPath $temporary -Destination $target -Force
  & node (Join-Path $appDir 'whisper.mjs') server 'https://whisper-api.rachida.dev'
} finally {
  if ($downloaded) {
    Remove-Item -LiteralPath $downloaded -Force -ErrorAction SilentlyContinue
  }
}

$userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
$entries = @($userPath -split ';' | Where-Object { $_ -and $_ -ne $binDir })
$pathEntries = @($binDir) + $entries
[Environment]::SetEnvironmentVariable('Path', ($pathEntries -join ';'), 'User')

Write-Host 'Installed Whisper terminal. Open a new terminal, then run: whisper'
if ($existing -and $existing.Source -ne $target) {
  Write-Host "Previous command: $($existing.Source) (still installed)."
  Write-Host 'If it still runs first, put WhisperTerminal\bin before its directory in PATH.'
}