param([string]$InstallRoot = $env:KODER_TUI_HOME, [string]$DownloadBase = $env:KODER_TUI_DOWNLOAD_BASE)
$ErrorActionPreference = 'Stop'
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$Version = '0.3.0'
$ProgressPreference = 'SilentlyContinue'
function Get-KoderFile([string]$Url, [string]$Destination, [int]$Timeout = 600) {
  $LastFailure = $null
  for ($Attempt = 1; $Attempt -le 3; $Attempt++) {
    try {
      Invoke-WebRequest -UseBasicParsing $Url -OutFile $Destination -TimeoutSec $Timeout
      return
    } catch {
      $LastFailure = $_
      if (Get-Command curl.exe -ErrorAction SilentlyContinue) {
        & curl.exe --fail --location --retry 2 --connect-timeout 20 --max-time $Timeout --output $Destination $Url
        if ($LASTEXITCODE -eq 0) { return }
      }
      if ($Attempt -lt 3) { Start-Sleep -Seconds $Attempt }
    }
  }
  throw "Download failed: $Url. Check your network/proxy or download the archive in a browser. $LastFailure"
}
if (!$InstallRoot) { $InstallRoot = Join-Path $env:LOCALAPPDATA 'koder-tui' }
$Bases = if ($DownloadBase) { @($DownloadBase.TrimEnd('/')) } else { @('https://karmenloop.com/install/tui-0.3.0', 'https://github.com/KarmenLoop/koder-tui/releases/download/tui-0.3.0') }
if (![Environment]::Is64BitOperatingSystem) { throw 'Koder TUI requires 64-bit Windows.' }
if ($env:KODER_TUI_EULA_ACCEPT -ne '1') {
  Write-Host 'Koder TUI is free for personal, noncommercial use under Koder-EULA-1.1.'
  Write-Host 'Read https://github.com/KarmenLoop/koder-tui/blob/main/EULA.md'
  Write-Host 'Commercial use requires separate permission. Installation does not authorize tools or accounts.'
  if ((Read-Host 'Type accept to install, or Enter to cancel') -cne 'accept') { throw 'Installation cancelled.' }
}
$File = "koder-tui-$Version-windows-x64.zip"
$Temp = Join-Path ([IO.Path]::GetTempPath()) ([Guid]::NewGuid().ToString('N'))
New-Item -ItemType Directory -Path $Temp | Out-Null
try {
  $Downloaded = $false
  foreach ($Base in $Bases) {
    try {
      Get-KoderFile "$Base/$File" (Join-Path $Temp $File)
      Get-KoderFile "$Base/SHA256SUMS" (Join-Path $Temp 'SHA256SUMS') 60
      $Downloaded = $true
      break
    } catch {
      Write-Warning $_
    }
  }
  if (!$Downloaded) { throw 'No download source succeeded. Installation stopped before changing your installation.' }
  $Rows = @(Get-Content (Join-Path $Temp 'SHA256SUMS') | Where-Object { $_ -match ('^[0-9a-f]{64}  ' + [regex]::Escape($File) + '$') })
  if ($Rows.Count -ne 1) { throw 'Missing or ambiguous checksum.' }
  $Expected = $Rows[0].Split(' ')[0]
  $Hasher = [Security.Cryptography.SHA256]::Create()
  $Stream = [IO.File]::OpenRead((Join-Path $Temp $File))
  try { $Actual = [BitConverter]::ToString($Hasher.ComputeHash($Stream)).Replace('-', '').ToLowerInvariant() }
  finally { $Stream.Dispose(); $Hasher.Dispose() }
  if ($Actual -cne $Expected) { throw 'Checksum mismatch.' }
  # .NET handles UTF-8 archive entry names without depending on the console code page.
  Add-Type -AssemblyName System.IO.Compression.FileSystem
  [IO.Compression.ZipFile]::ExtractToDirectory((Join-Path $Temp $File), $Temp)
  $Source = Join-Path $Temp 'koder-tui'
  & (Join-Path $Source 'runtime/node.exe') (Join-Path $Source 'packages/koder-tui/bin/koder-tui.mjs') --version
  if ($LASTEXITCODE -ne 0) { throw 'Runtime verification failed.' }
  $Dest = Join-Path $InstallRoot ("versions/$Version." + [Guid]::NewGuid().ToString('N').Substring(0,12))
  New-Item -ItemType Directory -Path (Split-Path $Dest -Parent) -Force | Out-Null
  if ([IO.Path]::GetPathRoot($Source) -eq [IO.Path]::GetPathRoot($Dest)) {
    [IO.Directory]::Move($Source, $Dest)
  } else {
    New-Item -ItemType Directory -Path $Dest | Out-Null
    Copy-Item "$Source/*" $Dest -Recurse
  }
  $Bin = Join-Path $InstallRoot 'bin'
  New-Item -ItemType Directory -Path $Bin -Force | Out-Null
  $Launcher = Join-Path $Bin 'koder-tui.cmd'
  if ((Test-Path $Launcher) -and !((Get-Content $Launcher -Raw).Contains('KODER_TUI_MANAGED_LAUNCHER'))) { throw 'Refusing to replace an unmanaged launcher.' }
  $Relative = "..\versions\" + (Split-Path $Dest -Leaf) + "\koder-tui.cmd"
  $Content = "@echo off`r`nrem KODER_TUI_MANAGED_LAUNCHER`r`ncall `"%~dp0$Relative`" %*`r`nexit /b %errorlevel%`r`n"
  [IO.File]::WriteAllText("$Launcher.new", $Content, [Text.Encoding]::ASCII)
  Move-Item -LiteralPath "$Launcher.new" -Destination $Launcher -Force
  $UserPath = [string][Environment]::GetEnvironmentVariable('Path', 'User')
  if (@($UserPath -split ';') -notcontains $Bin) { [Environment]::SetEnvironmentVariable('Path', (($UserPath.TrimEnd(';') + ';' + $Bin).TrimStart(';')), 'User') }
  $env:Path = "$Bin;$env:Path"
  Write-Host "Installed: $Launcher"
  Write-Host 'Open a new terminal and run koder-tui. Your existing CLI and configuration are unchanged.'
} finally { Remove-Item -LiteralPath $Temp -Recurse -Force -ErrorAction SilentlyContinue }