param(
  [string]$FlowusBaseUrl = $env:FLOWUS_CLI_RELEASE_BASE_URL,
  [string]$FlowusVersion = $env:FLOWUS_VERSION,
  [string]$FlowusInstallDir = $env:FLOWUS_INSTALL_DIR
)

$ErrorActionPreference = 'Stop'

if ([string]::IsNullOrWhiteSpace($FlowusBaseUrl)) {
  $FlowusBaseUrl = $env:FLOWUS_BASE_URL
}
if ([string]::IsNullOrWhiteSpace($FlowusBaseUrl)) {
  $FlowusBaseUrl = 'https://cdn2.flowus.cn/flowus-cli'
}
$FlowusBaseUrl = $FlowusBaseUrl.TrimEnd('/')

if ([string]::IsNullOrWhiteSpace($FlowusVersion)) {
  $FlowusVersion = 'latest'
}

if ($FlowusVersion -ne 'latest' -and $FlowusVersion -notmatch '^v?\d+\.\d+\.\d+(-[a-zA-Z0-9.]+)?$') {
  throw "invalid version `"$FlowusVersion`" -- expected latest or a semver like 1.2.3 or v1.2.3"
}

function Write-Info {
  param([string]$Message)
  Write-Host "==> $Message" -ForegroundColor Cyan
}

function Get-InstallDir {
  if (-not [string]::IsNullOrWhiteSpace($FlowusInstallDir)) {
    return $FlowusInstallDir
  }

  $userBin = Join-Path $env:LOCALAPPDATA 'Programs\FlowUs\bin'
  if (-not [string]::IsNullOrWhiteSpace($env:LOCALAPPDATA)) {
    return $userBin
  }

  if (-not [string]::IsNullOrWhiteSpace($env:USERPROFILE)) {
    return (Join-Path $env:USERPROFILE '.flowus\bin')
  }

  throw 'could not find a writable install directory. Set FLOWUS_INSTALL_DIR and rerun the installer.'
}

function Invoke-Download {
  param(
    [string]$Url,
    [string]$OutFile
  )

  $lastError = $null
  for ($attempt = 1; $attempt -le 3; $attempt++) {
    try {
      Invoke-WebRequest -Uri $Url -OutFile $OutFile -UseBasicParsing
      return
    } catch {
      $lastError = $_
      if ($attempt -lt 3) {
        Start-Sleep -Seconds 2
      }
    }
  }
  throw $lastError
}

function Resolve-Version {
  if ($FlowusVersion -eq 'latest') {
    $versionFile = Join-Path $TempDir 'version'
    Invoke-Download "$FlowusBaseUrl/latest/version" $versionFile
    return ((Get-Content -Raw $versionFile).Trim())
  }

  if ($FlowusVersion.StartsWith('v')) {
    return $FlowusVersion
  }
  return "v$FlowusVersion"
}

function Test-PathEntry {
  param([string]$Directory)

  $normalized = [System.IO.Path]::GetFullPath($Directory).TrimEnd('\')
  $pathValue = ''
  if ($env:Path) {
    $pathValue = $env:Path
  }
  foreach ($entry in ($pathValue -split ';')) {
    if ([string]::IsNullOrWhiteSpace($entry)) {
      continue
    }
    try {
      if ([System.IO.Path]::GetFullPath($entry).TrimEnd('\') -ieq $normalized) {
        return $true
      }
    } catch {
      continue
    }
  }
  return $false
}

if ($env:PROCESSOR_ARCHITECTURE -notin @('AMD64', 'x86')) {
  throw "unsupported Windows architecture: $env:PROCESSOR_ARCHITECTURE"
}

$InstallDir = Get-InstallDir
$TempDir = Join-Path ([System.IO.Path]::GetTempPath()) ([System.Guid]::NewGuid().ToString('n'))
New-Item -ItemType Directory -Force -Path $TempDir | Out-Null

try {
  $Version = Resolve-Version
  if ([string]::IsNullOrWhiteSpace($Version)) {
    throw "could not resolve version from $FlowusBaseUrl/latest/version"
  }

  $Artifact = 'flowus-windows-x64.zip'
  $ReleaseBase = "$FlowusBaseUrl/releases/$Version"
  $ArchiveUrl = "$ReleaseBase/$Artifact"
  $ChecksumUrl = "$ReleaseBase/SHA256SUMS"
  $ArchivePath = Join-Path $TempDir $Artifact
  $ChecksumPath = Join-Path $TempDir 'SHA256SUMS'
  $ExtractDir = Join-Path $TempDir 'extract'

  Write-Info "Downloading FlowUs CLI $Version for windows-x64"
  Invoke-Download $ArchiveUrl $ArchivePath
  Invoke-Download $ChecksumUrl $ChecksumPath

  $checksumLine = Get-Content $ChecksumPath | Where-Object { $_ -match "\s+$([regex]::Escape($Artifact))$" } | Select-Object -First 1
  if (-not $checksumLine) {
    throw "missing checksum for $Artifact"
  }
  $expectedHash = ($checksumLine -split '\s+')[0].ToLowerInvariant()
  $actualHash = (Get-FileHash -Algorithm SHA256 $ArchivePath).Hash.ToLowerInvariant()
  if ($actualHash -ne $expectedHash) {
    throw "checksum mismatch for $Artifact"
  }

  New-Item -ItemType Directory -Force -Path $ExtractDir | Out-Null
  Expand-Archive -Path $ArchivePath -DestinationPath $ExtractDir -Force

  $BinaryPath = Join-Path $ExtractDir 'flowus.exe'
  if (-not (Test-Path $BinaryPath)) {
    throw 'downloaded archive did not contain flowus.exe'
  }

  New-Item -ItemType Directory -Force -Path $InstallDir | Out-Null
  Copy-Item -Force $BinaryPath (Join-Path $InstallDir 'flowus.exe')

  Write-Host ''
  Write-Host '  FlowUs CLI'
  Write-Host ''
  Write-Host "  Installed flowus $Version to $(Join-Path $InstallDir 'flowus.exe')"
  Write-Host ''

  if (-not (Test-PathEntry $InstallDir)) {
    Write-Host '  Add flowus to your PATH:'
    Write-Host ''
    Write-Host "    [Environment]::SetEnvironmentVariable('Path', `$env:Path + ';$InstallDir', 'User')"
    Write-Host ''
    Write-Host '  Open a new PowerShell window after updating PATH.'
    Write-Host ''
  }

  Write-Host '  Get started:'
  Write-Host ''
  Write-Host '    flowus login'
  Write-Host '    flowus help'
  Write-Host ''
} finally {
  Remove-Item -Recurse -Force $TempDir -ErrorAction SilentlyContinue
}