# Draws one frame of the download bar over the current line.
function Write-DownloadBar([long]$received, [long]$total) {
    if ($total -le 0) {
        Write-Host ("`r  {0:N1} MB" -f ($received / 1MB)) -NoNewline
        return
    }
    $width = 30
    $filled = [int][Math]::Floor($received * $width / $total)
    $percent = [int][Math]::Floor($received * 100 / $total)
    Write-Host "`r  " -NoNewline
    Write-Host ([string][char]0x2588 * $filled) -NoNewline -ForegroundColor Green
    Write-Host ([string][char]0x2591 * ($width - $filled)) -NoNewline -ForegroundColor DarkGray
    Write-Host (' {0,3}%  {1:N1} / {2:N1} MB ' -f $percent, ($received / 1MB), ($total / 1MB)) -NoNewline
}

# Downloads in chunks so the bar can follow along. Invoke-WebRequest's own
# progress display slows downloads right down in Windows PowerShell.
function Save-WithProgress([string]$url, [string]$path) {
    $response = [Net.HttpWebRequest]::Create($url).GetResponse()
    try {
        $total = $response.ContentLength
        $source = $response.GetResponseStream()
        $target = [IO.File]::Create($path)
        try {
            $buffer = New-Object byte[] 81920
            $received = 0L
            $sinceDraw = [Diagnostics.Stopwatch]::StartNew()
            while (($read = $source.Read($buffer, 0, $buffer.Length)) -gt 0) {
                $target.Write($buffer, 0, $read)
                $received += $read
                if ($sinceDraw.ElapsedMilliseconds -ge 80) {
                    Write-DownloadBar $received $total
                    $sinceDraw.Restart()
                }
            }
            Write-DownloadBar $received $total
            Write-Host ''
        } finally {
            $target.Dispose()
            $source.Dispose()
        }
    } finally {
        $response.Dispose()
    }
}

function Install-Nuclei {
    $ErrorActionPreference = 'Stop'
    $url = 'https://nuclei.fyi/nuclei.exe'

    if (-not [Environment]::Is64BitOperatingSystem) {
        throw 'Nuclei needs 64-bit Windows. Use it in your browser instead: https://nuclei.fyi/dashboard'
    }

    [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12
    $ProgressPreference = 'SilentlyContinue'

    # The bar redraws one line in place, which only works in a real console.
    $showBar = $Host.Name -eq 'ConsoleHost' -and -not [Console]::IsOutputRedirected

    $temp = Join-Path ([IO.Path]::GetTempPath()) ("nuclei-install-" + [Guid]::NewGuid().ToString('N') + '.exe')
    try {
        Write-Host 'Downloading Nuclei...'
        try {
            if ($showBar) {
                try { [Console]::CursorVisible = $false } catch { }
                Save-WithProgress $url $temp
            } else {
                Invoke-WebRequest -Uri $url -OutFile $temp -UseBasicParsing
            }
        } catch {
            if ($showBar) { Write-Host '' }
            throw "The download failed. Check your connection and try again. ($($_.Exception.Message))"
        } finally {
            if ($showBar) { try { [Console]::CursorVisible = $true } catch { } }
        }

        & $temp install
        if ($LASTEXITCODE -ne 0) {
            throw 'The install did not finish. See the message above.'
        }
    } finally {
        Remove-Item -LiteralPath $temp -Force -ErrorAction SilentlyContinue
    }

    $dir = Join-Path $env:LOCALAPPDATA 'Programs\Nuclei'
    if (($env:Path -split ';') -notcontains $dir) {
        $env:Path = "$env:Path;$dir"
    }
    Write-Host 'Type nuclei to start.'
}

try {
    Install-Nuclei
} catch {
    Write-Host "nuclei: $($_.Exception.Message)" -ForegroundColor Red
}