ServerSentEvents-Client

[CmdletBinding()]
param
(
    [Parameter(Mandatory=$true, Position=0)]
    [uri] $Url,

    [Parameter(Mandatory=$true, Position=1)]
    [string]$BearerToken
)

$messageQueue = New-Object -TypeName "System.Collections.Generic.List[string]" -ArgumentList 1024
$receivedObjects = New-Object -TypeName "System.Collections.Generic.List[object]" -ArgumentList 100

Function Process-Lines([ref]$Queue, [ref]$List)
{
    $index = 0
    $lastEventIndex = -1
    for ($i = 0; $i -lt $Queue.Value.Count; $i++)
    {
        $line = $Queue.Value[$i]
        if ([string]::IsNullOrWhiteSpace($line))
        {
            continue
        }
        $line = $line.Trim()

        if ($line -like "event:*")
        {
            $lastEvent = [pscustomobject]@{
                Name = $line -replace "event:", ""
                Data = $null
            }

        }
        elseif ($line -like "data:*")
        {
            if ($null -eq $lastEvent)
            {
                continue
            }

            $lastEvent.Data = $line -replace 'data:', ''
            $List.Value.Add($lastEvent)

            Write-Host "`nFound event: $index"
            Write-Host "Name: $($lastEvent.Name)"
            Write-Host "Data: $($lastEvent.Data)"
            $index++
            $lastEventIndex = $i
        }
    }

    if ($lastEventIndex -ge 0)
    {
        $Queue.Value.RemoveRange(0, $lastEventIndex)
    }
}

Function Push-Text([string]$text, [ref]$Queue, [ref]$List)
{
    if ([string]::IsNullOrWhiteSpace($text))
    {
        return
    }

    $lines = $text.Trim() -split "`n"
    $Queue.Value.AddRange($lines)

    if ($text -like "*data:*")
    {
        Process-Lines -Queue $Queue -List $List
    }
}

Function Read-StreamForever([System.IO.Stream]$Stream, [ref]$Queue, [ref]$List)
{
    $encoding = [System.Text.Encoding]::UTF8
    [byte[]]$buffer = New-Object byte[] 2048
    while ($true)
    {
        if ($Stream.CanRead)
        {
            $length = $Stream.Read($buffer, 0, 2048)
            if ($length -gt 0)
            {
                $text = $encoding.GetString($buffer, 0, $length)
                Push-Text -Text $text -Queue $Queue -List $List
            }
        }
    }
}

Function Open-SSEStream([uri]$Url, [string]$token, [ref]$Queue, [ref]$List)
{
    $request = [System.Net.WebRequest]::CreateHttp($Url)
    $request.Headers.Add("Authorization", "Bearer $token")
    $request.AllowReadStreamBuffering = $false
    $response = $request.GetResponse()
    $stream = $response.GetResponseStream()

    Read-StreamForever -Queue $Queue -Stream $stream -List $List

    return $stream
}

Write-Host "Attempting to open stream"
$response = Open-SSEStream -Url $Url -Token $BearerToken -Queue ([ref]$messageQueue) -List ([ref]$receivedObjects)
if ($?)
{
    Write-Host "`nSuccess!"
}