<#
.SYNOPSIS
    Logs connection quality to the local gateway and a public target at the same
    time, so you can tell a wifi problem from an ISP problem.

.DESCRIPTION
    Dropped frames on stream are almost always one of three things: your own
    wifi, your ISP, or the ingest server. Pinging only 1.1.1.1 cannot tell the
    first two apart. This pings both the gateway and a public target every
    second and writes a CSV into the Diagnostics folder, which Claude can read.

    Run it during a stream that is misbehaving, or leave it going for an hour.
    Ctrl-C stops it and prints the summary.

    NOT a replacement for the standard tools, and not the first thing to reach
    for. OBS's own Stats dock tells you whether you even have a network problem;
    WinMTR or PingPlotter show per-hop loss; Twitch Inspector tests the actual
    path to ingest. This one covers what those do not: unattended logging over
    hours, in a CSV that Claude can read afterwards. Use it for intermittent
    problems the one-shot tests keep missing.

    Reading the result:
      gateway loss, internet fine   -> your wifi or cable. Fixable by you.
      gateway fine, internet loss   -> upstream. Your ISP, not your PC.
      both clean, stream still bad  -> ingest server or encoder. Change server
                                       in OBS, or lower the bitrate.

.PARAMETER Target
    Public host to test. Default 1.1.1.1.

.PARAMETER Minutes
    How long to run. 0 (default) means until Ctrl-C.

.EXAMPLE
    .\monitor-connection.ps1

.EXAMPLE
    .\monitor-connection.ps1 -Minutes 30
#>

[CmdletBinding()]
param(
    [string]$Target = "1.1.1.1",
    [int]$Minutes = 0,
    [int]$IntervalSeconds = 1,
    [string]$OutputRoot = "$env:USERPROFILE\Diagnostics"
)

$ErrorActionPreference = "Stop"

# --- Find the default gateway ---
$gateway = (Get-NetRoute -DestinationPrefix "0.0.0.0/0" -ErrorAction SilentlyContinue |
    Sort-Object RouteMetric |
    Select-Object -First 1).NextHop

if (-not $gateway -or $gateway -eq "0.0.0.0") {
    Write-Warning "Could not find a default gateway -- testing the public target only."
    $gateway = $null
}

$targets = @()
if ($gateway) { $targets += [PSCustomObject]@{ Label = "gateway"; Address = $gateway } }
$targets += [PSCustomObject]@{ Label = "internet"; Address = $Target }

New-Item -Path $OutputRoot -ItemType Directory -Force | Out-Null
$csv = Join-Path $OutputRoot "connection-$(Get-Date -Format 'yyyy-MM-dd_HHmmss').csv"
"timestamp,label,address,success,latency_ms" | Set-Content -Path $csv -Encoding UTF8

Write-Host ""
foreach ($t in $targets) { Write-Host "  $($t.Label.PadRight(9)) $($t.Address)" }
Write-Host ""
Write-Host "  Logging to $csv"
Write-Host "  Ctrl-C to stop$(if ($Minutes -gt 0) { " (or it stops after $Minutes min)" })."
Write-Host ""

$ping = New-Object System.Net.NetworkInformation.Ping
$stats = @{}
foreach ($t in $targets) { $stats[$t.Label] = [System.Collections.ArrayList]@() }

$start = Get-Date
$deadline = if ($Minutes -gt 0) { $start.AddMinutes($Minutes) } else { [datetime]::MaxValue }
$lastReport = Get-Date

function Show-Summary {
    Write-Host ""
    Write-Host "  ---- summary ----"
    foreach ($label in $stats.Keys) {
        $all = $stats[$label]
        if ($all.Count -eq 0) { continue }
        $ok = @($all | Where-Object { $_ -ge 0 })
        $lossPct = [math]::Round((($all.Count - $ok.Count) / $all.Count) * 100, 2)

        if ($ok.Count -gt 0) {
            $sorted = $ok | Sort-Object
            $p50 = $sorted[[int]($sorted.Count * 0.50)]
            $p95 = $sorted[[math]::Min([int]($sorted.Count * 0.95), $sorted.Count - 1)]
            $max = $sorted[-1]
            Write-Host ("  {0,-9} loss {1,6}%   p50 {2,4} ms   p95 {3,4} ms   max {4,5} ms   n={5}" -f `
                $label, $lossPct, $p50, $p95, $max, $all.Count)
        } else {
            Write-Host ("  {0,-9} loss {1,6}%   no successful replies   n={2}" -f $label, $lossPct, $all.Count)
        }
    }
    Write-Host ""
    Write-Host "  CSV: $csv"
    Write-Host "  Ask Claude: 'Read the newest connection CSV in Diagnostics and tell me"
    Write-Host "  whether my problem is local wifi or upstream.'"
    Write-Host ""
}

try {
    while ((Get-Date) -lt $deadline) {
        $now = Get-Date -Format "o"

        foreach ($t in $targets) {
            $latency = -1
            try {
                $reply = $ping.Send($t.Address, 1000)
                if ($reply.Status -eq "Success") { $latency = [int]$reply.RoundtripTime }
            } catch {
                $latency = -1
            }
            [void]$stats[$t.Label].Add($latency)
            "$now,$($t.Label),$($t.Address),$([int]($latency -ge 0)),$latency" |
                Add-Content -Path $csv -Encoding UTF8
        }

        # Console line every 15s so it is readable rather than a waterfall.
        if (((Get-Date) - $lastReport).TotalSeconds -ge 15) {
            $lastReport = Get-Date
            $parts = foreach ($label in $stats.Keys) {
                $recent = @($stats[$label] | Select-Object -Last 15)
                $lost = @($recent | Where-Object { $_ -lt 0 }).Count
                $good = @($recent | Where-Object { $_ -ge 0 })
                $avg = if ($good.Count) { [int](($good | Measure-Object -Average).Average) } else { 0 }
                "{0} {1} ms{2}" -f $label, $avg, $(if ($lost) { " ($lost lost)" } else { "" })
            }
            Write-Host ("  {0}  {1}" -f (Get-Date -Format "HH:mm:ss"), ($parts -join "   |   "))
        }

        Start-Sleep -Seconds $IntervalSeconds
    }
} finally {
    Show-Summary
}