param(
    [string]$OutputPath = ""
)

$ErrorActionPreference = "Stop"

$repositoryRoot = Split-Path -Parent $PSScriptRoot
if ([string]::IsNullOrWhiteSpace($OutputPath)) {
    $OutputPath = Join-Path $repositoryRoot "dist/gateway-benchmarks.txt"
}
elseif (-not [System.IO.Path]::IsPathRooted($OutputPath)) {
    $OutputPath = Join-Path $repositoryRoot $OutputPath
}
$OutputPath = [System.IO.Path]::GetFullPath($OutputPath)
if ([System.IO.Path]::GetExtension($OutputPath) -ne ".txt") {
    throw "OutputPath must end in .txt"
}

$revision = (& git -C $repositoryRoot rev-parse --verify HEAD 2>$null).Trim()
if ($LASTEXITCODE -ne 0 -or [string]::IsNullOrWhiteSpace($revision)) {
    throw "could not resolve the current Git revision"
}

$outputDirectory = Split-Path -Parent $OutputPath
New-Item -ItemType Directory -Force -Path $outputDirectory | Out-Null
@(
    "proxy-pool gateway microbenchmarks",
    "revision: $revision",
    "generated_at_utc: $([DateTime]::UtcNow.ToString('O'))",
    "go_version: $((& go version).Trim())",
    ""
) | Set-Content -LiteralPath $OutputPath -Encoding utf8

function Invoke-Benchmark {
    param(
        [string]$Package,
        [string]$Pattern
    )

    $arguments = @("test", "-count=1", "-run", "^$", "-bench", $Pattern, "-benchtime=1x", "-benchmem", $Package)
    "==> go $($arguments -join ' ')" | Tee-Object -FilePath $OutputPath -Append
    $lines = & go @arguments 2>&1
    $exitCode = $LASTEXITCODE
    $lines | Tee-Object -FilePath $OutputPath -Append
    if ($exitCode -ne 0) {
        throw "benchmark failed with exit code $exitCode"
    }
    "" | Tee-Object -FilePath $OutputPath -Append
}

Invoke-Benchmark -Package "./internal/gateway/dispatch" -Pattern "BenchmarkAcquire100k(Indexed|RoutingRoundRobin)"
Invoke-Benchmark -Package "./internal/gateway/snapshot" -Pattern "^BenchmarkStoreApply100k$"
Write-Host "benchmark evidence: $OutputPath"