[CmdletBinding()]
param(
    [string]$HostAddress = "127.0.0.1",
    [int]$Port = 8080,
    [int]$StartupTimeoutSeconds = 120
)

$ErrorActionPreference = "Stop"
if ($HostAddress -notin @("127.0.0.1", "localhost")) {
    throw "Refusing non-loopback llama.cpp host: $HostAddress"
}

$repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
$runtimeRoot = Join-Path $repoRoot ".local\llama.cpp"
$manifestPath = Join-Path $runtimeRoot "installed.json"
if (-not (Test-Path $manifestPath)) {
    throw "llama.cpp is not installed. Run scripts\Install-LlamaCpp.ps1 first."
}
$manifest = Get-Content $manifestPath -Raw | ConvertFrom-Json
$server = Join-Path $runtimeRoot "$($manifest.tag)\llama-server.exe"
$model = Join-Path $repoRoot "Assets\Model\Qwen3-4B-Instruct-2507-Q4_K_M.gguf"
$keyPath = Join-Path $runtimeRoot "api-key.txt"
$pidPath = Join-Path $runtimeRoot "server.pid"
$logPath = Join-Path $runtimeRoot "server.log"
$errorLogPath = Join-Path $runtimeRoot "server-error.log"

if (-not (Test-Path $server)) { throw "llama-server.exe is missing at $server" }
if (-not (Test-Path $model)) { throw "GGUF model is missing at $model" }
if (-not (Test-Path $keyPath)) {
    $bytes = New-Object byte[] 32
    $generator = [System.Security.Cryptography.RandomNumberGenerator]::Create()
    try {
        $generator.GetBytes($bytes)
    }
    finally {
        $generator.Dispose()
    }
    (($bytes | ForEach-Object { $_.ToString("x2") }) -join "") |
        Set-Content -LiteralPath $keyPath -Encoding ASCII -NoNewline
}
if (Test-Path $pidPath) {
    $recordedPid = Get-Content $pidPath -Raw
    if (-not [string]::IsNullOrWhiteSpace($recordedPid)) {
        $recordedPid = $recordedPid.Trim()
        $existingPid = [int]$recordedPid
        if (Get-Process -Id $existingPid -ErrorAction SilentlyContinue) {
            throw "A llama.cpp process recorded by $pidPath is already running."
        }
    }
    Set-Content -LiteralPath $pidPath -Value "" -Encoding ASCII -NoNewline
}

$arguments = @(
    "--model", $model,
    "--alias", "qwen3-4b-instruct-2507",
    "--host", $HostAddress,
    "--port", "$Port",
    "--api-key-file", $keyPath,
    "--ctx-size", "8192",
    # Current llama.cpp requires an integer; 999 means full offload and --fit may reduce it.
    "--gpu-layers", "999",
    "--fit", "on",
    "--flash-attn", "auto",
    "--cache-type-k", "q8_0",
    "--cache-type-v", "q8_0",
    "--parallel", "1",
    "--cache-ram", "1024",
    "--cache-prompt",
    "--jinja",
    "--reasoning", "off",
    "--no-ui",
    "--offline"
)

# Some hosts inject both Path and PATH. Windows PowerShell's Start-Process
# rejects that duplicate even though Windows normally treats them identically.
$processPath = [Environment]::GetEnvironmentVariable("Path", "Process")
[Environment]::SetEnvironmentVariable("PATH", $null, "Process")
[Environment]::SetEnvironmentVariable("Path", $processPath, "Process")

$process = Start-Process -FilePath $server -ArgumentList $arguments `
    -WorkingDirectory (Split-Path $server) -WindowStyle Hidden -PassThru `
    -RedirectStandardOutput $logPath -RedirectStandardError $errorLogPath
$process.Id | Set-Content -LiteralPath $pidPath -Encoding ASCII -NoNewline

$deadline = (Get-Date).AddSeconds($StartupTimeoutSeconds)
while ((Get-Date) -lt $deadline) {
    if ($process.HasExited) {
        throw "llama-server exited during startup. Inspect $logPath"
    }
    try {
        & (Join-Path $PSScriptRoot "Test-LlamaServer.ps1") -Port $Port -KeyPath $keyPath | Out-Null
        Write-Output "llama-server is ready on http://127.0.0.1:$Port (PID $($process.Id))."
        exit 0
    }
    catch {
        Start-Sleep -Milliseconds 750
    }
}
throw "llama-server did not become healthy within $StartupTimeoutSeconds seconds."