param(
    [switch]$DryRun
)

$ErrorActionPreference = "Stop"

$repoRoot = Split-Path -Parent $PSScriptRoot
$overlayDir = Join-Path $repoRoot "overlay"
$dataDir = Join-Path $repoRoot "data"
$launcherLog = Join-Path $dataDir "startup-launcher.log"

if (-not (Test-Path $dataDir)) {
    New-Item -ItemType Directory -Path $dataDir | Out-Null
}

function Write-LauncherLog {
    param([string]$Message)
    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
    Add-Content -Path $launcherLog -Value "[$timestamp] $Message"
}

function Resolve-PythonPath {
    $venvPython = Join-Path $repoRoot ".venv\Scripts\python.exe"
    if (Test-Path $venvPython) {
        return $venvPython
    }

    $pythonCmd = Get-Command python -ErrorAction SilentlyContinue
    if ($null -ne $pythonCmd) {
        return $pythonCmd.Source
    }

    throw "Could not find Python. Install Python or create .venv first."
}

function Resolve-NpmPath {
    $npmCmd = Get-Command npm.cmd -ErrorAction SilentlyContinue
    if ($null -ne $npmCmd) {
        return $npmCmd.Source
    }

    throw "Could not find npm.cmd. Install Node.js/npm first."
}

function Start-HiddenProcess {
    param(
        [string]$Name,
        [string]$FilePath,
        [string[]]$Arguments,
        [string]$WorkingDirectory,
        [string]$StdOutPath,
        [string]$StdErrPath
    )

    if ($DryRun) {
        Write-LauncherLog "DRY RUN -> $Name | $FilePath $($Arguments -join ' ')"
        return
    }

    Start-Process `
        -FilePath $FilePath `
        -ArgumentList $Arguments `
        -WorkingDirectory $WorkingDirectory `
        -WindowStyle Hidden `
        -RedirectStandardOutput $StdOutPath `
        -RedirectStandardError $StdErrPath | Out-Null

    Write-LauncherLog "Started $Name."
}

function Is-BackendRunning {
    $matches = Get-CimInstance Win32_Process -ErrorAction SilentlyContinue |
        Where-Object {
            $_.Name -like "python*" -and
            $_.CommandLine -and
            $_.CommandLine -like "*backend.main:app*"
        }
    return ($matches | Measure-Object).Count -gt 0
}

function Is-OverlayRunning {
    $matches = Get-CimInstance Win32_Process -ErrorAction SilentlyContinue |
        Where-Object {
            $_.CommandLine -and
            $_.CommandLine -like "*custom-streamdeck*overlay*"
        }
    return ($matches | Measure-Object).Count -gt 0
}

try {
    $pythonPath = Resolve-PythonPath
    $npmPath = Resolve-NpmPath

    if (-not (Test-Path (Join-Path $repoRoot "frontend\dist\index.html"))) {
        Write-LauncherLog "Warning: frontend/dist is missing. Build frontend for production view."
    }

    if (Is-BackendRunning) {
        Write-LauncherLog "Backend already running. Skipping backend launch."
    } else {
        $backendOut = Join-Path $dataDir "backend.stdout.log"
        $backendErr = Join-Path $dataDir "backend.stderr.log"
        Start-HiddenProcess `
            -Name "backend" `
            -FilePath $pythonPath `
            -Arguments @("-m", "uvicorn", "backend.main:app", "--host", "127.0.0.1", "--port", "8000") `
            -WorkingDirectory $repoRoot `
            -StdOutPath $backendOut `
            -StdErrPath $backendErr
    }

    if (Is-OverlayRunning) {
        Write-LauncherLog "Overlay already running. Skipping overlay launch."
    } else {
        $overlayOut = Join-Path $dataDir "overlay.stdout.log"
        $overlayErr = Join-Path $dataDir "overlay.stderr.log"
        Start-HiddenProcess `
            -Name "overlay" `
            -FilePath $npmPath `
            -Arguments @("run", "start") `
            -WorkingDirectory $overlayDir `
            -StdOutPath $overlayOut `
            -StdErrPath $overlayErr
    }
} catch {
    Write-LauncherLog "Launcher failed: $($_.Exception.Message)"
    throw
}