[CmdletBinding(SupportsShouldProcess = $true)]
param(
    [string]$ServiceName = "ScreenJobBackend",
    [string]$DisplayName = "ScreenJob Backend",
    [string]$Description = "Runs the ScreenJob backend (start_backend.ps1) as a Windows service.",
    [ValidateSet("Automatic", "Manual", "Disabled")]
    [string]$StartupType = "Automatic",
    [switch]$DelayedAutoStart,
    [switch]$ForceReinstall,
    [switch]$StartAfterInstall
)

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"

function Test-IsAdministrator {
    $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
    $principal = New-Object Security.Principal.WindowsPrincipal($identity)
    return $principal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
}

if (-not (Test-IsAdministrator)) {
    throw "Run this script from an elevated PowerShell session (Run as Administrator)."
}

$scriptDir = Split-Path -Parent $PSCommandPath
$backendScript = Join-Path $scriptDir "start_backend.ps1"
if (-not (Test-Path -LiteralPath $backendScript)) {
    throw "Backend launcher script not found: $backendScript"
}

$projectFile = Join-Path $scriptDir "service_host\ScreenJob.WindowsServiceHost\ScreenJob.WindowsServiceHost.csproj"
if (-not (Test-Path -LiteralPath $projectFile)) {
    throw "Windows service host project not found: $projectFile"
}

$dotnetCmd = Get-Command dotnet -ErrorAction SilentlyContinue
if ($null -eq $dotnetCmd) {
    throw "dotnet SDK was not found in PATH. Install .NET SDK 10+ and retry."
}

$publishDir = Join-Path $scriptDir "service_host\publish"
$serviceExe = Join-Path $publishDir "ScreenJob.WindowsServiceHost.exe"
$logDir = Join-Path $scriptDir "screenjob_runs\service"

if ($PSCmdlet.ShouldProcess($projectFile, "Publish Windows service host")) {
    & $dotnetCmd.Source publish `
        $projectFile `
        -c Release `
        -r win-x64 `
        --self-contained false `
        -p:PublishSingleFile=true `
        -o $publishDir

    if ($LASTEXITCODE -ne 0) {
        throw "dotnet publish failed with exit code $LASTEXITCODE."
    }
}

if (-not (Test-Path -LiteralPath $serviceExe)) {
    throw "Published service executable not found: $serviceExe"
}

$binaryPath = "`"$serviceExe`" --backend-script `"$backendScript`" --working-dir `"$scriptDir`" --log-dir `"$logDir`""

$existingService = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue
if ($null -ne $existingService) {
    if (-not $ForceReinstall) {
        throw "Service '$ServiceName' already exists. Re-run with -ForceReinstall to replace it."
    }

    if ($PSCmdlet.ShouldProcess($ServiceName, "Remove existing service")) {
        if ($existingService.Status -ne "Stopped") {
            Stop-Service -Name $ServiceName -Force -ErrorAction Stop
        }

        & sc.exe delete $ServiceName | Out-Null
        if ($LASTEXITCODE -ne 0) {
            throw "Failed to delete existing service '$ServiceName' (sc.exe exit code $LASTEXITCODE)."
        }
    }
}

if ($PSCmdlet.ShouldProcess($ServiceName, "Create service")) {
    New-Service `
        -Name $ServiceName `
        -BinaryPathName $binaryPath `
        -DisplayName $DisplayName `
        -Description $Description `
        -StartupType $StartupType

    if ($StartupType -eq "Automatic" -and $DelayedAutoStart) {
        & sc.exe config $ServiceName start= delayed-auto | Out-Null
        if ($LASTEXITCODE -ne 0) {
            throw "Failed to enable delayed auto-start for '$ServiceName' (sc.exe exit code $LASTEXITCODE)."
        }
    }

    # Restart on first/second/subsequent failure after 5 seconds.
    & sc.exe failure $ServiceName reset= 86400 actions= restart/5000/restart/5000/restart/5000 | Out-Null
    if ($LASTEXITCODE -ne 0) {
        throw "Failed to configure failure actions for '$ServiceName' (sc.exe exit code $LASTEXITCODE)."
    }

    if ($StartAfterInstall) {
        Start-Service -Name $ServiceName -ErrorAction Stop
    }
}

Write-Host "Service '$ServiceName' installed successfully." -ForegroundColor Green
Write-Host "Check status with: Get-Service -Name $ServiceName"
Write-Host "View logs in: $logDir"