[CmdletBinding()] # Fail on unknown args
param (
    [string]$mode,
    [string]$src,
    [switch]$nocloseeditor = $false,
    [switch]$dryrun = $false,
    [switch]$help = $false
)

function Print-Usage {
    Write-Output "Steve's UE4 Build Tool"
    Write-Output "   This is a WIP, only builds for dev right now"
    Write-Output "Usage:"
    Write-Output "  ue4-build.ps1 [-mode:]<dev|test|prod> [[-src:]sourcefolder] [Options]"
    Write-Output " "
    Write-Output "  -mode        : Build mode (required)"
    Write-Output "               : dev = build Development Editor, dlls only"
    Write-Output "               : dev = build Development Editor locally for editor"
    Write-Output "               : test = build Development and pacakge for test (TODO)"
    Write-Output "               : prod = build Shipping and package for production (TODO)"
    Write-Output "  -src         : Source folder (current folder if omitted)"
    Write-Output "               : (should be root of project)"
    Write-Output "  -nocloseeditor : Don't close UE4 editor (this will prevent DLL cleanup)"
    Write-Output "  -dryrun      : Don't perform any actual actions, just report on what you would do"
    Write-Output "  -help        : Print this help"
}

$ErrorActionPreference = "Stop"


if ($help) {
    Print-Usage
    Exit 0
}

if (-not $mode) {
    Print-Usage
    Write-Output "ERROR: Required argument: mode"
    Exit 3
}

if (-not (@('dev', 'test', 'prod') -contains $mode)) {
    Print-Usage
    Write-Output "ERROR: Invalid mode argument: $mode"
    Exit 3

}


$result = 0

try {
    if ($src -ne ".") { Push-Location $src }

    # Locate UE4 project file
    $uprojfile = Get-ChildItem *.uproject | Select-Object -expand Name
    if (-not $uprojfile) {
        throw "No Unreal project file found in $(Get-Location)! Aborting."
    }
    if ($uprojfile -is [array]) {
        throw "Multiple Unreal project files found in $(Get-Location)! Aborting."
    }

    Write-Output "Building $uprojfile for $mode"

    # Check version number of UE4 project so we know which version to run
    # We can read this from .uproject which is JSON
    $uproject = Get-Content $uprojfile | ConvertFrom-Json

    $uversion = $uproject.EngineAssociation

    # UE4INSTALL env var should point at the root of the *specific version* of 
    # UE4 you want to use. This is mainly for use in source builds, default is
    # to build it from version number and root of all UE4 binary installs
    $uinstall = $Env:UE4INSTALL

    if (-not $uinstall) {
        # UE4ROOT should be the parent folder of all UE versions
        $uroot = $Env:UE4ROOT
        if (-not $uroot) {
            $uroot = "C:\Program Files\Epic Games"
        } 

        $uinstall = Join-Path $uroot "UE_$uversion"
    }

    # Test we can find RunUAT.bat
    $uat = Join-Path "$uinstall" "Engine\Build\BatchFiles\RunUAT.bat"
    if (-not (Test-Path $uat -PathType Leaf)) {
        throw "Unreal Automation Tool doesn't exist at $uat : Aborting"
    }

    Write-Verbose "Running $uat"


    # Close UE4 as early as possible
    # if (-not $dryrun -and -not $nocloseeditor) {
    #     # Check if Unity is running, if so try to shut it gracefully
    #     $ue4proc = Get-Process UE4Editor | Where-Object {$_.MainWindowTitle -like "ue4localise*" }
    #     if ($ue4proc) {
    #         Write-Output "UE4 is currently running, trying to gracefully shut window "
    #         $ue4proc.CloseMainWindow()
    #         Start-Sleep 5
    #         if (!$ue4proc.HasExited) {
    #             throw "Couldn't close UE4 gracefully, aborting!"
    #         }
    #     }
    #     Remove-Variable ue4proc
    # }


    # Try to locate RunUAT.bat so we don't have to add UE4 version to PATH
    # Most likely in
    # C:\Program Files\Epic Games\UE_4.24\Engine\Build\BatchFiles


} catch {
        Write-Output "ERROR: $($_.Exception.Message)"
        $result = 9
} finally {
    if ($src -ne ".") { Pop-Location }
}


Exit $result