param(
    [Parameter(Mandatory = $true)]
    [string]$ProjectDir,
    [string]$FsFile = "",
    [ValidateSet(2, 4, 5, 6)]
    [int]$Operation = 2,
    [string]$GowinRoot = ""
)

$ErrorActionPreference = "Stop"

if (-not $GowinRoot) {
    $GowinRoot = "C:\Users\Administrator\Documents\fpga\tool-chain\Gowin\Gowin_V1.9.11.03_Education_x64"
}

$ProjectDir = (Resolve-Path $ProjectDir).Path
$cli = Join-Path $GowinRoot "Programmer\bin\programmer_cli.exe"
if (-not (Test-Path $cli)) { throw "programmer_cli.exe not found: $cli" }

$env:PATH = "$(Join-Path $GowinRoot 'Programmer\bin');$env:PATH"

Write-Host "Scanning cables..."
& $cli --scan
if ($LASTEXITCODE -ne 0) { throw "scan failed; check USB cable and board power" }

if (-not $FsFile) {
    $fs = Get-ChildItem (Join-Path $ProjectDir "impl\pnr\*.fs") |
        Sort-Object LastWriteTime -Descending | Select-Object -First 1
    if (-not $fs) { throw "No .fs found; build first" }
    $FsFile = $fs.FullName
} else {
    $FsFile = (Resolve-Path $FsFile).Path
}

Write-Host "Programming GW5A-25A op=$Operation file=$FsFile"
& $cli -d GW5A-25A --fsFile $FsFile -r $Operation
if ($LASTEXITCODE -ne 0) { throw "program failed" }
Write-Host "Download finished."