[CmdletBinding()]
param(
    [string]$Symbols = "",
    [int]$Limit = 0,
    [string]$Lookbacks = "",
    [string]$Architectures = "",
    [string]$HiddenSizes = "",
    [string]$Layers = "",
    [string]$Dropouts = "",
    [int]$Horizon = 0,
    [string]$Horizons = "",
    [string]$Features = "",
    [string]$ContextSymbols = "",
    [int]$Seed = 0,
    [int]$Epochs = 0,
    [int]$Patience = 0,
    [string]$Interval = "",
    [string]$EnvFile = "",
    [switch]$DeployToPi,
    [string]$PiHost = "",
    [string]$PiUser = "",
    [string]$PiRoot = "",
    [string]$PiSshKeyPath = "",
    [switch]$NoPiRestart,
    [switch]$SkipGuard
)

$ErrorActionPreference = "Stop"

$RepoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
$RuntimeDir = Join-Path $RepoRoot "runtime"
$LogFile = Join-Path $RuntimeDir "torch_retrain.log"
New-Item -ItemType Directory -Force -Path $RuntimeDir | Out-Null

function Write-RetrainLog {
    param([string]$Message)
    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ssK"
    "[$timestamp] $Message" | Tee-Object -FilePath $LogFile -Append
}

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

    $userPython = Join-Path $env:LOCALAPPDATA "Programs\TradeBotPython312\python.exe"
    if (Test-Path $userPython) {
        return $userPython
    }

    foreach ($candidate in @("python.exe", "python")) {
        $command = Get-Command $candidate -ErrorAction SilentlyContinue
        if (-not $command) {
            continue
        }
        return $command.Source
    }
    throw "Python was not found. Create .venv or install Python 3.12."
}

function Test-TorchArtifactFile {
    param([string]$Path)
    if (-not (Test-Path $Path)) {
        return $false
    }
    try {
        $payload = Get-Content -Raw -LiteralPath $Path | ConvertFrom-Json
        return $payload.type -eq "pytorch_recurrent_forecaster" -and $null -ne $payload.symbols
    }
    catch {
        return $false
    }
}

function Sync-AcceptedArtifactsToPi {
    if (-not ($DeployToPi -or $env:TORCH_RETRAIN_DEPLOY_TO_PI)) {
        Write-RetrainLog "Pi artifact sync disabled."
        return
    }

    $syncScript = Join-Path $RepoRoot "tools\sync_torch_artifacts_to_pi.ps1"
    if (-not (Test-Path $syncScript)) {
        throw "Pi sync script not found: $syncScript"
    }

    $syncArgs = @(
        "-NoProfile",
        "-ExecutionPolicy", "Bypass",
        "-File", $syncScript,
        "-RepoRoot", $RepoRoot
    )
    if ($PiHost) { $syncArgs += @("-RemoteHost", $PiHost) }
    if ($PiUser) { $syncArgs += @("-RemoteUser", $PiUser) }
    if ($PiRoot) { $syncArgs += @("-RemoteRoot", $PiRoot) }
    if ($PiSshKeyPath) { $syncArgs += @("-SshKeyPath", $PiSshKeyPath) }
    if ($NoPiRestart) { $syncArgs += "-NoRestart" }

    Write-RetrainLog "Syncing accepted Torch artifacts to Raspberry Pi."
    & powershell.exe @syncArgs 2>&1 | Tee-Object -FilePath $LogFile -Append
    if ($LASTEXITCODE -ne 0) {
        throw "Pi artifact sync failed with exit code $LASTEXITCODE."
    }
    Write-RetrainLog "Pi artifact sync completed."
}

if (-not $Symbols -and $env:TORCH_RETRAIN_SYMBOLS) { $Symbols = $env:TORCH_RETRAIN_SYMBOLS }
if ($Limit -le 0) {
    $Limit = if ($env:TORCH_RETRAIN_LIMIT) { [int]$env:TORCH_RETRAIN_LIMIT } else { 3000 }
}
if (-not $Lookbacks) { $Lookbacks = if ($env:TORCH_RETRAIN_LOOKBACKS) { $env:TORCH_RETRAIN_LOOKBACKS } else { "64" } }
if (-not $Architectures) { $Architectures = if ($env:TORCH_RETRAIN_ARCHITECTURES) { $env:TORCH_RETRAIN_ARCHITECTURES } else { "lstm,gru" } }
if (-not $HiddenSizes) { $HiddenSizes = if ($env:TORCH_RETRAIN_HIDDEN_SIZES) { $env:TORCH_RETRAIN_HIDDEN_SIZES } else { "64,96" } }
if (-not $Layers) { $Layers = if ($env:TORCH_RETRAIN_LAYERS) { $env:TORCH_RETRAIN_LAYERS } else { "2" } }
if (-not $Dropouts) { $Dropouts = if ($env:TORCH_RETRAIN_DROPOUTS) { $env:TORCH_RETRAIN_DROPOUTS } else { "0.15" } }
if ($Horizon -le 0 -and $env:TORCH_RETRAIN_HORIZON) { $Horizon = [int]$env:TORCH_RETRAIN_HORIZON }
if (-not $Horizons -and $env:TORCH_RETRAIN_HORIZONS) { $Horizons = $env:TORCH_RETRAIN_HORIZONS }
if (-not $Features -and $env:TORCH_RETRAIN_FEATURES) { $Features = $env:TORCH_RETRAIN_FEATURES }
if (-not $ContextSymbols -and $env:TORCH_RETRAIN_CONTEXT_SYMBOLS) { $ContextSymbols = $env:TORCH_RETRAIN_CONTEXT_SYMBOLS }
if ($Seed -le 0 -and $env:TORCH_RETRAIN_SEED) { $Seed = [int]$env:TORCH_RETRAIN_SEED }
if ($Epochs -le 0) { $Epochs = if ($env:TORCH_RETRAIN_EPOCHS) { [int]$env:TORCH_RETRAIN_EPOCHS } else { 70 } }
if ($Patience -le 0) { $Patience = if ($env:TORCH_RETRAIN_PATIENCE) { [int]$env:TORCH_RETRAIN_PATIENCE } else { 8 } }
if (-not $Interval -and $env:TORCH_RETRAIN_INTERVAL) { $Interval = $env:TORCH_RETRAIN_INTERVAL }
if (-not $EnvFile -and $env:TORCH_RETRAIN_ENV) { $EnvFile = $env:TORCH_RETRAIN_ENV }
if (-not $EnvFile -and (Test-Path (Join-Path $RepoRoot ".env"))) { $EnvFile = Join-Path $RepoRoot ".env" }

$ModelFile = if ($env:TIME_SERIES_LSTM_MODEL_PATH) { $env:TIME_SERIES_LSTM_MODEL_PATH } else { Join-Path $RuntimeDir "lstm_forecaster.json" }
if (-not [System.IO.Path]::IsPathRooted($ModelFile)) { $ModelFile = Join-Path $RepoRoot $ModelFile }
$CandidateFile = Join-Path $RuntimeDir "lstm_forecaster.candidate.json"
$CurrentCalibration = Join-Path $RuntimeDir "torch_guard_current.json"
$CandidateCalibration = Join-Path $RuntimeDir "torch_guard_candidate.json"
$GuardReport = Join-Path $RuntimeDir "torch_retrain_guard.json"

$mutex = New-Object System.Threading.Mutex($false, "TradeBotTorchRecurrentRetrainer")
$hasLock = $false
$pushedLocation = $false

try {
    $hasLock = $mutex.WaitOne(0)
    if (-not $hasLock) {
        Write-RetrainLog "Another PyTorch recurrent retrain is already running; skipping."
        exit 0
    }

    $python = Resolve-Python
    $trainerArgs = @(
        "-u",
        "tools\train_torch_recurrent_forecaster.py",
        "--limit", $Limit.ToString(),
        "--lookbacks", $Lookbacks,
        "--architectures", $Architectures,
        "--hidden-sizes", $HiddenSizes,
        "--layers", $Layers,
        "--dropouts", $Dropouts,
        "--epochs", $Epochs.ToString(),
        "--patience", $Patience.ToString(),
        "--output", $CandidateFile
    )
    if ($Symbols) { $trainerArgs += @("--symbols", $Symbols) }
    if ($Interval) { $trainerArgs += @("--interval", $Interval) }
    if ($EnvFile) { $trainerArgs += @("--env", $EnvFile) }
    if ($Horizon -gt 0) { $trainerArgs += @("--horizon", $Horizon.ToString()) }
    if ($Horizons) { $trainerArgs += @("--horizons", $Horizons) }
    if ($Features) { $trainerArgs += @("--features", $Features) }
    if ($ContextSymbols) { $trainerArgs += @("--context-symbols", $ContextSymbols) }
    if ($Seed -gt 0) { $trainerArgs += @("--seed", $Seed.ToString()) }

    Push-Location $RepoRoot
    $pushedLocation = $true
    Write-RetrainLog "Starting PyTorch recurrent retrain: $python $($trainerArgs -join ' ')"
    & $python @trainerArgs 2>&1 | Tee-Object -FilePath $LogFile -Append
    $trainerExitCode = $LASTEXITCODE
    if ($trainerExitCode -ne 0) {
        if (Test-TorchArtifactFile $CandidateFile) {
            Write-RetrainLog "WARNING: Trainer exited with code $trainerExitCode after writing a valid candidate artifact; continuing to guard."
        }
        else {
            throw "Trainer failed with exit code $trainerExitCode."
        }
    }
    Write-RetrainLog "Finished PyTorch recurrent retrain candidate: $CandidateFile"

    if ($SkipGuard -or -not (Test-Path $ModelFile)) {
        Move-Item -Force -LiteralPath $CandidateFile -Destination $ModelFile
        Write-RetrainLog "Accepted candidate without guard. Active artifact: $ModelFile"
        Sync-AcceptedArtifactsToPi
        exit 0
    }

    $calibrationBaseArgs = @(
        "-u",
        "tools\calibrate_torch_thresholds.py",
        "--limit", "3000",
        "--calibration-window", "1200",
        "--min-trades", "60",
        "--walk-forward-folds", "8",
        "--confidence-grid", "0.40"
    )
    if ($Symbols) { $calibrationBaseArgs += @("--symbols", $Symbols) }
    if ($EnvFile) { $calibrationBaseArgs += @("--env", $EnvFile) }

    Write-RetrainLog "Calibrating current artifact for guard."
    & $python @($calibrationBaseArgs + @("--artifact", $ModelFile, "--output", $CurrentCalibration)) 2>&1 | Tee-Object -FilePath $LogFile -Append
    if ($LASTEXITCODE -ne 0) {
        throw "Current artifact calibration failed with exit code $LASTEXITCODE."
    }

    Write-RetrainLog "Calibrating candidate artifact for guard."
    & $python @($calibrationBaseArgs + @("--artifact", $CandidateFile, "--output", $CandidateCalibration)) 2>&1 | Tee-Object -FilePath $LogFile -Append
    if ($LASTEXITCODE -ne 0) {
        throw "Candidate artifact calibration failed with exit code $LASTEXITCODE."
    }

    Write-RetrainLog "Running retrain guard."
    & $python -u "tools\accept_torch_candidate.py" `
        --current-report $CurrentCalibration `
        --candidate-report $CandidateCalibration `
        --candidate-artifact $CandidateFile `
        --target-artifact $ModelFile `
        --report $GuardReport 2>&1 | Tee-Object -FilePath $LogFile -Append
    if ($LASTEXITCODE -eq 2) {
        Write-RetrainLog "Candidate rejected by guard; keeping active artifact: $ModelFile"
        exit 0
    }
    if ($LASTEXITCODE -ne 0) {
        throw "Retrain guard failed with exit code $LASTEXITCODE."
    }
    if (Test-Path $CandidateCalibration) {
        Copy-Item -Force -LiteralPath $CandidateCalibration -Destination (Join-Path $RuntimeDir "torch_threshold_calibration.json")
        Write-RetrainLog "Updated active threshold calibration: $(Join-Path $RuntimeDir "torch_threshold_calibration.json")"
    }
    Write-RetrainLog "Candidate accepted by guard. Active artifact: $ModelFile"
    Sync-AcceptedArtifactsToPi
}
catch {
    Write-RetrainLog "ERROR: $($_.Exception.Message)"
    exit 1
}
finally {
    if ($pushedLocation) {
        Pop-Location -ErrorAction SilentlyContinue
    }
    if ($hasLock) {
        $mutex.ReleaseMutex()
    }
    $mutex.Dispose()
}