defmodule Microwaveprop.Workers.PskrCalibrationWorker do
  @moduledoc """
  Hourly cron that builds `Pskr.CalibrationSample` rows by joining
  PSKR spot density with HRRR atmospheric state and SWPC space
  weather at a given hour.

  Default behaviour fires for the previous full hour — by HH:25 UTC
  the HRRR cycle has analysis available and PSKR's hourly aggregator
  has flushed its accumulator. Pass `"hour_utc"` in the args map to
  rerun a specific hour:

      Microwaveprop.Workers.PskrCalibrationWorker.new(%{"hour_utc" => "2026-05-04T18:00:00Z"})

  The sampler is idempotent (UPSERT on `(hour_utc, band, midpoint_lat,
  midpoint_lon)`) so reruns are safe.

  Lives on the `:backfill_enqueue` queue rather than spawning a new
  one — the workload is small (~1 query window, in-memory join,
  bulk upsert) and cluster-wide single-slot is plenty for one fire
  per hour.
  """
  use Oban.Worker,
    queue: :backfill_enqueue,
    max_attempts: 3,
    unique: [
      period: 3600,
      states: [:available, :scheduled, :executing, :retryable]
    ]

  alias Microwaveprop.Pskr.CalibrationSampler

  require Logger

  @impl Oban.Worker
  def perform(%Oban.Job{args: args}) do
    hour = parse_hour(args)
    Logger.info("PskrCalibrationWorker: building samples for #{hour}")
    count = CalibrationSampler.build_for_hour(hour)
    Logger.info("PskrCalibrationWorker: upserted #{count} samples for #{hour}")
    :ok
  end

  defp parse_hour(%{"hour_utc" => iso}) when is_binary(iso) do
    {:ok, dt, _} = DateTime.from_iso8601(iso)
    dt
  end

  defp parse_hour(_) do
    # Default: the previous fully-completed hour.
    DateTime.utc_now()
    |> DateTime.add(-3600, :second)
    |> Map.put(:minute, 0)
    |> Map.put(:second, 0)
    |> Map.put(:microsecond, {0, 0})
  end
end