function json(data, status = 200) {
  return new Response(JSON.stringify(data), {
    status,
    headers: { "content-type": "application/json; charset=UTF-8" },
  });
}

function modelItem(prediction, probability, isCorrect) {
  if (prediction === null || prediction === undefined) return null;
  return {
    prediction: Number(prediction),
    probability: probability === null || probability === undefined ? null : Number(probability),
    is_correct: isCorrect === null || isCorrect === undefined ? null : Number(isCorrect) === 1,
  };
}

export async function onRequestGet(context) {
  const db = context.env.DB;
  if (!db) {
    return json({ success: false, error: "缺少 D1 绑定 DB" }, 500);
  }

  try {
    const date = context.params.date;
    const sql = `
      SELECT
        timestamp,
        hour,
        open_price,
        close_price,
        actual_result,
        dlinear_prediction,
        dlinear_prob,
        dlinear_correct,
        nbeats_prediction,
        nbeats_prob,
        nbeats_correct,
        ttm_prediction,
        ttm_prob,
        ttm_correct,
        ensemble_prediction,
        ensemble_correct
      FROM backup_hourly_model_predictions
      WHERE date = ?
      ORDER BY hour ASC
    `;

    const result = await db.prepare(sql).bind(date).all();
    const rows = (result.results || []).map((r) => ({
      timestamp_cst: r.timestamp,
      hour: r.hour,
      open_price: r.open_price === null || r.open_price === undefined ? null : Number(r.open_price),
      close_price: r.close_price === null || r.close_price === undefined ? null : Number(r.close_price),
      actual_result: r.actual_result === null || r.actual_result === undefined ? null : Number(r.actual_result),
      models: {
        Ensemble: modelItem(r.ensemble_prediction, null, r.ensemble_correct),
        DLinear: modelItem(r.dlinear_prediction, r.dlinear_prob, r.dlinear_correct),
        "N-BEATS": modelItem(r.nbeats_prediction, r.nbeats_prob, r.nbeats_correct),
        "TTM-R2": modelItem(r.ttm_prediction, r.ttm_prob, r.ttm_correct),
      },
    }));

    return json({ success: true, date, data: rows });
  } catch (error) {
    return json({ success: false, error: String(error) }, 500);
  }
}