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

function toInt(v, d) {
  const n = Number(v);
  return Number.isFinite(n) && n > 0 ? Math.floor(n) : d;
}

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 url = new URL(context.request.url);
    const page = toInt(url.searchParams.get("page"), 1);
    const limit = Math.min(100, toInt(url.searchParams.get("limit"), 10));
    const month = (url.searchParams.get("month") || "").trim();
    const day = (url.searchParams.get("day") || "").trim();
    const offset = (page - 1) * limit;

    const where = ["1=1"];
    const params = [];

    // 时间字段是 YYYY-MM-DD HH:MM:SS 文本，直接前缀过滤可走索引/减少转换成本
    if (month) {
      where.push("timestamp LIKE ?");
      params.push(`${month}%`);
    }
    if (day) {
      where.push("timestamp LIKE ?");
      params.push(`${day}%`);
    }

    const whereSql = where.join(" AND ");
    const dataSql = `
      SELECT *
      FROM backup_trades
      WHERE ${whereSql}
      ORDER BY timestamp DESC
      LIMIT ? OFFSET ?
    `;
    const countSql = `
      SELECT COUNT(*) AS cnt
      FROM backup_trades
      WHERE ${whereSql}
    `;

    const dataResult = await db.prepare(dataSql).bind(...params, limit, offset).all();
    const countResult = await db.prepare(countSql).bind(...params).first();

    const total = Number(countResult?.cnt || 0);
    const totalPages = total > 0 ? Math.ceil(total / limit) : 1;

    return json({
      success: true,
      data: dataResult.results || [],
      page,
      limit,
      total,
      total_pages: totalPages,
    });
  } catch (error) {
    return json({ success: false, error: String(error) }, 500);
  }
}