/**
 * Copyright (c) 2021 OceanBase
 * OceanBase CE is licensed under Mulan PubL v2.
 * You can use this software according to the terms and conditions of the Mulan PubL v2.
 * You may obtain a copy of Mulan PubL v2 at:
 *          http://license.coscl.org.cn/MulanPubL-2.0
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PubL v2 for more details.
 */

#define USING_LOG_PREFIX SQL_ENG
#include <math.h>
#include "share/object/ob_obj_cast.h"
#include "sql/engine/expr/ob_expr_log.h"
#include "sql/engine/expr/ob_expr_pow.h"
#include "sql/session/ob_sql_session_info.h"
#include "lib/number/ob_number_v2.h"
#include "sql/engine/expr/ob_expr_ln.h"

namespace oceanbase
{
using namespace oceanbase::common;

namespace sql
{
ObExprLog::ObExprLog(ObIAllocator &alloc)
    : ObExprOperator(alloc, T_FUN_SYS_LOG, N_LOG, 2, NOT_ROW_DIMENSION)
{
}

int ObExprLog::calc_result_type2(ObExprResType &type,
                                 ObExprResType &type1,
                                 ObExprResType &type2,
                                 ObExprTypeCtx &type_ctx) const
{
  int ret = OB_SUCCESS;
  if (lib::is_mysql_mode()) {
    if (NOT_ROW_DIMENSION != row_dimension_) {
      ret = OB_ERR_INVALID_TYPE_FOR_OP; // arithmetic not support row
    } else if (ObMaxType == type1.get_type() || ObMaxType == type2.get_type()) {
      ret = OB_ERR_INVALID_TYPE_FOR_OP;
    } else {
      type.set_double();
      type1.set_calc_type(type.get_type());
      type2.set_calc_type(type.get_type());
      ObExprOperator::calc_result_flag2(type, type1, type2);
    }
  } else if (OB_FAIL(calc_trig_function_result_type2(type, type1, type2, type_ctx))) {
    LOG_WARN("failed to calc_trig_function_result_type2", K(ret));
  } else {/*do nothing*/}
  return ret;
}

int calc_log_expr_double(const ObExpr &expr, ObEvalCtx &ctx,
                                ObDatum &res_datum)
{
  int ret = OB_SUCCESS;
  ObDatum *base = NULL;
  ObDatum *x = NULL;
  if (OB_FAIL(expr.args_[0]->eval(ctx, base)) ||
      OB_FAIL(expr.args_[1]->eval(ctx, x))) {
    LOG_WARN("eval arg failed", K(ret), K(expr));
  } else if (base->is_null() || x->is_null()) {
    res_datum.set_null();
  } else if (lib::is_mysql_mode() && (x->get_double() <= 0 || base->get_double() <= 0)) {
    LOG_USER_WARN(OB_EER_INVALID_ARGUMENT_FOR_LOGARITHM);
    res_datum.set_null();
  } else if (OB_FAIL(ObExprPow::safe_set_double(res_datum,
          std::log(x->get_double()) / std::log(base->get_double())))) {
    if (lib::is_mysql_mode() && OB_OPERATE_OVERFLOW == ret) {
      ret = OB_SUCCESS;
      LOG_USER_WARN(OB_EER_INVALID_ARGUMENT_FOR_LOGARITHM);
      res_datum.set_null();
    } else {
      LOG_WARN("set double failed", K(ret), K(base->get_double()), K(x->get_double()));
    }
  }
  return ret;
}

int calc_log_expr_number(const ObExpr &expr, ObEvalCtx &ctx,
                                ObDatum &res_datum)
{
  int ret = OB_SUCCESS;
  ObDatum *base = NULL;
  ObDatum *x = NULL;
  if (OB_FAIL(expr.args_[0]->eval(ctx, base)) ||
      OB_FAIL(expr.args_[1]->eval(ctx, x))) {
    LOG_WARN("eval arg failed", K(ret), K(expr));
  } else if (base->is_null() || x->is_null()) {
    res_datum.set_null();
  } else {
    const number::ObNumber base_nmb(base->get_number());
    const number::ObNumber x_nmb(x->get_number());
    number::ObNumber res_nmb;
    ObEvalCtx::TempAllocGuard alloc_guard(ctx);
    if (OB_FAIL(x_nmb.log(base_nmb, res_nmb, alloc_guard.get_allocator()))) {
      LOG_WARN("calc log failed", K(ret), K(base_nmb), K(x_nmb), K(res_nmb));
    } else {
      res_datum.set_number(res_nmb);
    }
  }
  return ret;
}

int ObExprLog::cg_expr(ObExprCGCtx &expr_cg_ctx, const ObRawExpr &raw_expr,
                       ObExpr &rt_expr) const
{
  int ret = OB_SUCCESS;
  UNUSED(expr_cg_ctx);
  UNUSED(raw_expr);
  if (OB_UNLIKELY(2 != raw_expr.get_param_count())) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("raw_expr should got two arg", K(ret), K(raw_expr));
  } else {
    const ObObjType base_res_type = rt_expr.args_[0]->datum_meta_.type_;
    const ObObjType x_res_type = rt_expr.args_[1]->datum_meta_.type_;
    if (ObNumberType == base_res_type && ObNumberType == x_res_type) {
      rt_expr.eval_func_ = calc_log_expr_number;
    } else if (ObDoubleType == base_res_type && ObDoubleType == x_res_type) {
      rt_expr.eval_func_ = calc_log_expr_double;
    } else {
      ret = OB_ERR_UNEXPECTED;
      LOG_WARN("invalid arg type", K(ret), K(rt_expr));
    }
  }
  return ret;
}

} // namespace sql
} // namespace oceanbase