/**
 * 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.
 */

#ifndef _OB_EXPR_DATUM_CAST_
#define _OB_EXPR_DATUM_CAST_

#include "common/object/ob_object.h"
#include "common/ob_zerofill_info.h"
#include "lib/timezone/ob_timezone_info.h"
#include "lib/timezone/ob_time_convert.h"
#include "sql/session/ob_sql_session_info.h"
#include "lib/charset/ob_charset.h"
#include "share/ob_errno.h"
#include "share/datum/ob_datum.h"
#include "share/object/ob_obj_cast.h"
#include "sql/engine/expr/ob_expr.h"

namespace oceanbase
{
namespace sql
{
class ObPhysicalPlanCtx;
// extract accuracy info from %expr and call datum_accuracy_check() below.
int datum_accuracy_check(const ObExpr &expr,
                         const uint64_t cast_mode,
                         ObEvalCtx &ctx,
                         bool has_lob_header,
                         const common::ObDatum &in_datum,
                         ObDatum &res_datum,
                         int &warning);

// check if accuracy in %in_datum is ok. if ok, call res_datum.set_datum(in_datum).
// if not, will trunc data in %in_datum and put it in res_datum.
// this func makes sure data in %in_datum and %in_datum itself will not be changed.
int datum_accuracy_check(const ObExpr &expr,
                         const uint64_t cast_mode,
                         ObEvalCtx &ctx,
                         const common::ObAccuracy &acc,
                         bool has_lob_header,
                         const common::ObDatum &in_datum,
                         ObDatum &res_datum,
                         int &warning);

// 根据in_type,force_use_standard_format信息，从session中获取fromat_str
int common_get_nls_format(const ObBasicSessionInfo *session,
                                 const ObObjType in_type,
                                 const bool force_use_standard_format,
                                 ObString &format_str);

// 检查str以check_cs_type作为字符集是否合法
// strict_mode下，如果上述检查失败，返回错误码
// 否则返回以check_cs_type作为字符集的最长合法字符串
int string_collation_check(const bool is_strict_mode,
                           const common::ObCollationType check_cs_type,
                           const common::ObObjType str_type,
                           common::ObString &str);

// 将datum中的值转换为ob_time结构
int ob_datum_to_ob_time_with_date(const common::ObDatum &datum,
                                  const common::ObObjType type,
                                  const common::ObTimeZoneInfo* tz_info,
                                  common::ObTime& ob_time,
                                  const int64_t cur_ts_value,
                                  const bool is_dayofmonth,
                                  const ObDateSqlMode date_sql_mode,
                                  const bool has_lob_header);
int ob_datum_to_ob_time_without_date(const common::ObDatum &datum,
                                    const common::ObObjType type,
                                    const common::ObTimeZoneInfo *tz_info,
                                    common::ObTime &ob_time,
                                    const bool has_lob_header);
// 进行datetime到string的转换，除了ob_datum_cast.cpp需要使用，有的表达式也需要将结果
// 从datetime转为string, 例如ObExprTimeStampAdd
int common_datetime_string(const common::ObObjType in_type,
                           const common::ObObjType out_type,
                           const common::ObScale in_scale,
                           bool force_use_std_nls_format,
                           const int64_t in_val, ObEvalCtx &ctx, char *buf,
                           int64_t buf_len, int64_t &out_len);
int padding_char_for_cast(int64_t padding_cnt, 
                          const common::ObCollationType &padding_cs_type,
                          common::ObIAllocator &alloc, 
                          common::ObString &padding_res);

// copied from ob_obj_cast.cpp，函数逻辑没有修改，只是将输入参数从ObObj变为ObDatum
class ObDatumHexUtils
{
public:
static int hextoraw_string(const ObExpr &expr,
                    const common::ObString &in_str,
                    ObEvalCtx &ctx,
                    ObDatum &res_datum,
                    bool &has_set_res);
static int hextoraw(const ObExpr &expr, const common::ObDatum &in,
                    const common::ObObjType &in_type,
                    const common::ObCollationType &in_cs_type,
                    ObEvalCtx &ctx, ObDatum &res);
static int get_uint(const common::ObObjType &in_type, const common::ObDatum &in,
                    common::ObIAllocator &alloc, common::number::ObNumber &out);
static int uint_to_raw(const common::number::ObNumber &uint_num, const ObExpr &expr,
                           ObEvalCtx &ctx, ObDatum &res_datum);
static int unhex(const ObExpr &expr,
                 const common::ObString &in_str,
                 ObEvalCtx &ctx,
                 ObDatum &res_datum,
                 bool &has_set_res);
static int rawtohex(const ObExpr &expr,
                    const common::ObString &in_str,
                    ObEvalCtx &ctx,
                    ObDatum &res_datum);
static int hex(const ObExpr &expr,
               const common::ObString &in_str,
               ObEvalCtx &ctx,
               common::ObIAllocator &calc_alloc,
               ObDatum &res_datum,
               bool upper_case = true);
};

class ObDatumCast 
{
public:
  static int get_implicit_cast_function(const common::ObObjType in_type,
                                        const common::ObCollationType in_cs_type,
                                        const common::ObObjType out_type,
                                        const common::ObCollationType out_cs_type,
                                        const int64_t cast_mode,
                                        ObExpr::EvalFunc &eval_func);
  // 根据in_type/out_type等信息，获取cast func
  static int choose_cast_function(const common::ObObjType in_type,
                                  const common::ObCollationType in_cs_type,
                                  const common::ObObjType out_type,
                                  const common::ObCollationType out_cs_type,
                                  const int64_t cast_mode,
                                  common::ObIAllocator &allocator,
                                  ObExpr &rt_expr);
  static int get_enumset_cast_function(const common::ObObjTypeClass in_tc,
                                       const common::ObObjType out_type,
                                       ObExpr::EvalEnumSetFunc &eval_func);
  // 检查转换是否合法，有些检查是没办法反映在转换矩阵里面
  // 举例：string/text -> string/text时，如果是nonblob -> blob，
  // 要求nonblob必须是char/varchar类型，这种检查在转换矩阵中是没法反映出来的
  // 这些检查都会在该方法中进行
  static int check_can_cast(const common::ObObjType in_type,
                            const common::ObCollationType in_cs_type,
                            const common::ObObjType out_type,
                            const common::ObCollationType out_cs_type);
  // 有些cast是什么事情都不用做的，例如int->bit，直接调用cast_eval_arg()计算参数的值即可
  // CG阶段会使用该方法判断是否可以不用给cast表达式分配结果空间，直接指向参数的结果即可
  static int is_trivial_cast(const common::ObObjType in_type,
                                const common::ObCollationType in_cs_type,
                                const common::ObObjType out_type,
                                const common::ObCollationType out_cs_type,
                                const common::ObCastMode &cast_mode,
                                bool &just_eval_arg);

  // 功能同:
  //    EXPR_DEFINE_CAST_CTX(expr_ctx, cast_mode)
  //    EXPR_CAST_OBJ_V2(obj_type, obj, res_obj)
  static int cast_obj(ObEvalCtx &ctx, common::ObIAllocator &alloc,
                      const common::ObObjType &dst_type,
                      const common::ObCollationType &dst_cs_type,
                      const common::ObObj &src_obj,
                      common::ObObj &dst_obj);

  static bool is_implicit_cast(const ObExpr &expr)
  {
    bool bret = false;
    if (T_FUN_SYS_CAST == expr.type_ && CM_IS_IMPLICIT_CAST(expr.extra_)) {
      bret = true;
    }
    return bret;
  }

  static bool is_explicit_cast(const ObExpr &expr)
  {
    bool bret = false;
    if (T_FUN_SYS_CAST == expr.type_ && CM_IS_EXPLICIT_CAST(expr.extra_)) {
      bret = true;
    }
    return bret;
  }
};

class ObDatumCaster {
public:
  ObDatumCaster()
    : inited_(false),
      eval_ctx_(NULL),
      cast_expr_(NULL),
      extra_cast_expr_(NULL) {}
  ~ObDatumCaster() {}

  // init eval_ctx_/cast_expr_/extra_cast_expr_/frame. all mem comes from ObExecContext.
  // frame layout:
  // ObDatum | ObDatum | ObDynReserveBuf | res_buf | ObDynReserveBuf | res_buf
  // res_buf_len is 128
  int init(ObExecContext &ctx);

  // same with ObObjCaster::to_type().
  // input is ObExpr, and output is ObDatum, it's better if input is also ObDatum.
  // we will do this later if necessary.
  int to_type(const ObDatumMeta &dst_type,
              const ObExpr &src_expr,
              const common::ObCastMode &cm,
              common::ObDatum *&res,
              int64_t batch_idx = 0);
  // for xxx -> enumset.
  int to_type(const ObDatumMeta &dst_type,
              const common::ObIArray<common::ObString> &str_values,
              const ObExpr &src_expr,
              const common::ObCastMode &cm,
              common::ObDatum *&res,
              int64_t batch_idx = 0);

  int destroy();
private:
  DISALLOW_COPY_AND_ASSIGN(ObDatumCaster);

  // setup following data member of ObExpr:
  // datum_meta_, obj_meta_, obj_datum_map_, eval_func_,
  // args_, arg_cnt_, parents_, parent_cnt_, basic_funcs_.
  int setup_cast_expr(const ObDatumMeta &dst_type,
                      const ObExpr &src_expr,
                      const common::ObCastMode cm,
                      ObExpr &cast_expr);
  bool inited_;
  ObEvalCtx *eval_ctx_;
  ObExpr *cast_expr_;
  ObExpr *extra_cast_expr_;
};

} // namespace sql
} // namespace oceanbase

#endif // _OB_EXPR_DATUM_CAST_