/**
 * 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 "sql/engine/expr/ob_expr_regexp_replace.h"
#include "lib/oblog/ob_log.h"
#include "share/object/ob_obj_cast.h"
#include "sql/engine/ob_exec_context.h"
#include "sql/engine/ob_physical_plan_ctx.h"
#include "sql/engine/ob_physical_plan.h"
#include "sql/engine/expr/ob_expr_util.h"
#include "sql/engine/expr/ob_expr_regexp_count.h"
#include "sql/engine/expr/ob_expr_operator.h"

using namespace oceanbase::common;

namespace oceanbase
{
namespace sql
{

ObExprRegexpReplace::ObExprRegexpReplace(ObIAllocator &alloc)
  : ObStringExprOperator(alloc, T_FUN_SYS_REGEXP_REPLACE, N_REGEXP_REPLACE, MORE_THAN_ONE)
{
}

ObExprRegexpReplace::~ObExprRegexpReplace()
{
}

int ObExprRegexpReplace::calc_result_typeN(ObExprResType &type,
                                           ObExprResType *types,
                                           int64_t param_num,
                                           common::ObExprTypeCtx &type_ctx) const
{
  UNUSED(type_ctx);
  int ret = OB_SUCCESS;
  CK(NULL != type_ctx.get_raw_expr());
  if (OB_FAIL(ret)) {
  } else if (OB_UNLIKELY(param_num < 2 || param_num > 6)) {
    ret = OB_ERR_PARAM_SIZE;
    LOG_WARN("param number of regexp_replace at least 2 and at most 6", K(ret), K(param_num));
  } else {
    for (int i = 0; OB_SUCC(ret) && i < param_num; i++) {
      if (!types[i].is_null() && !is_type_valid(types[i].get_type())) {
        ret = OB_INVALID_ARGUMENT;
        LOG_WARN("the parameter is not castable", K(ret), K(i));
      }
    }
    if (lib::is_oracle_mode()) {
      //deduce length
      ObExprResType &text = types[0];
      int64_t to_len = types[2].get_length();
      common::ObLength len = text.get_length();
      int64_t offset = len * to_len;
      len = static_cast<common::ObLength>(len + offset);
      CK(len <= INT32_MAX);
      type.set_length(static_cast<common::ObLength>(len));
      auto input_params = make_const_carray(&types[0]);
      OZ(aggregate_string_type_and_charset_oracle(
              *type_ctx.get_session(), input_params, type, PREFER_VAR_LEN_CHAR));
      OZ(deduce_string_param_calc_type_and_charset(*type_ctx.get_session(), type, input_params));
      OX(type.set_length_semantics(type_ctx.get_session()->get_actual_nls_length_semantics()));
    } else {
      const common::ObLengthSemantics default_length_semantics = (OB_NOT_NULL(type_ctx.get_session())
              ? type_ctx.get_session()->get_actual_nls_length_semantics()
              : common::LS_BYTE);
      if (types[0].is_lob()) {
        type.set_type(types[0].get_type());
      } else {
        type.set_varchar();
        type.set_length_semantics(types[0].is_varchar_or_char() ? types[0].get_length_semantics() : default_length_semantics);
      }
      //建表列的最大长度
      type.set_length(OB_MAX_COLUMN_NAMES_LENGTH);
      ret = aggregate_charsets_for_string_result(type, types, 1, type_ctx.get_coll_type());
    }
    if (OB_SUCC(ret)) {
      switch (param_num) {//because of regexp engine need utf8 code, here need reset calc collation type and can implicit cast.
        case 6:
          types[5].set_calc_type(ObVarcharType);
        case 5:
          if (lib::is_oracle_mode()) {
            types[4].set_calc_type(ObNumberType);
          } else {
            type_ctx.set_cast_mode(type_ctx.get_cast_mode() | CM_STRING_INTEGER_TRUNC);
            types[4].set_calc_type(ObIntType);
          }
        case 4:
          if (lib::is_oracle_mode()) {
            types[3].set_calc_type(ObNumberType);
          } else {
            type_ctx.set_cast_mode(type_ctx.get_cast_mode() | CM_STRING_INTEGER_TRUNC);
            types[3].set_calc_type(ObIntType);
          }
        case 3:
          types[2].set_calc_type(ObVarcharType);
          if (ObCharset::is_bin_sort(types[2].get_calc_collation_type())) {
            types[2].set_calc_collation_type(CS_TYPE_UTF8MB4_BIN);
          } else {
            types[2].set_calc_collation_type(CS_TYPE_UTF8MB4_GENERAL_CI);
          }
          types[2].set_calc_collation_level(type.get_collation_level());
        case 2:
          types[1].set_calc_type(ObVarcharType);
          if (ObCharset::is_bin_sort(types[1].get_calc_collation_type())) {
            types[1].set_calc_collation_type(CS_TYPE_UTF8MB4_BIN);
          } else {
            types[1].set_calc_collation_type(CS_TYPE_UTF8MB4_GENERAL_CI);
          }
          types[1].set_calc_collation_level(type.get_collation_level());
          if (!types[0].is_clob()) {
            types[0].set_calc_type(ObVarcharType);
            if (ObCharset::is_bin_sort(types[0].get_calc_collation_type())) {
              types[0].set_calc_collation_type(CS_TYPE_UTF8MB4_BIN);
            } else {
              types[0].set_calc_collation_type(CS_TYPE_UTF8MB4_GENERAL_CI);
            }
            types[0].set_calc_collation_level(type.get_collation_level());
          }
        default:
          // already check before
          break;
      }
    }
  }
  return ret;
}

int ObExprRegexpReplace::calc(common::ObString &ret_str,
                              const ObString &text,
                              const ObString &pattern,
                              const ObString &replacement_string,
                              int64_t position,
                              int64_t occurrence,
                              const ObCollationType cs_type,
                              const ObString &match_param,
                              int null_argument_idx,
                              bool reusable,
                              ObExprRegexContext* regexp_ptr,
                              ObExprStringBuf &string_buf,
                              ObIAllocator &exec_ctx_alloc)
{
  int ret = OB_SUCCESS;
  //begin with '^'
  bool from_begin = false;
  //end with '$'
  bool from_end = false;
  ret_str.reset();
  ObExprRegexContext *regexp_replace_ctx = regexp_ptr;
  ObSEArray<uint32_t, 4> begin_locations(common::ObModIds::OB_SQL_EXPR_REPLACE,
                                           common::OB_MALLOC_NORMAL_BLOCK_SIZE);
  int flags = 0, multi_flag = 0;
  if (OB_ISNULL(regexp_replace_ctx)) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("regexp ptr is null", K(ret));
  } else if (OB_FAIL(ObExprRegexpCount::get_regexp_flags(cs_type, match_param,
                                                         flags, multi_flag))) {
    LOG_WARN("fail to get regexp flags", K(ret), K(match_param));
  } else if (OB_FAIL(regexp_replace_ctx->init(pattern, flags,
                                              reusable ? exec_ctx_alloc : string_buf,
                                              reusable))) {
    LOG_WARN("fail to init regexp", K(flags));
  }
  if (OB_SUCC(ret)) {
    if (-1 != null_argument_idx) {
      //此处是为了更好的和oracle行为一致
      if ((null_argument_idx == 0 || (lib::is_oracle_mode() && null_argument_idx == 1)) &&
          text.length() != 0) {
        ret_str = text;
      } else {
        ret_str = ObString(); // NULL
      }
    } else if (position <= 0 || occurrence < 0) {
      if (lib::is_oracle_mode()) {
        ret = OB_ERR_ARGUMENT_OUT_OF_RANGE;
      } else {
        ret = OB_INVALID_ARGUMENT;
      }
      LOG_WARN("position or occurrence is invalid", K(ret), K(position), K(occurrence));
    } else {
      if (OB_NOT_NULL(pattern)) {
        const char* pat = pattern.ptr();
        if ('^' == pat[0]) {
          from_begin = true;
        } else if ('$' == pat[pattern.length() - 1]) {
          from_end = true;
        }
      }
      if (OB_FAIL(begin_locations.push_back(position - 1))) {
        LOG_WARN("begin_locations push_back error", K(ret));
      } else if (from_begin && 1 != position && !multi_flag) {
        ret_str = text;
      } else {
        ObSEArray<size_t, 4> byte_num;
        ObSEArray<size_t, 4> byte_offsets;
        if (OB_FAIL(ObExprUtil::get_mb_str_info(text,
                                                ObCharset::get_default_collation_oracle(CHARSET_UTF8MB4),
                                                byte_num,
                                                byte_offsets))) {
          LOG_WARN("failed to get mb str info", K(ret));
        } else if (multi_flag) {
          if (from_begin && 1 != position) {
            begin_locations.pop_back();
          }
          const char *text_ptr = text.ptr();
          for (int64_t idx = position; OB_SUCC(ret) && idx < byte_offsets.count() - 1; ++idx) {
            if (OB_UNLIKELY(byte_offsets.at(idx) >= text.length())) {
              ret = OB_ERR_UNEXPECTED;
              LOG_WARN("get unexpected error", K(byte_offsets.at(idx)), K(text.length()), K(ret));
            } else if (text_ptr[byte_offsets.at(idx)] == '\n') {
              if (OB_FAIL(begin_locations.push_back(idx + 1))) {
                LOG_WARN("begin_locations push_back error", K(ret));
              }
            }
          }
        }
        if (OB_SUCC(ret)) {
          if (OB_FAIL(regexp_replace_ctx->replace_substr(text, replacement_string,
                                                                occurrence, string_buf,
                                                                byte_offsets, ret_str, from_begin,
                                                                from_end, begin_locations))) {
            LOG_WARN("fail to replace substr", K(ret), K(text), K(replacement_string));
          }
        }
      }
    }
  }
  return ret;
}

int ObExprRegexpReplace::cg_expr(ObExprCGCtx &op_cg_ctx, const ObRawExpr &raw_expr, ObExpr &rt_expr) const
{
  int ret = OB_SUCCESS;
  UNUSED(op_cg_ctx);
  CK(2 <= rt_expr.arg_cnt_ && rt_expr.arg_cnt_ <= 6);
  CK(raw_expr.get_param_count() >= 2);
  if (OB_SUCC(ret)) {
    const ObRawExpr *text = raw_expr.get_param_expr(0);
    const ObRawExpr *pattern = raw_expr.get_param_expr(1);
    if (OB_ISNULL(text) || OB_ISNULL(pattern)) {
      ret = OB_ERR_UNEXPECTED;
      LOG_WARN("get unexpected null", K(text), K(pattern), K(ret));
    } else {
      const bool const_text = text->is_const_expr();
      const bool const_pattern = pattern->is_const_expr();
      rt_expr.extra_ = (!const_text && const_pattern) ? 1 : 0;
      rt_expr.eval_func_ = &eval_regexp_replace;
      LOG_DEBUG("regexp reeplace expr cg", K(const_text), K(const_pattern), K(rt_expr.extra_));
    }
  }
  return ret;
}

int ObExprRegexpReplace::eval_regexp_replace(
    const ObExpr &expr, ObEvalCtx &ctx, ObDatum &expr_datum)
{
  int ret = OB_SUCCESS;
  ObDatum *text = NULL;
  ObDatum *pattern = NULL;
  ObDatum *to = NULL;
  ObDatum *position = NULL;
  ObDatum *occurrence = NULL;
  ObDatum *flags = NULL;
  if (OB_FAIL(expr.eval_param_value(ctx, text, pattern, to, position, occurrence, flags))) {
    LOG_WARN("evaluate parameters failed", K(ret));
  } else if (lib::is_oracle_mode() && pattern->is_null()) {
    expr_datum.set_datum(*text);
  } else if (expr.args_[0]->datum_meta_.is_clob() && (0 == text->get_string().length())) {
    expr_datum.set_datum(*text);
  } else {
    // %to and %flags may be null
    bool is_flag_null = (NULL != flags && flags->is_null());
    const bool null_result = (text->is_null()
                              || (NULL != position && position->is_null())
                              || (NULL != occurrence && occurrence->is_null())
                              || (lib::is_mysql_mode() && NULL != pattern && pattern->is_null())
                              || (lib::is_mysql_mode() && NULL != to && to->is_null())
                              || (lib::is_mysql_mode() && is_flag_null));
    // same with calc_resultN
    int null_idx = -1;
    for (int64_t i = 0; i < expr.arg_cnt_; i++) {
      if (expr.locate_param_datum(ctx, i).is_null() && (i != 5 && i != 2)) {
        null_idx = null_idx > i ? null_idx : i;
      }
    }
    int64_t pos = 1;
    int64_t occur = 0;
    if (OB_FAIL(ObExprUtil::get_int_param_val(position, pos))
        || OB_FAIL(ObExprUtil::get_int_param_val(occurrence, occur))) {
      LOG_WARN("get integer parameter value failed", K(ret));
    } else if (pos < 0 || occur < 0) {
      ret = OB_INVALID_ARGUMENT;
      LOG_WARN("regexp_replace position or occurrence is invalid", K(ret), K(pos), K(occur));
    }
    ObString to_str = (NULL != to && !to->is_null()) ? to->get_string() : ObString();
    ObString match_param = (NULL != flags && !flags->is_null())
        ? flags->get_string()
        : ObString();

    ObString res;
    ObEvalCtx::TempAllocGuard alloc_guard(ctx);
    ObIAllocator &alloc = alloc_guard.get_allocator();
    ObExprRegexContext local_regex_ctx;
    ObExprRegexContext *regexp_ctx = &local_regex_ctx;
    const bool reusable = (0 != expr.extra_) && ObExpr::INVALID_EXP_CTX_ID != expr.expr_ctx_id_;
    if (OB_SUCC(ret) && reusable) {
      if (NULL == (regexp_ctx = static_cast<ObExprRegexContext *>(
                  ctx.exec_ctx_.get_expr_op_ctx(expr.expr_ctx_id_)))) {
        if (OB_FAIL(ctx.exec_ctx_.create_expr_op_ctx(expr.expr_ctx_id_, regexp_ctx))) {
          LOG_WARN("create expr regex context failed", K(ret), K(expr));
        } else if (OB_ISNULL(regexp_ctx)) {
          ret = OB_ERR_UNEXPECTED;
          LOG_WARN("NULL context returned", K(ret));
        }
      }
    }
    if (OB_FAIL(ret)) {
    } else if (lib::is_mysql_mode() && !pattern->is_null() &&
               pattern->get_string().empty() && !is_flag_null) {//compatible mysql
      ret = OB_ERR_REGEXP_ERROR;
      LOG_WARN("empty regex expression", K(ret));
    } else if (OB_FAIL(calc(res, text->get_string(), pattern->get_string(), to_str, pos, occur,
                            expr.datum_meta_.cs_type_, match_param,
                            null_idx, reusable, regexp_ctx, alloc,
                            ctx.exec_ctx_.get_allocator()))) {
      LOG_WARN("calc failed", K(ret));
    } else if (null_result) {
      expr_datum.set_null();
    } else {
      if (res.empty() && lib::is_oracle_mode()) {
        expr_datum.set_null();
      } else {
        ObExprStrResAlloc out_alloc(expr, ctx);
        ObString out;
        if (OB_FAIL(ObExprUtil::convert_string_collation(res,
                                                         expr.args_[0]->datum_meta_.cs_type_,
                                                         out,
                                                         expr.datum_meta_.cs_type_,
                                                         out_alloc))) {
          LOG_WARN("convert charset failed", K(ret));
        } else {
          if (out.ptr() == res.ptr()) {
            // res is allocated in temporary allocator, deep copy here.
            char *mem = expr.get_str_res_mem(ctx, res.length());
            if (OB_ISNULL(mem)) {
              ret = OB_ALLOCATE_MEMORY_FAILED;
              LOG_WARN("allocate memory failed", K(ret));
            } else {
              MEMCPY(mem, res.ptr(), res.length());
              expr_datum.set_string(mem, res.length());
            }
          } else {
            expr_datum.set_string(out.ptr(), out.length());
          }
        }
      }
    }
  }

  return ret;
}

}
}