/**
 * 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_OPT
#include "sql/optimizer/ob_log_distinct.h"
#include "sql/optimizer/ob_log_exchange.h"
#include "sql/optimizer/ob_log_sort.h"
#include "sql/optimizer/ob_log_set.h"
#include "sql/optimizer/ob_log_operator_factory.h"
#include "sql/optimizer/ob_join_order.h"
#include "sql/optimizer/ob_log_operator_factory.h"
#include "ob_opt_est_cost.h"
#include "ob_select_log_plan.h"
#include "ob_optimizer_util.h"
#include "ob_opt_selectivity.h"
#include "common/ob_smart_call.h"
#include "sql/rewrite/ob_transform_utils.h"

using namespace oceanbase;
using namespace sql;
using namespace oceanbase::common;

namespace oceanbase
{
namespace sql
{

const char *ObLogDistinct::get_name() const
{
  return MERGE_AGGREGATE == algo_ ? "MERGE DISTINCT" : "HASH DISTINCT";
}

int ObLogDistinct::get_plan_item_info(PlanText &plan_text,
                                      ObSqlPlanItem &plan_item)
{
  int ret = OB_SUCCESS;
  const ObIArray<ObRawExpr*> &distinct = distinct_exprs_;
  if (OB_FAIL(ObLogicalOperator::get_plan_item_info(plan_text, plan_item))) {
    LOG_WARN("failed to get base plan item info", K(ret));
  } else {
    BEGIN_BUF_PRINT;
    EXPLAIN_PRINT_EXPRS(distinct, type);
    if (OB_SUCC(ret) && is_block_mode_) {
      ret = BUF_PRINTF(", block");
    }
    END_BUF_PRINT(plan_item.special_predicates_,
                  plan_item.special_predicates_len_);
  }
  return ret;
}


int ObLogDistinct::inner_replace_op_exprs(ObRawExprReplacer &replacer)
{
  int ret = OB_SUCCESS;
  if(OB_FAIL(replace_exprs_action(replacer, distinct_exprs_))) {
    SQL_OPT_LOG(WARN, "failed to replace agg exprs in distinct op", K(ret));
  }
  return ret;
}

int ObLogDistinct::compute_op_ordering()
{
  int ret = OB_SUCCESS;
  ObLogicalOperator *child = NULL;
  if (algo_ == HASH_AGGREGATE) {
    // do nothing
  } else if (OB_FAIL(ObLogicalOperator::compute_op_ordering())) {
    LOG_WARN("failed to compute op ordering", K(ret));
  } else {
    is_local_order_ = is_fully_partition_wise() && !get_op_ordering().empty();
  }
  return ret;
}

int ObLogDistinct::est_width()
{
  int ret = OB_SUCCESS;
  double width = 0.0;
  ObSEArray<ObRawExpr*, 16> output_exprs;
  if (OB_ISNULL(get_plan())) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("invalid plan", K(ret));
  } else if (OB_FAIL(get_distinct_output_exprs(output_exprs))) {
    LOG_WARN("failed to get distinct output exprs", K(ret));
  } else if (OB_FAIL(ObOptEstCost::estimate_width_for_exprs(get_plan()->get_basic_table_metas(),
                                                            get_plan()->get_selectivity_ctx(),
                                                            output_exprs,
                                                            width))) {
    LOG_WARN("failed to estimate width for output distinct exprs", K(ret));
  } else {
    set_width(width);
    LOG_TRACE("est width for distinct", K(output_exprs), K(width));
  }
  return ret;
}

int ObLogDistinct::get_distinct_output_exprs(ObIArray<ObRawExpr *> &output_exprs)
{
  int ret = OB_SUCCESS;
  ObLogPlan *plan = NULL;
  ObSEArray<ObRawExpr*, 16> candi_exprs;
  ObSEArray<ObRawExpr*, 16> extracted_col_aggr_winfunc_exprs;
  if (OB_ISNULL(plan = get_plan())) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("invalid input", K(ret));
  } else if (OB_FAIL(append_array_no_dup(candi_exprs, plan->get_select_item_exprs_for_width_est()))) {
    LOG_WARN("failed to add into output exprs", K(ret));
  } else if (OB_FAIL(append_array_no_dup(candi_exprs, plan->get_orderby_exprs_for_width_est()))) {
    LOG_WARN("failed to add into output exprs", K(ret));  
  } else if (OB_FAIL(ObRawExprUtils::extract_col_aggr_winfunc_exprs(candi_exprs,
                                                                    extracted_col_aggr_winfunc_exprs))) {
  } else if (OB_FAIL(append_array_no_dup(output_exprs, extracted_col_aggr_winfunc_exprs))) {
    LOG_WARN("failed to add into output exprs", K(ret));
  } else {/*do nothing*/}
  return ret;
}

int ObLogDistinct::est_cost()
{
  int ret = OB_SUCCESS;
  double distinct_cost = 0.0;
  ObLogicalOperator *child = NULL;
  if (OB_ISNULL(child = get_child(ObLogicalOperator::first_child))) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpected null", K(child), K(ret));
  } else if (OB_UNLIKELY(total_ndv_ < 0)) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpected total ndv", K(total_ndv_), K(ret));
  } else if (OB_FAIL(inner_est_cost(get_parallel(), child->get_card(), total_ndv_, distinct_cost))) {
    LOG_WARN("failed to est distinct cost", K(ret));
  } else {
    set_op_cost(distinct_cost);
    set_cost(child->get_cost() + distinct_cost);
    set_card(total_ndv_);
  }
  return ret;
}

int ObLogDistinct::do_re_est_cost(EstimateCostInfo &param, double &card, double &op_cost, double &cost)
{
  int ret = OB_SUCCESS;
  ObLogicalOperator *child = NULL;
  if (OB_ISNULL(child = get_child(ObLogicalOperator::first_child))) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("unexpect null child", K(ret));
  } else if (OB_UNLIKELY(total_ndv_ < 0)) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpected total ndv", K(total_ndv_), K(ret));
  } else {
    double child_card = child->get_card();
    double child_cost = child->get_cost();
    double child_ndv = total_ndv_;
    const int64_t parallel = param.need_parallel_;
    double origin_child_card = child_card;
    bool need_scale_ndv = false;
    if (param.need_row_count_ >= 0 && 
        child_card > 0 &&
        total_ndv_ > 0 &&
        param.need_row_count_ < child_card &&
        param.need_row_count_ < total_ndv_) {
      child_ndv = param.need_row_count_;
      param.need_row_count_ = child_card * (1 - std::pow((1 - child_ndv / total_ndv_), total_ndv_ / child_card));
    } else {
      param.need_row_count_ = -1;
      need_scale_ndv = true;
    }
    if (OB_FAIL(SMART_CALL(child->re_est_cost(param, child_card, child_cost)))) {
      LOG_WARN("failed to re est child cost", K(ret));
    } else if (need_scale_ndv &&
               FALSE_IT(child_ndv = std::min(child_ndv, ObOptSelectivity::scale_distinct(child_card, origin_child_card, child_ndv)))) {
      // do nothing
    } else if (OB_FAIL(inner_est_cost(parallel, child_card, child_ndv, op_cost))) {
      LOG_WARN("failed to est distinct cost", K(ret));
    } else {
      cost = child_cost + op_cost;
      card = child_ndv;
      if (param.override_) {
        total_ndv_ = child_ndv;
      }
    }
  }
  return ret;
}

int ObLogDistinct::inner_est_cost(const int64_t parallel, double child_card, double child_ndv, double &op_cost)
{
  int ret = OB_SUCCESS;
  double per_dop_card = 0.0;
  double per_dop_ndv = 0.0;
  ObLogicalOperator *child = NULL;
  if (OB_ISNULL(get_plan()) ||
      OB_ISNULL(child = get_child(ObLogicalOperator::first_child))) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpected null", K(child), K(ret));
  } else if (OB_UNLIKELY(parallel < 1)) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpected parallel", K(parallel), K(ret));
  } else {
    ObOptimizerContext &opt_ctx = get_plan()->get_optimizer_context();
    per_dop_card = child_card / parallel;
    if (parallel > 1) {
      if (is_push_down()) {
        per_dop_ndv = ObOptSelectivity::scale_distinct(per_dop_card, child_card, child_ndv);
      } else {
        per_dop_ndv = child_ndv / parallel;
      }
    } else {
      per_dop_ndv = child_ndv;
    }

    if (MERGE_AGGREGATE == algo_) {
      op_cost = ObOptEstCost::cost_merge_distinct(per_dop_card,
                                                  per_dop_ndv,
                                                  child->get_width(),
                                                  distinct_exprs_,
                                                  opt_ctx);
    } else {
      op_cost = ObOptEstCost::cost_hash_distinct(per_dop_card,
                                                per_dop_ndv,
                                                child->get_width(),
                                                distinct_exprs_,
                                                opt_ctx);
    }
  }
  return ret;
}

uint64_t ObLogDistinct::hash(uint64_t seed) const
{
  seed = do_hash(algo_, seed);
  seed = ObLogicalOperator::hash(seed);

  return seed;
}

int ObLogDistinct::compute_fd_item_set()
{
  int ret = OB_SUCCESS;
  const ObLogicalOperator *child = NULL;
  ObFdItemSet *fd_item_set = NULL;
  ObTableFdItem *fd_item = NULL;
  if (OB_ISNULL(child = get_child(ObLogicalOperator::first_child)) ||
      OB_ISNULL(my_plan_) || OB_ISNULL(get_stmt())) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("get unexpect null", K(ret), K(child), K(my_plan_), K(get_stmt()));
  } else if (OB_FAIL(my_plan_->get_fd_item_factory().create_fd_item_set(fd_item_set))) {
    LOG_WARN("failed to create fd item set", K(ret));
  } else if (OB_FAIL(fd_item_set->assign(child->get_fd_item_set()))) {
    LOG_WARN("failed to assign fd item set", K(ret));
  } else if (!ObTransformUtils::need_compute_fd_item_set(distinct_exprs_)) {
    //do nothing
  }else if (OB_FAIL(my_plan_->get_fd_item_factory().create_table_fd_item(fd_item,
                                                                          true,
                                                                          distinct_exprs_,
                                                                          get_table_set()))) {
    LOG_WARN("failed to create fd item", K(ret));
  } else if (OB_FAIL(fd_item_set->push_back(fd_item))) {
    LOG_WARN("failed to push back fd item", K(ret));
  } else if (OB_FAIL(deduce_const_exprs_and_ft_item_set(*fd_item_set))) {
    LOG_WARN("falied to deduce fd item set", K(ret));
  } else {
    set_fd_item_set(fd_item_set);
  }
  return ret;
}

int ObLogDistinct::allocate_granule_pre(AllocGIContext &ctx)
{
  int ret = OB_SUCCESS;
  if (OB_FAIL(pw_allocate_granule_pre(ctx))) {
    LOG_WARN("failed to allocate partition wise granule", K(ret));
  } else { /*do nothing*/ }
  return ret;
}

int ObLogDistinct::allocate_granule_post(AllocGIContext &ctx)
{
  return pw_allocate_granule_post(ctx);
}

int ObLogDistinct::get_op_exprs(ObIArray<ObRawExpr*> &all_exprs)
{
  int ret = OB_SUCCESS;
  if (OB_FAIL(append(all_exprs, distinct_exprs_))) {
    LOG_WARN("failed to add exprs to ctx", K(ret));
  } else if (OB_FAIL(ObLogicalOperator::get_op_exprs(all_exprs))) {
    LOG_WARN("failed to get op exprs", K(ret));
  } else { /*do nothing*/ }

  return ret;
}

int ObLogDistinct::print_outline_data(PlanText &plan_text)
{
  int ret = OB_SUCCESS;
  char *buf = plan_text.buf_;
  int64_t &buf_len = plan_text.buf_len_;
  int64_t &pos = plan_text.pos_;
  const ObDMLStmt *stmt = NULL;
  ObString qb_name;
  const ObLogicalOperator *child = NULL;
  const ObLogicalOperator *op = NULL;
  if (is_push_down()) {
    /* print outline in top distinct */
  } else if (OB_ISNULL(get_plan()) || OB_ISNULL(stmt = get_plan()->get_stmt())
      || OB_ISNULL(child = get_child(ObLogicalOperator::first_child))) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("unexpected NULL", K(ret), K(get_plan()), K(stmt), K(child));
  } else if (OB_FAIL(child->get_pushdown_op(log_op_def::LOG_DISTINCT, op))) {
    LOG_WARN("failed to get push down distinct", K(ret));
  } else if (OB_FAIL(stmt->get_qb_name(qb_name))) {
    LOG_WARN("fail to get qb_name", K(ret), K(stmt->get_stmt_id()));
  } else if (NULL != op &&
             OB_FAIL(BUF_PRINTF("%s%s(@\"%.*s\")",
                                ObQueryHint::get_outline_indent(plan_text.is_oneline_),
                                ObHint::get_hint_name(T_DISTINCT_PUSHDOWN),
                                qb_name.length(),
                                qb_name.ptr()))) {
    LOG_WARN("fail to print buffer", K(ret), K(buf), K(buf_len), K(pos));
  } else if (HASH_AGGREGATE == algo_ &&
             OB_FAIL(BUF_PRINTF("%s%s(@\"%.*s\")",
                                ObQueryHint::get_outline_indent(plan_text.is_oneline_),
                                ObHint::get_hint_name(T_USE_HASH_DISTINCT),
                                qb_name.length(),
                                qb_name.ptr()))) {
    LOG_WARN("fail to print buffer", K(ret), K(buf), K(buf_len), K(pos));
  } else {/*do nothing*/}
  return ret;
}

int ObLogDistinct::print_used_hint(PlanText &plan_text)
{
  int ret = OB_SUCCESS;
  if (is_push_down()) {
    /* print outline in top distinct */
  } else if (OB_ISNULL(get_plan())) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("unexpected NULL", K(ret), K(get_plan()));
  } else {
    const ObHint *use_hash = get_plan()->get_log_plan_hint().get_normal_hint(T_USE_HASH_DISTINCT);
    const ObHint *pushdown = get_plan()->get_log_plan_hint().get_normal_hint(T_DISTINCT_PUSHDOWN);
    if (NULL != use_hash) {
      bool match_hint = (HASH_AGGREGATE == algo_ && use_hash->is_enable_hint())
                        || (MERGE_AGGREGATE == algo_ && use_hash->is_disable_hint());
      if (match_hint && OB_FAIL(use_hash->print_hint(plan_text))) {
        LOG_WARN("failed to print used hint for group by", K(ret), K(*use_hash));
      }
    }
    if (OB_SUCC(ret) && NULL != pushdown) {
      const ObLogicalOperator *child = NULL;
      const ObLogicalOperator *op = NULL;
      if (OB_ISNULL(child = get_child(ObLogicalOperator::first_child))) {
        ret = OB_ERR_UNEXPECTED;
        LOG_WARN("unexpected NULL", K(ret), K(child));
      } else if (OB_FAIL(child->get_pushdown_op(log_op_def::LOG_DISTINCT, op))) {
        LOG_WARN("failed to get push down distinct", K(ret));
      } else {
        bool match_hint = NULL == op ? pushdown->is_disable_hint()
                                     : pushdown->is_enable_hint();
        if (match_hint && OB_FAIL(pushdown->print_hint(plan_text))) {
          LOG_WARN("failed to print used hint for group by", K(ret), K(*pushdown));
        }
      }
    }
  }
  return ret;
}

int ObLogDistinct::get_card_without_filter(double &card)
{
  int ret = OB_SUCCESS;
  card = get_total_ndv();
  return ret;
}

}
}