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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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#include "vec/exec/distinct_vaggregation_node.h"

#include "runtime/runtime_state.h"
#include "vec/aggregate_functions/aggregate_function_uniq.h"
#include "vec/exec/vaggregation_node.h"

namespace doris {
class ObjectPool;
} // namespace doris

namespace doris::vectorized {

DistinctAggregationNode::DistinctAggregationNode(ObjectPool* pool, const TPlanNode& tnode,
                                                 const DescriptorTbl& descs)
        : AggregationNode(pool, tnode, descs) {
    dummy_mapped_data = pool->add(new char('A'));
}

Status DistinctAggregationNode::_distinct_pre_agg_with_serialized_key(
        doris::vectorized::Block* in_block, doris::vectorized::Block* out_block) {
    SCOPED_TIMER(_exec_timer);
    DCHECK(!_probe_expr_ctxs.empty());

    size_t key_size = _probe_expr_ctxs.size();
    ColumnRawPtrs key_columns(key_size);
    {
        SCOPED_TIMER(_expr_timer);
        for (size_t i = 0; i < key_size; ++i) {
            int result_column_id = -1;
            RETURN_IF_ERROR(_probe_expr_ctxs[i]->execute(in_block, &result_column_id));
            in_block->get_by_position(result_column_id).column =
                    in_block->get_by_position(result_column_id)
                            .column->convert_to_full_column_if_const();
            key_columns[i] = in_block->get_by_position(result_column_id).column.get();
        }
    }

    int rows = in_block->rows();
    _distinct_row.clear();
    _distinct_row.reserve(rows);

    RETURN_IF_CATCH_EXCEPTION(
            _emplace_into_hash_table_to_distinct(_distinct_row, key_columns, rows));

    bool mem_reuse = _make_nullable_keys.empty() && out_block->mem_reuse();
    if (mem_reuse) {
        for (int i = 0; i < key_size; ++i) {
            auto dst = out_block->get_by_position(i).column->assume_mutable();
            key_columns[i]->append_data_by_selector(dst, _distinct_row);
        }
    } else {
        ColumnsWithTypeAndName columns_with_schema;
        for (int i = 0; i < key_size; ++i) {
            auto distinct_column = key_columns[i]->clone_empty();
            key_columns[i]->append_data_by_selector(distinct_column, _distinct_row);
            columns_with_schema.emplace_back(std::move(distinct_column),
                                             _probe_expr_ctxs[i]->root()->data_type(),
                                             _probe_expr_ctxs[i]->root()->expr_name());
        }
        out_block->swap(Block(columns_with_schema));
    }
    return Status::OK();
}

void DistinctAggregationNode::_emplace_into_hash_table_to_distinct(IColumn::Selector& distinct_row,
                                                                   ColumnRawPtrs& key_columns,
                                                                   const size_t num_rows) {
    SCOPED_TIMER(_exec_timer);
    std::visit(
            [&](auto&& agg_method) -> void {
                SCOPED_TIMER(_hash_table_compute_timer);
                using HashMethodType = std::decay_t<decltype(agg_method)>;
                using AggState = typename HashMethodType::State;
                AggState state(key_columns);
                agg_method.init_serialized_keys(key_columns, num_rows);

                size_t row = 0;
                auto creator = [&](const auto& ctor, auto& key, auto& origin) {
                    HashMethodType::try_presis_key(key, origin, *_agg_arena_pool);
                    ctor(key, dummy_mapped_data);
                    distinct_row.push_back(row);
                };

                auto creator_for_null_key = [&](auto& mapped) {
                    mapped = dummy_mapped_data;
                    distinct_row.push_back(row);
                };

                SCOPED_TIMER(_hash_table_emplace_timer);
                for (; row < num_rows; ++row) {
                    agg_method.lazy_emplace(state, row, creator, creator_for_null_key);
                }

                COUNTER_UPDATE(_hash_table_input_counter, num_rows);
            },
            _agg_data->method_variant);
}

} // namespace doris::vectorized