// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

#pragma once

#include <memory>

#include <vector>

#include "core/block/block.h"

#include "exec/connector/skewed_partition_rebalancer.h"

#include "exec/partitioner/partitioner.h"

namespace doris {

class ScaleWriterPartitioner final : public PartitionerBase {

public:

    ScaleWriterPartitioner(int channel_size, int partition_count, int task_count,

                           int task_bucket_count,

                           long min_partition_data_processed_rebalance_threshold,

                           long min_data_processed_rebalance_threshold)

            : PartitionerBase(partition_count),

              _channel_size(channel_size),

              _partition_rebalancer(partition_count, task_count, task_bucket_count,

                                    min_partition_data_processed_rebalance_threshold,

                                    min_data_processed_rebalance_threshold),

              _partition_row_counts(partition_count, 0),

              _partition_writer_ids(partition_count, -1),

              _partition_writer_indexes(partition_count, 0),

              _task_count(task_count),

              _task_bucket_count(task_bucket_count),

              _min_partition_data_processed_rebalance_threshold(

                      min_partition_data_processed_rebalance_threshold),

              _min_data_processed_rebalance_threshold(min_data_processed_rebalance_threshold) {

        _crc_partitioner =

                std::make_unique<Crc32HashPartitioner<ShuffleChannelIds>>(_partition_count);

    }

    ~ScaleWriterPartitioner() override = default;

    Status init(const std::vector<TExpr>& texprs) override {

        return _crc_partitioner->init(texprs);

    }

    Status prepare(RuntimeState* state, const RowDescriptor& row_desc) override {

        return _crc_partitioner->prepare(state, row_desc);

    }

    Status open(RuntimeState* state) override { return _crc_partitioner->open(state); }

    Status close(RuntimeState* state) override { return _crc_partitioner->close(state); }

    Status do_partitioning(RuntimeState* state, Block* block) const override {

        _hash_vals.resize(block->rows());

        for (int partition_id = 0; partition_id < _partition_row_counts.size(); partition_id++) {

            _partition_row_counts[partition_id] = 0;

            _partition_writer_ids[partition_id] = -1;

        }

        _partition_rebalancer.rebalance();

        RETURN_IF_ERROR(_crc_partitioner->do_partitioning(state, block));

        const auto& channel_ids = _crc_partitioner->get_channel_ids();

        for (size_t position = 0; position < block->rows(); position++) {

            auto partition_id = channel_ids[position];

            _partition_row_counts[partition_id] += 1;

            // Get writer id for this partition by looking at the scaling state

            int writer_id = _partition_writer_ids[partition_id];

            if (writer_id == -1) {

                writer_id = _get_next_writer_id(partition_id);

                _partition_writer_ids[partition_id] = writer_id;

            }

            _hash_vals[position] = writer_id;

        }

        for (int partition_id = 0; partition_id < _partition_row_counts.size(); partition_id++) {

            _partition_rebalancer.add_partition_row_count(partition_id,

                                                          _partition_row_counts[partition_id]);

        }

        _partition_rebalancer.add_data_processed(block->bytes());

        return Status::OK();

    }

    const std::vector<HashValType>& get_channel_ids() const override { return _hash_vals; }

    Status clone(RuntimeState* state, std::unique_ptr<PartitionerBase>& partitioner) override {

        partitioner = std::make_unique<ScaleWriterPartitioner>(

                _channel_size, (int)_partition_count, _task_count, _task_bucket_count,

                _min_partition_data_processed_rebalance_threshold,

                _min_data_processed_rebalance_threshold);

        return Status::OK();

    }

private:

    int _get_next_writer_id(HashValType partition_id) const {

        return _partition_rebalancer.get_task_id(partition_id,

                                                 _partition_writer_indexes[partition_id]++);

    }

    int _channel_size;

    std::unique_ptr<PartitionerBase> _crc_partitioner;

    mutable SkewedPartitionRebalancer _partition_rebalancer;

    mutable std::vector<int> _partition_row_counts;

    mutable std::vector<int> _partition_writer_ids;

    mutable std::vector<int> _partition_writer_indexes;

    mutable std::vector<HashValType> _hash_vals;

    const int _task_count;

    const int _task_bucket_count;

    const long _min_partition_data_processed_rebalance_threshold;

    const long _min_data_processed_rebalance_threshold;

};

} // namespace doris