// 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 <gen_cpp/Opcodes_types.h>

#include "core/column/column.h"

#include "storage/segment/common.h"

namespace doris {

using ScoreMap = phmap::flat_hash_map<segment_v2::rowid_t, float>;

using ScoreMapIterator = ScoreMap::const_iterator;

enum class OrderType {

    ASC,

    DESC,

};

struct ScoreRangeFilter {

    TExprOpcode::type op;

    double threshold;

    bool pass(float score) const {

        return (op == TExprOpcode::GT) ? (score > threshold) : (score >= threshold);

    }

};

using ScoreRangeFilterPtr = std::shared_ptr<ScoreRangeFilter>;

class CollectionSimilarity {

public:

    CollectionSimilarity() { _bm25_scores.reserve(1024); }

    ~CollectionSimilarity() = default;

    void collect(segment_v2::rowid_t row_id, float score);

    // Hands the collected scores over to the caller and leaves this instance empty.

    // A reader that computes per-document scores inside its own query() cannot return them

    // through the query API, so it publishes them into a throwaway CollectionSimilarity that the

    // caller then relocates into a scorer. Moving instead of copying keeps that hand-off free of

    // a full rehash of a map that can hold one entry per matched row.

    ScoreMap release_scores() {

        ScoreMap released = std::move(_bm25_scores);

        // A moved-from flat_hash_map is valid but unspecified, not guaranteed empty, so make the

        // "leaves this instance empty" half of the contract true rather than merely likely.

        _bm25_scores.clear();

        return released;

    }

    void get_bm25_scores(roaring::Roaring* row_bitmap, IColumn::MutablePtr& scores,

                         std::unique_ptr<std::vector<uint64_t>>& row_ids,

                         const ScoreRangeFilterPtr& filter = nullptr) const;

    void get_topn_bm25_scores(roaring::Roaring* row_bitmap, IColumn::MutablePtr& scores,

                              std::unique_ptr<std::vector<uint64_t>>& row_ids, OrderType order_type,

                              size_t top_k, const ScoreRangeFilterPtr& filter = nullptr) const;

private:

    template <OrderType order>

    void find_top_k_scores(const roaring::Roaring* row_bitmap, const ScoreMap& all_scores,

                           size_t top_k, std::vector<std::pair<uint32_t, float>>& top_k_results,

                           const ScoreRangeFilterPtr& filter) const;

    ScoreMap _bm25_scores;

};

using CollectionSimilarityPtr = std::shared_ptr<CollectionSimilarity>;

} // namespace doris