// Copyright (C) 2019-2020 Zilliz. All rights reserved.
//
// Licensed 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 <limits>
#include <utility>

#include "common/Consts.h"
#include "common/Types.h"
#include "common/QueryResult.h"

using milvus::SearchResult;

struct SearchResultPair {
    milvus::PkType primary_key_;
    float distance_;
    milvus::SearchResult* search_result_;
    int64_t segment_index_;
    int64_t offset_;
    int64_t offset_rb_;  // right bound

    SearchResultPair(milvus::PkType primary_key,
                     float distance,
                     SearchResult* result,
                     int64_t index,
                     int64_t lb,
                     int64_t rb)
        : primary_key_(std::move(primary_key)),
          distance_(distance),
          search_result_(result),
          segment_index_(index),
          offset_(lb),
          offset_rb_(rb) {
    }

    bool
    operator>(const SearchResultPair& other) const {
        if (std::fabs(distance_ - other.distance_) < EPSILON) {
            return primary_key_ < other.primary_key_;
        }
        return distance_ > other.distance_;
    }

    void
    advance() {
        offset_++;
        if (offset_ < offset_rb_) {
            primary_key_ = search_result_->primary_keys_.at(offset_);
            distance_ = search_result_->distances_.at(offset_);
        } else {
            primary_key_ = INVALID_PK;
            distance_ = std::numeric_limits<float>::min();
        }
    }
};

struct SearchResultPairComparator {
    bool
    operator()(const SearchResultPair* lhs, const SearchResultPair* rhs) const {
        return *rhs > *lhs;
    }
};
