// Copyright (c) 2018 Benoit Chesneau
//
// This file is provided 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.

#include <sstream> 
#include <iostream>
#include <memory>
#include <list>
#include <algorithm>
#include <assert.h>

#include "rocksdb/slice.h"
#include "rocksdb/merge_operator.h"

#include "erl_nif.h"
#include "util.h"
#include "counter_merge_operator.h"

namespace erocksdb {

    CounterMergeOperator::CounterMergeOperator() {};

    bool CounterMergeOperator::Merge(
            const rocksdb::Slice& key,
            const rocksdb::Slice* existing_value,
            const rocksdb::Slice& value,
            std::string* new_value,
            rocksdb::Logger* logger) const {

        int counter = 0;
        if (existing_value) {
            counter = parse_int(existing_value->data());
        }
        int oper = parse_int(value.data());
        auto new_counter = counter + oper;
        *new_value = ToString<int>(new_counter);
        return true;
    }

    const char* CounterMergeOperator::Name() const  {
        return "CounterMergeOperator";
    }

    std::shared_ptr<CounterMergeOperator> CreateCounterMergeOperator() {
        return std::make_shared<CounterMergeOperator>();
    }
}