// 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.

#include "db/IDGenerator.h"

#include <assert.h>
#include <chrono>
#include <iostream>

namespace milvus {
namespace engine {

IDGenerator::~IDGenerator() = default;

constexpr size_t SimpleIDGenerator::MAX_IDS_PER_MICRO;

IDNumber
SimpleIDGenerator::GetNextIDNumber() {
    auto now = std::chrono::system_clock::now();
    auto micros = std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch()).count();
    return micros * MAX_IDS_PER_MICRO;
}

void
SimpleIDGenerator::NextIDNumbers(size_t n, IDNumbers& ids) {
    if (n > MAX_IDS_PER_MICRO) {
        NextIDNumbers(n - MAX_IDS_PER_MICRO, ids);
        NextIDNumbers(MAX_IDS_PER_MICRO, ids);
        return;
    }
    if (n <= 0) {
        return;
    }

    auto now = std::chrono::system_clock::now();
    auto micros = std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch()).count();
    micros *= MAX_IDS_PER_MICRO;

    for (int pos = 0; pos < n; ++pos) {
        ids.push_back(micros + pos);
    }
}

void
SimpleIDGenerator::GetNextIDNumbers(size_t n, IDNumbers& ids) {
    ids.clear();
    NextIDNumbers(n, ids);
}

}  // namespace engine
}  // namespace milvus
