/*
 * Copyright (c) 2022-2024, NVIDIA CORPORATION.  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 "tensorrt_llm/batch_manager/kvCacheManager.h"
#include "tensorrt_llm/batch_manager/llmRequest.h"

#include <algorithm>
#include <map>
#include <optional>

namespace tensorrt_llm::batch_manager::kv_cache_manager
{

class NoEvictScheduledBlocksManager
{
    using SizeType32 = tensorrt_llm::runtime::SizeType32;

public:
    explicit NoEvictScheduledBlocksManager(BaseKVCacheManager const& kvCacheManager)
        : mKvCacheManager(kvCacheManager)
        , mAvailableBlocks(mKvCacheManager.getBlockManager().getNumFreeBlocksPerWindowSize())
    {
    }

    void decrementReservedBlocks(LlmRequest const& req)
    {
        for (auto& [windowSize, availableBlocks] : mAvailableBlocks)
        {
            availableBlocks -= mKvCacheManager.getRemainingBlocksToCompletion(req, windowSize);
        }
    }

    bool enoughAvailableBlocks(LlmRequest const& req)
    {
        return std::all_of(mAvailableBlocks.cbegin(), mAvailableBlocks.cend(),
            [this, &req](auto const& pair)
            {
                auto const& [windowSize, availableBlocks] = pair;
                auto const neededBlocks = mKvCacheManager.getRemainingBlocksToCompletion(req, windowSize);
                return neededBlocks <= availableBlocks;
            });
    }

private:
    BaseKVCacheManager const& mKvCacheManager;
    std::map<SizeType32, SizeType32> mAvailableBlocks;
};

class MaxUtilizationScheduledBlocksManager
{
    using SizeType32 = tensorrt_llm::runtime::SizeType32;

public:
    MaxUtilizationScheduledBlocksManager(BaseKVCacheManager const& kvCacheManager, bool twoStepsLookAhead)
        : mKvCacheManager(kvCacheManager)
        , mTwoStepsLookAhead(twoStepsLookAhead)
    {
        auto const& windowSizes = mKvCacheManager.getBlockManager().getWindowSizesMetadata();
        for (auto const& [windowSize, _] : windowSizes)
        {
            mNumScheduledBlocks[windowSize] = 0;
        }
    }

    std::optional<std::map<SizeType32, SizeType32>> prepareNewNumberOfBlocksIfWeEndUpScheduling(LlmRequest const& req)
    {
        std::map<SizeType32, SizeType32> blocksIfScheduled;
        for (auto const& [windowSize, numScheduled] : mNumScheduledBlocks)
        {
            auto const required = mKvCacheManager.getNeededBlocksOneStep(req, mTwoStepsLookAhead, windowSize);

            TLLM_LOG_DEBUG("MaxUtilizationScheduler: request ID %lu required blocks %i for %i window size",
                req.mRequestId, required, windowSize);

            auto const scheduledTotal = numScheduled + required;
            bool const hasFreeBlocks
                = mKvCacheManager.getBlockManager().schedulingHasFreeBlocks(scheduledTotal, windowSize);
            if (!hasFreeBlocks)
            {
                return std::nullopt;
            }
            blocksIfScheduled[windowSize] = scheduledTotal;
        }
        return blocksIfScheduled;
    }

    void updateScheduledBlocks(std::map<SizeType32, SizeType32> const& numBlocksIfScheduled)
    {
        assert(numBlocksIfScheduled.size() == mNumScheduledBlocks.size());
        for (auto const& [windowSize, blocksIfScheduled] : numBlocksIfScheduled)
        {
            TLLM_LOG_DEBUG(
                "MaxUtilizationScheduler: scheduled blocks %i for window size %i", blocksIfScheduled, windowSize);
            mNumScheduledBlocks.at(windowSize) = blocksIfScheduled;
        }
    }

private:
    BaseKVCacheManager const& mKvCacheManager;
    std::map<SizeType32, SizeType32> mNumScheduledBlocks;
    bool const mTwoStepsLookAhead;
};

} // namespace tensorrt_llm::batch_manager::kv_cache_manager