/*
 * 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/runtime/cudaEvent.h"
#include "tensorrt_llm/runtime/cudaStream.h"
#include "tensorrt_llm/runtime/iTensor.h"
#include "tensorrt_llm/runtime/modelConfig.h"
#include "tensorrt_llm/runtime/worldConfig.h"

#include <memory>
#include <vector>

namespace tensorrt_llm::batch_manager
{
class DecoderInputBuffers;
class LlmRequest;
} // namespace tensorrt_llm::batch_manager

namespace tensorrt_llm::runtime
{
class SamplingConfig;

namespace decoder
{
class DecoderState;
}

//! GPT decoder class with support for in-flight batching
class IGptDecoderBatched
{
public:
    using CudaStreamPtr = std::shared_ptr<CudaStream>;
    using LlmRequestPtr = std::shared_ptr<tensorrt_llm::batch_manager::LlmRequest>;
    using RequestVector = std::vector<LlmRequestPtr>;
    using TensorPtr = std::shared_ptr<ITensor>;

    //! @brief Setup the decoder before calling `forward()`
    virtual void setup(executor::DecodingMode const& mode, SizeType32 maxNumSequences, SizeType32 maxBeamWidth,
        nvinfer1::DataType dtype, ModelConfig const& modelConfig, WorldConfig const& worldConfig)
        = 0;

    //! @brief Disable Lookahead decoding.
    virtual void disableLookahead(RequestVector const& genRequests, TensorPtr const& batchSlots) = 0;

    //! @brief Run one step for all requests without blocking the host process and return the token for synchronization.
    virtual CudaEvent forwardAsync(
        decoder::DecoderState const& decoderState, batch_manager::DecoderInputBuffers const& input)
        = 0;

    //! @brief Run one step for all requests and wait for completion on the host.
    virtual void forward(decoder::DecoderState const& decoderState, batch_manager::DecoderInputBuffers const& input)
        = 0;

    //! @brief Gather final beam search results for request `batchIdx`.
    //! Result will only be available after event returned
    [[nodiscard]] virtual CudaEvent finalize(decoder::DecoderState const& decoderState, SizeType32 batchSlot,
        SamplingConfig const& samplingConfig, bool streaming) const
        = 0;

protected:
    IGptDecoderBatched() = default;
    virtual ~IGptDecoderBatched() = default;
};

} // namespace tensorrt_llm::runtime