/*
 * Copyright (c) 2019-2023, 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 <cstddef>
#include <vector>

#include "src/fastertransformer/kernels/decoding_kernels.h"
#include "src/fastertransformer/layers/DynamicDecodeLayer.h"
#include "src/fastertransformer/models/decoder/Decoder.h"
#include "src/fastertransformer/models/decoding/DecodingWeight.h"

namespace fastertransformer {

// fallback to fp32 dynamic decoder when bf16 specified
template<typename T>
struct fallBackType {
    using Type = float;
};

template<>
struct fallBackType<half> {
    using Type = half;
};

template<typename T>
class Decoding: public BaseLayer {
private:
    // buffer handling
    size_t max_batch_size_  = 0;
    size_t max_seq_len_     = 0;
    size_t mem_max_seq_len_ = 0;
    // meta data
    size_t                 beam_width_;
    size_t                 head_num_;
    size_t                 size_per_head_;
    size_t                 inter_size_;
    size_t                 num_layer_;
    size_t                 vocab_size_;
    static constexpr float layernorm_eps_ = 1e-6f;

    int    start_id_;
    int    end_id_;
    float  beam_search_diversity_rate_;
    size_t hidden_units_;
    uint   top_k_;
    float  top_p_;
    float  temperature_;
    float  len_penalty_;
    float  repetition_penalty_;

    // calculated data
    size_t vocab_size_padded_;

    using DynamicDecodeType = typename fallBackType<T>::Type;

    Decoder<T>*                            decoder_;
    DynamicDecodeLayer<DynamicDecodeType>* dynamic_decode_layer_;

    void allocateBuffer() override;
    void freeBuffer() override;
    bool isValidBatchSize(size_t batch_size);
    bool isValidSeqLen(size_t seq_len);
    bool isValidMemSeqLen(size_t seq_len);

    void initialize();

protected:
    T*       padded_embedding_kernel_     = nullptr;
    T*       padded_embedding_bias_       = nullptr;
    const T* padded_embedding_kernel_ptr_ = nullptr;
    const T* padded_embedding_bias_ptr_   = nullptr;

    T*                 decoder_input_buf_         = nullptr;
    T*                 decoder_output_buf_        = nullptr;
    T*                 normed_decoder_output_buf_ = nullptr;
    DynamicDecodeType* logits_buf_                = nullptr;
    float*             cum_log_probs_             = nullptr;
    bool*              finished_buf_              = nullptr;
    bool*              h_finished_buf_            = nullptr;

    int* start_ids_buf_;
    int* end_ids_buf_;

    T*   key_cache_             = nullptr;
    T*   value_cache_           = nullptr;
    T*   key_mem_cache_         = nullptr;
    T*   value_mem_cache_       = nullptr;
    int* cache_indirections_[2] = {nullptr, nullptr};

    T* padded_pos_embedding_bias_ = nullptr;

    int* output_ids_buf_ = nullptr;
    int* parent_ids_buf_ = nullptr;

public:
    Decoding(size_t           max_batch_size,
             size_t           max_seq_len,
             size_t           mem_max_seq_len,
             size_t           beam_width,
             size_t           head_num,
             size_t           size_per_head,
             size_t           inter_size,
             size_t           num_layer,
             size_t           vocab_size,
             int              start_id,
             int              end_id,
             float            beam_search_diversity_rate,
             uint             top_k,
             float            top_p,
             float            temperature,
             float            len_penalty,
             float            repetition_penalty,
             cudaStream_t     stream,
             cublasMMWrapper* cublas_wrapper,
             IAllocator*      allocator,
             bool             is_free_buffer_after_forward,
             cudaDeviceProp*  cuda_device_prop);

    Decoding(Decoding<T> const& Decoding);

    ~Decoding();

    void forward(std::vector<Tensor>*       output_tensors,
                 const std::vector<Tensor>* input_tensors,
                 const DecodingWeight<T>*   Decoding_weights);

    void forward(std::unordered_map<std::string, Tensor>*       output_tensors,
                 const std::unordered_map<std::string, Tensor>* input_tensors,
                 const DecodingWeight<T>*                       Decoding_weights);

    void forward(TensorMap* output_tensors, TensorMap* input_tensors, const DecodingWeight<T>* Decoding_weights);
};

}  // namespace fastertransformer
