// Copyright (c) 2024 PaddlePaddle Authors. 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.

#include "paddle/extension.h"

#ifndef PD_BUILD_STATIC_OP
#define PD_BUILD_STATIC_OP(name) PD_BUILD_OP(static_op_##name)
#endif

__global__ void SpeculateRemovePadding(int64_t* output_data,
                                       const int64_t* input_data,
                                       const int64_t* draft_tokens,
                                       const int* seq_lens,
                                       const int* seq_lens_encoder,
                                       const int* cum_offsets,
                                       const int sequence_length,
                                       const int max_draft_tokens) {
    const int bi = blockIdx.x;
    const int tid = threadIdx.x;

    for (int i = tid; i < seq_lens[bi]; i += blockDim.x) {
        const int tgt_seq_id = bi * sequence_length - cum_offsets[bi] + i;
        if (seq_lens_encoder[bi] > 0) {
            const int src_seq_id = bi * sequence_length + i;
            output_data[tgt_seq_id] = input_data[src_seq_id];
        } else {
            const int src_seq_id = bi * max_draft_tokens + i;
            output_data[tgt_seq_id] = draft_tokens[src_seq_id];
        }
    }
}

__global__ void SpeculateGetPaddingOffsetKernel(int* batch_id_per_token,
                                                int* cum_offsets_out,
                                                int* cu_seqlens_q,
                                                int* cu_seqlens_k,
                                                const int* cum_offsets,
                                                const int* seq_lens,
                                                const int max_seq_len) {
    // get padding offset of each batch
    const int bi = blockIdx.x;
    const int ti = threadIdx.x;
    int cum_offset = bi == 0 ? 0 : cum_offsets[bi - 1];
    for (int i = ti; i < seq_lens[bi]; i += blockDim.x) {
        batch_id_per_token[bi * max_seq_len - cum_offset + i] = bi;
    }
    if (ti == 0) {
        cum_offsets_out[bi] = cum_offset;
        int cum_seq_len = (bi + 1) * max_seq_len - cum_offsets[bi];
        cu_seqlens_q[bi + 1] = cum_seq_len;
        cu_seqlens_k[bi + 1] = cum_seq_len;
    }
}

std::vector<paddle::Tensor> SpeculateGetPaddingOffset(
    const paddle::Tensor& input_ids,
    const paddle::Tensor& draft_tokens,
    const paddle::Tensor& cum_offsets,
    const paddle::Tensor& token_num,
    const paddle::Tensor& seq_len,
    const paddle::Tensor& seq_lens_encoder) {
    auto cu_stream = input_ids.stream();
    std::vector<int64_t> input_ids_shape = input_ids.shape();
    const int bsz = seq_len.shape()[0];
    const int seq_length = input_ids_shape[1];
    const int max_draft_tokens = draft_tokens.shape()[1];
    auto cum_offsets_out = cum_offsets.copy_to(cum_offsets.place(), false);
    auto cpu_token_num = token_num.copy_to(paddle::CPUPlace(), false);

    const int token_num_data = cpu_token_num.data<int64_t>()[0];
    auto x_remove_padding = paddle::full(
        {token_num_data}, 0, paddle::DataType::INT64, input_ids.place());
    auto batch_id_per_token = paddle::full(
        {token_num_data}, 0, paddle::DataType::INT32, input_ids.place());
    auto cu_seqlens_q =
        paddle::full({bsz + 1}, 0, paddle::DataType::INT32, input_ids.place());
    auto cu_seqlens_k =
        paddle::full({bsz + 1}, 0, paddle::DataType::INT32, input_ids.place());
    int blockSize = min((token_num_data + 32 - 1) / 32 * 32, 128);
    SpeculateGetPaddingOffsetKernel<<<bsz, 128, 0, cu_stream>>>(
        batch_id_per_token.data<int>(),
        cum_offsets_out.data<int>(),
        cu_seqlens_q.data<int>(),
        cu_seqlens_k.data<int>(),
        cum_offsets.data<int>(),
        seq_len.data<int>(),
        seq_length);
    SpeculateRemovePadding<<<bsz, blockSize, 0, cu_stream>>>(
        x_remove_padding.data<int64_t>(),
        input_ids.data<int64_t>(),
        draft_tokens.data<int64_t>(),
        seq_len.data<int>(),
        seq_lens_encoder.data<int>(),
        cum_offsets_out.data<int>(),
        seq_length,
        max_draft_tokens);
    return {x_remove_padding,
            cum_offsets_out,
            batch_id_per_token,
            cu_seqlens_q,
            cu_seqlens_k};  // , enc_token_num, dec_token_num};
}

std::vector<std::vector<int64_t>> SpeculateGetPaddingOffsetInferShape(
    const std::vector<int64_t>& input_ids_shape,
    const std::vector<int64_t>& draft_tokens_shape,
    const std::vector<int64_t>& cum_offsets_shape,
    const std::vector<int64_t>& token_num_shape,
    const std::vector<int64_t>& seq_len_shape,
    const std::vector<int64_t>& seq_lens_encoder_shape) {
    int64_t bsz = seq_len_shape[0];
    int64_t seq_len = input_ids_shape[1];
    return {{-1}, {bsz}, {-1}, {bsz + 1}, {bsz + 1}};
}

std::vector<paddle::DataType> SpeculateGetPaddingOffsetInferDtype(
    const paddle::DataType& input_ids_dtype,
    const paddle::DataType& draft_tokens_dtype,
    const paddle::DataType& cum_offsets_dtype,
    const paddle::DataType& token_num_dtype,
    const paddle::DataType& seq_len_dtype,
    const paddle::DataType& seq_lens_encoder_dtype) {
    return {input_ids_dtype,
            seq_len_dtype,
            seq_len_dtype,
            seq_len_dtype,
            seq_len_dtype};
}

PD_BUILD_STATIC_OP(speculate_get_padding_offset)
    .Inputs({"input_ids",
             "draft_tokens",
             "cum_offsets",
             "token_num",
             "seq_len",
             "seq_lens_encoder"})
    .Outputs({"x_remove_padding",
              "cum_offsets_out",
              "batch_id_per_token",
              "cu_seqlens_q",
              "cu_seqlens_k"})
    .SetKernelFn(PD_KERNEL(SpeculateGetPaddingOffset))
    .SetInferShapeFn(PD_INFER_SHAPE(SpeculateGetPaddingOffsetInferShape))
    .SetInferDtypeFn(PD_INFER_DTYPE(SpeculateGetPaddingOffsetInferDtype));
