// 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"

void set_value_by_flag_and_id(const bool *stop_flags,
                              int64_t *pre_ids_all,
                              const int64_t *input_ids,
                              const int *seq_lens_encoder,
                              const int *seq_lens_decoder,
                              const int64_t *step_idx,
                              int bs,
                              int length,
                              int length_input_ids) {
    for (int bi = 0; bi < bs; bi++) {
        if (!stop_flags[bi]) {
            const int seq_len_dec = seq_lens_decoder[bi];
            const int seq_len_enc = seq_lens_encoder[bi];
            int64_t *pre_ids_all_now = pre_ids_all + bi * length;
            const int64_t *input_ids_now = input_ids + bi * length_input_ids;
            if (seq_len_dec == 0) {
                pre_ids_all_now[step_idx[bi]] = input_ids_now[seq_len_enc - 1];
            } else {
                pre_ids_all_now[step_idx[bi]] = input_ids_now[0];
            }
        }
    }
}

void SetValueByFlagsAndIdx(const paddle::Tensor &pre_ids_all,
                           const paddle::Tensor &input_ids,
                           const paddle::Tensor &seq_lens_this_time,
                           const paddle::Tensor &seq_lens_encoder,
                           const paddle::Tensor &seq_lens_decoder,
                           const paddle::Tensor &step_idx,
                           const paddle::Tensor &stop_flags) {
    std::vector<int64_t> pre_ids_all_shape = pre_ids_all.shape();
    int bs = seq_lens_this_time.shape()[0];
    int length = pre_ids_all_shape[1];
    int length_input_ids = input_ids.shape()[1];

    set_value_by_flag_and_id(stop_flags.data<bool>(),
                             const_cast<int64_t *>(pre_ids_all.data<int64_t>()),
                             input_ids.data<int64_t>(),
                             seq_lens_encoder.data<int>(),
                             seq_lens_decoder.data<int>(),
                             step_idx.data<int64_t>(),
                             bs,
                             length,
                             length_input_ids);
}

PD_BUILD_STATIC_OP(set_value_by_flags_and_idx_cpu)
    .Inputs({"pre_ids_all",
             "input_ids",
             "seq_lens_this_time",
             "seq_lens_encoder",
             "seq_lens_decoder",
             "step_idx",
             "stop_flags"})
    .Outputs({"pre_ids_all_out"})
    .SetInplaceMap({{"pre_ids_all", "pre_ids_all_out"}})
    .SetKernelFn(PD_KERNEL(SetValueByFlagsAndIdx));