// Copyright (c) 2023 Huawei Technologies Co., Ltd
// All rights reserved.
//
// Licensed under the BSD 3-Clause License  (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://opensource.org/licenses/BSD-3-Clause
//
// 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 "torch_npu/csrc/aten/CustomFunctions.h"

#include "op_plugin/AclOpsInterface.h"
#include "op_plugin/utils/OpAdapter.h"

namespace acl_op {
using npu_preparation = at_npu::native::OpPreparation;
using npu_utils = at_npu::native::NpuUtils;
using calcu_op_util = at_npu::native::CalcuOpUtil;

namespace {
at::Tensor& cast_nocheck(at::Tensor& result, const at::Tensor& self)
{
    int64_t dst_data_type = calcu_op_util::ConvertToAclDataType(result.scalar_type());
    at_npu::native::OpCommand cmd;
    cmd.Name("Cast")
        .Input(self)
        .Output(result)
        .Attr("dst_type", dst_data_type)
        .Run();
    return result;
}

at::Tensor npu_dtype_cast_impl(const at::Tensor& self, at::ScalarType dtype)
{
    if (self.dtype() == dtype) {
        return self.clone();
    }
    at::Tensor result = npu_preparation::apply_tensor(self.sizes(), self.options().dtype(dtype), self);
    cast_nocheck(result, self);
    return result;
}
} // namespace

at::Tensor& npu_dtype_cast_(at::Tensor& self, const at::Tensor& src)
{
    if (self.dtype() == src.dtype()) {
        return self;
    }

    if (!npu_utils::check_match(&self)) {
        at::Tensor contiguous_self = npu_preparation::apply_tensor(self);
        cast_nocheck(contiguous_self, src);
        npu_utils::format_fresh_view(self, contiguous_self);
    } else {
        cast_nocheck(self, src);
    }
    return self;
}

// new implementation
at::Tensor npu_dtype_cast(
    const at::Tensor& self,
    int64_t dtype,
    c10::optional<int64_t> input_dtype)
{
    return npu_dtype_cast_impl(self, static_cast<at::ScalarType>(dtype));
}

at::Tensor _npu_dtype_cast(
    const at::Tensor& self,
    at::ScalarType dtype)
{
    return npu_dtype_cast_impl(self, dtype);
}

at::Tensor npu_dtype_cast_backward(
    const at::Tensor& grad,
    at::ScalarType dtype,
    c10::optional<int64_t> grad_dtype,
    c10::optional<int64_t> input_dtype)
{
    grad.requires_grad_();
    return at_npu::native::custom_ops::npu_dtype_cast(grad, static_cast<int64_t>(dtype), grad_dtype);
}

at::Tensor _npu_dtype_cast_backward(const at::Tensor& grad, at::ScalarType dtype)
{
    grad.requires_grad_();
    return at_npu::native::custom_ops::_npu_dtype_cast(grad, dtype);
}
}  // namespace acl_op