/*******************************************************************************
* Copyright 2021 Intel Corporation
*
* 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 "oneapi/dal/algo/linear_regression/parameters/cpu/train_parameters.hpp"
#include "oneapi/dal/algo/linear_regression/backend/cpu/finalize_train_kernel.hpp"
#include "oneapi/dal/algo/linear_regression/detail/finalize_train_ops.hpp"
#include "oneapi/dal/backend/dispatcher.hpp"

namespace oneapi::dal::linear_regression::detail {
namespace v1 {

using dal::detail::host_policy;

template <typename Policy, typename Float, typename Method, typename Task>
struct finalize_train_ops_dispatcher<Policy, Float, Method, Task> {
    train_result<Task> operator()(const Policy& ctx,
                                  const descriptor_base<Task>& desc,
                                  const train_parameters<Task>& params,
                                  const partial_train_result<Task>& input) const {
        return implementation(ctx, desc, params, input);
    }

    train_parameters<Task> select_parameters(const Policy& ctx,
                                             const descriptor_base<Task>& desc,
                                             const partial_train_result<Task>& input) const {
        using kernel_dispatcher_t = dal::backend::kernel_dispatcher< //
            KERNEL_SINGLE_NODE_CPU(parameters::train_parameters_cpu<Float, Method, Task>)>;
        return kernel_dispatcher_t{}(ctx, desc, input);
    }

    train_result<Task> operator()(const Policy& ctx,
                                  const descriptor_base<Task>& desc,
                                  const partial_train_result<Task>& input) const {
        const auto params = select_parameters(ctx, desc, input);
        return implementation(ctx, desc, params, input);
    }

private:
    inline auto implementation(const Policy& ctx,
                               const descriptor_base<Task>& desc,
                               const train_parameters<Task>& params,
                               const partial_train_result<Task>& input) const {
        using kernel_dispatcher_t = dal::backend::kernel_dispatcher< //
            KERNEL_SINGLE_NODE_CPU(backend::finalize_train_kernel_cpu<Float, Method, Task>)>;
        return kernel_dispatcher_t{}(ctx, desc, params, input);
    }
};
#define INSTANTIATE(F, M, T) \
    template struct ONEDAL_EXPORT finalize_train_ops_dispatcher<dal::detail::host_policy, F, M, T>;

INSTANTIATE(float, method::norm_eq, task::regression)
INSTANTIATE(double, method::norm_eq, task::regression)

} // namespace v1
} // namespace oneapi::dal::linear_regression::detail
