/* Copyright 2020 The TensorFlow 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 "tensorflow/lite/delegates/utils/simple_delegate.h"

#include <limits>
#include <memory>
#include <vector>

#include "tensorflow/lite/builtin_ops.h"
#include "tensorflow/lite/c/common.h"
#include "tensorflow/lite/context_util.h"
#include "tensorflow/lite/delegates/utils.h"
#include "tensorflow/lite/kernels/internal/compatibility.h"
#include "tensorflow/lite/minimal_logging.h"

namespace tflite {
namespace {
TfLiteRegistration GetDelegateKernelRegistration(
    SimpleDelegateInterface* delegate) {
  TfLiteRegistration kernel_registration;
  kernel_registration.profiling_string = nullptr;
  kernel_registration.builtin_code = kTfLiteBuiltinDelegate;
  kernel_registration.custom_name = delegate->Name();
  kernel_registration.version = 1;
  kernel_registration.free = [](TfLiteContext* context, void* buffer) -> void {
    delete reinterpret_cast<SimpleDelegateKernelInterface*>(buffer);
  };
  kernel_registration.init = [](TfLiteContext* context, const char* buffer,
                                size_t length) -> void* {
    const TfLiteDelegateParams* params =
        reinterpret_cast<const TfLiteDelegateParams*>(buffer);
    if (params == nullptr) {
      TF_LITE_KERNEL_LOG(context, "NULL TfLiteDelegateParams passed.");
      return nullptr;
    }
    auto* delegate =
        reinterpret_cast<SimpleDelegateInterface*>(params->delegate->data_);
    std::unique_ptr<SimpleDelegateKernelInterface> delegate_kernel(
        delegate->CreateDelegateKernelInterface());
    if (delegate_kernel->Init(context, params) != kTfLiteOk) {
      return nullptr;
    }
    return delegate_kernel.release();
  };
  kernel_registration.prepare = [](TfLiteContext* context,
                                   TfLiteNode* node) -> TfLiteStatus {
    if (node->user_data == nullptr) {
      TF_LITE_KERNEL_LOG(context, "Delegate kernel was not initialized");
      return kTfLiteError;
    }
    SimpleDelegateKernelInterface* delegate_kernel =
        reinterpret_cast<SimpleDelegateKernelInterface*>(node->user_data);
    return delegate_kernel->Prepare(context, node);
  };
  kernel_registration.invoke = [](TfLiteContext* context,
                                  TfLiteNode* node) -> TfLiteStatus {
    SimpleDelegateKernelInterface* delegate_kernel =
        reinterpret_cast<SimpleDelegateKernelInterface*>(node->user_data);
    TFLITE_DCHECK(delegate_kernel != nullptr);
    return delegate_kernel->Eval(context, node);
  };

  return kernel_registration;
}

TfLiteStatus DelegatePrepare(TfLiteContext* context,
                             TfLiteDelegate* base_delegate) {
  auto* delegate =
      reinterpret_cast<SimpleDelegateInterface*>(base_delegate->data_);
  auto delegate_options = delegate->DelegateOptions();
  if (delegate_options.max_delegated_partitions <= 0)
    delegate_options.max_delegated_partitions = std::numeric_limits<int>::max();

  TF_LITE_ENSURE_STATUS(delegate->Initialize(context));
  delegates::IsNodeSupportedFn node_supported_fn =
      [=](TfLiteContext* context, TfLiteNode* node,
          TfLiteRegistration* registration,
          std::string* unsupported_details) -> bool {
    return delegate->IsNodeSupportedByDelegate(registration, node, context);
  };
  // TODO(b/149484598): Update to have method that gets all supported nodes.
  delegates::GraphPartitionHelper helper(context, node_supported_fn);
  TF_LITE_ENSURE_STATUS(helper.Partition(nullptr));

  std::vector<int> supported_nodes = helper.GetNodesOfFirstNLargestPartitions(
      delegate_options.max_delegated_partitions,
      delegate_options.min_nodes_per_partition);

  TFLITE_LOG_PROD(tflite::TFLITE_LOG_INFO,
                  "%s delegate: %d nodes delegated out of %d nodes with "
                  "%d partitions.\n",
                  delegate->Name(), supported_nodes.size(),
                  helper.num_total_nodes(), helper.num_partitions());
  TfLiteRegistration delegate_kernel_registration =
      GetDelegateKernelRegistration(delegate);

  return context->ReplaceNodeSubsetsWithDelegateKernels(
      context, delegate_kernel_registration,
      BuildTfLiteIntArray(supported_nodes).get(), base_delegate);
}
}  // namespace

TfLiteDelegate* TfLiteDelegateFactory::CreateSimpleDelegate(
    std::unique_ptr<SimpleDelegateInterface> simple_delegate, int64_t flag) {
  if (simple_delegate == nullptr) {
    return nullptr;
  }
  auto delegate = new TfLiteDelegate();
  delegate->Prepare = &DelegatePrepare;
  delegate->flags = flag;
  delegate->CopyFromBufferHandle = nullptr;
  delegate->CopyToBufferHandle = nullptr;
  delegate->FreeBufferHandle = nullptr;
  delegate->data_ = simple_delegate.release();
  return delegate;
}

void TfLiteDelegateFactory::DeleteSimpleDelegate(TfLiteDelegate* delegate) {
  if (!delegate) return;
  SimpleDelegateInterface* simple_delegate =
      reinterpret_cast<SimpleDelegateInterface*>(delegate->data_);
  delete simple_delegate;
  delete delegate;
}
}  // namespace tflite
