//
// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
// SPDX-License-Identifier: MIT
//

#pragma once

#include <tensorflow/lite/builtin_ops.h>
#include <tensorflow/lite/c/builtin_op_data.h>
#include <tensorflow/lite/c/common.h>
#include <tensorflow/lite/kernels/internal/tensor_ctypes.h>
#include <tensorflow/lite/minimal_logging.h>

namespace armnnDelegate
{

TfLiteStatus VisitReduceOperator(DelegateData& delegateData,
                                 TfLiteContext* tfLiteContext,
                                 TfLiteNode* tfLiteNode,
                                 int nodeIndex,
                                 int32_t reduceOperatorCode)
{
    TF_LITE_ENSURE_STATUS(ValidateNumInputs(tfLiteContext, tfLiteNode, 2, nodeIndex));
    TF_LITE_ENSURE_STATUS(ValidateNumOutputs(tfLiteContext, tfLiteNode, 1, nodeIndex));

    const TfLiteTensor* tfLiteTensors = tfLiteContext->tensors;
    const TfLiteTensor& tfLiteInputTensor = tfLiteTensors[tfLiteNode->inputs->data[0]];
    if (!IsValid(tfLiteContext, tfLiteInputTensor, reduceOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const TfLiteTensor& tfLiteOutputTensor = tfLiteTensors[tfLiteNode->outputs->data[0]];
    if (!IsValid(tfLiteContext, tfLiteOutputTensor, reduceOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const armnn::TensorInfo& inputTensorInfo  = GetTensorInfoForTfLiteTensor(tfLiteInputTensor);
    const armnn::TensorInfo& outputTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteOutputTensor);

    // Get const axis value from model and set it to descriptor.
    const TfLiteTensor& tfLiteAxisTensor = tfLiteTensors[tfLiteNode->inputs->data[1]];
    if (!IsValid(tfLiteContext, tfLiteAxisTensor, reduceOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const armnn::TensorInfo& axisTensorInfo =   GetTensorInfoForTfLiteTensor(tfLiteAxisTensor);
    auto* axisTensorData = tflite::GetTensorData<int32_t>(&tfLiteAxisTensor);

    std::vector<int32_t> axis;
    // Add axis data to vector to be converter to unsigned int and assigned to descriptor axis.
    if (axisTensorData != nullptr)
    {
        for (unsigned int i = 0; i < axisTensorInfo.GetNumElements(); ++i)
        {
            axis.emplace_back(axisTensorData[i]);
        }
    }
    else
    {
        for (unsigned int i = 0; i < inputTensorInfo.GetNumDimensions(); ++i)
        {
            axis.push_back(i);
        }
    }

    // Convert the axis to unsigned int and remove duplicates.
    unsigned int rank = inputTensorInfo.GetNumDimensions();
    std::set<unsigned int> uniqueAxis;
    std::transform(axis.begin(),
                   axis.end(),
                   std::inserter(uniqueAxis, uniqueAxis.begin()),
                   [rank](int i)->unsigned int{ return (i + rank) % rank; });

    armnn::ReduceDescriptor desc;
    desc.m_vAxis.assign(uniqueAxis.begin(), uniqueAxis.end());

    auto* reducerParameters = reinterpret_cast<TfLiteReducerParams*>(tfLiteNode->builtin_data);
    desc.m_KeepDims = reducerParameters->keep_dims;
    if (reduceOperatorCode == kTfLiteBuiltinReduceMax)
    {
        desc.m_ReduceOperation = armnn::ReduceOperation::Max;
    }
    else if (reduceOperatorCode == kTfLiteBuiltinReduceMin)
    {
        desc.m_ReduceOperation = armnn::ReduceOperation::Min;
    }
    else if (reduceOperatorCode == kTfLiteBuiltinSum)
    {
        desc.m_ReduceOperation = armnn::ReduceOperation::Sum;
    }
    else if (reduceOperatorCode == kTfLiteBuiltinReduceProd)
    {
        desc.m_ReduceOperation = armnn::ReduceOperation::Prod;
    }
    else
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext,
            "TfLiteArmnnDelegate: Unsupported Reduction Operator #%d node #%d: ",
            reduceOperatorCode, nodeIndex);
        return kTfLiteError;
    }

    bool isSupported = false;
    auto validateFunc = [&](const armnn::TensorInfo& outInfo, bool& isSupported)
    {
        FORWARD_LAYER_SUPPORT_FUNC("REDUCE",
                                   tfLiteContext,
                                   IsReduceSupported,
                                   delegateData.m_Backends,
                                   isSupported,
                                   inputTensorInfo,
                                   outInfo,
                                   desc);
    };

    if (!delegateData.m_Network)
    {
        validateFunc(outputTensorInfo, isSupported);
        return isSupported ? kTfLiteOk : kTfLiteError;
    }

    // Add an Reduce layer
    armnn::IConnectableLayer* layer = delegateData.m_Network->AddReduceLayer(desc);
    ARMNN_ASSERT(layer != nullptr);

    armnn::IOutputSlot& outputSlot = layer->GetOutputSlot(0);
    outputSlot.SetTensorInfo(outputTensorInfo);

    // Connect
    return Connect(layer, tfLiteNode, delegateData);
}

} // namespace armnnDelegate