/*
 * Copyright (c) 2016, 2017 ARM Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include "arm_compute/core/Error.h"
#include "arm_compute/core/Validate.h"

#include <cmath>
#include <numeric>

namespace arm_compute
{
inline uint8_t delta_bilinear_c1u8(const uint8_t *pixel_ptr, size_t stride, float dx, float dy)
{
    ARM_COMPUTE_ERROR_ON(pixel_ptr == nullptr);

    const float dx1 = 1.0f - dx;
    const float dy1 = 1.0f - dy;

    const float a00 = *pixel_ptr;
    const float a01 = *(pixel_ptr + 1);
    const float a10 = *(pixel_ptr + stride);
    const float a11 = *(pixel_ptr + stride + 1);

    const float w1 = dx1 * dy1;
    const float w2 = dx * dy1;
    const float w3 = dx1 * dy;
    const float w4 = dx * dy;

    return a00 * w1 + a01 * w2 + a10 * w3 + a11 * w4;
}

inline uint8_t pixel_bilinear_c1u8(const uint8_t *first_pixel_ptr, size_t stride, float x, float y)
{
    ARM_COMPUTE_ERROR_ON(first_pixel_ptr == nullptr);

    const int32_t xi = std::floor(x);
    const int32_t yi = std::floor(y);

    const float dx = x - xi;
    const float dy = y - yi;

    return delta_bilinear_c1u8(first_pixel_ptr + xi + yi * stride, stride, dx, dy);
}

inline uint8_t pixel_bilinear_c1u8_clamp(const uint8_t *first_pixel_ptr, size_t stride, size_t width, size_t height, float x, float y)
{
    ARM_COMPUTE_ERROR_ON(first_pixel_ptr == nullptr);

    x = std::max(-1.f, std::min(x, static_cast<float>(width)));
    y = std::max(-1.f, std::min(y, static_cast<float>(height)));

    const float xi = std::floor(x);
    const float yi = std::floor(y);

    const float dx = x - xi;
    const float dy = y - yi;

    return delta_bilinear_c1u8(first_pixel_ptr + static_cast<int32_t>(xi) + static_cast<int32_t>(yi) * stride, stride, dx, dy);
}

inline uint8_t pixel_area_c1u8_clamp(const uint8_t *first_pixel_ptr, size_t stride, size_t width, size_t height, float wr, float hr, int x, int y)
{
    ARM_COMPUTE_ERROR_ON(first_pixel_ptr == nullptr);

    // Calculate sampling position
    float in_x = (x + 0.5f) * wr - 0.5f;
    float in_y = (y + 0.5f) * hr - 0.5f;

    // Get bounding box offsets
    int x_from = std::floor(x * wr - 0.5f - in_x);
    int y_from = std::floor(y * hr - 0.5f - in_y);
    int x_to   = std::ceil((x + 1) * wr - 0.5f - in_x);
    int y_to   = std::ceil((y + 1) * hr - 0.5f - in_y);

    // Clamp position to borders
    in_x = std::max(-1.f, std::min(in_x, static_cast<float>(width)));
    in_y = std::max(-1.f, std::min(in_y, static_cast<float>(height)));

    // Clamp bounding box offsets to borders
    x_from = ((in_x + x_from) < -1) ? -1 : x_from;
    y_from = ((in_y + y_from) < -1) ? -1 : y_from;
    x_to   = ((in_x + x_to) > width) ? (width - in_x) : x_to;
    y_to   = ((in_y + y_to) > height) ? (height - in_y) : y_to;

    // Get pixel index
    const int xi = std::floor(in_x);
    const int yi = std::floor(in_y);

    // Bounding box elements in each dimension
    const int x_elements = (x_to - x_from + 1);
    const int y_elements = (y_to - y_from + 1);
    ARM_COMPUTE_ERROR_ON(x_elements == 0 || y_elements == 0);

    // Sum pixels in area
    int sum = 0;
    for(int j = yi + y_from, je = yi + y_to; j <= je; ++j)
    {
        const uint8_t *ptr = first_pixel_ptr + j * stride + xi + x_from;
        sum                = std::accumulate(ptr, ptr + x_elements, sum);
    }

    // Return average
    return sum / (x_elements * y_elements);
}

template <size_t dimension>
struct IncrementIterators
{
    template <typename T, typename... Ts>
    static void unroll(T &&it, Ts &&... iterators)
    {
        it.increment(dimension);
        IncrementIterators<dimension>::unroll<Ts...>(std::forward<Ts>(iterators)...);
    }

    template <typename T>
    static void unroll(T &&it)
    {
        it.increment(dimension);
        // End of recursion
    }

    static void unroll()
    {
        // End of recursion
    }
};

template <size_t dim>
struct ForEachDimension
{
    template <typename L, typename... Ts>
    static void unroll(const Window &w, Coordinates &id, L &&lambda_function, Ts &&... iterators)
    {
        const auto &d = w[dim - 1];

        for(auto v = d.start(); v < d.end(); v += d.step(), IncrementIterators < dim - 1 >::unroll(iterators...))
        {
            id.set(dim - 1, v);
            ForEachDimension < dim - 1 >::unroll(w, id, lambda_function, iterators...);
        }
    }
};

template <>
struct ForEachDimension<0>
{
    template <typename L, typename... Ts>
    static void unroll(const Window &w, Coordinates &id, L &&lambda_function, Ts &&... iterators)
    {
        lambda_function(id);
    }
};

template <typename L, typename... Ts>
inline void execute_window_loop(const Window &w, L &&lambda_function, Ts &&... iterators)
{
    w.validate();

    Coordinates id;
    ForEachDimension<Coordinates::num_max_dimensions>::unroll(w, id, std::forward<L>(lambda_function), std::forward<Ts>(iterators)...);
}

inline constexpr Iterator::Iterator()
    : _ptr(nullptr), _dims()
{
}

inline Iterator::Iterator(const ITensor *tensor, const Window &win)
    : Iterator()
{
    ARM_COMPUTE_ERROR_ON(tensor == nullptr);
    const ITensorInfo *info = tensor->info();
    ARM_COMPUTE_ERROR_ON(info == nullptr);
    const Strides &strides = info->strides_in_bytes();

    _ptr = tensor->buffer() + info->offset_first_element_in_bytes();

    //Initialize the stride for each dimension and calculate the position of the first element of the iteration:
    for(unsigned int n = 0; n < info->num_dimensions(); ++n)
    {
        _dims[n]._stride = win[n].step() * strides[n];
        std::get<0>(_dims)._dim_start += strides[n] * win[n].start();
    }

    //Copy the starting point to all the dimensions:
    for(unsigned int n = 1; n < Coordinates::num_max_dimensions; ++n)
    {
        _dims[n]._dim_start = std::get<0>(_dims)._dim_start;
    }

    ARM_COMPUTE_ERROR_ON_WINDOW_DIMENSIONS_GTE(win, info->num_dimensions());
}

inline void Iterator::increment(const size_t dimension)
{
    ARM_COMPUTE_ERROR_ON(dimension >= Coordinates::num_max_dimensions);

    _dims[dimension]._dim_start += _dims[dimension]._stride;

    for(unsigned int n = 0; n < dimension; ++n)
    {
        _dims[n]._dim_start = _dims[dimension]._dim_start;
    }
}

inline constexpr int Iterator::offset() const
{
    return _dims.at(0)._dim_start;
}

inline constexpr uint8_t *Iterator::ptr() const
{
    return _ptr + _dims.at(0)._dim_start;
}

inline void Iterator::reset(const size_t dimension)
{
    ARM_COMPUTE_ERROR_ON(dimension >= Coordinates::num_max_dimensions - 1);

    _dims[dimension]._dim_start = _dims[dimension + 1]._dim_start;

    for(unsigned int n = 0; n < dimension; ++n)
    {
        _dims[n]._dim_start = _dims[dimension]._dim_start;
    }
}

inline bool auto_init_if_empty(ITensorInfo &info, const TensorShape &shape, int num_channels, DataType data_type, int fixed_point_position)
{
    if(info.tensor_shape().total_size() == 0)
    {
        info.set_data_type(data_type);
        info.set_num_channels(num_channels);
        info.set_tensor_shape(shape);
        info.set_fixed_point_position(fixed_point_position);
        return true;
    }

    return false;
}

inline bool set_shape_if_empty(ITensorInfo &info, const TensorShape &shape)
{
    if(info.tensor_shape().total_size() == 0)
    {
        info.set_tensor_shape(shape);
        return true;
    }

    return false;
}

inline bool set_format_if_unknown(ITensorInfo &info, Format format)
{
    if(info.data_type() == DataType::UNKNOWN)
    {
        info.set_format(format);
        return true;
    }

    return false;
}

inline bool set_data_type_if_unknown(ITensorInfo &info, DataType data_type)
{
    if(info.data_type() == DataType::UNKNOWN)
    {
        info.set_data_type(data_type);
        return true;
    }

    return false;
}

inline bool set_fixed_point_position_if_zero(ITensorInfo &info, int fixed_point_position)
{
    if(info.fixed_point_position() == 0 && (info.data_type() == DataType::QS8 || info.data_type() == DataType::QS16))
    {
        info.set_fixed_point_position(fixed_point_position);
        return true;
    }

    return false;
}

inline ValidRegion calculate_valid_region_scale(const ITensorInfo &src_info, const TensorShape &dst_shape, InterpolationPolicy policy, BorderSize border_size, bool border_undefined)
{
    const auto  wr = static_cast<float>(dst_shape[0]) / static_cast<float>(src_info.tensor_shape()[0]);
    const auto  hr = static_cast<float>(dst_shape[1]) / static_cast<float>(src_info.tensor_shape()[1]);
    Coordinates anchor;
    anchor.set_num_dimensions(src_info.tensor_shape().num_dimensions());
    TensorShape new_dst_shape(dst_shape);
    anchor.set(0, (policy == InterpolationPolicy::BILINEAR
                   && border_undefined) ?
               ((static_cast<int>(src_info.valid_region().anchor[0]) + border_size.left + 0.5f) * wr - 0.5f) :
               ((static_cast<int>(src_info.valid_region().anchor[0]) + 0.5f) * wr - 0.5f));
    anchor.set(1, (policy == InterpolationPolicy::BILINEAR
                   && border_undefined) ?
               ((static_cast<int>(src_info.valid_region().anchor[1]) + border_size.top + 0.5f) * hr - 0.5f) :
               ((static_cast<int>(src_info.valid_region().anchor[1]) + 0.5f) * hr - 0.5f));
    float shape_out_x = (policy == InterpolationPolicy::BILINEAR
                         && border_undefined) ?
                        ((static_cast<int>(src_info.valid_region().anchor[0]) + static_cast<int>(src_info.valid_region().shape[0]) - 1) - 1 + 0.5f) * wr - 0.5f :
                        ((static_cast<int>(src_info.valid_region().anchor[0]) + static_cast<int>(src_info.valid_region().shape[0])) + 0.5f) * wr - 0.5f;
    float shape_out_y = (policy == InterpolationPolicy::BILINEAR
                         && border_undefined) ?
                        ((static_cast<int>(src_info.valid_region().anchor[1]) + static_cast<int>(src_info.valid_region().shape[1]) - 1) - 1 + 0.5f) * hr - 0.5f :
                        ((static_cast<int>(src_info.valid_region().anchor[1]) + static_cast<int>(src_info.valid_region().shape[1])) + 0.5f) * hr - 0.5f;

    new_dst_shape.set(0, shape_out_x - anchor[0]);
    new_dst_shape.set(1, shape_out_y - anchor[1]);

    return ValidRegion(std::move(anchor), std::move(new_dst_shape));
}
} // namespace arm_compute