#include <migraphx/onnx/op_parser.hpp>
#include <migraphx/onnx/checks.hpp>
#include <migraphx/ranges.hpp>
#include <migraphx/shape_for_each.hpp>
#include <migraphx/instruction.hpp>
#include <migraphx/make_op.hpp>

namespace migraphx {
inline namespace MIGRAPHX_INLINE_NS {
namespace onnx {

const auto& get_nearest_op(const std::string& mode)
{
    using nearest_op = std::function<std::size_t(std::size_t, double)>;
    static std::unordered_map<std::string, nearest_op> const nearest_ops = {
        {"round_prefer_floor",
         [=](std::size_t d_in, double val) {
             val = std::max(0.0, std::min(d_in - 1.0, val));
             return static_cast<std::size_t>(std::ceil((val - 0.5)));
         }},
        {"round_prefer_ceil",
         [=](std::size_t d_in, double val) {
             val = std::max(0.0, std::min(d_in - 1.0, val));
             return static_cast<std::size_t>(std::round((val)));
         }},
        {"floor",
         [=](std::size_t d_in, double val) {
             val = std::max(0.0, std::min(d_in - 1.0, val));
             return static_cast<std::size_t>(std::floor((val)));
         }},
        {"ceil", [=](std::size_t d_in, double val) {
             val = std::max(0.0, std::min(d_in - 1.0, val));
             return static_cast<std::size_t>(std::ceil((val)));
         }}};

    if(!contains(nearest_ops, mode))
    {
        MIGRAPHX_THROW("PARSE_RESIZE: nearest_mode " + mode + " not supported!");
    }

    return nearest_ops.at(mode);
}

const auto& get_original_idx_op(const std::string& mode)
{
    using original_idx_op = std::function<double(std::size_t, std::size_t, std::size_t, double)>;
    static std::unordered_map<std::string, original_idx_op> const idx_ops = {
        {"half_pixel",
         [=](std::size_t, std::size_t, std::size_t idx, double scale) {
             return (idx + 0.5) / scale - 0.5;
         }},
        {"pytorch_half_pixel",
         [=](std::size_t, std::size_t l_out, std::size_t idx, double scale) {
             return l_out > 1 ? (idx + 0.5) / scale - 0.5 : 0.0;
         }},
        {"align_corners",
         [=](std::size_t l_in, std::size_t l_out, std::size_t idx, double) {
             return (l_out == 1) ? 0.0 : (1.0 * idx * (l_in - 1.0) / (l_out - 1.0));
         }},
        {"asymmetric",
         [=](std::size_t, std::size_t, std::size_t idx, double scale) { return idx / scale; }},
        {"tf_half_pixel_for_nn", [=](std::size_t, std::size_t, std::size_t idx, double scale) {
             return (idx + 0.5) / scale;
         }}};

    if(!contains(idx_ops, mode))
    {
        MIGRAPHX_THROW("PARSE_RESIZE: coordinate_transformation_mode " + mode + " not supported!");
    }

    return idx_ops.at(mode);
}

static std::vector<int>
calc_neighbor_points(const std::vector<std::vector<std::vector<std::size_t>>>& vvv_ind,
                     int i_dim,
                     const std::vector<std::vector<std::size_t>>& vec_dims,
                     const shape& in_s)
{
    if(i_dim == vvv_ind.size())
    {
        std::vector<int> vec_ind;
        vec_ind.resize(vec_dims.size());
        std::transform(vec_dims.begin(), vec_dims.end(), vec_ind.begin(), [&](auto idx) {
            return static_cast<int>(in_s.index(idx));
        });

        return vec_ind;
    }

    const auto& vv_ind = vvv_ind[i_dim];
    const auto& vv_lo  = vv_ind.at(0);
    std::vector<std::vector<std::size_t>> vec_dims1;
    for(std::size_t start = 0; start < vec_dims.size(); start += vv_lo.size())
    {
        std::transform(vv_lo.begin(),
                       vv_lo.end(),
                       vec_dims.begin() + start,
                       std::back_inserter(vec_dims1),
                       [](auto i, auto dim) {
                           dim.push_back(i);
                           return dim;
                       });
    }

    const auto& vv_hi = vv_ind.at(1);
    for(std::size_t start = 0; start < vec_dims.size(); start += vv_lo.size())
    {
        std::transform(vv_hi.begin(),
                       vv_hi.end(),
                       vec_dims.begin() + start,
                       std::back_inserter(vec_dims1),
                       [](auto i, auto dim) {
                           dim.push_back(i);
                           return dim;
                       });
    }

    return calc_neighbor_points(vvv_ind, i_dim + 1, vec_dims1, in_s);
}

static std::string get_coord_trans_mode(const onnx_parser::attribute_map& attr)
{
    std::string coord_trans_mode = "half_pixel";
    if(contains(attr, "coordinate_transformation_mode"))
    {
        coord_trans_mode = attr.at("coordinate_transformation_mode").s();
        // does not support transformation mode "tf_crop_and_resize"
        if(coord_trans_mode == "tf_crop_and_resize")
        {
            MIGRAPHX_THROW("PARSE_RESIZE: \"tf_crop_and_resize\" mode is not supported!");
        }
    }

    return coord_trans_mode;
}

static std::string get_mode(const onnx_parser::attribute_map& attr)
{
    std::string mode = "nearest";
    if(contains(attr, "mode"))
    {
        mode = attr.at("mode").s();
        if(mode != "nearest" and mode != "linear")
        {
            MIGRAPHX_THROW("PARSE_RESIZE: only nearest and linear modes are supported!");
        }
    }

    return mode;
}

static std::string get_nearest_mode(const onnx_parser::attribute_map& attr)
{
    std::string nearest_mode = "round_prefer_floor";
    if(contains(attr, "nearest_mode"))
    {
        nearest_mode = attr.at("nearest_mode").s();
    }

    return nearest_mode;
}

struct parse_resize : op_parser<parse_resize>
{
    std::vector<op_desc> operators() const { return {{"Resize"}}; }

    instruction_ref parse(const op_desc& /*opd*/,
                          const onnx_parser& /*parser*/,
                          onnx_parser::node_info info,
                          std::vector<instruction_ref> args) const
    {
        // coord transform mode
        std::string coord_trans_mode = get_coord_trans_mode(info.attributes);

        // mode: only nearest and linear modes are supported for now
        std::string mode = get_mode(info.attributes);

        // nearest mode
        std::string nearest_mode = get_nearest_mode(info.attributes);

        // check exclude_outside, only support 0
        if(contains(info.attributes, "exclude_outside") and
           info.attributes.at("exclude_outside").i() == 1)
        {
            MIGRAPHX_THROW("PARSE_RESIZE: exclude_outside 1 is not supported!");
        }

        // input data shape info
        auto in_s    = args[0]->get_shape();
        auto in_lens = in_s.lens();

        // output shape is explicitly specified
        std::vector<std::size_t> out_lens(in_lens.size());

        // scale
        std::vector<double> vec_scale;

        for(const auto& arg : args)
        {
            if(arg->name() == "undefined" or arg == args.front())
            {
                continue;
            }

            // skipped empty input
            auto lens = arg->get_shape().lens();
            if(lens.empty())
            {
                continue;
            }

            auto type = arg->get_shape().type();
            // output size
            if(type == shape::int64_type)
            {
                auto arg_out_s = arg->eval();
                check_arg_empty(arg_out_s, "PARSE_RESIZE: dynamic output size is not supported!");
                arg_out_s.visit([&](auto ol) { out_lens.assign(ol.begin(), ol.end()); });

                if(out_lens.size() != in_lens.size())
                {
                    MIGRAPHX_THROW("PARSE_RESIZE: specified output size does not match input size");
                }

                // compute the scale
                vec_scale.resize(in_lens.size());
                std::transform(in_lens.begin(),
                               in_lens.end(),
                               out_lens.begin(),
                               vec_scale.begin(),
                               [](auto iss, auto oss) { return 1.0 * oss / iss; });
            }
            else
            {

                // scale input
                if(lens[0] == in_lens.size())
                {
                    auto arg_scale = arg->eval();
                    check_arg_empty(arg_scale,
                                    "PARSE_RESIZE: dynamic input scale is not supported!");

                    arg_scale.visit([&](auto v) { vec_scale.assign(v.begin(), v.end()); });
                    if(in_lens.size() != vec_scale.size())
                    {
                        MIGRAPHX_THROW("PARSE_RESIZE: ranks of input and scale are different!");
                    }

                    std::transform(in_lens.begin(),
                                   in_lens.end(),
                                   vec_scale.begin(),
                                   out_lens.begin(),
                                   [&](auto idx, auto scale) {
                                       return static_cast<std::size_t>(idx * scale);
                                   });
                }
            }
        }

        shape out_s{in_s.type(), out_lens};
        std::size_t out_elements = out_s.elements();
        auto idx_op              = get_original_idx_op(coord_trans_mode);

        // reshape input to one-dimension
        std::vector<int64_t> rsp_lens = {static_cast<int64_t>(in_s.elements())};
        args[0]                       = info.make_contiguous(args[0]);
        auto rsp = info.add_instruction(make_op("reshape", {{"dims", rsp_lens}}), args[0]);

        if(mode == "nearest")
        {
            std::vector<int> ind(out_elements);

            // map out_idx to in_idx
            auto nearest_op = get_nearest_op(nearest_mode);
            shape_for_each(out_s, [&](auto idx) {
                auto in_idx = idx;
                for(auto ii = 0; ii < in_lens.size(); ++ii)
                {
                    auto idx_val = idx_op(in_lens[ii], out_lens[ii], idx[ii], vec_scale[ii]);
                    in_idx[ii]   = nearest_op(in_lens[ii], idx_val);
                }

                ind[out_s.index(idx)] = static_cast<int64_t>(in_s.index(in_idx));
            });

            shape ind_s{shape::int32_type, out_lens};
            auto ins_ind = info.add_literal(literal(ind_s, ind));
            return info.add_instruction(make_op("gather", {{"axis", 0}}), rsp, ins_ind);
        }
        // linear mode
        else
        {
            auto nearest_floor = get_nearest_op("floor");
            auto nearest_ceil  = get_nearest_op("ceil");

            // get the number of dimensions
            std::size_t n_dim = out_lens.size();
            std::vector<std::vector<std::size_t>> vv_ind(2, std::vector<std::size_t>(out_elements));
            std::vector<std::vector<std::vector<std::size_t>>> vvv_ind(n_dim, vv_ind);
            std::vector<std::vector<float>> delta(n_dim, std::vector<float>(out_elements));

            shape_for_each(out_s, [&](auto idx) {
                auto in_idx  = idx;
                auto out_idx = out_s.index(idx);
                for(auto ii = 0; ii < in_lens.size(); ++ii)
                {
                    auto idx_val = idx_op(in_lens[ii], out_lens[ii], idx[ii], vec_scale[ii]);
                    vvv_ind[ii][0][out_idx] = nearest_floor(in_lens[ii], idx_val);
                    vvv_ind[ii][1][out_idx] = nearest_ceil(in_lens[ii], idx_val);
                    delta[ii][out_idx]      = idx_val - vvv_ind[ii][0][out_idx];
                }
            });

            std::vector<std::vector<std::size_t>> vec_dims(out_elements);
            auto ind      = calc_neighbor_points(vvv_ind, 0, vec_dims, in_s);
            auto ind_lens = out_lens;
            ind_lens[0] *= (std::size_t{1} << n_dim);
            shape ind_s{shape::int32_type, ind_lens};
            auto ins_ind = info.add_literal(literal(ind_s, ind));
            auto data    = info.add_instruction(make_op("gather", {{"axis", 0}}), rsp, ins_ind);

            auto dim_lens = out_lens;
            dim_lens[0] *= (std::size_t{1} << (n_dim - 1));
            for(std::size_t i = 0; i < n_dim; ++i)
            {
                shape dim_s{shape::float_type, dim_lens};
                const auto& dim_delta = delta[n_dim - i - 1];
                std::vector<float> delta_data;
                for(std::size_t j = 0; j < dim_lens[0] / out_lens[0]; ++j)
                {
                    delta_data.insert(delta_data.begin(), dim_delta.begin(), dim_delta.end());
                }
                auto ins_delta = info.add_literal(dim_s, delta_data);

                // slice the data
                int64_t slc_stride = static_cast<int64_t>(dim_lens[0]);
                auto low           = info.add_instruction(
                    make_op("slice", {{"axes", {0}}, {"starts", {0}}, {"ends", {slc_stride}}}),
                    data);
                auto hi = info.add_instruction(
                    make_op("slice",
                            {{"axes", {0}}, {"starts", {slc_stride}}, {"ends", {2 * slc_stride}}}),
                    data);
                auto diff = info.add_instruction(make_op("sub"), hi, low);
                auto ddf  = info.add_instruction(make_op("mul"), diff, ins_delta);
                data      = info.add_instruction(make_op("add"), ddf, low);
                dim_lens[0] /= 2;
            }

            return data;
        }
    }
};

} // namespace onnx

} // namespace MIGRAPHX_INLINE_NS
} // namespace migraphx