// Copyright (C) 2023 RozK
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef RK_ENGINE_VERTEX_FORMAT_H
#define RK_ENGINE_VERTEX_FORMAT_H

#include "render_opengles.hpp"
#include <limits>

namespace rk_vertex {

#pragma pack(push, 1)

template<typename _type>
struct alignas(alignof(_type)) rk_input {
    _type input;
};

template<typename _type, typename _input, bool _signed, bool _normalized>
struct alignas(alignof(_type)) rk_output {
    _type output;

    [[RK_FAST]]
    inline void convert(
        rk_input<_input> const & __restrict src) {
        output = static_cast<_type>(src.input);
    }
};

template<typename _type, bool _signed>
struct alignas(alignof(_type)) rk_output<_type, rk_float, _signed, true> {
    _type output;

    [[RK_FAST]]
    inline void convert(
        rk_input<rk_float> const & __restrict src) {
        enum : _type { max = std::numeric_limits<_type>::max() };
        output = static_cast<_type>(src.input * static_cast<float>(max));
    }
};

#pragma pack(4)

template<typename _input, unsigned _cols>
struct alignas(4) rk_input_row {
    rk_input<_input> input_col[_cols];
};

template<typename _output, typename _input, unsigned _cols, bool _signed, bool _normalized>
struct alignas(4) rk_output_row {
    rk_output<_output, _input, _signed, _normalized> output_col[_cols];

    [[RK_FAST, RK_FLATTEN, RK_UNROLLED]]
    inline void convert(
        rk_input_row<_input, _cols> const & __restrict src) {
        for (unsigned col = 0; col < _cols; ++col) {
            output_col[col].convert(src.input_col[col]);
        }
    }
};

template<typename _input, unsigned _cols, bool _signed, bool _normalized>
struct alignas(4) rk_output_row<rk_packed<_signed, _cols>, _input, _cols, _signed, _normalized> {
    rk_output<rk_packed<_signed, _cols>, _input, _signed, _normalized> output_cols;

    [[RK_FAST, RK_FLATTEN]]
    inline void convert(
        rk_input_row<_input, _cols> const & __restrict src) {
        output_cols.convert(src);
    }
};

template<typename _input, unsigned _cols, unsigned _rows>
struct alignas(4) rk_input_format {
    rk_input_row<_input, _cols> input_row[_rows];
};

template<typename _output, typename _input, unsigned _cols, unsigned _rows, bool _signed, bool _normalized>
struct alignas(4) rk_output_format {
    rk_output_row<_output, _input, _cols, _signed, _normalized> output_row[_rows];

    [[RK_FAST, RK_FLATTEN, RK_UNROLLED]]
    inline void convert(
        rk_input_format<_input, _cols, _rows> const & __restrict src) {
        for (unsigned row = 0; row < _rows; ++row) {
            output_row[row].convert(src.input_row[row]);
        }
    }
};

template<typename _input, bool _signed, bool _normalized>
struct alignas(alignof(rk_packed<_signed, 3>)) rk_output<rk_packed<_signed, 3>, _input, _signed, _normalized> {
    rk_packed<_signed, 3> output;

    [[RK_FAST]]
    inline void convert(
        rk_input_row<_input, 3> const & __restrict src) {
        typedef typename rk_packed<_signed, 3>::type packed_type;
        output.packed =
            ((static_cast<packed_type>(src.input_col[0].input) & 1023)) |
            ((static_cast<packed_type>(src.input_col[1].input) & 1023) << 10) |
            ((static_cast<packed_type>(src.input_col[2].input) & 1023) << 20);
    }
};

template<typename _input, bool _signed, bool _normalized>
struct alignas(alignof(rk_packed<_signed, 4>)) rk_output<rk_packed<_signed, 4>, _input, _signed, _normalized> {
    rk_packed<_signed, 4> output;

    [[RK_FAST]]
    inline void convert(
        rk_input_row<_input, 4> const & __restrict src) {
        typedef typename rk_packed<_signed, 4>::type packed_type;
        output.packed =
            ((static_cast<packed_type>(src.input_col[0].input) & 1023)) |
            ((static_cast<packed_type>(src.input_col[1].input) & 1023) << 10) |
            ((static_cast<packed_type>(src.input_col[2].input) & 1023) << 20) |
            ((static_cast<packed_type>(src.input_col[3].input) &    3) << 30);
    }
};

template<>
struct alignas(alignof(rk_packed<true, 3>)) rk_output<rk_packed<true, 3>, rk_float, true, true> {
    rk_packed<true, 3> output;

    [[RK_FAST]]
    inline void convert(
        rk_input_row<rk_float, 3> const & __restrict src) {
        output.packed =
            ((static_cast<rk_int>(src.input_col[0].input * 511.f) & 1023)) |
            ((static_cast<rk_int>(src.input_col[1].input * 511.f) & 1023) << 10) |
            ((static_cast<rk_int>(src.input_col[2].input * 511.f) & 1023) << 20);
    }
};

template<>
struct alignas(alignof(rk_packed<true, 4>)) rk_output<rk_packed<true, 4>, rk_float, true, true> {
    rk_packed<true, 4> output;

    [[RK_FAST]]
    inline void convert(
        rk_input_row<rk_float, 4> const & __restrict src) {
        output.packed =
            ((static_cast<rk_uint>(src.input_col[0].input * 511.f) & 1023)) |
            ((static_cast<rk_uint>(src.input_col[1].input * 511.f) & 1023) << 10) |
            ((static_cast<rk_uint>(src.input_col[2].input * 511.f) & 1023) << 20) |
            ((static_cast<rk_uint>(src.input_col[3].input)         &    3) << 30);
    }
};

#pragma pack(pop)

template<typename _output, typename _input, unsigned _cols, unsigned _rows, bool _signed, bool _normalized>
struct rk_format {
    typedef rk_input<_input> input;
    typedef rk_output<_output, input, _signed, _normalized> output;

    typedef rk_input_row<_input, _cols> input_row;
    typedef rk_output_row<_output, _input, _cols, _signed, _normalized> output_row;

    typedef rk_input_format<_input, _cols, _rows> input_format;
    typedef rk_output_format<_output, _input, _cols, _rows, _signed, _normalized> output_format;

    static_assert(sizeof(input) == sizeof(_input));
    static_assert(sizeof(output) == sizeof(_output));
    static_assert((sizeof(input_row) % sizeof(rk_vertex_input)) == 0);
    static_assert((sizeof(output_row) % sizeof(rk_vertex_output)) == 0);
    static_assert((sizeof(input_format) % sizeof(rk_vertex_input)) == 0);
    static_assert((sizeof(output_format) % sizeof(rk_vertex_output)) == 0);

    static unsigned get_input_size() {
        return sizeof(input_format);
    }

    static unsigned get_output_size() {
        return sizeof(output_format);
    }

    static unsigned get_output_offset(unsigned const index) {
        return index * sizeof(output_row);
    }

    [[RK_FAST, RK_FLATTEN]]
    inline static void convert(
        output_format & __restrict dst,
        input_format const & __restrict src) {
        dst.convert(src);
    }

    [[RK_HOT, RK_FAST, RK_FLATTEN]]
    static void param_packer(
        unsigned const count,
        rk_instance_index const * const __restrict indices,
        rk_param_output * __restrict _dst,
        rk_param_input const * const __restrict _src) {
        rk_instance_index const * const last_index = indices + count;
        output_format * __restrict dst = reinterpret_cast<output_format *>(_dst);
        input_format const * const __restrict src = reinterpret_cast<input_format const *>(_src);
        for (rk_instance_index const * __restrict index = indices; index < last_index; ++index, ++dst) {
            dst->convert(src[*index]);
        }
    }
};

} // namepace rk_vertex

typedef rk_vertex::rk_format<rk_float,            rk_float, 3, 1, true,  false> rk_vec3_float;
typedef rk_vertex::rk_format<rk_short,            rk_float, 3, 1, true,  false> rk_vec3_short;
typedef rk_vertex::rk_format<rk_short,            rk_float, 3, 1, true,  true>  rk_vec3_short_norm;
typedef rk_vertex::rk_format<rk_packed<true,  3>, rk_float, 3, 1, true,  false> rk_vec3_int10;
typedef rk_vertex::rk_format<rk_packed<true,  3>, rk_float, 3, 1, true,  true>  rk_vec3_int10_norm;
typedef rk_vertex::rk_format<rk_packed<false, 3>, rk_float, 3, 1, false, false> rk_vec3_uint10;
typedef rk_vertex::rk_format<rk_packed<false, 3>, rk_float, 3, 1, false, true>  rk_vec3_uint10_norm;
typedef rk_vertex::rk_format<rk_float,            rk_float, 3, 3, true,  false> rk_mat3_float;
typedef rk_vertex::rk_format<rk_packed<true,  3>, rk_float, 3, 3, true,  false> rk_mat3_int10;
typedef rk_vertex::rk_format<rk_packed<true,  3>, rk_float, 3, 3, true,  true>  rk_mat3_int10_norm;

#endif // RK_ENGINE_VERTEX_FORMAT_H