#pragma once
/*
 *  Copyright (C) 2024  Brett Terpstra
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef COSC_4P80_ASSIGNMENT_2_COMMON_H
#define COSC_4P80_ASSIGNMENT_2_COMMON_H

#include <iostream>
#include <blt/iterator/enumerate.h>

#ifdef BLT_USE_GRAPHICS
    
    #include "blt/gfx/renderer/batch_2d_renderer.h"
    #include "blt/gfx/window.h"
    #include <imgui.h>

#endif

namespace assign2
{
    using Scalar = float;
//    const inline Scalar learn_rate = 0.001;
    inline Scalar learn_rate = 0.1;
    
    template<typename T>
    decltype(std::cout)& print_vec(const std::vector<T>& vec)
    {
        for (auto [i, v] : blt::enumerate(vec))
        {
            std::cout << v;
            if (i != vec.size() - 1)
                std::cout << ", ";
        }
        return std::cout;
    }
    
    struct error_data_t
    {
        Scalar error;
        Scalar d_error;
        
        error_data_t& operator+=(const error_data_t& e)
        {
            error += e.error;
            d_error += e.d_error;
            return *this;
        }
    };
    
    class layer_t;
    
    class network_t;
    
    struct function_t
    {
        [[nodiscard]] virtual Scalar call(Scalar) const = 0;
        
        [[nodiscard]] virtual Scalar derivative(Scalar) const = 0;
    };
    
    struct weight_view
    {
        public:
            weight_view(Scalar* data, blt::size_t size): m_data(data), m_size(size)
            {}
            
            inline Scalar& operator[](blt::size_t index) const
            {
#if BLT_DEBUG_LEVEL > 0
                if (index >= size)
                    throw std::runtime_error("Index is out of bounds!");
#endif
                return m_data[index];
            }
            
            [[nodiscard]] inline blt::size_t size() const
            {
                return m_size;
            }
            
            [[nodiscard]] auto begin() const
            {
                return m_data;
            }
            
            [[nodiscard]] auto end() const
            {
                return m_data + m_size;
            }
        
        private:
            Scalar* m_data;
            blt::size_t m_size;
    };
    
    /**
     * this class exists purely as an optimization
     */
    class weight_t
    {
        public:
            weight_t() = default;
            
            weight_t(const weight_t& copy) = delete;
            
            weight_t& operator=(const weight_t& copy) = delete;
            
            weight_t(weight_t&& move) noexcept: place(std::exchange(move.place, 0)), data(std::move(move.data))
            {}
            
            weight_t& operator=(weight_t&& move) noexcept
            {
                place = std::exchange(move.place, place);
                data = std::exchange(move.data, std::move(data));
                return *this;
            }
            
            void preallocate(blt::size_t amount)
            {
                data.resize(amount);
            }
            
            weight_view allocate_view(blt::size_t count)
            {
                auto size = place;
                place += count;
                return {&data[size], count};
            }
            
            void debug() const
            {
                std::cout << "Weights: ";
                print_vec(data) << std::endl;
            }
        
        private:
            blt::size_t place = 0;
            std::vector<Scalar> data;
    };
    
    inline bool is_thinks_bad(const std::vector<Scalar>& out)
    {
        return out[0] < out[1];
    }
    
}

#endif //COSC_4P80_ASSIGNMENT_2_COMMON_H