#pragma once
#ifndef _NB_BUFFER
#define _NB_BUFFER

#include <exception>
#include <string>
#include <vector>

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "Shader.h"

namespace NB{

class BufferWarning : public std::runtime_error {
public:
    BufferWarning(const std::string& msg) : std::runtime_error(msg) {}
};

template<typename T>
class BufferManager {
public:
    BufferManager(
        GLenum buffer_type,
        bool keep_local=true,
        GLenum usage=GL_STATIC_DRAW
    ) : _buffer_type(buffer_type), _initialized(false), _keep_local(keep_local), _usage(usage),
        _size(0), _max_size(0) {}
    BufferManager(
        GLenum buffer_type,
        const std::vector<T>& data,
        bool keep_local=true,
        GLenum usage=GL_STATIC_DRAW
    ) : _buffer_type(buffer_type), _keep_local(keep_local), _usage(usage) {
        setData(data);
    }
    BufferManager(
        GLenum buffer_type,
        unsigned int size,
        bool keep_local=true,
        GLenum usage=GL_STATIC_DRAW
    ) : BufferManager<T>(buffer_type, std::vector<T>(size), keep_local, usage) {}

    GLenum bufferType() const { return _buffer_type; }
    GLenum usageType() const { return _usage; }
    unsigned int id() const { return _id; }
    unsigned int size() const { return _size; }
    unsigned int capacity() const { return _max_size; }
    bool isInitialized() const { return _initialized; }
    bool keepLocal() const { return _keep_local; }
    std::vector<T> getDataDirect() const {
        std::vector<T> ret(_size);
        glBindBuffer(_buffer_type, _id);
        glGetBufferSubData(_buffer_type, 0, sizeof(T)*_size, ret.data());
        glBindBuffer(_buffer_type, 0);

        return ret;
    }
    std::vector<T> getData() const {
        if(_keep_local) {
            return _data;
        } else {
            return getDataDirect();
        }
    }
    unsigned int bind() const { glBindBuffer(_buffer_type, _id); return _id; }
    bool isBound() const { return (getBound(_buffer_type) == _id); }

    GLenum usageType(GLenum usage) { _usage=usage; return usageType(); }
    bool keepLocal(bool keep_local) {
        if(keep_local && !_keep_local) {
            _data = getDataDirect();
        }
        _keep_local = keep_local;
        return _keep_local;
    }
    bool initialize(unsigned int n=1) {
        if (!_initialized) {
            setData(std::vector<T>(n));
        }
        return _initialized;
    }
    void loadData(const std::vector<T>& newData, unsigned int offset=0) {
        if ( newData.size()+offset > _max_size ) {
            throw BufferWarning("Attempting to overflow buffer of capacity " + std::to_string(_max_size) + ".");
        }
        glBindBuffer(_buffer_type, _id);
        glBufferSubData(_buffer_type, offset*sizeof(T), sizeof(T)*newData.size(), newData.data());
        if(_keep_local) {
            memcpy(_data.data()+offset*sizeof(T), newData.data(), sizeof(T)*newData.size());
        }
        glBindBuffer(_buffer_type, 0);
    }
    void setData(const std::vector<T>& set_data) {
        if (_keep_local) {_data = set_data;}
        if (!_initialized) {
            glGenBuffers(1, &_id);
            _initialized = true;
        }
        glBindBuffer(_buffer_type, _id);
        if (set_data.size() <= _max_size) {
            glBufferSubData(_buffer_type, 0, sizeof(T)*_size, _data.data());
            _size = _data.size();
        } else {
            _size = _data.size();
            _max_size = _size;
            glBufferData(_buffer_type, sizeof(T)*_max_size, _data.data(), _usage);
        }
        glBindBuffer(_buffer_type, 0);
    }
    unsigned int resize(unsigned int n) {
        if (_keep_local) { _data.resize(n); }
        if (n > _max_size) {
            _max_size = n;
            if (_initialized) {
                glBindBuffer(_buffer_type, _id);
                glBufferData(_buffer_type, sizeof(T)*_max_size, _data.data(), _usage);
                glBindBuffer(_buffer_type, 0);
            }
        }
        _size = n;
        return _size;
    }
    unsigned int shrink_to_fit() {
        if (_size < _max_size) {
            if (_keep_local) {
                _data.shrink_to_fit();
                _size = _data.size();
                glBindBuffer(_buffer_type, _id);
                glBufferData(_buffer_type, _size*sizeof(T), _data.data(),_usage);
                glBindBuffer(_buffer_type, 0);
                _max_size = _size;
            } else {
                _data = getDataDirect();
                _size = _data.data();
                _max_size = _size;
            }
        }
        return _size;
    }

    static unsigned int getBound(GLenum buffer) {
        unsigned int ret;
        glGetIntegerv(buffer, &ret);
        return ret;
    }

private:
    const GLenum _buffer_type;

    GLenum _usage;
    std::vector<T> _data;
    unsigned int _id, _size, _max_size;
    bool _initialized;
    bool _keep_local;

};


}

#endif