#pragma once
#ifndef _NB_VERTEX_ARRAY
#define _NB_VERTEX_ARRAY

#include "GLLoad.hpp"

#include <NBCore/Errors.hpp>

#include "Buffers.hpp"
#include "OGLObjects.hpp"


namespace nb {

static uint8_t GLSLTypeSize(GLenum type) {
    switch(type) {
    case GL_SHORT:
    case GL_UNSIGNED_SHORT:
    case GL_HALF_FLOAT:
        return 2;
        break;
    case GL_INT:
    case GL_UNSIGNED_INT:
    case GL_FLOAT:
        return 4;
        break;
    case GL_DOUBLE:
        return 8;
        break;
    default:
        return 1;
        break;
    }
}

struct VertexAttributeLayout {
    int32_t offset = 0;
    GLsizei stride = 0;
    GLuint divisor = 0;
};

struct VertexAttribute {
    GLint GLSLSize;
    GLenum GLSLType;
    GLboolean GLSLNormalization;
    VertexAttributeLayout layout;
};

struct VertexAttributePointer {
    VertexAttribute attribute;
    GLuint buffer;
    GLuint index;
};

static bool isIndexInVertexAttribute(int i, const VertexAttribute& va) {
    if ((i -= va.layout.offset) < 0) { return false; }
    return (i%va.layout.stride) < GLSLTypeSize(va.GLSLType) * va.GLSLSize;
}

typedef std::vector<VertexAttribute> VertexAttributeList;
typedef std::vector<VertexAttributePointer> VertexAttributePointerList;

class VAOError : public Error<VAOError> {
    using Base = Error<VAOError>;
    
    public:
    using Base::Base;
    
    enum Codes : unsigned int {
        UNDEFINED, INVALID_ATTRIBUTE
    };

    static const std::string type;
    static const ErrorCodeMap ErrorMessages;
};

class VAO : public OpenGLObject {
    using Base = OpenGLObject;
    using Codes = VAOError::Codes;

    public:
    using Base::Base;
    VAO() = default;
    VAO(const VertexAttributePointerList&);
    VAO(VAO&&);

    VAO& operator=(VAO&&);

    virtual void bind() const override {
        if(_id) {
            glBindVertexArray(_id);
        } else {
            THROW(OGLError(
                OGLError::Codes::INVALID_OBJECT,
                "w/ VertexArrayObject"
            ));
        }
    }
    virtual void unbind() const override { glBindVertexArray(0); }

    VertexAttributePointerList attributes() const;
    VertexAttributePointerList attributes(const VertexAttributePointerList&);
    VertexAttributePointer attr(GLuint) const;
    void enable() const;
    void enable(GLuint) const;
    void disable() const;
    void disable(GLuint) const;

    protected:
    using Base::_id;
    VertexAttributePointerList _attrs;

    virtual void remove() override {
        if(_id) {
            disable();
            bind();
            glDeleteVertexArrays(1, &_id);
            _id = 0;
        }
    }
    virtual GLuint declare() override {
        if (!_id) {
            glGenVertexArrays(1, &_id);
        }
        bind();
        return _id;
    }

};

class VertexError : public Error<VertexError> {
    protected:
    using Base = Error<VertexError>;
    
    public:
    using Base::Base;
    enum Codes : unsigned int {
        UNDEFINED, MISALIGNED_DATA
    };
    static const std::string type;
    static const ErrorCodeMap ErrorMessages;

};

using VBO = ArrayBuffer;
using VertBufVec = SharedVector<VBO>;
using EBO = ElementBuffer;

struct VertexData {
    std::shared_ptr<VBO> vbo;
    VertexAttributeList attrs;
};

using VertexDataVec = std::vector<VertexData>;

class VertexGroup {
    protected:
    using Codes = VertexError::Codes;
    VertexDataVec _vertex_data;
    std::shared_ptr<EBO> _ebo;
    std::shared_ptr<VAO> _vao;
    GLenum _primitive;

    public:
    GLenum primitive=GL_TRIANGLES;
    VertexGroup(VertexGroup&&);
    VertexGroup& operator=(VertexGroup&&);
    
    VertexGroup(
        const VertexDataVec& vertex_data,
        const std::shared_ptr<EBO>& ebo
    )
    : _vao(std::make_shared<VAO>()), _ebo(ebo) {
        setBuffers(vertex_data);
    }

    template<typename... T>
    VertexGroup(
        const VertexDataVec& vertex_data,
        T... args
    )
    : VertexGroup(vertex_data, std::make_shared<EBO>(args...)) {
        setBuffers(vertex_data);
    }
    
    template<typename... T>
    VertexGroup(
        const VertexData& vertex_data,
        T... args
    )
    : VertexGroup(VertexDataVec{vertex_data}, args...) {}
    
    template<typename... T>
    VertexGroup(
        const ByteVector& vertex_data,
        const VertexAttributeList& vertex_specification,
        T... args
    ) : VertexGroup({
        std::make_shared<VBO>(vertex_data),
        vertex_specification},
        args...
    ) {}

    void bind() const {
        _vao->bind();
        _ebo->bind();
    }
    void unbind() const {
        _vao->unbind();
        _ebo->unbind();
    }

    void draw() const;

    VertexDataVec getBuffers();
    VertexData getBuffers(size_t);
    size_t setBuffers(const VertexDataVec&);
    size_t addBuffer(const VertexData&);
    size_t addBuffer(const ByteVector& data, const VertexAttributeList& attrs);
    VertexDataVec dropBuffers();
    VertexData dropBuffer(size_t);

    VertexAttributePointer attribute(size_t) const;
    void enableAttr(GLuint);
    void disableAttr(GLuint);
    void enableBuffer(size_t);
    void disableBuffer(size_t);
    void enable();
    void disable();

    std::shared_ptr<EBO> indices() const;
    std::shared_ptr<EBO> indices(const std::vector<unsigned int>& data);
    std::shared_ptr<EBO> indices(std::shared_ptr<EBO> buffer);

};

} // namespace nb
#endif // _NB_VERTEX_ARRAY