#ifndef OPENGLHANDLER_H
#define OPENGLHANDLER_H

#include <QtCore>
#include <QImage>
#include <QOpenGLContext>
#include <QOffscreenSurface>
#include <QOpenGLFramebufferObject>
#include <QOpenGLShaderProgram>
#include <QOpenGLTexture>
#include <QOpenGLBuffer>
#include <ft2build.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <QtGui/QOpenGLFunctions_3_3_Core>

#include FT_FREETYPE_H

struct VertexData
{
    QVector2D position;
    QVector2D texCoord;
};

struct Character {
    unsigned int TextureID;  //ID handle of the glyph texture
    glm::ivec2 Size;         //Size of glyph
    glm::ivec2 Bearing;      //Offset from baseline to left/top of glyph
    long Advance;    //Offset to advance to next glyph
};

class OpenGLHandler
{
public:
    OpenGLHandler();
    ~OpenGLHandler();

    void run();
    void processImage(const QImage& image,
                      const QString& vertexShader,
                      const QString& fragmentShader,
                      const QString& textureVar,
                      const QString& vertexPosVar,
                      const QString& textureCoordVar);

private:
    QOpenGLFunctions_3_3_Core* fun;
    QOpenGLContext _context;
    QOffscreenSurface _surface;
    QOpenGLFramebufferObject* _fbo;
    QImage* _image;
    QOpenGLShaderProgram* _shader;
    QOpenGLTexture _texture;
    FT_Library _ft;
    FT_Face _face;
    QMap<char, Character> _characters;

    QString vertexShader =
        "attribute vec4 aPosition;\n"
        "attribute vec2 aTexCoord;\n"
        "varying vec2 vTexCoord;\n"
        "void main()\n"
        "{\n"
        "   gl_Position = aPosition;\n"
        "   vTexCoord = aTexCoord;\n"
        "}";

    QString fragmentShader =
        "uniform sampler2D texture;\n"
        "varying vec2 vTexCoord;\n"
        "void main()\n"
        "{\n"
        "   gl_FragColor = texture2D(texture, vTexCoord);\n"
        "}";

    unsigned int chVAO, chVBO;
    bool prepareShader(QString vertexShader, QString fragmentShader);
    bool prepareTexture(const QImage& image);
    bool prepareCoords(QOpenGLBuffer vertexBuf, QOpenGLBuffer indexBuf);

    void loadChars();
    void processText();
    void RenderText(std::string text, float x, float y, float scale, glm::vec3 color);
    bool prepareCoords2(QOpenGLBuffer vertexBuf, QOpenGLBuffer indexBuf);
    void flipImage();
    QString getImage(QImage img);
};

#endif //OPENGLHANDLER_H