#include <QImageReader>
#include <QOpenGLFunctions>
#include <QOpenGLBuffer>

#include "OpenGLHandler.h"

OpenGLHandler::OpenGLHandler() : _texture(QOpenGLTexture::Target2D)
{
    if(!_context.create())
    {
        qDebug() << "Can't create GL _context.";

        return;
    }
    _surface.setFormat(_context.format());
    _surface.create();

    if(!_surface.isValid())
    {
        qDebug() << "_surface not valid.";

        return;
    }

    if(!_context.makeCurrent(&_surface))
    {
        qDebug() << "Can't make _context current.";

        return;
    }
    _image = new QImage("/home/mmt/Desktop/Projects/OpenGLOffscreen/sono.jpg");
    _fbo = new QOpenGLFramebufferObject(_image->size());

    _context.functions()->glViewport(0, 0, _image->width(), _image->height());
    fun = new QOpenGLFunctions_3_3_Core();

    if(!fun->initializeOpenGLFunctions())
    {
        qDebug() << "Can't init GL functions.";

        return;
    }
    _shader = new QOpenGLShaderProgram(&_context);
    loadChars();
}

bool OpenGLHandler::prepareShader(QString vertexShader, QString fragmentShader)
{
    if(!_shader->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, vertexShader))
    {
        qDebug() << "Can't add vertex shader.";

        return false;
    }
    if(!_shader->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShader))
    {
        qDebug() << "Can't add fragment shader.";

        return {};
    }
    if(!_shader->link())
    {
        qDebug() << "Can't link program.";

        return false;
    }
    if(!_shader->bind())
    {
        qDebug() << "Can't bind program.";

        return false;
    }

    return true;
}

bool OpenGLHandler::prepareTexture(const QImage& image)
{
    _texture.setData(image);
    _texture.bind();
    if(!_texture.isBound())
    {
        qDebug() << "Texture not bound.";

        return false;
    }

    return true;
}

bool OpenGLHandler::prepareCoords(QOpenGLBuffer vertexBuf, QOpenGLBuffer indexBuf)
{
    VertexData vertices[] =
    {
        {{ -0.5f, +0.5f }, { 0.0f, 0.0f }}, //top-left
        {{ +0.5f, +0.5f }, { 1.0f, 0.0f }}, //top-right
        {{ -0.5f, -0.5f }, { 0.0f, 1.0f }}, //bottom-left
        {{ +0.5f, -0.5f }, { 1.0f, 1.0f }} //bottom-right
//{{ -0.5f, +0.5f }, { 0.0f, 0.0f }}, //top-left
//{{ +0.5f, +0.5f }, { 1.0f, 0.0f }}, //top-right
//{{ -0.5f, -0.5f }, { 0.0f, 1.0f }}, //bottom-left
//{{ +0.5f, -0.5f }, { 1.0f, 1.0f }} //bottom-right
    };

    GLuint indices[] =
    {
        0, 1, 2, 3
    };

    if(!vertexBuf.create())
    {
        qDebug() << "Can't create vertex buffer.";

        return {};
    }

    if(!indexBuf.create())
    {
        qDebug() << "Can't create index buffer.";

        return {};
    }

    if(!vertexBuf.bind())
    {
        qDebug() << "Can't bind vertex buffer.";

        return {};
    }
    vertexBuf.allocate(vertices, 4 * sizeof(VertexData));
    if(!indexBuf.bind())
    {
        qDebug() << "Can't bind index buffer.";

        return {};
    }
    indexBuf.allocate(indices, 4 * sizeof(GLuint));

    return true;
}

void OpenGLHandler::loadChars()
{
    if(FT_Init_FreeType(&_ft))
    {
        qDebug() << "ERROR::FREETYPE: Could not init FreeType Library";
    }

    if(FT_New_Face(_ft, "/home/mmt/.fonts/Roboto-Black.ttf", 0, &_face))
    {
        qDebug() << "ERROR::FREETYPE: Failed to load font";
    }
    FT_Set_Pixel_Sizes(_face, 0, 48);
    if(FT_Load_Char(_face, 'X', FT_LOAD_RENDER))
    {
        qDebug() << "ERROR::FREETYTPE: Failed to load Glyph";
    }

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1); //disable byte-alignment restriction

    int i = 0;
    for(unsigned char c = 0; c < 128; c++)
    {
        //load character glyph
        if(FT_Load_Char(_face, c, FT_LOAD_RENDER))
        {
            qDebug() << "ERROR::FREETYTPE: Failed to load Glyph\n";
            continue;
        }
//// generate texture
        unsigned int texture;
        glGenTextures(1, &texture);
        glBindTexture(GL_TEXTURE_2D, texture);
        glTexImage2D(
            GL_TEXTURE_2D,
            0,
            GL_RED,
            _face->glyph->bitmap.width,
            _face->glyph->bitmap.rows,
            0,
            GL_RED,
            GL_UNSIGNED_BYTE,
            _face->glyph->bitmap.buffer
            );
//qDebug() << _face->glyph->bitmap.palette_mode;
//QImage chImage(_face->glyph->bitmap.buffer, _face->glyph->bitmap.width,
//_face->glyph->bitmap.rows,
//QImage::Format::Format_Grayscale8);
//chImage.save("/home/mmt/Desktop/chr/" + static_cast<QString>(i++) + ".png");

//// set texture options
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        //now store character for later use
        Character character = {
            texture,
            glm::ivec2(_face->glyph->bitmap.width, _face->glyph->bitmap.rows),
            glm::ivec2(_face->glyph->bitmap_left, _face->glyph->bitmap_top),
            _face->glyph->advance.x
        };
        _characters.insert(c, character);
    }
    glBindTexture(GL_TEXTURE_2D, 0);
    FT_Done_Face(_face);
    FT_Done_FreeType(_ft);
}

void OpenGLHandler::processText()
{
    QString vertexShadre =
        "#version 330 core\n"
        "layout (location = 4) in vec4 vertex;"
        "out vec2 TexCoords;"
        "uniform mat4 projection;"
        "void main()"
        "{"
        "    gl_Position = projection * vec4(vertex.xy, 0.0, 1.0);"
        "    TexCoords.x = vertex.z;"
        "    TexCoords.y = vertex.w;"
        "}";
    QString fragShadre =
        "#version 330 core\n"
        "in vec2 TexCoords;"
        "out vec4 color;"
        "uniform sampler2D text;"
        "uniform vec3 textColor;"
        "void main()"
        "{"
        "    vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TexCoords).r);"
        "    color = vec4(textColor, 1.00) * sampled;"
        "}";
    prepareShader(vertexShadre, fragShadre);
//_shader->link();
//_shader->bind();
//fun->glEnable(GL_CULL_FACE);
    fun->glEnable(GL_BLEND);
//glBlendFunc(GL_ONE, GL_ZERO);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    QMatrix4x4 qProjection;
    QRect temp(0.0f, static_cast<float>(320), 0.0f, static_cast<float>(480));
    qProjection.ortho(temp);
    _shader->setUniformValueArray(_shader->uniformLocation("projection"), &qProjection, 1);
    fun->glGenVertexArrays(1, &chVAO);
    fun->glGenBuffers(1, &chVBO);
    fun->glBindVertexArray(chVAO);
    fun->glBindBuffer(GL_ARRAY_BUFFER, chVBO);
    fun->glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
    fun->glEnableVertexAttribArray(4);
    fun->glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
    fun->glBindBuffer(GL_ARRAY_BUFFER, 0);
    fun->glBindVertexArray(0);

    RenderText("This is sample text", -0.8f, -.8f, .003f, glm::vec3(0.5, 0.8f, 0.2f));
    RenderText("(C) LearnOpenGL.com", -0.5f, 0.00f, 0.005f, glm::vec3(0.3, 0.7f, 0.9f));
    //glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
    //-------------------------------------------------------------------------------
//glfwSwapBuffers(_window);
//glfwPollEvents();
    auto log = _shader->log();
    if(log != "")
    {
        qDebug() << "log : " << log;
    }

    fun->glDeleteVertexArrays(1, &chVAO);
    fun->glDeleteBuffers(1, &chVBO);
    _shader->removeAllShaders();
    fun->glDisable(GL_BLEND);
    glDisable(GL_CULL_FACE);
}

void OpenGLHandler::RenderText(std::string text, float x, float y, float scale, glm::vec3 color)
{
    //activate corresponding render state
    _shader->setUniformValue(_shader->uniformLocation("textColor"), color.x, color.y, color.z);
    glActiveTexture(GL_TEXTURE0);
    fun->glBindVertexArray(chVAO);

    //iterate through all characters
    std::string::const_iterator c;
    for(c = text.begin(); c != text.end(); c++)
    {
//qDebug() << "here";
        Character ch = _characters[*c];

        float xpos = x + ch.Bearing.x * scale;
        float ypos = y - (ch.Size.y - ch.Bearing.y) * scale;
        //qDebug() << "xpos = " << xpos;
        float w = ch.Size.x * scale;
        float h = ch.Size.y * scale;
//qDebug() << ypos + h;
        //update VBO for each character
        float vertices[6][4] = {
            { xpos, ypos + h, 0.0f, 0.0f },
            { xpos, ypos, 0.0f, 1.0f },
            { xpos + w, ypos, 1.0f, 1.0f },

            { xpos, ypos + h, 0.0f, 0.0f },
            { xpos + w, ypos, 1.0f, 1.0f },
            { xpos + w, ypos + h, 1.0f, 0.0f }
        };
        //render glyph texture over quad
        glBindTexture(GL_TEXTURE_2D, ch.TextureID);
        //update content of VBO memory
        fun->glBindBuffer(GL_ARRAY_BUFFER, chVBO);
        fun->glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices); //be sure to use
        //glBufferSubData and not
        //glBufferData

        fun->glBindBuffer(GL_ARRAY_BUFFER, 0);
        //render quad
        glDrawArrays(GL_TRIANGLES, 0, 6);
        //now advance cursors for next glyph (note that advance is number of 1/64 pixels)
        x += (ch.Advance >> 6) * scale; //bitshift by 6 to get value in pixels (2^6 = 64 (divide
                                        //amount of 1/64th pixels by 64 to get amount of pixels))
    }
    fun->glBindVertexArray(0);
    glBindTexture(GL_TEXTURE_2D, 0);
}

bool OpenGLHandler::prepareCoords2(QOpenGLBuffer vertexBuf, QOpenGLBuffer indexBuf)
{
    VertexData vertices[] =
    {
        {{ -1.0f, +1.0f }, { 0.0f, 1.0f }}, //top-left
        {{ +1.0f, +1.0f }, { 1.0f, 1.0f }},     //top-right
        {{ -1.0f, -1.0f }, { 0.0f, 0.0f }},     //bottom-left
        {{ +1.0f, -1.0f }, { 1.0f, 0.0f }}      //bottom-right
    };

    GLuint indices[] =
    {
        0, 1, 2, 3
    };

    if(!vertexBuf.create())
    {
        qDebug() << "Can't create vertex buffer.";

        return {};
    }

    if(!indexBuf.create())
    {
        qDebug() << "Can't create index buffer.";

        return {};
    }

    if(!vertexBuf.bind())
    {
        qDebug() << "Can't bind vertex buffer.";

        return {};
    }
    vertexBuf.allocate(vertices, 4 * sizeof(VertexData));
    if(!indexBuf.bind())
    {
        qDebug() << "Can't bind index buffer.";

        return {};
    }
    indexBuf.allocate(indices, 4 * sizeof(GLuint));

    return true;
}

QString OpenGLHandler::getImage(QImage img)
{
    QByteArray byteArray;
    QBuffer buffer(&byteArray);
    buffer.open(QIODevice::WriteOnly);
    img.save(&buffer, "png");
    //save image data in string
    QString image("data:image/png;base64,");
    image.append(QString::fromLatin1(byteArray.toBase64().data()));

    return image;
}

OpenGLHandler::~OpenGLHandler()
{
    delete _image;
    delete _fbo;
    delete _shader;
}

void OpenGLHandler::processImage(const QImage& image,
                                 const QString& vertexShader,
                                 const QString& fragmentShader,
                                 const QString& textureVar,
                                 const QString& vertexPosVar,
                                 const QString& textureCoordVar)
{
//fun->glEnable(GL_BLEND);
    bool a;
    QOpenGLBuffer vertexBuf(QOpenGLBuffer::VertexBuffer);
    QOpenGLBuffer indexBuf(QOpenGLBuffer::IndexBuffer);
    a = prepareShader(vertexShader, fragmentShader);
    a = prepareTexture(image);
    a = prepareCoords(vertexBuf, indexBuf);

    int offset = 0;
    _shader->enableAttributeArray(vertexPosVar.toLatin1().data());
    _shader->setAttributeBuffer(vertexPosVar.toLatin1().data(), GL_FLOAT, offset, 2,
                                sizeof(VertexData));
    offset += sizeof(QVector2D);
    _shader->enableAttributeArray(textureCoordVar.toLatin1().data());
    _shader->setAttributeBuffer(textureCoordVar.toLatin1().data(), GL_FLOAT, offset, 2,
                                sizeof(VertexData));

    _shader->setUniformValue(textureVar.toLatin1().data(), 0);

    fun->glDrawElements(GL_TRIANGLE_STRIP, 4, GL_UNSIGNED_INT, Q_NULLPTR);

    _shader->disableAttributeArray(vertexPosVar.toLatin1().data());
    _shader->disableAttributeArray(textureCoordVar.toLatin1().data());
    _shader->disableAttributeArray(textureVar.toLatin1().data());

    _shader->removeAllShaders();
}

void OpenGLHandler::flipImage()
{
    QString textureVar = "texture";
    QString vertexPosVar = "aPosition";
    QString textureCoordVar = "aTexCoord";
    QString flipVertexShader =
        "attribute vec4 aPosition;\n"
        "attribute vec2 aTexCoord;\n"
        "varying vec2 vTexCoord;\n"
        "void main()\n"
        "{\n"
        "   gl_Position = aPosition;\n"
        "   vTexCoord.x = -aTexCoord.x;\n"
        "   vTexCoord.y = aTexCoord.y;\n"
        "}";
    QString flipFragmentShader =
        "uniform sampler2D texture;\n"
        "varying vec2 vTexCoord;\n"
        "void main()\n"
        "{\n"
        "   gl_FragColor = texture2D(texture, vTexCoord);\n"
        "}";
    prepareShader(flipVertexShader, "");
    QOpenGLBuffer vertexBuf(QOpenGLBuffer::VertexBuffer);
    QOpenGLBuffer indexBuf(QOpenGLBuffer::IndexBuffer);
    prepareCoords2(vertexBuf, indexBuf);

    int offset = 0;
    _shader->enableAttributeArray(vertexPosVar.toLatin1().data());
    _shader->setAttributeBuffer(vertexPosVar.toLatin1().data(), GL_FLOAT, offset, 2,
                                sizeof(VertexData));
    offset += sizeof(QVector2D);
    _shader->enableAttributeArray(textureCoordVar.toLatin1().data());
    _shader->setAttributeBuffer(textureCoordVar.toLatin1().data(), GL_FLOAT, offset, 2,
                                sizeof(VertexData));

    _shader->setUniformValue(textureVar.toLatin1().data(), 0);
    fun->glDrawElements(GL_TRIANGLE_STRIP, 4, GL_UNSIGNED_INT, Q_NULLPTR);
    _shader->disableAttributeArray(vertexPosVar.toLatin1().data());
    _shader->disableAttributeArray(textureCoordVar.toLatin1().data());
    _shader->disableAttributeArray(textureVar.toLatin1().data());
    _shader->removeAllShaders();
}

void OpenGLHandler::run()
{
//fun->glClearColor(0, 1, 1, 1);
//fun->glClear(GL_COLOR_BUFFER_BIT);
    processImage(*_image, vertexShader, fragmentShader, "texture", "aPosition",
                 "aTexCoord");
    processText();
//flipImage();
    auto ret = _fbo->toImage(true);
//auto address = getImage(ret);

    ret.save("/home/mmt/Desktop/test.png");
}