void showDebugImage(std::string name, const char *data, size_t width, size_t height) {
    glfwInit();

    static GLFWwindow *debugWindow = nullptr;
    if (!debugWindow) {
        debugWindow = glfwCreateWindow(width, height, name.c_str(), nullptr, nullptr);
        if (!debugWindow) {
            glfwTerminate();
            fprintf(stderr, "Failed to initialize window\n");
            exit(1);
        }
    }

    GLFWwindow *currentWindow = glfwGetCurrentContext();

    glfwSetWindowSize(debugWindow, width, height);
    glfwMakeContextCurrent(debugWindow);

    int fbWidth, fbHeight;
    glfwGetFramebufferSize(debugWindow, &fbWidth, &fbHeight);
    float scale = static_cast<float>(fbWidth) / static_cast<float>(width);

    {
        gl::PreservePixelZoom pixelZoom;
        gl::PreserveRasterPos rasterPos;

        MBGL_CHECK_ERROR(glPixelZoom(scale, -scale));
        MBGL_CHECK_ERROR(glRasterPos2f(-1.0f, 1.0f));
        MBGL_CHECK_ERROR(glDrawPixels(width, height, GL_LUMINANCE, GL_UNSIGNED_BYTE, data));
    }

    glfwSwapBuffers(debugWindow);

    glfwMakeContextCurrent(currentWindow);
}

 inline static Type Get() {
     GLint sfail, dpfail, dppass;
     MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_FAIL, &sfail));
     MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &dpfail));
     MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &dppass));
     return { static_cast<GLenum>(sfail), static_cast<GLenum>(dpfail), static_cast<GLuint>(dppass) };
 }

void LinepatternShader::bind(GLbyte* offset) {
    MBGL_CHECK_ERROR(glEnableVertexAttribArray(a_pos));
    MBGL_CHECK_ERROR(glVertexAttribPointer(a_pos, 2, GL_SHORT, false, 8, offset + 0));

    MBGL_CHECK_ERROR(glEnableVertexAttribArray(a_data));
    MBGL_CHECK_ERROR(glVertexAttribPointer(a_data, 4, GL_UNSIGNED_BYTE, false, 8, offset + 4));
}

void Painter::renderClipMasks() {
    config.stencilTest = GL_FALSE;
    config.depthTest = GL_FALSE;
    config.program = 0;
    config.colorMask = { GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE };

#ifndef GL_ES_VERSION_2_0
    config.pixelZoom = { 1, 1 };
    config.rasterPos = {{ -1, -1, 0, 0 }};

    // Read the stencil buffer
    const auto& fbSize = frame.framebufferSize;
    auto pixels = std::make_unique<uint8_t[]>(fbSize[0] * fbSize[1]);
    MBGL_CHECK_ERROR(glReadPixels(
                0,                // GLint x
                0,                // GLint y
                fbSize[0],        // GLsizei width
                fbSize[1],        // GLsizei height
                GL_STENCIL_INDEX, // GLenum format
                GL_UNSIGNED_BYTE, // GLenum type
                pixels.get()      // GLvoid * data
                ));

    // Scale the Stencil buffer to cover the entire color space.
    auto it = pixels.get();
    auto end = it + fbSize[0] * fbSize[1];
    const auto factor = 255.0f / *std::max_element(it, end);
    for (; it != end; ++it) {
        *it *= factor;
    }

    MBGL_CHECK_ERROR(glWindowPos2i(0, 0));
    MBGL_CHECK_ERROR(glDrawPixels(fbSize[0], fbSize[1], GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels.get()));
#endif // GL_ES_VERSION_2_0
}

void ObjectStore::performCleanup() {
    for (GLuint id : abandonedPrograms) {
        MBGL_CHECK_ERROR(glDeleteProgram(id));
    }
    abandonedPrograms.clear();

    for (GLuint id : abandonedShaders) {
        MBGL_CHECK_ERROR(glDeleteShader(id));
    }
    abandonedShaders.clear();

    if (!abandonedBuffers.empty()) {
        MBGL_CHECK_ERROR(glDeleteBuffers(int(abandonedBuffers.size()), abandonedBuffers.data()));
        abandonedBuffers.clear();
    }

    if (!abandonedTextures.empty()) {
        MBGL_CHECK_ERROR(glDeleteTextures(int(abandonedTextures.size()), abandonedTextures.data()));
        abandonedTextures.clear();
    }

    if (!abandonedVAOs.empty()) {
        MBGL_CHECK_ERROR(gl::DeleteVertexArrays(int(abandonedVAOs.size()), abandonedVAOs.data()));
        abandonedVAOs.clear();
    }
}

void Painter::renderDepthBuffer() {
    context.stencilTest = GL_FALSE;
    context.depthTest = GL_FALSE;
    context.program = 0;
    context.colorMask = { GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE };

#ifndef GL_ES_VERSION_2_0
    context.pixelZoom = { 1, 1 };
    context.rasterPos = {{ -1, -1, 0, 0 }};

    // Read the stencil buffer
    const auto& fbSize = frame.framebufferSize;
    auto pixels = std::make_unique<GLubyte[]>(fbSize[0] * fbSize[1]);

    const double base = 1.0 / (1.0 - depthRangeSize);
    glPixelTransferf(GL_DEPTH_SCALE, base);
    glPixelTransferf(GL_DEPTH_BIAS, 1.0 - base);

    MBGL_CHECK_ERROR(glReadPixels(
                0,                  // GLint x
                0,                  // GLint y
                fbSize[0],          // GLsizei width
                fbSize[1],          // GLsizei height
                GL_DEPTH_COMPONENT, // GLenum format
                GL_UNSIGNED_BYTE,   // GLenum type
                pixels.get()        // GLvoid * data
                ));

    MBGL_CHECK_ERROR(glWindowPos2i(0, 0));
    MBGL_CHECK_ERROR(glDrawPixels(fbSize[0], fbSize[1], GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels.get()));
#endif // GL_ES_VERSION_2_0
}

inline void end_group() {
    if (gl::PopDebugGroup != nullptr) {
        MBGL_CHECK_ERROR(gl::PopDebugGroup());
    } else if (gl::PopGroupMarkerEXT != nullptr) {
        MBGL_CHECK_ERROR(gl::PopGroupMarkerEXT());
    }
    // indent--;
}

void Raster::updateFilter() {
    MBGL_CHECK_ERROR(glTexParameteri(
        GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
        filter == Scaling::Linear
            ? (mipmap == MipMap::Yes ? GL_LINEAR_MIPMAP_NEAREST : GL_LINEAR)
            : (mipmap == MipMap::Yes ? GL_NEAREST_MIPMAP_NEAREST : GL_NEAREST)));
    MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
                                     filter == Scaling::Linear ? GL_LINEAR : GL_NEAREST));
}

// static int indent = 0;
inline void start_group(const std::string &str) {
    if (gl::PushDebugGroup != nullptr) {
        MBGL_CHECK_ERROR(gl::PushDebugGroup(GL_DEBUG_SOURCE_APPLICATION, 0, GLsizei(str.size()), str.c_str()));
    } else if (gl::PushGroupMarkerEXT != nullptr) {
        MBGL_CHECK_ERROR(gl::PushGroupMarkerEXT(GLsizei(str.size() + 1), str.c_str()));
    }
    // fprintf(stderr, "%s%s\n", std::string(indent * 4, ' ').c_str(), str.c_str());
    // indent++;
}

void enable() {
    if (!DebugMessageControl || !DebugMessageCallback) {
        return;
    }

    // This will enable all messages including performance hints
    //MBGL_CHECK_ERROR(DebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DONT_CARE, 0, nullptr, GL_TRUE));

    // This will only enable high and medium severity messages
    MBGL_CHECK_ERROR(DebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_HIGH, 0, nullptr, GL_TRUE));
    MBGL_CHECK_ERROR(DebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_MEDIUM, 0, nullptr, GL_TRUE));
    MBGL_CHECK_ERROR(DebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_NOTIFICATION, 0, nullptr, GL_FALSE));

    MBGL_CHECK_ERROR(DebugMessageCallback(debugCallback, nullptr));
}

void VertexArrayObject::bindVertexArrayObject() {
    if (!GenVertexArrays || !BindVertexArray) {
        static bool reported = false;
        if (!reported) {
            Log::Warning(Event::OpenGL, "Not using Vertex Array Objects");
            reported = true;
        }
        return;
    }

    if (!vao) {
        MBGL_CHECK_ERROR(GenVertexArrays(1, &vao));
    }
    MBGL_CHECK_ERROR(BindVertexArray(vao));
}

void Painter::drawClippingMasks(PaintParameters& parameters, const std::map<UnwrappedTileID, ClipID>& stencils) {
    MBGL_DEBUG_GROUP("clipping masks");

    auto& plainShader = parameters.shaders.plain;
    auto& arrayCoveringPlain = parameters.shaders.coveringPlainArray;

    mat4 matrix;
    const GLuint mask = 0b11111111;

    config.program = plainShader.getID();
    config.stencilOp.reset();
    config.stencilTest = GL_TRUE;
    config.depthTest = GL_FALSE;
    config.depthMask = GL_FALSE;
    config.colorMask = { GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE };
    config.stencilMask = mask;

    arrayCoveringPlain.bind(plainShader, tileStencilBuffer, BUFFER_OFFSET_0, store);

    for (const auto& stencil : stencils) {
        const auto& id = stencil.first;
        const auto& clip = stencil.second;

        MBGL_DEBUG_GROUP(std::string{ "mask: " } + util::toString(id));
        state.matrixFor(matrix, id);
        matrix::multiply(matrix, projMatrix, matrix);
        plainShader.u_matrix = matrix;

        const GLint ref = (GLint)(clip.reference.to_ulong());
        config.stencilFunc = { GL_ALWAYS, ref, mask };
        MBGL_CHECK_ERROR(glDrawArrays(GL_TRIANGLES, 0, (GLsizei)tileStencilBuffer.index()));
    }
}

void AttributeBinding<T, N>::bind(Context& context, AttributeLocation location, std::size_t vertexOffset) const {
    // FillProgram will attempt to bind at location -1 because it includes
    // a fill-outline-color paint property but does not use it or have an
    // a_outline_color shader attribute - in this case, we have nothing to bind.
    if (location == -1) return;

    context.vertexBuffer = vertexBuffer;
    MBGL_CHECK_ERROR(glEnableVertexAttribArray(location));
    MBGL_CHECK_ERROR(glVertexAttribPointer(
        location,
        static_cast<GLint>(attributeSize),
        static_cast<GLenum>(DataTypeOf<T>),
        static_cast<GLboolean>(false),
        static_cast<GLsizei>(vertexSize),
        reinterpret_cast<GLvoid*>(attributeOffset + (vertexSize * vertexOffset))));
}

 // Transfers this buffer to the GPU and binds the buffer to the GL context.
 void bind() {
     if (buffer) {
         MBGL_CHECK_ERROR(glBindBuffer(bufferType, buffer));
     } else {
         MBGL_CHECK_ERROR(glGenBuffers(1, &buffer));
         MBGL_CHECK_ERROR(glBindBuffer(bufferType, buffer));
         if (array == nullptr) {
             Log::Debug(Event::OpenGL, "Buffer doesn't contain elements");
             pos = 0;
         }
         MBGL_CHECK_ERROR(glBufferData(bufferType, pos, array, GL_STATIC_DRAW));
         if (!retainAfterUpload) {
             cleanup();
         }
     }
 }

 // Transfers this buffer to the GPU and binds the buffer to the GL context.
 void bind(gl::ObjectStore& store) {
     if (buffer) {
         MBGL_CHECK_ERROR(glBindBuffer(bufferType, *buffer));
     } else {
         buffer = store.createBuffer();
         MBGL_CHECK_ERROR(glBindBuffer(bufferType, *buffer));
         if (array == nullptr) {
             Log::Debug(Event::OpenGL, "Buffer doesn't contain elements");
             pos = 0;
         }
         MBGL_CHECK_ERROR(glBufferData(bufferType, pos, array, GL_STATIC_DRAW));
         if (!retainAfterUpload) {
             cleanup();
         }
     }
 }

void FrameHistory::bind(gl::ObjectStore& store, gl::Config& config, uint32_t unit) {
    if (!texture) {
        texture = store.createTexture();
        config.activeTexture = unit;
        config.texture[unit] = *texture;
#ifndef GL_ES_VERSION_2_0
        MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0));
#endif
        MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE));
        MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE));
        MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
        MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
    } else if (config.texture[unit] != *texture) {
        config.activeTexture = unit;
        config.texture[unit] = *texture;
    }
}

void SymbolBucket::drawCollisionBoxes(CollisionBoxShader &shader) {
    GLbyte *vertex_index = BUFFER_OFFSET_0;
    auto& collisionBox = renderData->collisionBox;
    for (auto &group : collisionBox.groups) {
        group->array[0].bind(shader, collisionBox.vertices, vertex_index);
        MBGL_CHECK_ERROR(glDrawArrays(GL_LINES, 0, group->vertex_length));
    }
}

void showColorDebugImage(std::string name, const char *data, size_t logicalWidth, size_t logicalHeight, size_t width, size_t height) {
    glfwInit();

    static GLFWwindow *debugWindow = nullptr;
    if (!debugWindow) {
        debugWindow = glfwCreateWindow(logicalWidth, logicalHeight, name.c_str(), nullptr, nullptr);
        if (!debugWindow) {
            glfwTerminate();
            fprintf(stderr, "Failed to initialize window\n");
            exit(1);
        }
    }

    GLFWwindow *currentWindow = glfwGetCurrentContext();

    glfwSetWindowSize(debugWindow, logicalWidth, logicalHeight);
    glfwMakeContextCurrent(debugWindow);

    int fbWidth, fbHeight;
    glfwGetFramebufferSize(debugWindow, &fbWidth, &fbHeight);
    float xScale = static_cast<float>(fbWidth) / static_cast<float>(width);
    float yScale = static_cast<float>(fbHeight) / static_cast<float>(height);

    MBGL_CHECK_ERROR(glClearColor(0.8, 0.8, 0.8, 1));
    MBGL_CHECK_ERROR(glClear(GL_COLOR_BUFFER_BIT));
    MBGL_CHECK_ERROR(glEnable(GL_BLEND));
    MBGL_CHECK_ERROR(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));

    MBGL_CHECK_ERROR(glPixelZoom(xScale, -yScale));
    MBGL_CHECK_ERROR(glRasterPos2f(-1.0f, 1.0f));
    MBGL_CHECK_ERROR(glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8_REV, data));
    glfwSwapBuffers(debugWindow);

    glfwMakeContextCurrent(currentWindow);
}

void SymbolBucket::drawIcons(IconShader &shader) {
    char *vertex_index = BUFFER_OFFSET(0);
    char *elements_index = BUFFER_OFFSET(0);
    for (auto &group : icon.groups) {
        assert(group);
        group->array[1].bind(shader, icon.vertices, icon.triangles, vertex_index);
        MBGL_CHECK_ERROR(glDrawElements(GL_TRIANGLES, group->elements_length * 3, GL_UNSIGNED_SHORT, elements_index));
        vertex_index += group->vertex_length * icon.vertices.itemSize;
        elements_index += group->elements_length * icon.triangles.itemSize;
    }
}

void HeadlessView::clearBuffers() {
    assert(isActive());

    MBGL_CHECK_ERROR(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0));

    if (fbo) {
        MBGL_CHECK_ERROR(glDeleteFramebuffersEXT(1, &fbo));
        fbo = 0;
    }

    if (fboColor) {
        MBGL_CHECK_ERROR(glDeleteTextures(1, &fboColor));
        fboColor = 0;
    }

    if (fboDepthStencil) {
        MBGL_CHECK_ERROR(glDeleteRenderbuffersEXT(1, &fboDepthStencil));
        fboDepthStencil = 0;
    }
}