#include "Window.hpp"

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <chrono>
#include <iostream>
#include <thread>
#include <unordered_set>

#include "debug/Logger.hpp"
#include "graphics/core/ImageData.hpp"
#include "graphics/core/Texture.hpp"
#include "settings.hpp"
#include "util/ObjectsKeeper.hpp"
#include "Events.hpp"

#include "util/platform.hpp"

static debug::Logger logger("window");

namespace {
    GLFWwindow* window = nullptr;
    DisplaySettings* settings = nullptr;
    std::stack<glm::vec4> scissorStack;
    glm::vec4 scissorArea;
    int framerate = -1;
    double prevSwap = 0.0;
    bool fullscreen = false;
    CursorShape cursor = CursorShape::ARROW;
    int posX = 0;
    int posY = 0;
}

uint Window::width = 0;
uint Window::height = 0;

static util::ObjectsKeeper observers_keeper;
static std::unordered_set<std::string> extensionsCache;

static const char* gl_error_name(int error) {
    switch (error) {
        case GL_DEBUG_TYPE_ERROR: return "ERROR";
        case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR: return "DEPRECATED_BEHAVIOR";
        case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR: return "UNDEFINED_BEHAVIOR";
        case GL_DEBUG_TYPE_PORTABILITY: return "PORTABILITY";
        case GL_DEBUG_TYPE_PERFORMANCE: return "PERFORMANCE";
        case GL_DEBUG_TYPE_OTHER: return "OTHER";
    }
    return "UNKNOWN";
}

static const char* gl_severity_name(int severity) {
    switch (severity) {
        case GL_DEBUG_SEVERITY_LOW: return "LOW";
        case GL_DEBUG_SEVERITY_MEDIUM: return "MEDIUM";
        case GL_DEBUG_SEVERITY_HIGH: return "HIGH";
        case GL_DEBUG_SEVERITY_NOTIFICATION: return "NOTIFICATION";
    }
    return "UNKNOWN";
}

static void GLAPIENTRY gl_message_callback(
    GLenum source,
    GLenum type,
    GLuint id,
    GLenum severity,
    GLsizei length,
    const GLchar* message,
    const void* userParam
) {
    if (severity == GL_DEBUG_SEVERITY_NOTIFICATION) {
        return;
    }
    if (!ENGINE_DEBUG_BUILD && severity != GL_DEBUG_SEVERITY_HIGH) {
        return;
    }
    std::cerr << "GL:" << gl_error_name(type) << ":"
              << gl_severity_name(severity) << ": " << message << std::endl;
}

static void cursor_position_callback(GLFWwindow*, double xpos, double ypos) {
    Events::setPosition(xpos, ypos);
}

static void mouse_button_callback(GLFWwindow*, int button, int action, int) {
    Events::setButton(button, action == GLFW_PRESS);
}

static void key_callback(
    GLFWwindow*, int key, int /*scancode*/, int action, int /*mode*/
) {
    if (key == GLFW_KEY_UNKNOWN) return;
    if (action == GLFW_PRESS) {
        Events::setKey(key, true);
        Events::pressedKeys.push_back(static_cast<keycode>(key));
    } else if (action == GLFW_RELEASE) {
        Events::setKey(key, false);
    } else if (action == GLFW_REPEAT) {
        Events::pressedKeys.push_back(static_cast<keycode>(key));
    }
}

static void scroll_callback(GLFWwindow*, double xoffset, double yoffset) {
    Events::scroll += yoffset;
}

static void character_callback(GLFWwindow*, unsigned int codepoint) {
    Events::codepoints.push_back(codepoint);
}

static void window_size_callback(GLFWwindow*, int width, int height) {
    if (width && height) {
        glViewport(0, 0, width, height);
        Window::width = width;
        Window::height = height;

        if (!Window::isFullscreen() && !Window::isMaximized()) {
            Window::getSettings()->width.set(width);
            Window::getSettings()->height.set(height);
        }
    }
    Window::resetScissor();
}

bool Window::isMaximized() {
    return glfwGetWindowAttrib(window, GLFW_MAXIMIZED);
}

bool Window::isIconified() {
    return glfwGetWindowAttrib(window, GLFW_ICONIFIED);
}

bool Window::isFocused() {
    return glfwGetWindowAttrib(window, GLFW_FOCUSED);
}

static const char* glfw_error_name(int error) {
    switch (error) {
        case GLFW_NO_ERROR:
            return "no error";
        case GLFW_NOT_INITIALIZED:
            return "not initialized";
        case GLFW_NO_CURRENT_CONTEXT:
            return "no current context";
        case GLFW_INVALID_ENUM:
            return "invalid enum";
        case GLFW_INVALID_VALUE:
            return "invalid value";
        case GLFW_OUT_OF_MEMORY:
            return "out of memory";
        case GLFW_API_UNAVAILABLE:
            return "api unavailable";
        case GLFW_VERSION_UNAVAILABLE:
            return "version unavailable";
        case GLFW_PLATFORM_ERROR:
            return "platform error";
        case GLFW_FORMAT_UNAVAILABLE:
            return "format unavailable";
        case GLFW_NO_WINDOW_CONTEXT:
            return "no window context";
        default:
            return "unknown error";
    }
}

static void glfw_error_callback(int error, const char* description) {
    auto logline = logger.error();
    logline << "GLFW error [0x" << std::hex << error << " - "
            << glfw_error_name(error) << "]";
    if (description) {
        logline << ": " << description;
    }
}

static GLFWcursor* standard_cursors[static_cast<int>(CursorShape::LAST) + 1] = {};

class GLFWInput : public Input {
public:
    void pollEvents() override {
        Events::pollEvents();
    }

    const char* getClipboardText() const override {
        return glfwGetClipboardString(::window);
    }

    int getScroll() override {
        return Events::getScroll();
    }

    bool pressed(keycode keycode) const override {
        return Events::pressed(keycode);
    }
    bool jpressed(keycode keycode) const override {
        return Events::jpressed(keycode);
    }

    bool clicked(mousecode mousecode) const override {
        return Events::clicked(mousecode);
    }
    bool jclicked(mousecode mousecode) const override {
        return Events::jclicked(mousecode);
    }

    CursorState getCursor() const override {
        return {
            Events::isCursorLocked(),
            Events::cursor,
            Events::delta
        };
    }

    void toggleCursor() override {
        Events::toggleCursor();
    }

    Bindings& getBindings() override {
        return Events::bindings;
    }

    const Bindings& getBindings() const override {
        return Events::bindings;
    }

    observer_handler addKeyCallback(keycode key, KeyCallback callback) override {
        return Events::addKeyCallback(key, std::move(callback));
    }

    const std::vector<keycode>& getPressedKeys() const override {
        return Events::pressedKeys;
    }

    const std::vector<uint>& getCodepoints() const override {
        return Events::codepoints;
    }
};
static_assert(!std::is_abstract<GLFWInput>());

std::unique_ptr<Input> Window::initialize(DisplaySettings* settings) {
    ::settings = settings;
    Window::width = settings->width.get();
    Window::height = settings->height.get();

    std::string title = "VoxelCore v" +
                        std::to_string(ENGINE_VERSION_MAJOR) + "." +
                        std::to_string(ENGINE_VERSION_MINOR);
    if (ENGINE_DEBUG_BUILD) {
        title += " [debug]";
    }

    glfwSetErrorCallback(glfw_error_callback);
    if (glfwInit() == GLFW_FALSE) {
        logger.error() << "failed to initialize GLFW";
        return nullptr;
    }

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_COCOA_RETINA_FRAMEBUFFER, GLFW_FALSE);
#else
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_ANY_PROFILE);
#endif
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
    glfwWindowHint(GLFW_SAMPLES, settings->samples.get());

    window = glfwCreateWindow(width, height, title.c_str(), nullptr, nullptr);
    if (window == nullptr) {
        logger.error() << "failed to create GLFW window";
        glfwTerminate();
        return nullptr;
    }
    glfwMakeContextCurrent(window);

    glewExperimental = GL_TRUE;

    GLenum glewErr = glewInit();
    if (glewErr != GLEW_OK) {
        if (glewErr == GLEW_ERROR_NO_GLX_DISPLAY) {
            // see issue #240
            logger.warning()
                << "glewInit() returned GLEW_ERROR_NO_GLX_DISPLAY; ignored";
        } else {
            logger.error() << "failed to initialize GLEW:\n"
                           << glewGetErrorString(glewErr);
            return nullptr;
        }
    }

    if (isGlExtensionSupported("GL_KHR_debug")) {
        glEnable(GL_DEBUG_OUTPUT);
        glDebugMessageCallback(gl_message_callback, nullptr);
    }

    glViewport(0, 0, width, height);
    glClearColor(0.0f, 0.0f, 0.0f, 1);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    GLint maxTextureSize[1] {static_cast<GLint>(Texture::MAX_RESOLUTION)};
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, maxTextureSize);
    if (maxTextureSize[0] > 0) {
        Texture::MAX_RESOLUTION = maxTextureSize[0];
        logger.info() << "max texture size is " << Texture::MAX_RESOLUTION;
    }

    glfwSetKeyCallback(window, key_callback);
    glfwSetMouseButtonCallback(window, mouse_button_callback);
    glfwSetCursorPosCallback(window, cursor_position_callback);
    glfwSetWindowSizeCallback(window, window_size_callback);
    glfwSetCharCallback(window, character_callback);
    glfwSetScrollCallback(window, scroll_callback);

    observers_keeper = util::ObjectsKeeper();
    observers_keeper.keepAlive(settings->fullscreen.observe(
        [](bool value) {
            if (value != isFullscreen()) {
                toggleFullscreen();
            }
        },
        true
    ));

    glfwSwapInterval(1);
    setFramerate(settings->framerate.get());
    const GLubyte* vendor = glGetString(GL_VENDOR);
    const GLubyte* renderer = glGetString(GL_RENDERER);
    logger.info() << "GL Vendor: " << reinterpret_cast<const char*>(vendor);
    logger.info() << "GL Renderer: " << reinterpret_cast<const char*>(renderer);
    logger.info() << "GLFW: " << glfwGetVersionString();
    glm::vec2 scale;
    glfwGetMonitorContentScale(glfwGetPrimaryMonitor(), &scale.x, &scale.y);
    logger.info() << "monitor content scale: " << scale.x << "x" << scale.y;

    input_util::initialize();

    for (int i = 0; i <= static_cast<int>(CursorShape::LAST); i++) {
        int cursor = GLFW_ARROW_CURSOR + i;
        // GLFW 3.3 does not support some cursors
        if (GLFW_VERSION_MAJOR <= 3 && GLFW_VERSION_MINOR <= 3 && cursor > GLFW_VRESIZE_CURSOR) {
            break;
        }
        standard_cursors[i] = glfwCreateStandardCursor(cursor);
    }
    return std::make_unique<GLFWInput>();
}

void Window::clear() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void Window::clearDepth() {
    glClear(GL_DEPTH_BUFFER_BIT);
}

void Window::setBgColor(glm::vec3 color) {
    glClearColor(color.r, color.g, color.b, 1.0f);
}

void Window::setBgColor(glm::vec4 color) {
    glClearColor(color.r, color.g, color.b, color.a);
}

void Window::viewport(int x, int y, int width, int height) {
    glViewport(x, y, width, height);
}

void Window::setCursorMode(int mode) {
    glfwSetInputMode(window, GLFW_CURSOR, mode);
}

void Window::resetScissor() {
    scissorArea = glm::vec4(0.0f, 0.0f, width, height);
    scissorStack = std::stack<glm::vec4>();
    glDisable(GL_SCISSOR_TEST);
}

void Window::pushScissor(glm::vec4 area) {
    if (scissorStack.empty()) {
        glEnable(GL_SCISSOR_TEST);
    }
    scissorStack.push(scissorArea);

    area.z += glm::ceil(area.x);
    area.w += glm::ceil(area.y);

    area.x = glm::max(area.x, scissorArea.x);
    area.y = glm::max(area.y, scissorArea.y);

    area.z = glm::min(area.z, scissorArea.z);
    area.w = glm::min(area.w, scissorArea.w);

    if (area.z < 0.0f || area.w < 0.0f) {
        glScissor(0, 0, 0, 0);
    } else {
        glScissor(
            area.x,
            Window::height - area.w,
            std::max(0, static_cast<int>(glm::ceil(area.z - area.x))),
            std::max(0, static_cast<int>(glm::ceil(area.w - area.y)))
        );
    }
    scissorArea = area;
}

void Window::popScissor() {
    if (scissorStack.empty()) {
        logger.warning() << "extra Window::popScissor call";
        return;
    }
    glm::vec4 area = scissorStack.top();
    scissorStack.pop();
    if (area.z < 0.0f || area.w < 0.0f) {
        glScissor(0, 0, 0, 0);
    } else {
        glScissor(
            area.x,
            Window::height - area.w,
            std::max(0, int(area.z - area.x)),
            std::max(0, int(area.w - area.y))
        );
    }
    if (scissorStack.empty()) {
        glDisable(GL_SCISSOR_TEST);
    }
    scissorArea = area;
}

void Window::terminate() {
    observers_keeper = util::ObjectsKeeper();
    for (int i = 0; i <= static_cast<int>(CursorShape::LAST); i++) {
        glfwDestroyCursor(standard_cursors[i]);
    }
    glfwTerminate();
}

bool Window::isShouldClose() {
    return glfwWindowShouldClose(window);
}

void Window::setShouldClose(bool flag) {
    glfwSetWindowShouldClose(window, flag);
}

void Window::setFramerate(int framerate) {
    if ((framerate != -1) != (::framerate != -1)) {
        glfwSwapInterval(framerate == -1);
    }
    ::framerate = framerate;
}

void Window::toggleFullscreen() {
    fullscreen = !fullscreen;

    GLFWmonitor* monitor = glfwGetPrimaryMonitor();
    const GLFWvidmode* mode = glfwGetVideoMode(monitor);

    if (Events::isCursorLocked()){
        Events::toggleCursor();
    }

    if (fullscreen) {
        glfwGetWindowPos(window, &posX, &posY);
        glfwSetWindowMonitor(
            window, monitor, 0, 0, mode->width, mode->height, GLFW_DONT_CARE
        );
    } else {
        glfwSetWindowMonitor(
            window,
            nullptr,
            posX,
            posY,
            settings->width.get(),
            settings->height.get(),
            GLFW_DONT_CARE
        );
    }

    double xPos, yPos;
    glfwGetCursorPos(window, &xPos, &yPos);
    Events::setPosition(xPos, yPos);
}

bool Window::isFullscreen() {
    return fullscreen;
}

void Window::swapBuffers() {
    glfwSwapBuffers(window);
    Window::resetScissor();
    if (framerate > 0) {
        auto elapsedTime = time() - prevSwap;
        auto frameTime = 1.0 / framerate;
        if (elapsedTime < frameTime) {
            platform::sleep(
                static_cast<size_t>((frameTime - elapsedTime) * 1000)
            );
        }
    }
    prevSwap = time();
}

double Window::time() {
    return glfwGetTime();
}

DisplaySettings* Window::getSettings() {
    return settings;
}

void Window::setCursor(CursorShape shape) {
    if (cursor == shape) {
        return;
    }
    cursor = shape;
    // NULL cursor is valid for GLFW
    glfwSetCursor(window, standard_cursors[static_cast<int>(shape)]);
}

std::unique_ptr<ImageData> Window::takeScreenshot() {
    auto data = std::make_unique<ubyte[]>(width * height * 3);
    glPixelStorei(GL_PACK_ALIGNMENT, 1);
    glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, data.get());
    return std::make_unique<ImageData>(
        ImageFormat::rgb888, width, height, data.release()
    );
}

void Window::setClipboardText(const char* text) {
    glfwSetClipboardString(window, text);
}

void Window::setIcon(const ImageData* image) {
    GLFWimage icon {
        static_cast<int>(image->getWidth()),
        static_cast<int>(image->getHeight()),
        image->getData()};
    glfwSetWindowIcon(window, 1, &icon);
}

static void initGlExtensionsCache() {
    if (!extensionsCache.empty()) {
        return;
    }

    GLint numExtensions = 0;
    glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);

    for (GLint i = 0; i < numExtensions; ++i) {
        const char *ext = reinterpret_cast<const char *>(glGetStringi(GL_EXTENSIONS, i));
        if (ext) {
            extensionsCache.insert(ext);
        }
    }
}

bool Window::isGlExtensionSupported(const char *extension) {
    if (!extension || !*extension) {
        return false;
    }

    initGlExtensionsCache();

    return extensionsCache.find(extension) != extensionsCache.end();
}