// While (re)writing this file, I have been looking at many other libraries since all the
// "official" documentation was horrible, at least those parts that I was able to find.
// Kudos to the Pyglet folks (http://www.pyglet.org/) who wrote code that was much easier to
// understand than that!

#include <Gosu/Window.hpp>
#include <Gosu/Timing.hpp>
#include <Gosu/Utility.hpp>
#include <Gosu/Input.hpp>
#include <Gosu/Graphics.hpp>
#include <Gosu/Audio.hpp>
#include <boost/bind.hpp>
#include <stdexcept>
#include <algorithm>
#include <vector>

#include <GL/glx.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include "X11vroot.h"

namespace
{
    template<typename T>
    class scoped_resource
    {
        T* pointer;
        typedef boost::function<void(T*)> Deleter;
        Deleter deleter;
        
    public:
        scoped_resource(T* pointer, const Deleter& deleter)
        : pointer(pointer), deleter(deleter)
        {
        }
        
        void reset(T* newPointer = 0)
        {
            if (pointer)
                deleter(pointer);
            pointer = newPointer;
        }
        
        T* get() const
        {
            return pointer;
        }
        
        T* operator->() const
        {
            return get();
        }
        
        ~scoped_resource()
        {
            reset(0);
        }
    };
}

struct Gosu::Window::Impl
{
    boost::scoped_ptr<Graphics> graphics;
    boost::scoped_ptr<Input> input;
    boost::scoped_ptr<Audio> audio;

    ::Display* display;
    
    bool mapped, showing, active;
    
    ::GLXContext context;
    ::Window window;
    ::XVisualInfo* visual;
    
    // Last set title
    std::wstring title;
    // Last known position
    int x, y;
    // Last known size
    int width, height;


    double updateInterval;
    bool fullscreen;

    Impl(unsigned width, unsigned height, unsigned fullscreen, double updateInterval)
    :   mapped(false), showing(false), active(true),
        x(0), y(0), width(width), height(height),
        updateInterval(updateInterval), fullscreen(fullscreen)
    {
        
    }
    
    void executeAndWait(boost::function<void(Display*, ::Window)> function, int forMessage)
    {
        XSelectInput(display, window, StructureNotifyMask);
        function(display, window);
        while (true)
        {
            ::XEvent event;
            XNextEvent(display, &event);
            if (event.type == forMessage)
                break;
        }
        XSelectInput(display, window, 0x1ffffff & ~PointerMotionHintMask & ~ResizeRedirectMask);
    }

    void doTick(Window* window)
    {
        while (::XPending(display))
        {
            ::XEvent event;
            XNextEvent(display, &event);
            
            // Override redirect fix (thanks for Pyglet folks again):
            if (event.type == ButtonPress && fullscreen && !active)
                XSetInputFocus(display, this->window, RevertToParent, CurrentTime);
            
            if (!window->input().feedXEvent(event, window))
            {
                if (event.type == ConfigureNotify)
                {
                    // Only boring stuff to do? Let's do something random:
                    glXMakeCurrent(display, this->window, context);
                }
                else if (event.type == ClientMessage)
                {
                    if (static_cast<unsigned>(event.xclient.data.l[0]) ==
                            XInternAtom(display, "WM_DELETE_WINDOW", false))
                        window->close();
                }
                else if (event.type == FocusIn)
                    active = true;
                else if (event.type == FocusOut)
                    active = false;
            }
        }

        if (window->graphics().begin(Colors::black))
        {
            window->draw();
            window->graphics().end();
            glXSwapBuffers(display, this->window);
        }

        window->input().update();
        window->update();
    }
};

Gosu::Window::Window(unsigned width, unsigned height, bool fullscreen,
        double updateInterval)
:   pimpl(new Impl(width, height, fullscreen, updateInterval))
{
    pimpl->display = XOpenDisplay(NULL);
    if (!pimpl->display)
        throw std::runtime_error("Cannot find display");
    
    ::Window root = DefaultRootWindow(pimpl->display);

    // Setup GLX visual
    static int glxAttributes[] =
    {
        GLX_RGBA,
        GLX_DOUBLEBUFFER,
        GLX_RED_SIZE, 1,
        GLX_GREEN_SIZE, 1,
        GLX_BLUE_SIZE, 1,
        GLX_DEPTH_SIZE, 1,
        None
    };
    pimpl->visual = glXChooseVisual(pimpl->display, DefaultScreen(pimpl->display), glxAttributes);

    // Create GLX context    
    pimpl->context = glXCreateContext(pimpl->display, pimpl->visual, 0, GL_TRUE);

    // Set up window attributes (& mask)
    XSetWindowAttributes windowAttributes;
    windowAttributes.colormap = XCreateColormap(pimpl->display, root, pimpl->visual->visual, AllocNone);
    windowAttributes.bit_gravity = NorthWestGravity;
    windowAttributes.background_pixel = 0;
    unsigned mask = CWColormap | CWBitGravity | CWBackPixel;

    // Create window
    pimpl->window = XCreateWindow(pimpl->display, root, 0, 0, width, height, 0,
        pimpl->visual->depth, InputOutput, pimpl->visual->visual,
        mask, &windowAttributes);    

    // Request a close button for the window
    Atom atoms[] = { XInternAtom(pimpl->display, "WM_DELETE_WINDOW", false) };
    XSetWMProtocols(pimpl->display, pimpl->window, atoms, 1);

    Screen* screen = XScreenOfDisplay(pimpl->display,
                        DefaultScreen(pimpl->display));

    if (fullscreen)
    {
        pimpl->width = screen->width;
        pimpl->height = screen->height;
        XMoveResizeWindow(pimpl->display, pimpl->window, 0, 0,
            screen->width, screen->height);
            
        XSetWindowAttributes windowAttributes;
        windowAttributes.override_redirect = true;
        unsigned mask = CWOverrideRedirect;
        XChangeWindowAttributes(pimpl->display, pimpl->window, mask, &windowAttributes);
    }
    else
        ; // Window already has requested size

    // Set window to be non resizable
    scoped_resource<XSizeHints> sizeHints(XAllocSizeHints(), XFree);
    sizeHints->flags = PMinSize | PMaxSize;
    sizeHints->min_width = sizeHints->max_width = pimpl->width;
    sizeHints->min_height = sizeHints->max_height = pimpl->height;
    XSetWMNormalHints(pimpl->display, pimpl->window, sizeHints.get());
    sizeHints.reset();

    // TODO: Window style (_MOTIF_WM_HINTS)?        

    XColor black, dummy;
    XAllocNamedColor(pimpl->display, screen->cmap, "black", &black, &dummy);    
    char emptyData[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
    Pixmap emptyBitmap =
        XCreateBitmapFromData(pimpl->display, pimpl->window, emptyData, 8, 8);
    Cursor emptyCursor = XCreatePixmapCursor(pimpl->display, emptyBitmap,
        emptyBitmap, &black, &black, 0, 0);
    XDefineCursor(pimpl->display, pimpl->window, emptyCursor);
    XFreeCursor(pimpl->display, emptyCursor);

    // Must be current already so that Graphics' constructor can set up things
    glXMakeCurrent(pimpl->display, pimpl->window, pimpl->context);

    // Now set up major Gosu components
    pimpl->graphics.reset(new Gosu::Graphics(pimpl->width, pimpl->height, fullscreen));
    pimpl->input.reset(new Gosu::Input(pimpl->display));    
    input().onButtonDown = boost::bind(&Window::buttonDown, this, _1);
    input().onButtonUp = boost::bind(&Window::buttonUp, this, _1);
    
    // Fix coordinates for fullscreen screen-scaling
    if (fullscreen)
    {
        graphics().setResolution(width, height);
        input().setMouseFactors(1.0 * width / pimpl->width,
                  1.0 * height / pimpl->height);
    }
}

Gosu::Window::~Window()
{    
    XDestroyWindow(pimpl->display, pimpl->window);
    XSync(pimpl->display, false);
}

std::wstring Gosu::Window::caption() const
{
    return pimpl->title;
}

void Gosu::Window::setCaption(const std::wstring& caption)
{
    // TODO: Update to _NET_WM_NAME

    pimpl->title = caption;

    // TODO: Why?!
    //if (!pimpl->showing)
    //    return;

    std::string tmpString(pimpl->title.begin(), pimpl->title.end());
    std::vector<char> title(pimpl->title.size() + 1);
    std::copy(tmpString.begin(), tmpString.end(), title.begin());
    title.back() = 0;

    XTextProperty titleprop;
    char* titlePtr = &title[0];
    XStringListToTextProperty(&titlePtr, 1, &titleprop);

    XSetWMName(pimpl->display, pimpl->window, &titleprop);
    XFree(titleprop.value);
    XSync(pimpl->display, false);
}

namespace GosusDarkSide
{
    // TODO: Find a way for this to fit into Gosu's design.
    // This can point to a function that wants to be called every
    // frame, e.g. rb_thread_schedule.
    typedef void (*HookOfHorror)();
    HookOfHorror oncePerTick = 0;
}

// TODO: Some exception safety

void Gosu::Window::show()
{
    // Map window
    pimpl->executeAndWait(XMapRaised, MapNotify);
    pimpl->mapped = true;
    
    // Make glx current
    glXMakeCurrent(pimpl->display, pimpl->window, pimpl->context);
    
    if (pimpl->fullscreen)
        XSetInputFocus(pimpl->display, pimpl->window, RevertToParent, CurrentTime);

    setCaption(pimpl->title);

    unsigned startTime, endTime;

    pimpl->showing = true;
    while (pimpl->showing)
    {
        startTime = milliseconds();
        pimpl->doTick(this);
        if (GosusDarkSide::oncePerTick) GosusDarkSide::oncePerTick();
        endTime = milliseconds();

        if (startTime < endTime && (endTime - startTime) < pimpl->updateInterval)
            sleep(pimpl->updateInterval - (endTime - startTime));
    }

    glXMakeCurrent(pimpl->display, 0, 0);
    pimpl->executeAndWait(XUnmapWindow, UnmapNotify);
    pimpl->mapped = false;
}

void Gosu::Window::close()
{
    pimpl->showing = false;
}

const Gosu::Graphics& Gosu::Window::graphics() const
{
    return *pimpl->graphics;
}

Gosu::Graphics& Gosu::Window::graphics()
{
    return *pimpl->graphics;
}

const Gosu::Audio& Gosu::Window::audio() const
{
    if (!pimpl->audio)
        pimpl->audio.reset(new Gosu::Audio());
    return *pimpl->audio;
}

Gosu::Audio& Gosu::Window::audio()
{
    if (!pimpl->audio)
        pimpl->audio.reset(new Gosu::Audio());
    return *pimpl->audio;
}

const Gosu::Input& Gosu::Window::input() const
{
    return *pimpl->input;
}

Gosu::Input& Gosu::Window::input()
{
    return *pimpl->input;
}

namespace
{
    void makeCurrentContext(Display* dpy, GLXDrawable drawable, GLXContext context) {
        if (!glXMakeCurrent(dpy, drawable, context))
            printf("glXMakeCurrent failed\n");
    }

    void releaseContext(Display* dpy, GLXContext context) {
        glXDestroyContext(dpy, context);
    }
}

Gosu::Window::SharedContext Gosu::Window::createSharedContext() {
    const char* displayName = DisplayString( pimpl->display );
    Display* dpy2 = XOpenDisplay( displayName );
    if (!dpy2)
        throw std::runtime_error("Could not duplicate X display");
    
	GLXContext ctx = glXCreateContext(dpy2, pimpl->visual, pimpl->context, True);
	if (!ctx)
        throw std::runtime_error("Could not create shared GLX context");
    
    return SharedContext(
        new boost::function<void()>(boost::bind(makeCurrentContext, dpy2, pimpl->window, ctx)),
        boost::bind(releaseContext, dpy2, ctx));
}