#ifndef APPLICATION_UNIX_CPP
#error This file may only be included from ApplicationUnix.cpp
#endif

#include "boo/IApplication.hpp"

#include <X11/Xlib.h>
#include <X11/XKBlib.h>
#include <X11/extensions/XInput2.h>
#include <GL/glx.h>
#include <GL/glxext.h>
#include <locale>

#include <dbus/dbus.h>
DBusConnection* RegisterDBus(const char* appName, bool& isFirst);

#include "logvisor/logvisor.hpp"

#include <signal.h>
#include <sys/param.h>
#include <thread>
#include <mutex>
#include <condition_variable>

#include "XlibCommon.hpp"
#include <X11/cursorfont.h>

#if BOO_HAS_VULKAN
#include <X11/Xlib-xcb.h>
#include <vulkan/vulkan.h>
#include <dlfcn.h>
#endif

namespace boo
{
static logvisor::Module Log("boo::ApplicationXlib");
XlibCursors X_CURSORS;

int XINPUT_OPCODE = 0;

static Window GetWindowOfEvent(XEvent* event, bool& windowEvent)
{
    switch (event->type)
    {
    case SelectionRequest:
    {
        windowEvent = true;
        return event->xselectionrequest.owner;
    }
    case ClientMessage:
    {
        windowEvent = true;
        return event->xclient.window;
    }
    case Expose:
    {
        windowEvent = true;
        return event->xexpose.window;
    }
    case ConfigureNotify:
    {
        windowEvent = true;
        return event->xconfigure.window;
    }
    case KeyPress:
    case KeyRelease:
    {
        windowEvent = true;
        return event->xkey.window;
    }
    case ButtonPress:
    case ButtonRelease:
    {
        windowEvent = true;
        return event->xbutton.window;
    }
    case MotionNotify:
    {
        windowEvent = true;
        return event->xmotion.window;
    }
    case EnterNotify:
    case LeaveNotify:
    {
        windowEvent = true;
        return event->xcrossing.window;
    }
    case FocusIn:
    case FocusOut:
    {
        windowEvent = true;
        return event->xfocus.window;
    }
    case GenericEvent:
    {
        if (event->xgeneric.extension == XINPUT_OPCODE)
        {
            switch (event->xgeneric.evtype)
            {
            case XI_Motion:
            case XI_TouchBegin:
            case XI_TouchUpdate:
            case XI_TouchEnd:
            {
                XIDeviceEvent* ev = (XIDeviceEvent*)event;
                windowEvent = true;
                return ev->event;
            }
            }
        }
    }
    }
    windowEvent = false;
    return 0;
}
    
std::shared_ptr<IWindow> _WindowXlibNew(std::string_view title,
                         Display* display, void* xcbConn,
                         int defaultScreen, XIM xIM, XIMStyle bestInputStyle, XFontSet fontset,
                         GLXContext lastCtx, void* vulkanHandle, uint32_t drawSamples);

static XIMStyle ChooseBetterStyle(XIMStyle style1, XIMStyle style2)
{
    XIMStyle s,t;
    XIMStyle preedit = XIMPreeditArea | XIMPreeditCallbacks |
        XIMPreeditPosition | XIMPreeditNothing | XIMPreeditNone;
    XIMStyle status = XIMStatusArea | XIMStatusCallbacks |
        XIMStatusNothing | XIMStatusNone;
    if (style1 == 0) return style2;
    if (style2 == 0) return style1;
    if ((style1 & (preedit | status)) == (style2 & (preedit | status)))
        return style1;
    s = style1 & preedit;
    t = style2 & preedit;
    if (s != t) {
        if (s | t | XIMPreeditCallbacks)
            return (s == XIMPreeditCallbacks)?style1:style2;
        else if (s | t | XIMPreeditPosition)
            return (s == XIMPreeditPosition)?style1:style2;
        else if (s | t | XIMPreeditArea)
            return (s == XIMPreeditArea)?style1:style2;
        else if (s | t | XIMPreeditNothing)
            return (s == XIMPreeditNothing)?style1:style2;
    }
    else { /* if preedit flags are the same, compare status flags */
        s = style1 & status;
        t = style2 & status;
        if (s | t | XIMStatusCallbacks)
            return (s == XIMStatusCallbacks)?style1:style2;
        else if (s | t | XIMStatusArea)
            return (s == XIMStatusArea)?style1:style2;
        else if (s | t | XIMStatusNothing)
            return (s == XIMStatusNothing)?style1:style2;
    }
    return 0;
}
    
class ApplicationXlib final : public IApplication
{
    IApplicationCallback& m_callback;
    const std::string m_uniqueName;
    const std::string m_friendlyName;
    const std::string m_pname;
    const std::vector<std::string> m_args;

    /* DBus single-instance */
    bool m_singleInstance;
    DBusConnection* m_dbus = nullptr;

    /* All windows */
    std::unordered_map<Window, std::weak_ptr<IWindow>> m_windows;

    Display* m_xDisp = nullptr;
    XIM m_xIM = nullptr;
    XFontSet m_fontset;
    XIMStyle m_bestStyle = 0;
    int m_xDefaultScreen = 0;
    int m_x11Fd, m_dbusFd, m_maxFd;

#if BOO_HAS_VULKAN
    /* Vulkan enable */
    xcb_connection_t* m_xcbConn;

    void* m_vkHandle = nullptr;
    PFN_vkGetInstanceProcAddr m_getVkProc = 0;
    bool loadVk()
    {
        const char filename[] = "libvulkan.so";
        void *handle, *symbol;

#ifdef UNINSTALLED_LOADER
        handle = dlopen(UNINSTALLED_LOADER, RTLD_LAZY);
        if (!handle)
            handle = dlopen(filename, RTLD_LAZY);
#else
        handle = dlopen(filename, RTLD_LAZY);
#endif

        if (handle)
            symbol = dlsym(handle, "vkGetInstanceProcAddr");

        if (!handle || !symbol) {

            if (handle)
                dlclose(handle);
            return false;
        }

        m_vkHandle = handle;
        m_getVkProc = reinterpret_cast<PFN_vkGetInstanceProcAddr>(symbol);
        return true;
    }
#endif
    
    void _deletedWindow(IWindow* window)
    {
        m_windows.erase((Window)window->getPlatformHandle());
    }
    
public:
    ApplicationXlib(IApplicationCallback& callback,
                    std::string_view uniqueName,
                    std::string_view friendlyName,
                    std::string_view pname,
                    const std::vector<std::string>& args,
                    bool singleInstance)
    : m_callback(callback),
      m_uniqueName(uniqueName),
      m_friendlyName(friendlyName),
      m_pname(pname),
      m_args(args),
      m_singleInstance(singleInstance)
    {
#if BOO_HAS_VULKAN
        /* Check for Vulkan presence and preference */
        bool tryVulkan = true;
        for (const std::string& arg : args)
        {
            if (!arg.compare("--gl"))
            {
                tryVulkan = false;
                break;
            }
        }

        if (tryVulkan)
            loadVk();

        if (m_getVkProc)
            Log.report(logvisor::Info, "using Vulkan renderer");
        else
#endif
            Log.report(logvisor::Info, "using OpenGL renderer");

        /* DBus single instance registration */
        bool isFirst;
        m_dbus = RegisterDBus(uniqueName.data(), isFirst);
        if (m_singleInstance)
        {
            if (!isFirst)
            {
                /* This is a duplicate instance, send signal and return */
                if (args.size())
                {
                    /* create a signal & check for errors */
                    DBusMessage*
                    msg = dbus_message_new_signal("/boo/signal/FileHandler",
                                                  "boo.signal.FileHandling",
                                                  "Open");

                    /* append arguments onto signal */
                    DBusMessageIter argsIter;
                    dbus_message_iter_init_append(msg, &argsIter);
                    for (const std::string& arg : args)
                    {
                        const char* sigvalue = arg.c_str();
                        dbus_message_iter_append_basic(&argsIter, DBUS_TYPE_STRING, &sigvalue);
                    }

                    /* send the message and flush the connection */
                    dbus_uint32_t serial;
                    dbus_connection_send(m_dbus, msg, &serial);
                    dbus_connection_flush(m_dbus);
                    dbus_message_unref(msg);
                }
                return;
            }
            else
            {
                /* This is the first instance, register for signal */
                // add a rule for which messages we want to see
                DBusError err = {};
                dbus_bus_add_match(m_dbus, "type='signal',interface='boo.signal.FileHandling'", &err);
                dbus_connection_flush(m_dbus);
            }
        }

        if (!XInitThreads())
        {
            Log.report(logvisor::Fatal, "X doesn't support multithreading");
            return;
        }

        /* Program is portable to all locales */
        setlocale(LC_ALL, "");

        /* Open Xlib Display */
        m_xDisp = XOpenDisplay(0);
        if (!m_xDisp)
        {
            Log.report(logvisor::Fatal, "Can't open X display");
            return;
        }

#if BOO_HAS_VULKAN
        /* Cast Display to XCB connection for vulkan */
        m_xcbConn = XGetXCBConnection(m_xDisp);
        if (!m_xcbConn)
        {
            Log.report(logvisor::Fatal, "Can't cast Display to XCB connection for Vulkan");
            return;
        }
#endif

        /* Configure locale */
        if (!XSupportsLocale()) {
            Log.report(logvisor::Fatal, "X does not support locale %s.",
                       setlocale(LC_ALL, nullptr));
            return;
        }
        if (XSetLocaleModifiers("") == nullptr)
            Log.report(logvisor::Warning, "Cannot set locale modifiers.");

        if ((m_xIM = XOpenIM(m_xDisp, nullptr, nullptr, nullptr)))
        {
            char** missing_charsets;
            int num_missing_charsets = 0;
            char* default_string;
            m_fontset = XCreateFontSet(m_xDisp,
                                       "-adobe-helvetica-*-r-*-*-*-120-*-*-*-*-*-*,\
                                        -misc-fixed-*-r-*-*-*-130-*-*-*-*-*-*",
                                       &missing_charsets, &num_missing_charsets,
                                       &default_string);

            /* figure out which styles the IM can support */
            XIMStyles* im_supported_styles;
            XIMStyle app_supported_styles;
            XGetIMValues(m_xIM, XNQueryInputStyle, &im_supported_styles, nullptr);
            /* set flags for the styles our application can support */
            app_supported_styles = XIMPreeditNone | XIMPreeditNothing | XIMPreeditPosition;
            app_supported_styles |= XIMStatusNone | XIMStatusNothing;
            /*
             * now look at each of the IM supported styles, and
             * chose the "best" one that we can support.
             */
            for (int i=0 ; i<im_supported_styles->count_styles ; ++i)
            {
                XIMStyle style = im_supported_styles->supported_styles[i];
                if ((style & app_supported_styles) == style) /* if we can handle it */
                    m_bestStyle = ChooseBetterStyle(style, m_bestStyle);
            }
            /* if we couldn't support any of them, print an error and exit */
            if (m_bestStyle == 0)
            {
                Log.report(logvisor::Fatal, "interaction style not supported.");
                return;
            }
            XFree(im_supported_styles);
        }

        m_xDefaultScreen = DefaultScreen(m_xDisp);
        X_CURSORS.m_pointer = XCreateFontCursor(m_xDisp, XC_left_ptr);
        X_CURSORS.m_hArrow = XCreateFontCursor(m_xDisp, XC_sb_h_double_arrow);
        X_CURSORS.m_vArrow = XCreateFontCursor(m_xDisp, XC_sb_v_double_arrow);
        X_CURSORS.m_ibeam = XCreateFontCursor(m_xDisp, XC_xterm);
        X_CURSORS.m_crosshairs = XCreateFontCursor(m_xDisp, XC_cross);
        X_CURSORS.m_wait = XCreateFontCursor(m_xDisp, XC_watch);

        /* The xkb extension requests that the X server does not
         * send repeated keydown events when a key is held */
        XkbQueryExtension(m_xDisp, &XINPUT_OPCODE, nullptr, nullptr, nullptr, nullptr);
        XkbSetDetectableAutoRepeat(m_xDisp, True, nullptr);

        /* Get file descriptors of xcb and dbus interfaces */
        m_x11Fd = ConnectionNumber(m_xDisp);
        dbus_connection_get_unix_fd(m_dbus, &m_dbusFd);
        m_maxFd = MAX(m_x11Fd, m_dbusFd);

        XFlush(m_xDisp);
    }

    ~ApplicationXlib()
    {
        XCloseDisplay(m_xDisp);
    }
    
    EPlatformType getPlatformType() const
    {
        return EPlatformType::Xlib;
    }
    
    /* Empty handler for SIGINT */
    static void _sigint(int) {}

    int run()
    {
        if (!m_xDisp)
            return 1;

        /* SIGINT will be used to cancel main thread when client thread ends
         * (also enables graceful quitting via ctrl-c) */
        pthread_t mainThread = pthread_self();
        struct sigaction s;
        s.sa_handler = _sigint;
        sigemptyset(&s.sa_mask);
        s.sa_flags = 0;
        sigaction(SIGINT, &s, nullptr);
        sigaction(SIGUSR2, &s, nullptr);

        sigset_t waitmask, origmask;
        sigemptyset(&waitmask);
        sigaddset(&waitmask, SIGINT);
        sigaddset(&waitmask, SIGUSR2);
        pthread_sigmask(SIG_BLOCK, &waitmask, &origmask);

        /* Spawn client thread */
        int clientReturn = INT_MIN;
        std::mutex initmt;
        std::condition_variable initcv;
        std::unique_lock<std::mutex> outerLk(initmt);
        std::thread clientThread([&]()
        {
            std::unique_lock<std::mutex> innerLk(initmt);
            innerLk.unlock();
            initcv.notify_one();
            std::string thrName = std::string(getFriendlyName()) + " Client Thread";
            logvisor::RegisterThreadName(thrName.c_str());
            clientReturn = m_callback.appMain(this);
            pthread_kill(mainThread, SIGUSR2);
        });
        initcv.wait(outerLk);

        /* Begin application event loop */
        while (clientReturn == INT_MIN)
        {
            fd_set fds;
            FD_ZERO(&fds);
            FD_SET(m_x11Fd, &fds);
            FD_SET(m_dbusFd, &fds);
            if (pselect(m_maxFd+1, &fds, NULL, NULL, NULL, &origmask) < 0)
            {
                /* SIGINT/SIGUSR2 handled here */
                if (errno == EINTR)
                    break;
            }

            if (FD_ISSET(m_x11Fd, &fds))
            {
                XLockDisplay(m_xDisp);
                while (XPending(m_xDisp))
                {
                    XEvent event;
                    XNextEvent(m_xDisp, &event);
                    if (XFilterEvent(&event, None)) continue;
                    bool windowEvent;
                    Window evWindow = GetWindowOfEvent(&event, windowEvent);
                    if (windowEvent)
                    {
                        auto window = m_windows.find(evWindow);
                        if (window != m_windows.end())
                            if (std::shared_ptr<IWindow> w = window->second.lock())
                                w->_incomingEvent(&event);
                    }
                }
                XUnlockDisplay(m_xDisp);
            }

            if (FD_ISSET(m_dbusFd, &fds))
            {
                DBusMessage* msg;
                dbus_connection_read_write(m_dbus, 0);
                while ((msg = dbus_connection_pop_message(m_dbus)))
                {
                    /* check if the message is a signal from the correct interface and with the correct name */
                    if (dbus_message_is_signal(msg, "boo.signal.FileHandling", "Open"))
                    {
                        /* read the parameters */
                        std::vector<std::string> paths;
                        DBusMessageIter iter;
                        dbus_message_iter_init(msg, &iter);
                        while (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_INVALID)
                        {
                            const char* argVal;
                            dbus_message_iter_get_basic(&iter, &argVal);
                            paths.push_back(argVal);
                            dbus_message_iter_next(&iter);
                        }
                        m_callback.appFilesOpen(this, paths);
                    }
                    dbus_message_unref(msg);
                }
            }
        }

        m_callback.appQuitting(this);
        clientThread.join();
        return clientReturn;
    }

    std::string_view getUniqueName() const
    {
        return m_uniqueName;
    }

    std::string_view getFriendlyName() const
    {
        return m_friendlyName;
    }
    
    std::string_view getProcessName() const
    {
        return m_pname;
    }
    
    const std::vector<std::string>& getArgs() const
    {
        return m_args;
    }
    
    std::shared_ptr<IWindow> newWindow(std::string_view title, uint32_t drawSamples)
    {
#if BOO_HAS_VULKAN
        std::shared_ptr<IWindow> newWindow = _WindowXlibNew(title, m_xDisp, m_xcbConn, m_xDefaultScreen, m_xIM,
                                             m_bestStyle, m_fontset, m_lastGlxCtx, (void*)m_getVkProc, drawSamples);
#else
        std::shared_ptr<IWindow> newWindow = _WindowXlibNew(title, m_xDisp, nullptr, m_xDefaultScreen, m_xIM,
                                             m_bestStyle, m_fontset, m_lastGlxCtx, nullptr, drawSamples);
#endif
        m_windows[(Window)newWindow->getPlatformHandle()] = newWindow;
        return newWindow;
    }

    /* Last GLX context */
    GLXContext m_lastGlxCtx = nullptr;
};

void _XlibUpdateLastGlxCtx(GLXContext lastGlxCtx)
{
    static_cast<ApplicationXlib*>(APP)->m_lastGlxCtx = lastGlxCtx;
}
    
}