// Copyright (C) 2022 RozK
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "../events.hpp"
#include <X11/Xlib.h>

extern Display * rk_display;
extern Window rk_window;

unsigned rk_events_mask = FocusChangeMask |
    KeyPressMask | KeyReleaseMask | ButtonPressMask | ButtonReleaseMask | PointerMotionMask;

static XIM rk_input_manager = nullptr;
static XIC rk_input_context = nullptr;

static bool rk_focused = false;
static bool rk_keyboard_autorepeat = false;
static XKeyboardState rk_previous_keyboard_state;
static int rk_previous_accel_numerator, rk_accel_numerator = 1;
static int rk_previous_accel_denominator, rk_accel_denominator = 1;
static int rk_previous_threshold, rk_accel_threshold = 0;

static void rk_backup_setup() {
    XGetKeyboardControl(rk_display, &rk_previous_keyboard_state);
    XGetPointerControl(rk_display,
        &rk_previous_accel_numerator, &rk_previous_accel_denominator, &rk_previous_threshold);
}

static void rk_restore_setup() {
    if (AutoRepeatModeOn == rk_previous_keyboard_state.global_auto_repeat) {
        XAutoRepeatOn(rk_display);
    } else {
        XAutoRepeatOff(rk_display);
    }
    XChangePointerControl(rk_display, True, True,
        rk_previous_accel_numerator, rk_previous_accel_denominator, rk_previous_threshold);
}

static void rk_apply_setup() {
    if (rk_keyboard_autorepeat) {
        XAutoRepeatOn(rk_display);
    } else {
        XAutoRepeatOff(rk_display);
    }
    XChangePointerControl(rk_display, True, True, rk_accel_numerator, rk_accel_denominator, rk_accel_threshold);
}

bool rk_initialize_events() {
    rk_focused = false;
    rk_backup_setup();
    rk_keyboard_autorepeat = (AutoRepeatModeOn == rk_previous_keyboard_state.global_auto_repeat);
    rk_accel_numerator = rk_previous_accel_numerator;
    rk_accel_denominator = rk_previous_accel_denominator;
    rk_accel_threshold = rk_previous_threshold;
    rk_input_manager = XOpenIM(rk_display, nullptr, nullptr, nullptr);
    if (!rk_input_manager) {
        return false;
    }
    rk_input_context = XCreateIC(rk_input_manager,
        XNInputStyle, XIMPreeditNone | XIMStatusNone,
        XNClientWindow, rk_window,
        NULL);
    if (!rk_input_context) {
        return false;
    }
    XSetICFocus(rk_input_context);
    return true;
}

void rk_terminate_events() {
    rk_restore_setup();
    if (rk_input_context) {
        XUnsetICFocus(rk_input_context);
        XDestroyIC(rk_input_context);
        rk_input_context = nullptr;
    }
    if (rk_input_manager) {
        XCloseIM(rk_input_manager);
        rk_input_manager = nullptr;
    }
}

static void rk_focus_in() {
    if (!rk_focused) {
        rk_backup_setup();
        rk_apply_setup();
        XGrabPointer(rk_display, rk_window, True,
            ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
            GrabModeAsync, GrabModeAsync, rk_window, None, CurrentTime);
        rk_focused = true;
    }
}

static void rk_focus_out() {
    if (rk_focused) {
        XUngrabPointer(rk_display, CurrentTime);
        rk_restore_setup();
        rk_focused = false;
    }
}

void rk_set_autorepeat(
    rk_bool autorepeat) {
    rk_keyboard_autorepeat = autorepeat;
    if (rk_focused) {
        rk_apply_setup();
    }
}

void rk_set_acceleration(
    rk_uint numerator,
    rk_uint denominator,
    rk_uint threshold) {
    rk_accel_numerator = numerator;
    rk_accel_denominator = denominator;
    rk_accel_threshold = threshold;
    if (rk_focused) {
        rk_apply_setup();
    }
}

rk_uint rk_consume_events(
    rk_event * events,
    rk_uint max_events) {
    static wchar_t string[256];
    if (!events || !max_events) {
        return 0;
    }
    XEvent x11_event;
    KeySym keysym;
    Status status;
    unsigned nevents = 0;
    while (nevents < max_events && XCheckWindowEvent(rk_display, rk_window, rk_events_mask, &x11_event)) {
        if (XFilterEvent(&x11_event, 0)) {
            continue;
        }
        rk_event & event = events[nevents];
        switch (x11_event.type) {

            case FocusIn:
                if (NotifyNormal == x11_event.xfocus.mode) {
                    rk_focus_in();
                    event.type = RK_EVENT_FOCUS_IN;
                    ++nevents;
                }
                break;

            case FocusOut:
                if (NotifyNormal == x11_event.xfocus.mode) {
                    rk_focus_out();
                    event.type = RK_EVENT_FOCUS_OUT;
                    ++nevents;
                }
                break;

            case KeyPress:
                event.type = RK_EVENT_KEY_PRESS;
                event.key.code = x11_event.xkey.keycode;
                XwcLookupString(rk_input_context, &x11_event.xkey, string, 256, &keysym, &status);
                switch (status) {
                    case XLookupChars:
                        event.key.symbol = XLookupKeysym(&x11_event.xkey, 0);
                        event.key.character = string[0];
                        break;
                    case XLookupKeySym:
                        event.key.symbol = keysym;
                        event.key.character = 0;
                        break;
                    case XLookupBoth:
                        event.key.symbol = keysym;
                        event.key.character = string[0];
                        break;
                    default:
                        event.key.symbol = 0;
                        event.key.character = 0;
                        break;
                }
                ++nevents;
                break;

            case KeyRelease:
                event.type = RK_EVENT_KEY_RELEASE;
                event.key.code = x11_event.xkey.keycode;
                event.key.symbol = XLookupKeysym(&x11_event.xkey, 0);
                event.key.character = 0;
                ++nevents;
                break;

            case ButtonPress:
                event.type = RK_EVENT_BUTTON_PRESS;
                event.button.index = x11_event.xbutton.button;
                ++nevents;
                break;

            case ButtonRelease:
                event.type = RK_EVENT_BUTTON_RELEASE;
                event.button.index = x11_event.xbutton.button;
                ++nevents;
                break;

            case MotionNotify:
                event.type = RK_EVENT_MOTION;
                event.motion.x = x11_event.xbutton.x;
                event.motion.y = x11_event.xbutton.y;
                ++nevents;
                break;
        }
    }
    return nevents;
}