/*
 * This file is part of espanso.
 *
 * Copyright (C) 2019 Federico Terzi
 *
 * espanso is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * espanso 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with espanso.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "bridge.h"

#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <array>
#include <string.h>

#include <X11/Xlibint.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/cursorfont.h>
#include <X11/keysymdef.h>
#include <X11/keysym.h>
#include <X11/extensions/record.h>
#include <X11/extensions/XTest.h>
#include <X11/XKBlib.h>
#include <X11/Xatom.h>
extern "C" {  // Needed to avoid C++ compiler name mangling
    #include <xdo.h>
}

/*
This code uses the X11 Record Extension to receive keyboard
events. Documentation of this library can be found here:
https://www.x.org/releases/X11R7.6/doc/libXtst/recordlib.html

We will refer to this extension as RE from now on.
*/

/*
This struct is needed to receive events from the RE.
The funny thing is: it's not defined there, it should though.
The only place this is mentioned is the libxnee library,
so check that out if you need a reference.
*/
typedef union {
    unsigned char    type ;
    xEvent           event ;
    xResourceReq     req   ;
    xGenericReply    reply ;
    xError           error ;
    xConnSetupPrefix setup;
} XRecordDatum;

/*
Connections to the X server, RE recommends 2 connections:
one for recording control and one for reading the recorded data.
*/
Display *data_disp = NULL;
Display *ctrl_disp = NULL;

XRecordRange  *record_range;
XRecordContext context;

xdo_t * xdo_context;

// Callback invoked when a new key event occur.
void event_callback (XPointer, XRecordInterceptData*);

KeypressCallback keypress_callback;
void * context_instance;

void register_keypress_callback(KeypressCallback callback) {
    keypress_callback = callback;
}


int32_t initialize(void * _context_instance) {
    setlocale(LC_ALL, "");

    context_instance = _context_instance;

    /*
    Open the connections to the X server.
    RE recommends to open 2 connections to the X server:
    one for the recording control and one to read the protocol
    data.
    */
    ctrl_disp = XOpenDisplay(NULL);
    data_disp = XOpenDisplay(NULL);

    if (!ctrl_disp || !data_disp) {  // Display error
        return -1;
    }

    /*
    We must set the ctrl_disp to sync mode, or, when we the enable
    context in data_disp, there will be a fatal X error.
    */
    XSynchronize(ctrl_disp, True);

    int dummy;

    // Make sure the X RE is installed in this system.
    if (!XRecordQueryVersion(ctrl_disp, &dummy, &dummy)) {
        return -2;
    }

    // Make sure the X Keyboard Extension is installed
    if (!XkbQueryExtension(ctrl_disp, &dummy, &dummy, &dummy, &dummy, &dummy)) {
        return -3;
    }

    // Initialize the record range, that is the kind of events we want to track.
    record_range = XRecordAllocRange ();
    if (!record_range) {
        return -4;
    }
    record_range->device_events.first = KeyPress;
    record_range->device_events.last = KeyRelease;

    // We want to get the keys from all clients
    XRecordClientSpec  client_spec;
    client_spec = XRecordAllClients;

    // Initialize the context
    context = XRecordCreateContext(ctrl_disp, 0, &client_spec, 1, &record_range, 1);
    if (!context) {
        return -5;
    }

    xdo_context = xdo_new(NULL);

    return 1;
}

int32_t eventloop() {
    if (!XRecordEnableContext (data_disp, context, event_callback, NULL)) {
        return -1;
    }

    return 1;
}

void cleanup() {
    XRecordDisableContext(ctrl_disp, context);
    XRecordFreeContext(ctrl_disp, context);
    XFree (record_range);
    XCloseDisplay(data_disp);
    XCloseDisplay(ctrl_disp);
    xdo_free(xdo_context);
}

void event_callback(XPointer p, XRecordInterceptData *hook)
{
    // Make sure the event comes from the X11 server
    if (hook->category != XRecordFromServer) {
        XRecordFreeData(hook);
        return;
    }

    // Cast the event payload to a XRecordDatum, needed later to access the fields
    // This struct was hard to find and understand. Turn's out that all the
    // required data are included in the "event" field of this structure.
    // The funny thing is that it's not a XEvent as one might expect,
    // but a xEvent, a very different beast defined in the Xproto.h header.
    // I suggest you to look at that header if you want to understand where the
    // upcoming field where taken from.
    XRecordDatum *data = (XRecordDatum*) hook->data;

    int event_type = data->type;
    int key_code = data->event.u.u.detail;

    // In order to convert the key_code into the corresponding string,
    // we need to synthesize an artificial XKeyEvent, to feed later to the
    // XLookupString function.
    XKeyEvent event;
    event.display     = ctrl_disp;
    event.window      = data->event.u.focus.window;
    event.root        = XDefaultRootWindow(ctrl_disp);
    event.subwindow   = None;
    event.time        = data->event.u.keyButtonPointer.time;
    event.x           = 1;
    event.y           = 1;
    event.x_root      = 1;
    event.y_root      = 1;
    event.same_screen = True;
    event.keycode     = key_code;
    event.state       = data->event.u.keyButtonPointer.state;
    event.type = KeyPress;

    // Extract the corresponding chars.
    std::array<char, 10> buffer;
    int res = XLookupString(&event, buffer.data(), buffer.size(), NULL, NULL);

    switch (event_type) {
        case KeyPress:
            //printf ("%d %d %s\n", key_code, res, buffer.data());
            if (res > 0 && key_code != 22) {  // Printable character, but not backspace
                keypress_callback(context_instance, buffer.data(), buffer.size(), 0, key_code);
            }else{ // Modifier key
                keypress_callback(context_instance, NULL, 0, 1, key_code);
            }
            break;
        default:
            break;
    }

    XRecordFreeData(hook);
}

void send_string(const char * string) {
    xdo_enter_text_window(xdo_context, CURRENTWINDOW, string, 12000);
}

void delete_string(int32_t count) {
    for (int i = 0; i<count; i++) {
        xdo_send_keysequence_window(xdo_context, CURRENTWINDOW, "BackSpace", 8000);
    }
}

void trigger_paste() {
    xdo_send_keysequence_window(xdo_context, CURRENTWINDOW, "Control_L+v", 8000);
}

void trigger_terminal_paste() {
    xdo_send_keysequence_window(xdo_context, CURRENTWINDOW, "Control_L+Shift+v", 8000);
}

// SYSTEM MODULE

// Function taken from the wmlib tool source code
char *get_property(Display *disp, Window win,
                          Atom xa_prop_type, char *prop_name, unsigned long *size)
{
    unsigned long ret_nitems, ret_bytes_after, tmp_size;
    Atom xa_prop_name, xa_ret_type;
    unsigned char *ret_prop;
    int ret_format;
    char *ret;
    int size_in_byte;

    xa_prop_name = XInternAtom(disp, prop_name, False);

    if (XGetWindowProperty(disp, win, xa_prop_name, 0, 4096 / 4, False,
                           xa_prop_type, &xa_ret_type, &ret_format, &ret_nitems,
                           &ret_bytes_after, &ret_prop) != Success)
        return NULL;

    if (xa_ret_type != xa_prop_type)
    {
        XFree(ret_prop);
        return NULL;
    }

    switch(ret_format) {
        case 8:	size_in_byte = sizeof(char); break;
        case 16:	size_in_byte = sizeof(short); break;
        case 32:	size_in_byte = sizeof(long); break;
    }

    tmp_size = size_in_byte * ret_nitems;
    ret = (char*) malloc(tmp_size + 1);
    memcpy(ret, ret_prop, tmp_size);
    ret[tmp_size] = '\0';

    if (size) *size = tmp_size;

    XFree(ret_prop);
    return ret;
}

// Function taken from Window Management Library for Ruby
char *xwm_get_win_title(Display *disp, Window win)
{
    char *wname = (char*)get_property(disp,win, XA_STRING, "WM_NAME", NULL);
    char *nwname = (char*)get_property(disp,win, XInternAtom(disp,
                                                             "UTF8_STRING", False), "_NET_WM_NAME", NULL);

    return nwname ? nwname : (wname ? wname : NULL);
}

int32_t get_active_window_name(char * buffer, int32_t size) {
    Display *disp = XOpenDisplay(NULL);

    if (!disp) {
        return -1;
    }

    // Get the active window
    Window win;
    int revert_to_return;
    XGetInputFocus(disp, &win, &revert_to_return);

    char * title = xwm_get_win_title(disp, win);

    snprintf(buffer, size, "%s", title);

    XFree(title);

    XCloseDisplay(disp);

    return 1;
}

int32_t get_active_window_class(char * buffer, int32_t size) {
    Display *disp = XOpenDisplay(NULL);

    if (!disp) {
        return -1;
    }

    // Get the active window
    Window win;
    int revert_to_return;
    XGetInputFocus(disp, &win, &revert_to_return);

    XClassHint hint;

    if (XGetClassHint(disp, win, &hint)) {
        snprintf(buffer, size, "%s", hint.res_class);
        XFree(hint.res_name);
        XFree(hint.res_class);
    }

    XCloseDisplay(disp);

    return 1;
}

int32_t get_active_window_executable(char *buffer, int32_t size) {
    Display *disp = XOpenDisplay(NULL);

    if (!disp) {
        return -1;
    }

    // Get the active window
    Window win;
    int revert_to_return;
    XGetInputFocus(disp, &win, &revert_to_return);

    // Get the window process PID
    char *pid_raw = (char*)get_property(disp,win, XA_CARDINAL, "_NET_WM_PID", NULL);
    if (pid_raw == NULL) {
        return -2;
    }

    int pid = pid_raw[0] | pid_raw[1] << 8 | pid_raw[2] << 16 | pid_raw[3] << 24;

    // Get the executable path from it
    char proc_path[250];
    snprintf(proc_path, 250, "/proc/%d/exe", pid);

    readlink(proc_path, buffer, size);

    XFree(pid_raw);
    XCloseDisplay(disp);

    return 1;
}

int32_t is_current_window_terminal() {
    char class_buffer[250];
    int res = get_active_window_class(class_buffer, 250);
    if (res > 0) {
        if (strstr(class_buffer, "terminal") != NULL) {
            return 1;
        }
    }

    return 0;
}