/* Copyright (c) 2022, Anthony LaTorre <tlatorre9 at gmail dot com>
 * All rights reserved.
 *
 * This program 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, version 2.
 *
 * 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 General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.  */
#include <gtk/gtk.h>
#include <sys/time.h>
#include <stdlib.h>
#include <gdk/gdkkeysyms.h>

/* Time in milliseconds it takes to write a character, i.e. if you hold down
 * the mouse button for this many ms it will write the character and move on to
 * the next character (or emoji).
 *
 * Initially had this set to 500 ms (half a second), but that was a bit short,
 * so I've updated it to one second. */
#define CLICK_TIME 1000

#define LEN(x) ((sizeof(x)/sizeof(0[x])) / ((size_t)(!(sizeof(x) % sizeof(0[x])))))

/* Returns the current time in seconds and milliseconds since the epoch.
 * Mostly useful for calculating time intervals. */
static void aeGetTime(long *seconds, long *milliseconds)
{
    struct timeval tv;

    gettimeofday(&tv, NULL);
    *seconds = tv.tv_sec;
    *milliseconds = tv.tv_usec/1000;
}

GtkWidget *text_widget;
GtkTextTag *tag;

/* List of emojis. */
#define TELEVISION "\xf0\x9f\x93\xba"
#define THOUGHT_BALLOON "\xf0\x9f\x92\xad"
#define STOP "\xf0\x9f\x9b\x91"
#define THANK_YOU "\xf0\x9f\x99\x8f"
#define UNAMUSED "\xf0\x9f\x98\x92"
#define SLEEPING "\xf0\x9f\x98\xb4"
#define BED "\xf0\x9f\x9b\x8f"
#define CHAIR "\xf0\x9f\xaa\x91"
#define NURSE "\xf0\x9f\x91\xa9\xe2\x80\x8d\xe2\x9a\x95\xef\xb8\x8f"
#define ROLLING_EYES "\xf0\x9f\x99\x84"
#define OVERHEATED "\xf0\x9f\xa5\xb5"
#define FREEZING "\xf0\x9f\xa5\xb6"
#define NAUSEOUS "\xf0\x9f\xa4\xa2"
#define THINKING "\xf0\x9f\xa4\x94"
#define THUMBS_UP "\xf0\x9f\x91\x8d"
#define THUMBS_DOWN "\xf0\x9f\x91\x8e"
#define LEFT_ARROW "\xe2\x86\x90"
#define CLEAR_SCREEN "\xe2\x8e\x9a"
#define SOUND "\xf0\x9f\x94\x8a"
#define DROPLET "\xf0\x9f\x92\xa7"
#define FOOD "\xf0\x9f\x8d\xb2"
#define TIRED "\xf0\x9f\x98\xab"
#define HAPPY "\xf0\x9f\x98\x80"
#define LAUGHING "\xf0\x9f\x98\x84"
#define NEWLINE "\xe2\x86\xb5"

typedef struct chars
{
    const char **characters;
    int len;
} chars;

const char *emoji_array[] = {
    THINKING,
    THUMBS_UP,
    THUMBS_DOWN,
    STOP,
    HAPPY,
    LAUGHING,
    TIRED,
    FREEZING,
    OVERHEATED,
    NAUSEOUS,
    ROLLING_EYES,
    SLEEPING,
    UNAMUSED,
    THANK_YOU,
    NURSE,
    DROPLET,
    CHAIR,
    BED,
    THOUGHT_BALLOON,
    TELEVISION,
    //FOOD,
    LEFT_ARROW,
    CLEAR_SCREEN,
};

const char *alphabet_array[] = {
    "a",
    "b",
    "c",
    "d",
    "e",
    "f",
    "g",
    "h",
    "i",
    "j",
    "k",
    "l",
    "m",
    "n",
    "o",
    "p",
    "q",
    "r",
    "s",
    "t",
    "u",
    "v",
    "w",
    "x",
    "y",
    "z",
    LEFT_ARROW,
    CLEAR_SCREEN,
    SOUND,
    "_",
    NEWLINE,
    "!",
    "?",
    "."
};

chars emoji = { emoji_array, LEN(emoji_array)};
chars alphabet = {alphabet_array, LEN(alphabet_array)};
chars *current_chars = &emoji;

char buf[100000];

/* The current alphabetical letter. */
int current_letter = 0;
/* The current position in the buffer.
 *
 * FIXME: What to do if we run out of buffer space?. */
int current_position = 0;

/* Time the mouse was clicked (seconds) */
long pressed_time_sec = 0;
/* Time the mouse was clicked (milliseconds) */
long pressed_time_msec = 0;
/* Time the mouse was released (seconds) */
long released_time_sec = 0;
/* Time the mouse was released (milliseconds) */
long released_time_msec = 0;

/* Is the left mouse button currently pressed? */
int left_click_pressed = FALSE;

/* Has the current character been processed? */
int processed = FALSE;

void backspace(void)
{
    GtkTextBuffer *text_buffer;
    GtkTextIter start, end;

    if (current_position > 0) {
        text_buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(text_widget));
        gtk_text_buffer_set_text(text_buffer, buf, -1);

        gtk_text_buffer_get_iter_at_offset(text_buffer, &start, 0);
        gtk_text_buffer_get_iter_at_offset(text_buffer, &end, g_utf8_strlen(buf,-1)-2);
        current_position = strlen(gtk_text_buffer_get_slice(text_buffer,&start,&end,TRUE));
    }
}

static void write_buf(void)
{
    GtkTextBuffer *text_buffer;
    GtkTextIter start, end;

    text_buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(text_widget));
    sprintf(buf+current_position,"%s",current_chars->characters[current_letter % current_chars->len]);

    gtk_text_buffer_set_text(text_buffer, buf, -1);

    gtk_text_buffer_get_iter_at_offset(text_buffer, &start, g_utf8_strlen(buf,-1)-1);
    gtk_text_buffer_get_iter_at_offset(text_buffer, &end, -1);
    gtk_text_buffer_apply_tag(text_buffer, tag, &start, &end);
}

static int right_click_pressed(GtkWidget *widget, gpointer data)
{
    if (current_chars == &emoji)
        current_chars = &alphabet;
    else if (current_chars == &alphabet)
        current_chars = &emoji;
    current_letter = 0;
    write_buf();
    return TRUE;
}

static int right_click_released(GtkWidget *widget, gpointer data)
{
    return TRUE;
}

static int pressed(GtkWidget *widget, gpointer data)
{
    aeGetTime(&pressed_time_sec,&pressed_time_msec);
    left_click_pressed = TRUE;
    processed = FALSE;
    return TRUE;
}

/* Timer function which runs every 10 ms. This function checks if the left
 * mouse button is clicked, and if so, checks if it's been clicked for more
 * than CLICK_TIME milliseconds. If so, it adds the current character to the
 * buffer and sets processed to TRUE, so that when the mouse button is released
 * it doesn't move to the next character.
 *
 * Always returns TRUE to make sure the function keeps running. */
gboolean timer(gpointer data)
{
    const char *current_char;

    /* If the left mouse button isn't clicked, there is nothing to do. */
    if (left_click_pressed == FALSE) return TRUE;

    aeGetTime(&released_time_sec,&released_time_msec);
    long long diff = (released_time_sec - pressed_time_sec)*1000 + (released_time_msec - pressed_time_msec);

    if (diff > 10000) {
        /* If the mouse button has been clicked for more than 10 seconds, clear
         * the screen. */
        current_position = 0;
        current_letter = 0;
        write_buf();
        processed = TRUE;
        aeGetTime(&pressed_time_sec,&pressed_time_msec);
    } else if ((processed == FALSE) && (diff > CLICK_TIME)) {
        /* If the mouse button has been clicked for more than CLICK_TIME
         * milliseconds, add the current character to the buffer. */
        current_char = current_chars->characters[current_letter % current_chars->len];
        if (!strcmp(current_char,LEFT_ARROW)) {
            backspace();
        } else if (!strcmp(current_char,CLEAR_SCREEN)) {
            current_position = 0;
            current_letter = 0;
        } else if (!strcmp(current_char,SOUND)) {
            char cmd[1000000];
            buf[current_position] = '\0';
            sprintf(cmd, "gtts-cli \"%s\" --output moji.mp3", buf);
            if (!system(cmd)) {
                system("mpg123 moji.mp3");
                system("rm moji.mp3");
            }
        } else if (!strcmp(current_char,"_")) {
            sprintf(buf+current_position," ");
            current_position += strlen(current_char);
        } else if (!strcmp(current_char,NEWLINE)) {
            sprintf(buf+current_position,"\n");
            current_position += 1;
        } else {
            sprintf(buf+current_position,"%s",current_char);
            current_position += strlen(current_char);
        }
        if (current_position > LEN(buf) - 1) {
            /* FIXME: better way to do this? */
            current_position = 0;
        }
        /* Uncomment the next line to start over at the beginning of the
         * alphabet after a new letter is entered. But, I think it's better
         * to keep the current letter. The reason is that you might want to
         * delete a whole word and so when you navigate to the backspace you
         * just have to keep entering the same letter. */
        current_letter = 0;

        write_buf();
        aeGetTime(&pressed_time_sec,&pressed_time_msec);
        processed = TRUE;
    }

    return TRUE;
}

static int released(GtkWidget *widget, gpointer   data)
{
    left_click_pressed = FALSE;

    aeGetTime(&released_time_sec,&released_time_msec);
    long long diff = (released_time_sec - pressed_time_sec)*1000 + (released_time_msec - pressed_time_msec);

    if ((processed == FALSE) && (diff < CLICK_TIME)) {
        current_letter += 1;
    }

    write_buf();

    return TRUE;
}

gboolean on_key_press(GtkEventControllerKey *, guint keyval, guint keycode, GdkModifierType mod, gpointer user_data)
{
    switch (keyval)
    {
    case GDK_KEY_space:
        if (current_chars == &emoji)
            current_chars = &alphabet;
        else if (current_chars == &alphabet)
            current_chars = &emoji;
        current_letter = 0;
        write_buf();
        break;
    case GDK_KEY_BackSpace:
        backspace();
        write_buf();
        break;
    default:
      return FALSE; 
    }
    return FALSE; 
}

static void activate(GtkApplication *app, gpointer user_data)
{
    GtkWidget *window;
    GtkTextBuffer *text_buffer;
    GtkCssProvider *provider;
    GtkStyleContext *context;
    GtkGesture *gesture, *right_click_gesture;
    GtkEventController *event_controller;

    window = gtk_application_window_new(app);
    gtk_window_set_title(GTK_WINDOW(window), "Moji");
    gtk_window_set_default_size(GTK_WINDOW(window), 200, 200);

    event_controller = gtk_event_controller_key_new();
    g_signal_connect(event_controller, "key-pressed", G_CALLBACK(on_key_press), NULL);
    gtk_widget_add_controller(window, event_controller);

    right_click_gesture = gtk_gesture_click_new();
    gtk_gesture_single_set_button(GTK_GESTURE_SINGLE (right_click_gesture), 3);
    g_signal_connect(right_click_gesture, "pressed", G_CALLBACK(right_click_pressed), NULL);
    g_signal_connect(right_click_gesture, "released", G_CALLBACK(right_click_released), NULL);
    gtk_widget_add_controller(window, GTK_EVENT_CONTROLLER(right_click_gesture));

    gesture = gtk_gesture_click_new();
    g_signal_connect(gesture, "pressed", G_CALLBACK(pressed), NULL);
    g_signal_connect(gesture, "released", G_CALLBACK(released), NULL);
    gtk_widget_add_controller(window, GTK_EVENT_CONTROLLER(gesture));

    text_widget = gtk_text_view_new();
    gtk_text_view_set_editable((GtkTextView *) text_widget, FALSE);
    gtk_text_view_set_cursor_visible((GtkTextView *) text_widget, TRUE);
    gtk_text_view_set_wrap_mode((GtkTextView *) text_widget, GTK_WRAP_CHAR);
    gtk_widget_set_can_focus(text_widget, FALSE);
    gtk_widget_set_can_target(text_widget, FALSE);
    text_buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(text_widget));

    /* Change default font and color throughout the widget */
    provider = gtk_css_provider_new();
    gtk_css_provider_load_from_data(provider,
                                    "textview {"
                                    " font: 144pt monospace;"
                                    "  color: black;"
                                    "}",
                                    -1);
    context = gtk_widget_get_style_context(text_widget);
    gtk_style_context_add_provider(context, GTK_STYLE_PROVIDER(provider), GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);

    /* Use a tag to change the color for just one part of the widget */
    tag = gtk_text_buffer_create_tag(text_buffer, "red_foreground", "foreground", "red", NULL);  
    write_buf();

    g_timeout_add(10, timer, NULL);

    gtk_window_set_child(GTK_WINDOW(window), text_widget);

    gtk_window_fullscreen(GTK_WINDOW(window));

    gtk_window_present(GTK_WINDOW(window));
}

int main(int argc, char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new("org.gtk.example", G_APPLICATION_FLAGS_NONE);
  g_signal_connect(app, "activate", G_CALLBACK(activate), NULL);
  status = g_application_run(G_APPLICATION(app), argc, argv);
  g_object_unref(app);

  return status;
}