#include <iostream>
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/Fl_Text_Editor.H>
#include <FL/Fl_Text_Buffer.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Input.H>
#include <cstdlib>
#include <string>

using namespace std;

Fl_Double_Window *win;
Fl_Text_Editor *ted;
Fl_Button *buta;
Fl_Text_Buffer *buf;
Fl_Text_Buffer *style_buffer;

//UNNEEDED int position = 0;
//UNNEEDED int inserted = 0;
//UNNEEDED int deleted = 0;
//UNNEEDED const char* deleted_text;
//UNNEEDED int *start_s = NULL;
//UNNEEDED int *end_s   = NULL;

Fl_Text_Editor::Style_Table_Entry styles[] = {
    {FL_BLACK,FL_HELVETICA,16},         // "A" (our "default font")
    {FL_RED,FL_HELVETICA_BOLD,16}       // "B" (our "bold font")
};

// void change_cback(..) { }		// UNNEEDED FOR THIS DEMO

void change_text(Fl_Widget *wid, void *data)
{
    // Get text buffer's text selection
    const Fl_Text_Selection *ts = buf->primary_selection();
    int start = ts->start();
    int end   = ts->end();
    // No selection? do nothing..
    if ( start == end ) return; // no selection? do nothing..
    // Make style buffer changes to the selected region
    string s_char;
    for (int i=start; i<end; i++ ) s_char += "B";	// use bold style
    style_buffer->replace(start, end-1, s_char.c_str());
    ted->redraw();
}

// When text buffer is modified, sync changes with the style buffer
void text_modified(int pos,                 // I - Position of update
                   int nInserted,           // I - Number of inserted chars
                   int nDeleted,            // I - Number of deleted chars
                   int nRestyled,           // I - Number of restyled chars
                   const char *deletedText, // I - Text that was deleted
                   void *cbArg)             // I - Callback data
{
    // Text buffer changed? Update style buffer too..
    if (nInserted > 0) {
        // Insert characters into the style buffer...
        char *style = new char[nInserted + 1];
        memset(style, 'A', nInserted);              // use default font
        style[nInserted] = '\0';
        style_buffer->replace(pos, pos + nDeleted, style);
        delete[] style;
    } else {
        // Just delete characters from style buffer...
        style_buffer->remove(pos, pos + nDeleted);
    }
}

int main()
{
    win  = new Fl_Double_Window(800,700,"Test_Window");
    ted  = new Fl_Text_Editor(50,50,600,500);
    buta = new Fl_Button(50,600,80,40,"Bold");
    buf  = new Fl_Text_Buffer();
    ted->buffer(buf);
    style_buffer = new Fl_Text_Buffer();
    // Associate style buffer with editor
    int styles_size = sizeof(styles)/sizeof(Fl_Text_Display::Style_Table_Entry);
    ted->highlight_data(style_buffer,
                        styles,
                        styles_size,
                        'A',            // default style
                        0,
                        0);
    buf->add_modify_callback(text_modified, ted);        // updates style buffer when user types
    // Now preload editor with some text. text_modified() will handle setting default style.
    buf->text("0123456789012345678901234567890123456789");
    // buf->add_modify_callback(change_cback,ted); // UNNEEDED FOR DEMO
    buta->callback(change_text);
    win->show();
    return(Fl::run()); // sets event loop
}