#Using GNU Readline and Ncurses together.txt

//@BAKE g++ $@ $(pkg-config --cflags --libs ncurses readline)
/* NOTE:
 *  We are using C++ here to have access to lambdas.
 *  The C version would look exactly like this, but with traditional callback functions.
 */
#include <ncurses.h>
#include <readline/readline.h>

#define WINDOW_WIDTH  32
#define WINDOW_HEIGHT  3

int scr_h, scr_w;
WINDOW * myWindow;

int input_available = false;	// C style bool to track when to stop reading
char input;						// our input; since we read char-by-char this is all the buffering we need

static inline
void init(){
    // Ncurses (nothing special)
    initscr();
    noecho();
    curs_set(0);

    getmaxyx(stdscr, scr_h, scr_w);
    myWindow = newwin(WINDOW_HEIGHT, WINDOW_WIDTH, 
            ( scr_h / 2 ) - 1, ( scr_w - WINDOW_WIDTH) / 2);
    refresh();

    box(myWindow, 0, 0);
    // Readline
    //   make readline shut up
    rl_bind_key('\t', rl_insert);	// make tab insert itself
    rl_catch_signals = 0;			// do not install signal handlers
    rl_catch_sigwinch = 0;			// do not care about window change signals
    rl_prep_term_function = NULL;	// do not initialize the ternimal
    rl_deprep_term_function = NULL; // do not clean up
    rl_change_environment = 0;		// ?!
    //   bind callbacks, for seemless integration
    rl_getc_function = +[](FILE* ignore){	// define how Readline is handed chars
        input_available = false; // since we read 1 char at the time we know that there will be no more available
        return (int)input;
    };
    rl_input_available_hook = +[]{	// let Readline know that it shall call it rl_getc_function
        return input_available;
    };
    rl_redisplay_function = +[]{	// instruct Readline what to do after rl_line_buffer has changed
        // echo rl_line_buffer (without using the terminals built in echo)
        wmove(myWindow, 1, 1);
        wclrtoeol(myWindow);
        box(myWindow, 0, 0);	// wclrtoeol(), screws with the box
        waddstr(myWindow, rl_line_buffer);
        wrefresh(myWindow);
        return;
    };
    rl_callback_handler_install("", +[](char *line){	// instruct Readline what to do once rl_line_buffer is submitted (enter hit)
        // print the submitted line to the top of the screen
        wmove(stdscr, 0, 0);
        wclrtoeol(stdscr);
        waddstr(stdscr, line);
        wrefresh(stdscr);
        return;
    });
}

signed main(){
    init();
    wrefresh(myWindow);

    while(1){
        input = wgetch(myWindow);
        input_available = true;
        rl_callback_read_char();
    }
}