#!/usr/bin/env perl6
use v6;
use Readline;
use NativeCall; # For libc declarations

# sub cb_linehandler ( Str ); # forward definition

my Int $running;
my Str $prompt = "cb prompt here ('exit' to exit>)> ";

# Callback function called for each line when accept-line executed, EOF
# seen, or EOF character read.  This sets a flag and returns; it could
# also call exit(3).

sub cb_linehandler( Str $line ) {
    # Can use ^D (stty eof) or `exit' to exit.
    if !$line.defined or $line ~~ /exit/ {
        if !$line.defined {
            say();
        }
        say "exit";
        # This function needs to be called to reset the terminal settings,
        # and calling it from the line handler keeps one extra prompt from
        # being displayed.
        rl_callback_handler_remove();
        $running = 0;
    }
    else {
        if $line ~~ /\S/ {
            add_history( $line );
        }
        say "input line: {$line}";
        # free( $line );
    }
}

sub perror ( Str ) is native( 'libc' ) { * }

sub MAIN( ) returns Int { # c and v are unused, ignore arguments.
    #my fd_set $fds; # struct
    my $r = 0;

    # Install the line handler.
    rl_callback_handler_install( $prompt, &cb_linehandler );

    # Enter a simple event loop.  This waits until something is available
    # to read on readline's input stream (defaults to standard input) and
    # calls the builtin character read callback to read it.  It does not
    # have to modify the user's terminal settings.

    $running = 1;
    while $running {
        #FD_ZERO( \$fds );
        #FD_SET( fileno( $rl_instream ), \$fds );

        #$r = select( FD_SETSIZE, \$fds, Nil, Nil, Nil );

        if $r < 0 {
            perror( "rltest: select" );
            rl_callback_handler_remove();
            last;
        }

        #if FD_ISSET (fileno (rl_instream), &fds) {
            rl_callback_read_char( );
        #}
    }
    
    say "rltest: Event loop has exited";
    return 0;
}

# #my $rl_instream := cglobal( LIB, 'rl_instream', Pointer );


#############################################################################
# 
# static void cb_linehandler (char *);
# 
# int running;
# const char *prompt = "rltest$ ";
# 
# /* Callback function called for each line when accept-line executed, EOF
#    seen, or EOF character read.  This sets a flag and returns; it could
#    also call exit(3). */
# static void
# cb_linehandler (char *line)
# {
#   /* Can use ^D (stty eof) or `exit' to exit. */
#   if (line == NULL || strcmp (line, "exit") == 0)
#     {
#       if (line == 0)
#         printf ("\n");
#       printf ("exit\n");
#       /* This function needs to be called to reset the terminal settings,
#          and calling it from the line handler keeps one extra prompt from
#          being displayed. */
#       rl_callback_handler_remove ();
# 
#       running = 0;
#     }
#   else
#     {
#       if (*line)
#         add_history (line);
#       printf ("input line: %s\n", line);
#       free (line);
#     }
# }
# 
# int
# main (int c, char **v)
# {
#   fd_set fds;
#   int r;
# 
#   /* Install the line handler. */
#   rl_callback_handler_install (prompt, cb_linehandler);
# 
#   /* Enter a simple event loop.  This waits until something is available
#      to read on readline's input stream (defaults to standard input) and
#      calls the builtin character read callback to read it.  It does not
#      have to modify the user's terminal settings. */
#   running = 1;
#   while (running)
#     {
#       FD_ZERO (&fds);
#       FD_SET (fileno (rl_instream), &fds);    
# 
#       r = select (FD_SETSIZE, &fds, NULL, NULL, NULL);
#       if (r < 0)
#         {
#           perror ("rltest: select");
#           rl_callback_handler_remove ();
#           break;
#         }
# 
#       if (FD_ISSET (fileno (rl_instream), &fds))
#         rl_callback_read_char ();
#     }
# 
#   printf ("rltest: Event loop has exited\n");
#   return 0;
# }
# 
#############################################################################