#!/usr/bin/perl

#this is equivalent to the basic more program presented in the book

use strict;

my $SCREEN_ROWS = 23;

my $c=$#ARGV+1;

if ($c==0) {
    do_more_of(\*STDIN);
}
else {
    while (@ARGV) {
	my $name=shift;
	open(FILE, $name) || die("skipping $name...");
	do_more_of(\*FILE);
    }
}

sub do_more_of {
    my $num_of_lines=$SCREEN_ROWS;
    my $stream=shift;
    while(1) {
	if ($num_of_lines == 0) {
	    $num_of_lines=get_user_input();
	    if ($num_of_lines==-1) {
		last;
	    }
	}
	else {
	    my $line=<$stream>;
	    if ($line) {
		print $line;
	    }
	    else {
		return;
	    }
	    $num_of_lines--;
	}
    }
}

sub get_user_input {
    print "\033[7m more? \033[m";
    my $c=<STDIN>;
    chomp($c);
    if ($c eq '') {
	return 1;
    }
    if ($c eq 'q') {
	return -1;
    }
    if ($c eq ' ') {
	return $SCREEN_ROWS;
    }
    return 0;
}