#!/bin/bash

# Text "scaling"
# $Id: unix3-scale.sh 191 2006-03-29 11:07:00Z cactus $
#
# (C) 2005 Dr. ERDI Gergo <cactus@cactus.rulez.org>
#
# See http://cactus.rulez.org/elte/2005-1-unix/#3 for a description of what it does
#
# Licensed under the GNU General Public License, version 2


function help () {
    self=`basename $0`

    cat << EOF
Usage: $self {-mxn|+mxn} [FILE]
Scales or shrinks the contents of FILE (or the standard input) based on MODE.
MODE can be +mxn for scaling horizontally by a factor of m, and vertically
by a factor of n, or -mxn for shrinking.

Options:
    -help   Display this help message

(C) 2005 Dr. ERDI Gergo <cactus@cactus.rulez.org>

Version: \$Id: unix3-scale.sh 191 2006-03-29 11:07:00Z cactus $
EOF
    exit 0
}

function error () {
    echo ERROR: $@! >&2
    exit 1
}

function options () {
    [ -z "$1" ] && return
    case "$1" in
	-help)
	    help
	    ;;
	-*)
	    mode=shrink
	    mxn=$(echo $1|cut -f2 -d-)
	    m=$(echo $mxn|cut -f1 -dx)
	    n=$(echo $mxn|cut -f2 -dx)
	    shift
	    options "$@"
	    ;;
	+*)
	    mode=zoom
	    mxn=$(echo $1|cut -f2 -d+)
	    m=$(echo $mxn|cut -f1 -dx)
	    n=$(echo $mxn|cut -f2 -dx)
	    shift
	    options "$@"
	    ;;
	*)
	    [ $# -gt 1 ] && error "Too many arguments"
	    [ -f "$1" -a -r "$1" ] || error "$1: Unable to open file"
	    exec <"$1"
	    ;;
    esac
}

function zoom () {
    AWKPROG='
BEGIN {
  FS="";
}

{
  sor = ""
    
  for (i = 1; i != NF+1; i++)
    for (j = 0; j != m; j++)
	sor = sprintf ("%s%s", sor, $i);
  for (i = 0; i != n; i++)
    print sor;
}'    
    awk -v m=$m -v n=$n "$AWKPROG" 2>/dev/null
}

function shrink () {
    AWKPROG='
BEGIN {
  FS="";
}

{
  if (sor == 0) {
    for (i = 1; i < NF+1; i += m)
      printf "%s", $i;
    print "";
  }

  sor++;
  if (sor == n)
    sor = 0;
}'
    awk -v m=$m -v n=$n "$AWKPROG" 2>/dev/null
}

options "$@"
[ -z $mode ] && error "Scaling mode argument missing"

case -$mode in
    -zoom)
	zoom
	;;
    -shrink)
        shrink
	;;
    *)
	error "Bad scaling mode"
	;;
esac