#!/bin/bash

# Horizontal text mirroring
# $Id: unix1-mirror.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/#1 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 [-c] [-s] [FILE]
Horizontally mirrors the lines of FILE (or the standard input)

Options:
    -c      Replace certain graphical characters with their mirrored
            counterparts
    -s      Strip leading spaces from result
    -help   Display this help message

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

Version: \$Id: unix1-mirror.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 "$1" in
	-help)
	    help
	    ;;
	-c)
	    do_mirror_chars=1
	    shift
	    options "$@"
	    ;;
	-s)
	    do_truncate_beginning=1
	    shift
	    options "$@"
	    ;;
	*)
	    [ $# -gt 1 ] && error "Too many arguments"
	    [ -f "$1" -a -r "$1" ] || error "$1: Unable to open file"
	    exec <"$1"
	    ;;
    esac
}


# Mivel a feladat lenyegebol kovetkezik, hogy ismernunk kell a leghosszabb
# sort, nem tudjuk "azonnal" feldolgozni, hanem ideiglenesen el kell eloszor
# tarolnunk az osszes sort.
# Ez biztositja, hogy programunk lassu es nagy memoriaigenyu is lesz.
#
# Eredetileg pure Bash-ben irtam meg, de az borzaszto lassu lett (2
# perces teszt-futasidok, ugyhogy Awk lett belole.

function mirror ()
{
AWKPROG='
BEGIN {
    width = 0
}

{
    lines[size++] = $0;
    
    if (length () > width)
	width = length ();
}


END {
    for (i = 0; i != size; i++) {	
        for (j = length (lines[i]); j < width; j++)
	    printf " ";
    
        for (j = length (lines[i]); j != 0; j--)
	    printf "%s", substr (lines[i], j, 1)
        print "";
    }
    
}'
    awk "$AWKPROG" 2>/dev/null
}

function mirror_chars ()
{
    [ -z $do_mirror_chars ] && (cat; return)

    # Hogy en mit szenvedtem, mire megfelelo " es ' vedelmeket
    # talaltam ezekhez...

    local class1='()<>\\/'"\`'"'\]\[}{'
    local class2=')(></\\'"'\`"'\[\]{}'

    tr "$class1" "$class2" 2>/dev/null
}

function truncate_beginning ()
{
    [ -z $do_truncate_beginning ] && (cat; return)

    sed -e 's/^ *//' 2>/dev/null
}

options "$@"
mirror | sed -e 's/ *$//' | truncate_beginning | mirror_chars