#!/usr/bin/env bash

# Bash Utility
#
# Copyright (C) 2018 Alessandro Alfonsi
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#

## Examples
#

STRING="Abcdez"
DEC="97"

## Function
#

count_str() {
# count_str() - returns the lentgh of a string
        local str="$1"
        echo "${#str}"
}

ord() {
# ord() - converts ASCII character to its decimal value
        local char="$1"
        printf "%d" "'${char}"
}


chr() {
# chr() - converts decimal value to its ASCII character representation
        local num="$1"
        printf '%b' "$(printf '\%03o' "${num}")"
}

to_upper() {
# to_upper() - returns an uppercase string
        local str="$1"
        echo "${str}" | tr '[:lower:]' '[:upper:]'
}

to_lower() {
# to_lower() - returns a lowercase string
        local str="$1"
        echo "${str}" | tr '[:upper:]' '[:lower:]'
}

rot1() {
# rot1() - encrypt a string with rot1 (replace each letter with the letter 1 position after)
        local str="$1"
        echo "${str}" | tr 'a-zA-Z' 'b-zaB-ZA'
}

rot13() {
# rot13() - encrypt a string with rot13 (replace each letter with the letter 13 position after)
        local str="$1"
        echo "${str}" | tr 'a-zA-Z' 'n-za-mN-ZA-M'
}

## Main
#

FIRST_CHR="${STRING:0:1}"

echo "String: ${STRING}"
echo "String length: $(count_str "${STRING}")"
echo "First character of the string: ${FIRST_CHR}"
echo "Ord of character ${FIRST_CHR}: $(ord "${FIRST_CHR}")"
echo "Chr of number ${DEC}: $(chr "${DEC}")"
echo "Convert a string to uppercase: $(to_upper "${STRING}")"
echo "Convert a string to lowercase: $(to_lower "${STRING}")"
echo "Encrypt a string with ROT1: $(rot1 "${STRING}")"
echo "Encrypt a string with ROT13: $(rot13 "${STRING}")"

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