#!/bin/bash

echo "Enter the keyword:"
read keyWord

declare -a keySquare
declare -a plainText
allCharacters="ABCDEFGHIKLMNOPQRSTUVWXYZ"

#Function to find the location of char in key-square
locateInKeySquare() {
	char=$1
	for((j=0;j<${#keySquare[@]};j++)) 
	do
		if [ "${keySquare[$j]}" == "$char" ]
		then
			return $j
		fi
	done
}

#Function to add a given character into the key-square
addToKeySquare() {
	char=$1
	
	#change character to uppercase
	char=`echo $char | tr '[:lower:]' '[:upper:]'`

	#If the character is 'J', then change it to 'I'
	if [ "$char" == 'J' ]
	then
		char='I'
	fi
	
	#Return if the parameter is not a character
	if [ `echo $allCharacters | grep -c "$char"` -eq 0 ]
	then
		return
	fi
	
	#If the character is already present, then quit
	if [ `echo ${keySquare[@]} | grep -c "$char"` -ne 0 ]
	then
		return;
	fi

	keySquare=( ${keySquare[@]} $char )
}

#Function to print the key-square
printKeySquare() {
	for((i=0;i<${#keySquare[@]};i++))
	do
		if [ `echo $i%5 | bc` -eq 0 ]
		then
			echo ""
		fi
	
		echo -n ${keySquare[$i]}
	done	
	echo ""
}

#Add all the characters from the keyword into the key-square
for((i=1;i<=${#keyWord};i++))
do
	cur=`echo $keyWord | cut -c $i`
	addToKeySquare $cur
done

#Add the remaining characters into the key-square
for((i=1;i<=${#allCharacters};i++))
do
	cur=`echo $allCharacters | cut -c $i`
	addToKeySquare $cur
done

printKeySquare

echo "Enter the plain string:"
read plainTextString

tmp=""

for((i=1;i<=${#plainTextString};i++))
do
	char=`echo $plainTextString | cut -c $i`

	#change character to uppercase
	char=`echo $char | tr '[:lower:]' '[:upper:]'`

	#If the character is 'J', then change it to 'I'
	if [ "$char" == 'J' ]
	then
		char='I'
	fi
	
	#Return if the parameter is not a character
	if [ `echo $allCharacters | grep -c "$char"` -eq 0 ]
	then
		continue
	fi
	
	if [ "$tmp" == "$char" ]
	then
		continue
	fi
	
	tmp="$tmp$char"
	
	if [ ${#tmp} -eq 2 ]
	then
		plainText=( ${plainText[@]} $tmp )
		tmp=""
	fi
done

if [ ${#tmp} -eq 1 ]
then
	tmp=$tmp"X"
	plainText=( ${plainText[@]} $tmp )
fi

echo ${plainText[*]}

for((i=0;i<${#plainText[@]};i++))
do
	char1=`echo ${plainText[$i]} | cut -c 1`
	char2=`echo ${plainText[$i]} | cut -c 2`
	
	locateInKeySquare $char1
	pos1=$?
	
	locateInKeySquare $char2
	pos2=$?
	
	r1=`echo "(($pos1)/5)" | bc`
	c1=`echo "(($pos1)%5)" | bc`

	r2=`echo "(($pos2)/5)" | bc`
	c2=`echo "(($pos2)%5)" | bc`
	
	#Rule 1
	if [ $r1 -eq $r2 ]
	then
		c1=`echo "(($c1+1)%5)" | bc`
		c2=`echo "(($c2+1)%5)" | bc`

	#Rule 2
	elif [ $c1 -eq $c2 ]
	then
		r1=`echo "(($r1+1)%5)" | bc`
		r2=`echo "(($r2+1)%5)" | bc`
	
	#Rule 3
	else
		tmp=$c1
		c1=$c2
		c2=$tmp
	fi

	pos1=`echo "($r1*5)+$c1" | bc`
	pos2=`echo "($r2*5)+$c2" | bc`
	
	char1=${keySquare[$pos1]}
	char2=${keySquare[$pos2]}
	
	echo -n $char1$char2
done
echo ""