#!/bin/bash

attachmentSpecified=false
numAttachments=0
numRecipients=0

while true
do
echo -n 'Specify sender email address: '
# Retrieve the sender's email address from input
read senderEmail

shopt -s nocasematch

# Check against test@example.com email format
if [[ "$senderEmail" =~ [A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4} ]]; then
  echo "$senderEmail has been added"
  break
else
  echo "Invalid sender email address specified: $senderEmail"
fi
done

while true
do
	echo -n 'Specify recipient email address: '
	# Retrieve the recipient's email address from input
	read recipientEmail
	shopt -s nocasematch

	# Check against test@example.com email format
	if [[ "$recipientEmail" =~ [A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4} ]]; then
		# Increment the numRecipients counter by 1
		numRecipients=$((numRecipients+1))
		# Add the recipient email address to the array
		recipientArr[$numRecipients]=$recipientEmail
		# Tell the user the recipient's email address has been added
		echo "$recipientEmail has been added"
		
		while true
		do
			echo -n 'Add another recipient? (y|n) '
			read ltr1 rest
			case ${ltr1} in
				[Yy])	break;; # Do not break out of the loop
				[Nn])	break;; # Break out of the loop
				*)	echo; echo Unrecognized choice: ${ltr1} ;;
			esac
		done
	else
	  echo "Invalid recipient email address specified: $recipientEmail"
	fi

	case ${ltr1} in
		[Nn])	break;; # Break out of the loop
	esac

done

echo -n 'Specify email subject: '
# Retrieve the email subject from input
read subject

while true
do
	echo -n 'Add an attachment? (y|n) '
	# Retrieve user's response and save as ltr
	read ltr2 rest
	case ${ltr2} in
		[Yy])	while true
			do
				echo -n 'Specify a directory that contains the attachments: '
				read directory

				if [ -d "$directory" ]; then 
					# User specified a valid directory. Break out of the loop
					break
				else
					# User specified an invalid directory. Show an error message and prompt again
					echo "$directory is not a directory"
				fi
			done
			cd $directory
			echo "$directory contains the following files:"
			ls -l | grep ^- | awk '{print $9}'
			while true
			do
				echo -n 'Specify the name of an attachment you want to include: '
				read attachment

				if [ -f $attachment ];
				then
				   # Increment the numAttachments counter by 1
				   numAttachments=$((numAttachments+1))
				   # Add the attachment name to the array
				   attachmentArr[$numAttachments]=$attachment
				   # Tell the user the attachment has been added
				   echo "The $attachment has been added"
				   while true
				   do
				   echo -n 'Do you want to add another attachment? (y|n) '
				   # Retrieve user's response and save as ltr3
				   read ltr3 rest
				   
					   case ${ltr3} in
						[Yy])	break;; # Do not break out of the loop
						[Nn])	break;; # Break out of the loop
						*)	echo; echo Unrecognized choice: ${ltr3} ;;
					   esac
				   done
				else
				   echo "File $attachment does not exist."
				fi
				
				case ${ltr3} in
					[Nn])	break;; # Break out of the loop
				esac				
				
			done
			
			while true
			do
				echo -n 'Enter your message: '
				read message
				if [ "$message" == "" ]
				then
					echo -n 'Are you sure you do not want to enter a message? (y|n) '
					# Retrieve user's response and save as ltr4
					read ltr4 rest
					
					   case ${ltr4} in
						[Yy])	break;; # Proceed to next step
						[Nn])	;; # Stay in the loop to be prompted again
						*)	echo; echo Unrecognized choice: ${ltr4} ;;
					   esac
				else
				echo $message > message.txt
				break
				fi
			done
			
			# Show email recipients
			counter=1
			for i in "${recipientArr[@]}"
				do
				   :
				   if [ "$numRecipients" == "1" ]
				   then
				   	echo -n "To: $i"
				   	echo ""
				   	# Only one recipient so counter not needed
				   
				   elif [ "$counter" == "1" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n "To: $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" \< "$numRecipients" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n ", $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" == "$numRecipients" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n ", and $i"
				   	echo ""
				   	counter=$((counter+1))
				   fi
				done
			
			# Show email sender
			echo "From: $senderEmail"
			echo ""
			
			# Show email subject
			echo "Subject: $subject"
			echo ""
			
			# Show email message
			echo "Message: $message"
			echo ""
			
			# Show email attachments
			counter=1
			for i in "${attachmentArr[@]}"
				do
				   :
				   if [ "$numAttachments" == "1" ]
				   then
				   	echo -n "Attachments: $i"
				   	echo ""
				   	# Only one attachment so counter not needed
				   
				   elif [ "$counter" == "1" -a "$numAttachments" \> "1" ]
				   then
				   	echo -n "Attachments: $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" \< "$numAttachments" -a "$numAttachments" \> "1" ]
				   then
				   	echo -n ", $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" == "$numAttachments" -a "$numAttachments" \> "1" ]
				   then
				   	echo -n ", and $i"
				   	echo ""
				   	counter=$((counter+1))
				   fi
				done
			
			# End add an attachment yes choice
			break;;
		[Nn])	while true
			do
				echo -n 'Enter your message: '
				read message
				if [ "$message" == "" ]
				then
					echo -n 'Are you sure you do not want to enter a message? (y|n) '
					# Retrieve user's response and save as ltr4
					read ltr4 rest
					
					   case ${ltr4} in
						[Yy])	echo " " > message.txt
							break;; # Proceed to next step
						[Nn])	;; # Stay in the loop to be prompted again
						*)	echo; echo Unrecognized choice: ${ltr4} ;;
					   esac
				else
				echo $message > message.txt
				break
				fi
			done
			
			# Show email recipients
			counter=1
			for i in "${recipientArr[@]}"
				do
				   :
				   if [ "$numRecipients" == "1" ]
				   then
				   	echo -n "To: $i"
				   	echo ""
				   	# Only one recipient so counter not needed
				   
				   elif [ "$counter" == "1" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n "To: $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" \< "$numRecipients" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n ", $i"
				   	counter=$((counter+1))
				   
				   elif [ "$counter" == "$numRecipients" -a "$numRecipients" \> "1" ]
				   then
				   	echo -n ", and $i"
				   	echo ""
				   	counter=$((counter+1))
				   fi
				done
			
			# Show email sender
			echo "From: $senderEmail"
			echo ""
			
			# Show email subject
			echo "Subject: $subject"
			echo ""
			
			# Show email message
			echo "Message: $message"
			echo ""
			# End add an attachment no choice
			break;;
		*)	echo; echo Unrecognized choice: ${ltr2} ;;
	esac
done

recipientStr=""
recipientStr=$(printf " %s" "${recipientArr[@]}")
recipientStr=${recipientStr:1}

echo $recipientStr



# Add sender email to mail string
mailstr="mail -c '"$senderEmail"' "

# Add subject to mail string
mailstr=$mailstr" -s '"$subject"' "

# Add attachments to mail string

for i in "${attachmentArr[@]}"
do
   :
   attachmenttmp=" -a '"$directory"/"$i"' "
   mailstr=$mailstr$attachmenttmp
done

# Add recipient emails to mail string

for i in "${recipientArr[@]}"
do
   :
   recipienttmp=" '"$i"' "
   mailstr=$mailstr$recipienttmp
done

# Add message.txt to mail string
cronlocation=$(pwd)
mailstr=$mailstr' < '$cronlocation'/message.txt'

echo -n "1) Add a crontab entry to send the email  2) Send the email now "
# Retrieve user's response and save as ltr5
read ltr5 rest

   case ${ltr5} in
	[1])	while true
		do

		echo -n "1) Specify date and time to send email (24 hour clock) 2) Specify time interval to send email (minutes) "
		read ltr7
		case ${ltr7} in
			[1])	while true
				do
					echo -n 'Specify the month (jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec) '
					# Retrieve month from input
					read month

					# Check if specified month is a valid choice
					if [[ $month == "jan" ]] || [[ $month == "feb" ]] || [[ $month == "mar" ]] || [[ $month == "apr" ]] || [[ $month == "may" ]] || [[ $month == "jun" ]] || [[ $month == "jul" ]] || [[ $month == "aug" ]] || [[ $month == "sep" ]] || [[ $month == "oct" ]] || [[ $month == "nov" ]] || [[ $month == "dec" ]] || [[ $month == "JAN" ]] || [[ $month == "FEB" ]] || [[ $month == "MAR" ]] || [[ $month == "APR" ]] || [[ $month == "MAY" ]] || [[ $month == "JUN" ]] || [[ $month == "JUL" ]] || [[ $month == "AUG" ]] || [[ $month == "SEP" ]] || [[ $month == "OCT" ]] || [[ $month == "NOV" ]] || [[ $month == "DEC" ]]; then
					  break
					else
					  echo "Invalid month specified: $month"
					fi
				done
			
				while true
				do
					echo -n 'Specify the day '
					# Retrieve day from input
					read day
					# Jan 31 | Feb 29 Check for leap years | Mar 31 | Apr 30 | May 31 | Jun 30 | Jul 31 | Aug 31 | Sep 30 | Oct 31 | Nov 30 | Dec 31
					# Check if specified day is within range
					if [ "$month" == "jan" ] || [ "$month" == "JAN" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in January"
					  fi
					fi

					if [ "$month" == "feb" ] || [ "$month" == "FEB" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "30" ]; then
					  	break
					  else
						echo "There are only 29 days in February except on a leap year"
					  fi
					fi

					if [ "$month" == "mar" ] || [ "$month" == "MAR" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in March"
					  fi
					fi

					if [ "$month" == "apr" ] || [ "$month" == "APR" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "31" ]; then
					  	break
					  else
						echo "There are only 30 days in April"
					  fi
					fi
				
					if [ "$month" == "may" ] || [ "$month" == "MAY" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in May"
					  fi
					fi

					if [ "$month" == "jun" ] || [ "$month" == "JUN" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "31" ]; then
					  	break
					  else
						echo "There are only 30 days in June"
					  fi
					fi

					if [ "$month" == "jul" ] || [ "$month" == "JUL" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in July"
					  fi
					fi

					if [ "$month" == "aug" ] || [ "$month" == "AUG" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in August"
					  fi
					fi

					if [ "$month" == "sep" ] || [ "$month" == "SEP" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "31" ]; then
					  	break
					  else
						echo "There are only 30 days in September"
					  fi
					fi

					if [ "$month" == "oct" ] || [ "$month" == "OCT" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in October"
					  fi
					fi

					if [ "$month" == "nov" ] || [ "$month" == "NOV" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "31" ]; then
					  	break
					  else
						echo "There are only 30 days in November"
					  fi
					fi

					if [ "$month" == "dec" ] || [ "$month" == "Dec" ]; then
					  if [ "$day" -gt "0" ] && [ "$day" -lt "32" ]; then
					  	break
					  else
						echo "There are only 31 days in December"
					  fi
					fi
				done
			
				while true
				do
					echo -n 'Specify the hour (24 hour clock) '
					# Retrieve hour from input
					read hour

					# Check if specified hour is between 0 and 23 inclusive
					if [ "$hour" -gt "-1" ] && [ "$hour" -lt "24" ]; then
					  break
					else
					  echo "Hour must be between 0 and 23 inclusive"
					fi
				done

				while true
				do
					echo -n 'Specify the minute '
					# Retrieve minute from input
					read minute

					# Check if specified minute is between 0 and 59 inclusive
					if [ "$minute" -gt "-1" ] && [ "$minute" -lt "60" ]; then
					  break
					else
					  echo "Minute must be between 0 and 59 inclusive"
					fi
				done
			
				echo "$minute $hour $day $month * $year"
			
				cronlocation=$(pwd)
				crondate=$(date | awk '{print $2" "$3", "$6" @ "$4}')
				crontab -l > "cronbackup $crondate"
				echo -n 'A backup copy of cron has been saved at '$cronlocation'/cronbackup '$crondate
				echo "$minute $hour $day $month * $mailstr" >> mycron
				crontab mycron
				rm mycron
			
				break;;
			[2])	while true
				do
				echo -n "Specify time interval (minutes) "
				read minute
				if ! [[ "$minute" =~ ^[0-9]+$ ]] ; then
				   exec >&2; echo "Minute needs to be a whole number"
				else
				break
				fi
				done
				hour=$(expr $minute / 60)
				minute=$(expr $minute - $(expr $hour \* 60))
			
				if [ "$hour" != "0" ]; then
				hour='*/'$hour
				else
				hour='*'
				fi
			
				if [ "$minute" != "0" ]; then
				minute='*/'$minute
				else
				minute='*'
				fi
			
				echo "Hours: $hour"
				echo "Minutes: $minute"
			
				cronlocation=$(pwd)
				crondate=$(date | awk '{print $2" "$3", "$6" @ "$4}')
				crontab -l > "cronbackup $crondate"
				echo -n 'A backup copy of cron has been saved at '$cronlocation'/cronbackup '$crondate
				echo "$minute $hour * * * $mailstr" >> mycron
				crontab mycron
				rm mycron
			
				break;;
			*)	echo; echo Unrecognized choice: ${ltr7} ;;
		   esac

		   done
		;;
	[2])	# Execute mail string
		eval $mailstr
		;;
	*)	echo; echo Unrecognized choice: ${ltr5} ;;
   esac
#done