EmailCust

#!/bin/bash
# Kevin Fan (26/24/17)
# Description: This script allows the user to search for an existing email 
# and enter a message subject and message text to send the email 

# clear the terminal
clear

# A function that serves as the first menu that the script calls. This function gives options to the user
# to email all customers or to search for a matching email
function emailMenu 
{	
	# Local variable to control while loop
	validChoice=false
	while [[ $validChoice = false ]]; do
		printf "\n\t1. Email all customers\n"
		printf "\n\t2. Search by email\n"
		printf "\n\t3. Search by name\n"
		printf "\n\t4. Search by alias\n"
		printf "\n\t5. Search by address\n"
		printf "\n\t6. Search by phone number\n"
		printf "\n\t===========================\n"
		printf "\n\t0. Exit\n"
		printf "\nEnter a number: "
		read choice 
		clear
		# Case statement for relevant options
		case $choice in
			# When users enter 1, awk search the @ symabal from only the email field and to assign all emails to emailAddresses variable.
			# Set validChoice variable to valid to exit loop and call the email function
			1)	emailAddresses=$(awk -v search="$@" '$1 ~ search {print $1}' CustomerDetails )
				validChoice=valid
				email ;;
			# When user enter 2, set validChoice variable to valid to exit loop and call the readInput function to allow user to enter details for search
			2)	printf "Enter the email to search for: "
				searchAndDisplay 1 ;;
			3)	printf "Enter the name to search for: "
				searchAndDisplay 2 ;;
			4)	printf "Enter the alias to search for: "
				searchAndDisplay 3 ;;
			5)	printf "Enter the address to search for: "
				searchAndDisplay 4 ;;
			6)	printf "Enter the number to search for: "
				searchAndDisplay 5 ;;
			0)	validChoice=valid ;;
			*)	printf "Not a valid option" ;;
		esac
	done
}

# Function that takes in a passed in variable to search for a specific column on CustomerDetails (minimize code duplication)
# (i.e if 1 is passed in, only the email column is searched, if 2 is passed in, only the name column is searched etc)
function searchAndDisplay 
{
	# Assign the validChoice variable from the emailMEenu to valid to exit emailMenu loop
	validChoice=valid
	# Incoming number/paramenter is assigned to variable called incomingNum
	incomingNum="$1"
	# A variable string that concatenates the incoming variable to form a string - used in the awk count 
	searchString=("\$$incomingNum ~ search")
	# A variable string that concatenates the searchString variable to form a string - used in the awk display
	displayString=("$searchString {print \$1}")
	# Reads in the search by the user
	read searchTerm
	# Converts the search term to all lowercase - to perform a case insensitive search
	lowerCaseInput=${searchTerm,,}
	# A variable that uses awk, the lowerCaseInput variable and the searchString variable with the wc -l to count the number of line
	searchCount=$(awk -v search="$lowerCaseInput" "$searchString" CustomerDetails | wc -l) 
	# A variable that stores the email result from the lowerCaseInput 
	searchResult=$(awk -v search="$lowerCaseInput" "$displayString" CustomerDetails) 
	# call the checkInput to validate the searchTerm
	checkInput 
}

# Function that checks the search term input and displays relevant options
function checkInput
{
	# If no input is detected, the emailMenu function is called again for user to re-enter
	if [ -z $lowerCaseInput ]; then
		printf "\nNo entry detected. Please re-enter search term"
		emailMenu
	# If matches are found, the number of matches and the matching emails are displayed. Matching emails from an awk search of the emails only are 
	# assigned to the emailAddresses variabl and the actionAfterSearch is called
	elif [[ $searchCount -ne 0 ]]; then
		clear
		printf "\n$searchCount matches were found:\n"
		emailAddresses=$searchResult
		printf "\n$searchResult"
		actionAfterSearch
	# If no matches are found, display message and the actionAfterSearch is called
	elif [[ $searchCount -eq 0 ]]; then
		clear
		printf "\nNo matches were found\n"
		actionAfterSearch
	fi
}

# Function that displays options for user after the first search
# Users can perform another search or return to main menu
# If an invalid option is entered, the script returns the the main menu
function actionAfterSearch
{
	# Local variable to control while loop
	validChoice=false;
	while [[ $validChoice = false ]]; do
		printf "\n\t1) Email to these address\n"
		printf "\n\t2) Perform another search\n"
		printf "\n\t============================\n"
		printf "\n\t0) Exit to main menu\n"
		printf "\nEnter choice: "
		read choice
		clear
			case $choice in
				# When user enter 1, set validChoice variable to valid to exit loop and call the email function to construct email
				1)	validChoice=valid
					email ;;
				# When user enter 2, set validChoice variable to valid to exit loop and call the readInput function to allow user to enter details for search
				2)	validChoice=valid
					emailMenu ;;
				# When user enter 0, set validChoice variable to valid to exit loop and return to menu script
				0)	validChoice=valid ;;
				# All other cases, print out invalid option
				*)	printf "\nNot a valid option\n" ;;
			esac
	done
}

# Function that constructs the email
function email
{
	# While loop that continually loops until the message is non-blank
	while [[ -z $message ]]; do
		printf "\n\tEnter the email message: "
		read message
	done

	# While loop that continually loops until the emailSubject is non-blank
	while [[ -z $emailSubject ]]; do
		printf "\n\tEnter the email subject: "
		read emailSubject
	done

	# Until loop that continually loops until the option entered is Y or N
	until [[ ${option^^} = 'Y' || ${option^^} = 'N' ]]; do
		printf "\nSend email (Y/N): "
		read option
	done

	# If/Else statement that sends the email or discard the email depending on the user option
	if [[ ${option^^} = 'Y' ]]; then
		echo $message | mail -s $emailSubject $emailAddresses 
		printf "\nEmail sent"
	elif [[ ${option^^} = 'N' ]]; then
		printf "\nEmail discarded"
	fi
}

# Calls the emailMenu function that begins the loop
emailMenu