#!/bin/sh
#
# email_account, Copyright © 2010 Thomas Preud'homme
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
# email_account is a helper to create e-mail accounts in a configuration
# using Postfix mail transport agent with vhosts and Cyrus IMAP server,
# in a Debian environment.

set -u

# Display usage.
usage ()
{
	local - progname
	progname=$1
	echo "Usage :"
	echo
	echo "$progname emailaccount [emailalias]"
	echo "$progname -h"
	echo
	echo "First form adds an email account named emailaccount if it doesn't already exist"
	echo "and creates an alias named emailalias for this email account if specified."
	echo
	echo "Second form prints this help."
}

# Test an email is valid and exit if it isn't.
test_email ()
{
	local -
	user=$(echo "$1" | cut -d '@' -f 1)
	if [ -z "$user" ]
	then
		echo "Error! Missing user in email account." >&2
		exit 1
	fi
	domain=$(echo "$1" | cut -d '@' -f 2)
	if echo "$domain" | grep -E -v "^([[:alnum:]]+\.)+[[:alnum:]]+$" > /dev/null
	then
		echo "Error! Invalid domain for email account." >&2
		exit 1
	fi
}

# Ask a question to the user. Return 1 if the answer is negative,
# or 0 if it is positive.
ask_user_default_no ()
{
	local - answer
	answer="unset"
	echo -n "$1 [y/N] "
	while [ -n "$answer" -a "$answer" != "y" -a "$answer" != "Y" -a "$answer" != "n" -a "$answer" != "N" ]
	do
		read answer
		if [ -z "$answer" -o "$answer" = "n" -o "$answer" = "N" ]
		then
			return 1
		fi
		if [ "$answer" = "y" -o "$answer" = "Y" ]
		then
			break
		fi
		echo -n "$2 [y/N] "
	done
	return 0
}

# Test number of argument is correct and their value are correct also.
test_args ()
{
	local - user domain
	while getopts "h" opt
	do
		case $opt in
			"h") 
				if [ $# -gt 1 ]
				then
					echo "Error! Too many arguments." >&2
					exit 1
				fi
				usage $(basename "$0")
				exit 0 ;;
		esac
	done
	if [ $# -eq 1 -a -z "$1" ]
	then
		usage $(basename "$0")
		exit 0
	fi
	if [ $# -gt $((OPTIND+1)) ]
	then
		echo "Error! Too many arguments." >&2
		exit 1
	fi
	# Test email arguments
	eval test_email "\$$OPTIND"
	emailuser="$user"
	emaildomain="$domain"
	if [ $# -eq $((OPTIND+1)) ]
	then
		eval test_email "\$$((OPTIND+1))"
		aliasuser="$user"
		aliasdomain="$domain"
		if [ "$emaildomain" != "$aliasdomain" ]
		then
			echo "Error! Domain of the alias must be identical to the domain of the email account." >&2
			exit 1
		fi
	fi
}

# Are we root?
must_sudo ()
{
	uid="$(id -u)"
	[ ! $uid -eq 0 ]
	return $?
}

# This function tries to become root with sudo and execute this script.
# NB: This function doesn't return.
try_sudo ()
{
	local - ret
	echo "You aren't root. Trying to use sudo to become root…"
	sudo $0 "$@" # Try to execute the script with sudo
	ret=$?
	if [ ! $ret -eq 0 ]
	then
		echo "Error! You must be root or being able to become root by sudo without password to create an email account or add an email alias." >&2
	fi
	exit $ret
}

# Test cyrus password is OK.
test_cyrus_admin ()
{
	local -
	cyruser=$(grep -E "^[[:blank:]]*admins:" /etc/imapd.conf | cut -d ':' -f 2- | sed -r "s/[[:alnum:]]+@[[:alnum:].]+//g" | tr -d ' ')
	cyrpwd=$(cat /root/passwords/cyrus_main_admin_password)
	testsaslauthd -u $cyruser -p $cyrpwd > /dev/null || { echo "Error! Password for main cyrus admin has changed but has not been modified in /root/" >&2 && exit 1 ; }
}

# Ask a password to the user and create the entry in sasldb database.
ask_and_create_password ()
{
	local - newemailpassword
	emailpassword=""
	newemailpassword="different"
	while [ "$emailpassword" != "$newemailpassword" ]
	do
		emailpassword=""
		echo "What password do you want for your email account?"
		while [ -z "$emailpassword" ]
		do
			echo -n "Password: "
			read emailpassword
		done
		newemailpassword=""
		echo "Please re-enter your password to ensure you typed it correctly."
		while [ -z "$newemailpassword" ]
		do
			echo -n "Password (bis): "
			read newemailpassword
		done
		if [ "$emailpassword" != "$newemailpassword" ]
		then
			echo "Passwords don't match!"
		fi
	done
	echo "$emailpassword" | saslpasswd2 -p -u "$emaildomain" "$emailuser"
}

# Check if a password already exists in the sasldb database.
# Then ask a password to the user and create the entry in sasldb
# database if password doesn't exist are user want to change it.
create_sasldb_password ()
{
	local - first_ask next_ask
	sasldblistusers2 | grep "$emailuser@$emaildomain" > /dev/null
	if [ $? -eq 0 ]
	then
		first_ask="There is already a password for this user, do you want to change it?"
		next_ask="Do you want to change the existing password for your email account?"
		ask_user_default_no "$first_ask" "$next_ask"
		if [ $? -eq 0 ]
		then
			ask_and_create_password
		else
			emailpassword="has remained unchanged"
		fi
	else
		ask_and_create_password
	fi
}

# Add the domain of the email account to the list of virtual domain
# in cyrus and postfix if necessary.
update_virtual_domains ()
{
	local -
	grep "loginrealms:" /etc/imapd.conf | grep "$emaildomain" > /dev/null
	if [ ! $? -eq 0 ]
	then
		sed -r -i "s/^([[:blank:]]*loginrealms): ?(.*)$/\1: $emaildomain \2/" /etc/imapd.conf
	fi
	grep -E "virtual_mailbox_domains[[:blank:]]*=" /etc/postfix/main.cf | grep "$emaildomain" /dev/null
	if [ ! $? -eq 0 ]
	then
		sed -r -i "s/^([[:blank:]]*virtual_mailbox_domains[[:blank:]]*)= ?(.*)$/\1= $emaildomain \2/" /etc/postfix/main.cf
	fi
}

# Print the first parameter and then the second parameter at a distance
# of $3 tabs.
echo_with_tabs ()
{
	local - nbchars nbtabs
	nbchars=$(echo "$1" | wc -m)
	nbtabs=$(($3-nbchars/8))
	[ $nbtabs -lt 1 ] && nbtabs=1
	echo -n "$1"
	for i in $(seq $nbtabs)
	do
		echo -n "\t"
	done
	echo "$2"
}

# Add requested alias to postfix virtual_alias_maps.
update_email_aliases ()
{
	local -
	grep -E "[[:blank:]]*$aliasuser@$aliasdomain[[:blank:]]+$emailuser@$emaildomain" /etc/postfix/virtual > /dev/null
	if [ ! $? -eq 0 ]
	then
		echo_with_tabs "$aliasuser@$aliasdomain" "$emailuser@$emaildomain" 4 >> /etc/postfix/virtual
	fi
	postmap /etc/postfix/virtual
}

display_infos ()
{
	local - imap imaps imapret imapsret security
	set +u
	grep "defaultdomain:" /etc/imapd.conf | grep "$emaildomain" > /dev/null
	if [ $? -eq 0 ]
	then
		echo "Your email login is $emailuser and your password $emailpassword"
	else
		echo "Your email login is $emailuser@$emaildomain and your password $emailpassword"
	fi 
	echo -n "Supported mechanism for imap authentification are: "
	sed -r -n "{s/sasl_mech_list: *(.*)$/\1/;t success;T;: success;p}" /etc/imapd.conf
	echo -n "The imap server listen on port "
	imap=$(grep -E "^[^#]+cmd=\"imapd[^#]+listen=\"imap\"" /etc/cyrus.conf)
	imapret=$?
	if [ $imapret -eq 0 ]
	then
		security=$(echo "$imap" | sed -r -n "{s/^.*cmd=\".* -s.*$/(SSL\/TLS)/;t success;T;: success;p}")
		if [ -z "$security" ]
		then
			security="(STARTTLS)"
		fi
		echo -n "143 ($security)"
	fi
	imaps=$(grep -E "^[^#]+cmd=\"imapd[^#]+listen=\"imaps\"" /etc/cyrus.conf)
	imapsret=$?
	if [ $imapsret -eq 0 ]
	then
		security=$(echo "$imaps" | sed -r -n "{s/^.*cmd=\".* -s.*$/(SSL\/TLS)/;t success;T;: success;p}")
		if [ -z "$security" ]
		then
			security="(STARTTLS)"
		fi
		if [ $imapret -eq 0 ]
		then
			echo -n " and on port "
		fi
		echo -n "993 ($security)"
	fi
	echo "."
}

# Ask Postfix and Cyrus to reload their configuration
reload_config ()
{
	local -
	invoke-rc.d --quiet cyrus2.2 reload
	if [ ! $? -eq 0 ]
	then
		echo "Error! Cyrus failed to reload its configuration." >&2
		exit 1
	fi
	invoke-rc.d --quiet postfix reload
	if [ ! $? -eq 0 ]
	then
		echo "Error! Postfix failed to reload its configuration." >&2
		exit 1
	fi
}

# Create the mailbox
create_mail_account ()
{
	local - nblines
	nblines=$(echo "listmailbox user/$emailuser@$emaildomain" | cyradm --user $cyruser --pass $cyrpwd localhost | wc -l)
	if [ $nblines -eq 0 ]
	then
		echo "Mailbox for $emailuser@$emaildomain doesn't exist, creating it…"
		echo "createmailbox user/$emailuser@$emaildomain" | cyradm --user $cyruser --pass $cyrpwd localhost
	fi

}

main ()
{
	local - ret
	# This test should be useless if rights on this file are corrects
	# (that is 770 for root:gt owner)
	test_args "$@"
	if must_sudo
	then
		try_sudo "$@"
	fi
	test_cyrus_admin
	create_sasldb_password
	update_virtual_domains
	aliasuser="${aliasuser:-""}"
	if [ -n "$aliasuser" ]
	then
		update_email_aliases
	fi
	create_mail_account
	display_infos
	reload_config
	return 0
}

main "${@:-""}"
exit $?