#!/bin/sh
#VERSION=0.0.2
# This script is written by Martynas Bendorius and DirectAdmin
# It is used to gzip all emails in Maildir directory
# Official DirectAdmin webpage: http://www.directadmin.com
# Usage:
# ./dovecot_compress.sh </home/user/imap/domains/domain.com/email/Maildir>
MYUID=`/usr/bin/id -u`
if [ "${MYUID}" != 0 ]; then
	echo "You require Root Access to run this script";
	exit 0;
fi

if [ $# -lt 1 ]; then
	echo "Usage:";
	echo "$0 /home/user/imap/domains/domain.com/email/Maildir";
	echo "you gave #$#: $0 $1";
	exit 0;
fi

MAILDIR_PATH="${1}"
if ! echo "${MAILDIR_PATH}" | grep -m1 -q '/Maildir$'; then
	echo "Path does not end with /Maildir: ${MAILDIR_PATH}. Exiting.."
	exit 1
fi

if [ ! -d "${MAILDIR_PATH}/cur" ]; then
	echo "${MAILDIR_PATH}/cur does not exist, exiting..."
	exit 1
fi

cd "${MAILDIR_PATH}"
if [ $? -ne 0 ]; then
	echo "Failed to cd to ${MAILDIR_PATH}. Exiting..."
	exit 1
fi

echo "Checking for directories in ${MAILDIR_PATH}..."

# https://wiki.dovecot.org/Plugins/Zlib
find . -maxdepth 1 -mindepth 1 -type d -print0 | while read -d $'\0' directory; do {
	if [ "${directory}" = "tmp" ]; then
		continue
	fi
	cd "${MAILDIR_PATH}/${directory}"
	if [ $? -ne 0 ]; then
		echo "Failed to cd to ${MAILDIR_PATH}/${directory}. Skipping..."
		continue
	fi
	if [ ! -d "${MAILDIR_PATH}/${directory}/tmp" ]; then
		mkdir -p ${MAILDIR_PATH}/${directory}/tmp
		chown --reference=${MAILDIR_PATH}/${directory} ${MAILDIR_PATH}/${directory}/tmp
	fi
	find ./tmp/ -maxdepth 1 -group mail -type f -delete
	# ignore all files with "*,S=*" (dovecot needs to know the size of the email, when it's gzipped) and "*,*:2,*,*Z*" (dovecot recommends adding Z to the end of gzipped files just to know which ones are gzipped) in their names, also skip files that are also compressed (find skips all other 'exec' after first failure)
	# dovecot: Note that if the filename doesn't contain the ',S=<size>' before compression, adding it afterwards changes the base filename and thus the message UID. The safest thing to do is simply to not compress such files.
	find . -type f -name "*,S=*" ! -name "*,*:2,*,*Z*" ! -exec gzip -t {} 2>/dev/null \; -exec sh -c 'gzip --best --stdout $1 > ./tmp/$1' x {} \; -exec sh -c 'chown --reference=$1 ./tmp/$1' x {} \; -exec sh -c 'chmod --reference=$1 ./tmp/$1' x {} \; -exec sh -c 'touch --reference=$1 ./tmp/$1' x {} \;
	#if there are any compressed files, maildirlock the directory
	if ! find ./tmp -maxdepth 0 -type d -empty | grep -m1 -q '\.'; then
		echo "Size before compression: `du -sh \"${MAILDIR_PATH}/${directory}\" | awk '{print $1}'`"
		MAILDIRLOCK=/usr/libexec/dovecot/maildirlock
		if [ ! -x ${MAILDIRLOCK} ]; then
			MAILDIRLOCK=/usr/lib/dovecot/maildirlock
		fi
		if [ ! -x ${MAILDIRLOCK} ]; then
			echo "Unable to find ${MAILDIRLOCK}, exiting..."
			find ./tmp/ -maxdepth 1 -group mail -type f -delete
			exit 2
		fi
		# If we're able to create the maildirlock, then continue with moving compressed emails back
		#MAILDIRLOCK had a bug, which is patched in CB 2.0
		if PIDOFMAILDIRLOCK=`${MAILDIRLOCK} "${MAILDIR_PATH}/${directory}" 10`; then
			# Move email only if it exists in destination folder, otherwise it's been removed at the time we converted it
			find ${MAILDIR_PATH}/${directory}/tmp -maxdepth 1 -type f -exec sh -c "if [ -s \"\${1}\" ]; then mv -f \${1} ${MAILDIR_PATH}/${directory}/; fi" x {} \;
			kill ${PIDOFMAILDIRLOCK}
			echo "Compressed ${MAILDIR_PATH}/${directory}..."
			# Remove dovecot index files to have no issues with mails
			find "${MAILDIR_PATH}" -type f -name dovecot.index\* -delete
			echo "Size after compression: `du -sh \"${MAILDIR_PATH}/${directory}\" | awk '{print $1}'`"
		else
			echo "Failed to lock: ${MAILDIR_PATH}/${directory}" >&2
			find ./tmp/ -maxdepth 1 -group mail -type f -delete
		fi
    fi
};
done
exit 0