#!/bin/bash

#
# Settings
#

# Prevents the script to continue running when one command fails
set -e
# set -x

# Enabling extended syntax (useful for excluding files in rm commands)
shopt -s extglob

#
# Functions
#

# Prints help message
function usage {
	echo "This program allows you to delete files according to a pattern, in the given directories, by excluding the directories defined by the user."
	echo "Arguments:"
	echo -e "  -h\t\t\tPrints this help message"
	echo -e "  -p <pattern>\t\tThe pattern that will be used to delete the files"
	echo -e "  -d directory1[,...]\tA comma separated list of directories in which to delete the files based on the pattern"
	echo -e "  -e directory1[,...]\tA comma separated list of the directories to exclude"
	echo -e "  -o n{smhdw}\t\tOnly the files older than n seconds, n minutes, etc will be deleted."
	echo
	echo "The arguments -p and -d are mandatory."
}

# Deletes the files in the given directory and its subdirectories
# $1: pattern
# $2: directory in which files must be deleted based on the pattern
# $3: excluded directories
function rm_in_subdirs {
	local pattern=$1
	local dir=$2

	cd $dir

	exclusion=""
	if [ ! -z "$EXCLUDED" ]; then
		local excluded=( `echo "$EXCLUDED"` )
		echo "Excluded dirs: ${excluded[@]}"
		exclusion="-path ./${excluded[0]}"
		for excluded_dir in "${excluded[@]:1}"
		do
			exclusion="$exclusion -o -path ./$excluded_dir "
		done
	fi

	if [ -z "$MTIME_ARG" ]; then
		mtime=""
	else
		mtime="-mtime +$MTIME_ARG"
	fi

	if [ -z "$exclusion" ]; then
		find . -type f -name "file*.txt" $mtime | xargs rm
	else
		find . \! \( \( $exclusion \) -prune \) -type f -name "file*.txt" $mtime | xargs rm
	fi
}

#
# Handling command line option
#
while getopts d:e:p:o:h option
do
	IFS=','
	case "$option" in
		d)
			read -ra DIRECTORIES <<< "$OPTARG"
			;;
		e)
			read -ra EXCLUDED_DIR <<< "$OPTARG"
			;;
		p)
			export PATTERN=$OPTARG
			;;
		o)
			# output date format: to comply with touch -t option
			export MTIME_ARG=$OPTARG
			;;
		h)
			usage
			exit 0
			;;
	esac
	unset IFS
done

echo "Directories : ${DIRECTORIES[@]}"
echo "Excuded ones: ${EXCLUDED_DIR[@]}"
echo "Pattern     : $PATTERN"
echo

# If one of the mandatory params is not present: print help, leave the program.
if [ -z $PATTERN ] || [ -z $DIRECTORIES ]; then
	usage
	exit 1
fi

#
# Deleting the files.
#
for directory in "${DIRECTORIES[@]}"
do
	export EXCLUDED=${EXCLUDED_DIR[@]}
	rm_in_subdirs $PATTERN $directory
done

echo "done"

unset EXCLUDED
unset PATTERN
unset MTIME_ARG