#!/bin/bash
# Author: Edgar Roncero
# Email: eroncero@digitalstack.es
# Date: 04-july-2023
# Purpose: This script is to either backup or restore Moodle database, www-site and moodledata.
# License: GPLv3 <https://www.gnu.org/licenses/>
###############################################################################################

### Backup target directory ###################################################################
global_backup_absolutepath="/home/edgar/backups"
global_backup_dirname="backups" # This var isn't really used yet.

### Database credentials ######################################################################
mariadb_host="localhost"
mariadb_user="moodle"
mariadb_db="moodle"
mariadb_pw="secret"

### www/site source path ######################################################################
www_absolutepath="/var/www/moodle"
www_dirname="moodle"

### moodledata source path ####################################################################
moodledata_absolutepath="/var/moodledata"
moodledata_dirname="moodledata"
###############################################################################################

### .sql file to restore. It can either be .sql or .sql.gz, script is wise enough. ############
sqlfile_to_restore_absolutepath="/home/edgar/backups/legacy_db_20230706_152414.sql.gz" # ex: 2023129318.sql or 2023129318.sql.gz
sqlfile_to_restore_filename="" # This var isn't really used yet.
###############################################################################################

#####################################
# Functions to check if dir exists. #
#####################################
#
fn_check_backup_dirname() {
	if [ -d "$global_backup_absolutepath" ]; then
		echo "${0} info: OK! The directory ${global_backup_absolutepath} exists."
	else
		echo "${0} info: ERROR! The directory ${global_backup_absolutepath} does not exist, please check global_backup_absolutepath=\"\". Exiting..." >&2 ;sleep 1 ;exit 1
	fi
}

fn_check_www_dirname() {
	if [ -d "${www_absolutepath}" ]; then
		echo "${0} info: OK! The directory ${www_absolutepath} exists."
	else
		echo "${0} info: ERROR! The directory ${www_absolutepath} does not exist, please check www_absolutepath=\"\". Exiting..." >&2 ;sleep 1 ;exit 1
	fi
}

fn_check_moodledata_dirname() {
	if [ -d "${moodledata_absolutepath}" ]; then
		echo "${0} info: OK! The directory ${moodledata_absolutepath} exists."
	else
		echo "${0} info: ERROR! The directory ${moodledata_absolutepath} does not exists, please check moodledata_absolutepath=\"\". Exiting..." >&2 ;sleep 1 ;exit 1
	fi
}

fn_check_mariadb_restore() {
	echo "Function to be implemented. For now it is somehow implemented in the perform function instead."
}

######################################################################
# Function to check the current user's identity and group membership #
######################################################################
#
fn_check_user_and_group() {
    # Get the current user name
    current_user=$(whoami)

    # Check if the user is "apache," "www-data," or "root"
    if [ "$current_user" = "apache" ] || [ "$current_user" = "www-data" ] || [ "$current_user" = "root" ]; then
        echo "${0} info: OK! The current user is $current_user. It appears valid to perform backups."
    else
        echo "${0} info: ERROR! The current user is neither apache, www-data, nor root. It is $current_user. It wont't be able to backup www or moodledata properly due to insufficient permissions." >&2 ;sleep 1 ;exit 1
    fi

    # Check if the user belongs to the "www-data" or "apache" group
    if groups "$current_user" | grep -q -w "www-data\|apache\|root"; then
        echo "${0} info: OK! The current user $current_user belongs to the 'www-data' or 'apache' group."; sleep 1
    else
        echo "${0} info: ERROR! The current user $current_user does not belong to the 'www-data' or 'apache', or 'root' group. It wont't be able to backup www or moodledata properly due to insufficient permissions." >&2 ;sleep 1 ;exit 1
    fi
}

##############################################
# Performs the following functions in a row. #
##############################################
#
fn_initial_check() {
	fn_check_backup_dirname
	fn_check_user_and_group
	fn_check_www_dirname
	fn_check_moodledata_dirname
}

#####################
# Restore functions #
#####################
#
fn_restore_mariadb() {
    if [[ ${sqlfile_to_restore_absolutepath} == *.gz ]]; then
        gunzip < ${sqlfile_to_restore_absolutepath} | mysql --user=${mariadb_user} --password=${mariadb_pw} ${mariadb_db}
    else
        mysql --user=${mariadb_user} --password=${mariadb_pw} ${mariadb_db} < ${sqlfile_to_restore_absolutepath}
    fi
    local mysql_exitcode=${?}

    echo "${0} info: gunzip or mysql action of fn_restore_mariadb() returned exit code ${mysql_exitcode}"

    if [ ${mysql_exitcode} -ne 0 ]; then
        echo "${0} info: ERROR!" ; exit ${mysql_exitcode}
    fi
}


fn_restore_wwwsite() {
	echo "Sorry, this function is not here yet. Why? Because it can ve very evil if you misunderstood the variable value, say you typed www_absolutepath=\"/var\". You breake the Operating System." && sleep 1
	echo "Please restore it manually instead."
}

fn_restore_moodledata() {

	echo "Sorry, this function is not here yet. Why? Because it can ve very evil if you misunderstood the variable value, say you typed moodledata_absolutepath=\"/var\". You breake the Operating System." && sleep 1
	echo "Please restore it manually instead."
}


datetime_now=$(date +"%Y%m%d_%H%M%S") # es te que instanciar just al moment del backup aixi la data es correcta.

##################
# MariaDB backup #
##################
#
fn_backup_mariadb() {
	local file_backup_name=${mariadb_db}_${datetime_now}.sql
	local generated_backup=${global_backup_absolutepath}/${file_backup_name} # generated_backup is the abosutepath + fullname of the file ending with .sql extension

	echo "running mysqldump" && mysqldump --default-character-set=utf8mb4 -h ${mariadb_host} -u ${mariadb_user} --password=${mariadb_pw} -C -Q -e --create-options ${mariadb_db} > ${generated_backup} && gzip ${generated_backup}
	generated_backup="${generated_backup}.gz" # after generating the .sql file, it compresses it to .gz, so var needs to be renamed properly.
	local mysqldump_exitcode=${?} #2do, it doensn't hande error for gzip and mysql separately.
	echo "${0} info: mysqldump action of fn_backup_mariadb() returned exit code ${mysqldump_exitcode}"

	if [ ${mysqldump_exitcode} -ne 0 ]; then
		echo "Removing incomplete backup file" ;rm ${generated_backup} ; echo "${0} info: ERROR!" ;exit ${mysqldump_exitcode}
	fi
}

###################
# www/site backup #
###################
#
fn_backup_wwwsite() {
	local file_backup_name="www_${datetime_now}.tar.gz"
	cd ${www_absolutepath}/.. # it goes to the parent directory where moodledata directory is located
	echo "running tar" && tar -czf ${global_backup_absolutepath}/${file_backup_name} ${www_dirname} # it compresses moodledata with a custom filename, ex: moodledata_2023000000.tar.gz
	local tar_exitcode=${?}
	echo "${0} info: tar action of fn_backup_wwwsite() returned exit code ${tar_exitcode}"

	if [ ${tar_exitcode} -ne 0 ]; then
		echo "Removing incomplete backup file" ;rm ${global_backup_absolutepath}/${file_backup_name} ; echo "${0} info: ERROR!" ;exit ${tar_exitcode}
	fi
}

#####################
# moodledata backup #
#####################
#
fn_backup_moodledata() {
	local file_backup_name="moodledata_${datetime_now}.tar.gz"
	cd ${moodledata_absolutepath}/.. # it goes to the parent directory where moodledata directory is located
	echo "running tar" && tar -czf ${global_backup_absolutepath}/${file_backup_name} ${moodledata_dirname} # it compresses moodledata with a custom filename, ex: moodledata_2023000000.tar.gz
	local tar_exitcode=${?}
	echo "${0} info: tar action of fn_backup_moodledata() returned exit code ${tar_exitcode}"

	if [ ${tar_exitcode} -ne 0 ]; then
		echo "Removing incomplete backup file" ;rm ${global_backup_absolutepath}/${file_backup_name} ; echo "${0} info: ERROR!" ;exit ${tar_exitcode}
	fi
}
#####################
# backup everything #
#####################
#
fn_backup_everything() {
	fn_backup_mariadb
	fn_backup_wwwsite
	fn_backup_moodledata
	echo "" && echo "Listing ALL backup files:" && find ${global_backup_absolutepath} -type f
	du -hs ${global_backup_absolutepath}
}

##########################################
# Function to display usage instructions #
##########################################
#
display_help() {
    echo "Usage: $0 [OPTION]"
    echo "Options:"
    echo "  --initial-check       It will check if everything is properly set in order to do backups"
    echo "  --backup-everything   Perform FULL backup"
    echo "  --backup-mariadb      Perform mariadb backup"
    echo "  --backup-wwwsite      Perform www site backup"
    echo "  --backup-moodledata   Perform moodledata backup"
    echo "  --restore-mariadb     Perform mariadb restore"
    echo "  --restore-wwwsite     Perform www-site restore"
    echo "  --restore-moodledata  Perform moodledata restore"
    echo "  --help                Display this help message"
}

#################################################################
# Check if no arguments are provided and display help if needed #
#################################################################
#
if [ $# -eq 0 ]; then
    display_help
    exit 0
fi

###################################################################
# Check the argument provided and call the corresponding function #
###################################################################
#
case "$1" in
    --initial-check)
        fn_initial_check
        ;;
    --backup-everything)
        fn_backup_everything
        ;;
    --backup-mariadb)
        fn_backup_mariadb
        ;;
    --backup-wwwsite)
        fn_backup_wwwsite
        ;;
    --backup-moodledata)
        fn_backup_moodledata
        ;;
    --restore-mariadb)
	fn_restore_mariadb
	;;
    --restore-wwwsite)
	fn_restore_wwwsite
	;;
    --restore-moodledata)
	fn_restore_moodledata
	;;
    --help)
        display_help
        ;;
    *)
        echo "Invalid option. Use '$0 --help' to see available options."
        exit 1
        ;;
esac