#!/bin/bash
# backup.sh - Backup and encrypt your files.
# backup.sh is a POSIX compliant, modular and lightweight
# backup utility to save and encrypt your files.
#
# To specify the source directories to backup,
# create a text file with the following syntax:
#
# <LABEL>=<PATH>
#
# for example(filename: 'sources.bk'):
#   nginx=/etc/nginx/
#   ssh=/etc/ssh/
#   logs=/var/log/
#
# After that you can launch the script with(sample usage):
#   sudo ./backup.sh --backup sources.bk john badpw1234
#
# This will create an encrypted tar archive(password: 'badpw1234')
# in '/home/john/backup-<hostname>-<YYYMMDD>.tar.gz.enc' containing
# the following three directories:
#   backup-nginx-<YYYYMMDD>
#   backup-ssh-<YYYYMMDD>
#   backup-logs-<YYYYMMDD>
#
# You can then decrypt it using:
#   ./backup.sh --extract backup-<hostname>-<YYYMMDD>.tar.gz.enc badpw1234
#
# You can read the full guide on https://github.com/ice-bit/backup.sh
# or on the manual page.
# Copyright (c) 2018,2023 Marco Cetica <email@marcocetica.com>
#

set -e

# Check if dependencies are installed
missing_dep=0
for dep in rsync tar openssl ; do
    if ! command -v $dep > /dev/null 2>&1; then
        echo "Cannot find '$dep', please install it."
        missing_dep=1
    fi
done

if [ $missing_dep -ne 0 ]; then
    exit 1
fi

make_backup() {
    BACKUP_SH_SOURCES_PATH="$1"
    BACKUP_SH_USER="$2"
    BACKUP_SH_PASS="$3"
    BACKUP_SH_COMMAND="rsync -aPhvrq --delete"
    BACKUP_SH_DATE="$(date +'%Y%m%d')"
    BACKUP_SH_FOLDER="backup.sh.tmp"
    BACKUP_SH_OUTPUT="/home/$BACKUP_SH_USER/$BACKUP_SH_FOLDER"
    BACKUP_SH_START_TIME="$(date +%s)"
    declare -A BACKUP_SH_SOURCES

    # Check for root permissions
    if [ "$(id -u)" -ne 0 ]; then
        echo "Run this tool as root!"
        exit 1
    fi

    # Check whether the sources file exists or not
    if [ ! -f "$BACKUP_SH_SOURCES_PATH" ]; then
        echo "$BACKUP_SH_SOURCES_PATH does not exist."
        exit 1
    fi

    # Read associative array from file
    readarray -t lines < "$BACKUP_SH_SOURCES_PATH"
    for line in "${lines[@]}"; do
        label=${line%%=*}
        path=${line#*=}
        BACKUP_SH_SOURCES[$label]=$path
    done

    # Create temporary directory
    mkdir -p "$BACKUP_SH_OUTPUT"

    # For each item in the array, make a backup
    BACKUP_SH_PROGRESS=1
    for item in "${!BACKUP_SH_SOURCES[@]}"; do
        # Define a subdir for each backup entry
        BACKUP_SH_SUBDIR="$BACKUP_SH_OUTPUT/backup-$item-$BACKUP_SH_DATE"
        mkdir -p "$BACKUP_SH_SUBDIR"

        echo "Copying $item($BACKUP_SH_PROGRESS/${#BACKUP_SH_SOURCES[*]})"
        $BACKUP_SH_COMMAND "${BACKUP_SH_SOURCES[$item]}" "$BACKUP_SH_SUBDIR"
        BACKUP_SH_PROGRESS=$((BACKUP_SH_PROGRESS+1))
    done

    # Compress and encrypt backup directory
    echo "Compressing and encrypting backup..."
    tar -cz -C /home/"$BACKUP_SH_USER" $BACKUP_SH_FOLDER | \
        openssl enc -aes-256-cbc -md sha512 -pbkdf2 -iter 100000 -salt -k "$BACKUP_SH_PASS" \
        > /home/"$BACKUP_SH_USER"/"backup-$(uname -n)-$BACKUP_SH_DATE.tar.gz.enc"

    # Remove temporary files
    rm -rf "$BACKUP_SH_OUTPUT"

    # Print elapsed time
    BACKUP_SH_END_TIME="$(date +%s)"
    echo "Elapsed time: $(("$BACKUP_SH_END_TIME" - "$BACKUP_SH_START_TIME")) seconds."
}

extract_backup() {
    BACKUP_SH_ARCHIVE_PATH="$1"
    BACKUP_SH_ARCHIVE_PW="$2"

    openssl enc -aes-256-cbc -md sha512 -pbkdf2 -iter 100000 -salt -d \
        -in "$BACKUP_SH_ARCHIVE_PATH" \
        -k  "$BACKUP_SH_ARCHIVE_PW" | tar xvz
}

helper() {
    CLI_NAME="$1"

    cat <<EOF
backup.sh - POSIX compliant, modular and lightweight backup utility.

Syntax: $CLI_NAME [-b|-e|-h]
options:
-b|--backup  SOURCES USER PASS  Backup folders from SOURCES file.
-e|--extract ARCHIVE PASS       Extract ARCHIVE using PASS.
-h|--help                       Show this helper.
EOF
}


if [ $# -eq 0 ]; then
    echo "Please, specify an argument."
    echo "For more information, try --help."
    exit 1
fi

# Parse CLI arguments
while [ $# -gt 0 ]; do
    case $1 in
        -b|--backup)
            BACKUP_SH_SOURCES_PATH="$2"
            BACKUP_SH_USER="$3"
            BACKUP_SH_PASSWORD="$4"

            if [ -z "$BACKUP_SH_SOURCES_PATH" ] || [ -z "$BACKUP_SH_USER" ] || [ -z "$BACKUP_SH_PASSWORD" ]; then
                echo "Please, specify a source file, a user and a password."
                echo "For more informatio, try --help"
                exit 1
            fi
            make_backup "$BACKUP_SH_SOURCES_PATH" "$BACKUP_SH_USER" "$BACKUP_SH_PASSWORD"
            exit 0
            ;;
        -e|--extract)
            BACKUP_SH_ARCHIVE_PATH="$2"
            BACKUP_SH_ARCHIVE_PW="$3"

            if [ -z "$BACKUP_SH_ARCHIVE_PATH" ] || [ -z "$BACKUP_SH_ARCHIVE_PW" ]; then
                echo "Please, specify an encrypted archive and a password."
                echo "For more informatio, try --help"
                exit 1
            fi
            extract_backup "$BACKUP_SH_ARCHIVE_PATH" "$BACKUP_SH_ARCHIVE_PW"
            exit 0
            ;;
        -h|--help)
            helper "$0"
            exit 0
            ;;
        *)
            echo "Unknown option $1."
            echo "For more information, try --help"
            exit 1
            ;;
    esac
done