backup_tool_borg.sh

#!/usr/bin/env bash
set -euo pipefail
# set -x

# --- Configuration & Defaults ---
HOSTNAME="$(hostname)"
readonly HOSTNAME
readonly CONFIG_DIR="${HOME}/.config/borg"
readonly LOCK_FILE="/tmp/borg_backup_${HOSTNAME}.lock"

# Load local overrides
if [[ -f "${CONFIG_DIR}/config.conf" ]]; then
    # shellcheck source=/dev/null
    source "${CONFIG_DIR}/config.conf"
fi

export BORG_REPO="${BORG_REPO:-/backups/${HOSTNAME}-backup}"
readonly RETENTION_AGE="${RETENTION_AGE:-1m}"

# Disable encryption & suppress interactive prompts
export BORG_PASSPHRASE=""
export BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK="yes"

# --- Global dry-run flag ---
DRY_RUN_OPTS=()

# --- Functions ---
setup_environment() {
    if ! command -v borg >/dev/null 2>&1; then
        echo "Error: borg is not installed or not in PATH" >&2
        exit 1
    fi

    mkdir -p "${CONFIG_DIR}"
    touch "${CONFIG_DIR}/exclude.conf" "${CONFIG_DIR}/include.conf"

    # Create target dir only for local paths
    if [[ "${BORG_REPO}" == /* ]]; then
        mkdir -p "${BORG_REPO}"
    fi

    # Initialize repository if it doesn't exist yet
    if ! borg info >/dev/null 2>&1; then
        echo "Initializing new borg repository at ${BORG_REPO}"
        borg init --encryption=none
    fi
}

usage() {
    cat <<EOF
Universal Borg Backup Script

Usage: $(basename "$0") [OPTIONS] COMMAND

Commands:
    backup          Perform backup and prune old backups
    status          Show backup repository status
    list            List files in latest backup
    verify          Verify repository integrity
    prune           Remove backups older than ${RETENTION_AGE}
    cleanup         Release stale repository lock
    help            Show this help message

Options:
    --dry-run       Simulate operation without making changes

Configuration:
    Override defaults by creating: ${CONFIG_DIR}/config.conf
    Example config.conf:
        BORG_REPO="ssh://backup_user@192.168.1.100/remote-backup"
        RETENTION_AGE="3m"
    Include paths: ${CONFIG_DIR}/include.conf (one path per line)
    Exclude patterns: ${CONFIG_DIR}/exclude.conf (one glob pattern per line)
EOF
}

notify() {
    local message="$1"
    local title="${2:-Backup}"

    command -v notify-send >/dev/null 2>&1 || return 0
    notify-send \
        --icon=drive-harddisk \
        --app-name="System Backup" \
        --urgency=low \
        "${title}" "${message}" || true
}

remove_old_backups() {
    echo "Pruning old backups"
    borg prune \
        --list \
        --keep-within "${RETENTION_AGE}" \
        --force \
        --save-space \
        "${DRY_RUN_OPTS[@]}"

    if [[ ${#DRY_RUN_OPTS[@]} -eq 0 ]]; then
        borg compact
    fi
}

backup() {
    # Ensure lock cleanup on script exit
    trap 'rm -f "${LOCK_FILE}"' EXIT

    exec 9>"${LOCK_FILE}"
    if ! flock -n 9; then
        echo "Error: Another backup is currently running." >&2
        exit 1
    fi

    # Read source paths from include.conf
    local -a source_paths=()
    while IFS= read -r line || [[ -n "${line}" ]]; do
        [[ -z "${line}" || "${line}" == \#* ]] && continue
        source_paths+=("${line}")
    done <"${CONFIG_DIR}/include.conf"

    if [[ ${#source_paths[@]} -eq 0 ]]; then
        echo "Error: ${CONFIG_DIR}/include.conf is empty. Add paths to back up." >&2
        exit 1
    fi

    echo "Starting backup to ${BORG_REPO}..."
    local output
    output=$(
        borg create \
            --stats \
            --compression auto,zstd \
            --exclude-caches \
            --json \
            --exclude-from "${CONFIG_DIR}/exclude.conf" \
            "${DRY_RUN_OPTS[@]}" \
            "::${HOSTNAME}-$(date '+%Y-%m-%dT%H:%M:%S')" \
            "${source_paths[@]}" 2>&1
    ) || {
        echo "Backup failed! See details below:" >&2
        echo "${output}" >&2
        notify "Backup failed. Check logs for details." "Backup Failed"
        exit 1
    }

    echo "Backup completed. Processing statistics..."
    echo "${output}"
    remove_old_backups

    duration=$(echo "${output}" | jq -r '.archive.duration // 0' 2>/dev/null)
    nfiles=$(echo "${output}" | jq -r '.archive.stats.nfiles // 0' 2>/dev/null)
    orig_size=$(echo "${output}" | jq -r '.archive.stats.original_size // 0' 2>/dev/null)
    dedup_size=$(echo "${output}" | jq -r '.archive.stats.deduplicated_size // 0' 2>/dev/null)

    # Format sizes (e.g., 107437043447 -> 101GiB)
    orig_human=$(numfmt --to=iec-i --suffix=B "${orig_size}" 2>/dev/null || echo "${orig_size}B")
    dedup_human=$(numfmt --to=iec-i --suffix=B "${dedup_size}" 2>/dev/null || echo "${dedup_size}B")

    dur_human=$(date -d@"${duration%.*}" -u +%H:%M:%S)

    summary="Time: ${dur_human}\nFiles: ${nfiles}\nProcessed: ${orig_human}\nAdded to Repo: ${dedup_human}"
    notify "${summary}" "Backup Successful"

}

# --- Main ---
if [[ ${1:-} == --dry-run ]]; then
    DRY_RUN_OPTS=(--dry-run)
    echo "DRY RUN MODE: No changes will be made"
    shift
fi

cmd="${1:-}"
case "${cmd}" in
backup)
    setup_environment
    backup
    ;;
cleanup)
    setup_environment
    borg break-lock
    echo "Repository lock released."
    ;;
prune)
    setup_environment
    remove_old_backups
    ;;
status)
    setup_environment
    borg info
    ;;
list)
    setup_environment
    latest=$(borg list --last 1 --format '{name}{NL}' 2>/dev/null | head -1 || true)
    if [[ -n "${latest}" ]]; then
        borg list "::${latest}"
    else
        echo "No archives found in repository." >&2
        exit 1
    fi
    ;;
verify)
    setup_environment
    borg check --verify-data
    ;;
help)
    usage
    ;;
*)
    echo "Error: unknown command '${cmd}'" >&2
    usage
    exit 1
    ;;
esac