#!/bin/bash
# 
# Copyright (C) 2025 LINUXexpert.org
# 
# This program is free software: you can redistribute it and/or modify it 
# under the terms of the GNU General Public License as published by the 
# Free Software Foundation, version 3 of the License.
# 
# This program is distributed in the hope that it will be useful, but 
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
# for more details.
# 
# You should have received a copy of the GNU General Public License along 
# with this program. If not, see <https://www.gnu.org/licenses/>.

set -euo pipefail

# Ensure script is run as root or sudo
if [ "$EUID" -ne 0 ]; then
    echo "❌ This script must be run as root or with sudo."
    exit 1
fi

# Prompt for email and backup directory
read -p "Enter Zimbra username (email address): " EMAIL
read -p "Enter backup directory (absolute path) [/opt/zimbra/backups]: " BACKUP_DIR

# Reject anything that is not a plain address. $EMAIL is used both as a
# command argument and as part of the backup filename, so a "/" here
# would write outside $BACKUP_DIR entirely.
if ! [[ "$EMAIL" =~ ^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$ ]]; then
    echo "❌ Not a valid email address: $EMAIL"
    exit 1
fi

# Use default if none provided
BACKUP_DIR=${BACKUP_DIR:-/opt/zimbra/backups}

# Ensure directory exists
mkdir -p "$BACKUP_DIR"
chown zimbra:zimbra "$BACKUP_DIR"

# Generate timestamped filename
TIMESTAMP=$(date +%F_%H-%M-%S)
BACKUP_FILE="${BACKUP_DIR}/${EMAIL}_${TIMESTAMP}.tgz"

# Confirm action
echo "Backing up mailbox for $EMAIL to $BACKUP_FILE"
read -p "Proceed? (y/n): " CONFIRM
if [[ ! "$CONFIRM" =~ ^[Yy]$ ]]; then
    echo "❌ Backup cancelled."
    exit 0
fi

# Run zmmailbox command as zimbra user
echo "📦 Starting backup..."
# The script body is single-quoted so nothing is interpolated into it;
# $EMAIL arrives as a positional argument instead. Interpolating it (as
# this line previously did) let any shell metacharacter in the address
# run commands as the zimbra user, which owns the whole mail store.
# The redirect is performed by this shell, which is root -- not by the
# sudo'd zimbra process. That is intentional (root can always write
# here, and a pipe into `tee` would put tee's exit status in $? and mask
# a zmmailbox failure), but it means the file lands root-owned inside a
# directory chowned to zimbra, so ownership is handed over below.
# shellcheck disable=SC2024
# Tested inline rather than via `$?` on the next line: under set -e a
# failure would exit before any check ran, making the error branch below
# dead code.
if sudo -u zimbra bash -c '/opt/zimbra/bin/zmmailbox -z -m "$1" getRestURL "//?fmt=tgz"' _ "$EMAIL" > "$BACKUP_FILE"; then
    # A zero exit is not sufficient: getRestURL can write an HTTP error
    # body and still succeed, which previously produced a cheerful "✅"
    # over a file containing an error page. Require a plausible size and
    # a readable gzip container.
    size="$(stat -c %s -- "$BACKUP_FILE" 2>/dev/null || echo 0)"
    if [ "$size" -lt 1024 ]; then
        echo "❌ Backup is only ${size} bytes -- almost certainly an error response, not a mailbox."
        echo "   Leaving it at ${BACKUP_FILE}.suspect for inspection."
        mv -- "$BACKUP_FILE" "${BACKUP_FILE}.suspect"
        exit 1
    fi
    if ! gzip -t -- "$BACKUP_FILE" 2>/dev/null; then
        echo "❌ Backup is not a valid gzip stream -- treating as failed."
        echo "   Leaving it at ${BACKUP_FILE}.suspect for inspection."
        mv -- "$BACKUP_FILE" "${BACKUP_FILE}.suspect"
        exit 1
    fi
    chown zimbra:zimbra "$BACKUP_FILE" 2>/dev/null || true
    echo "✅ Backup completed: $BACKUP_FILE ($(numfmt --to=iec "$size" 2>/dev/null || echo "$size bytes"))"
else
    echo "❌ Backup failed. Check if the user exists or zmmailbox is working."
    rm -f -- "$BACKUP_FILE"
    exit 1
fi