#!/usr/bin/env bash

LOGFILE="/var/log/btrfs-backup.log"
SNAP_DATE=$(date '+%Y-%m-%d_%H%M%S')

send_matrix_webhook() {
    /usr/local/bin/send-matrix-webhook "btrfs-backup failed on $(hostname)"
}

trap send_matrix_webhook SIGINT SIGTERM EXIT

# Check if device is mounted
if ! grep "/srv/backup" /etc/mtab >/dev/null; then
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] Backup device is not mounted." | tee -a "$LOGFILE"
    notify-send -i computer-fail "Backup device is not mounted"
    exit 1
fi

create_snapshot() {
    if ! btrfs subvolume snapshot -r "$1" "${1}/.snapshots/$2-$SNAP_DATE" >/dev/null; then
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] Error creating snapshot of $1" | tee -a "$LOGFILE"
        notify-send -i computer-fail "Error creating snapshot of $1"
        exit 1
    else
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] Create snapshot of $1: OK" | tee -a "$LOGFILE"
    fi
}

send_snapshot() {
    mkdir -p "/srv/backup/$SNAP_DATE"
    if ! btrfs send -q "${1}/.snapshots/$2-$SNAP_DATE" | btrfs receive -q "/srv/backup/$SNAP_DATE"; then
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] Error sending snapshot of $1 to /srv/backup" | tee -a "$LOGFILE"
        notify-send -i computer-fail "Error sending snapshot of $1 to /srv/backup"
        exit 1
    else
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] Send snapshot of $1 to /srv/backup: OK" | tee -a "$LOGFILE"
    fi
}

# Create root and home snapshots
create_snapshot "/" "root"
create_snapshot "/home" "home"

# Send root and home snapshots
send_snapshot "/" "root"
send_snapshot "/home" "home"