#!/bin/bash
#
# Purpose : Configure Snapper so update can snapshot / before each upgrade
#           (updates.d/09-snapshot.sh). Only applies when / is btrfs, which is
#           archinstall's default. /home is a separate subvolume and is not
#           included in the snapshots.

if [ "$(findmnt -no FSTYPE /)" != "btrfs" ]; then
  echo "/ is not btrfs; skipping Snapper setup."
  exit 0
fi

set -e

source "$HOME/.local/share/coredesktop/utils.sh"

install_packages snapper

if [ ! -f /etc/snapper/configs/root ]; then
  echo "Creating Snapper config for /..."

  # create-config makes its own /.snapshots subvolume and fails if the path
  # already exists. archinstall mounts a separate @.snapshots subvolume there,
  # so follow the Arch wiki: unmount it, let snapper create its config, then
  # swap snapper's nested subvolume back out for the @.snapshots mount.
  if mountpoint -q /.snapshots; then
    sudo umount /.snapshots
    sudo rmdir /.snapshots
    sudo snapper -c root create-config /
    sudo btrfs subvolume delete /.snapshots
    sudo mkdir /.snapshots
    sudo mount /.snapshots
  else
    if [ -e /.snapshots ] && ! sudo rmdir /.snapshots 2>/dev/null; then
      echo "/.snapshots exists and isn't an empty directory. Move it aside and run this again."
      exit 1
    fi
    sudo snapper -c root create-config /
  fi

  # Keep only the last 5 pre-update snapshots, and no hourly timeline. Only set
  # on a config we created, so a config you made yourself keeps its settings.
  sudo snapper -c root set-config \
    TIMELINE_CREATE=no \
    NUMBER_CLEANUP=yes \
    NUMBER_MIN_AGE=0 \
    NUMBER_LIMIT=5 \
    NUMBER_LIMIT_IMPORTANT=5
  sudo systemctl disable --now snapper-timeline.timer 2> /dev/null || true
else
  echo "Snapper config for / already exists."
fi

sudo systemctl enable --now snapper-cleanup.timer