#!/bin/bash
# =============================================================================
# plugin/sbin/podman-backup.sh
#
# Rollback support — see docs/ARCHITECTURE.md section 14 (Rollback). Two
# independent kinds of backup, matching the two kinds of thing an update can
# break:
#
#   PACKAGES  plugin/podman.plg downloads each release's .txz files
#             straight into $PODMAN_BOOT_DIR/backup/packages/<plugin-version>/
#             — all 7 component packages of one plugin release share a
#             single directory named after the PLUGIN version (not each
#             component's own version), since a rollback means "go back to
#             plugin release X" as one unit — rather than into a scratch
#             dir that gets discarded, so the previously installed
#             version's packages are automatically still on disk after an
#             update, with no separate copy step. `restore-packages
#             <plugin-version>` reinstalls every package from one of those
#             directories.
#
#   CONFIG    Before a config schema migration (see podman.cfg's
#             CONFIG_SCHEMA_VERSION), the plg's postinstall calls
#             `snapshot-config` to copy the current *.conf + podman.cfg
#             into $PODMAN_BOOT_DIR/backup/config/<timestamp>/.
#             `restore-config <timestamp>` copies them back.
#
# `prune` bounds how many old snapshots of each kind are kept, since flash
# space is limited (see ARCHITECTURE.md section 14, "Rollback-Historie
# begrenzen").
#
# Usage:
#   podman-backup.sh snapshot-config
#   podman-backup.sh restore-config <timestamp>
#   podman-backup.sh restore-packages <version>
#   podman-backup.sh list
#   podman-backup.sh prune [--keep N]
# =============================================================================

set -eu

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=./podman-common.sh
. "$SCRIPT_DIR/podman-common.sh"

DEFAULT_KEEP=3

cmd_snapshot_config() {
  local ts
  ts=$(date -u +%Y%m%dT%H%M%SZ)
  local dest="$PODMAN_BACKUP_DIR/config/$ts"
  mkdir -p "$dest"

  local f
  for f in podman.cfg containers.conf storage.conf registries.conf policy.json; do
    [ -f "$PODMAN_BOOT_DIR/$f" ] && cp "$PODMAN_BOOT_DIR/$f" "$dest/"
  done

  podman_log "backup: config snapshot saved to $dest"
  echo "$ts"
}

cmd_restore_config() {
  local ts="${1:?usage: podman-backup.sh restore-config <timestamp>}"
  local src="$PODMAN_BACKUP_DIR/config/$ts"

  if [ ! -d "$src" ]; then
    podman_log_error "backup: no config snapshot found at $src"
    exit 1
  fi

  local f
  for f in "$src"/*; do
    [ -f "$f" ] || continue
    cp "$f" "$PODMAN_BOOT_DIR/$(basename "$f")"
  done

  podman_log "backup: config restored from snapshot $ts — restart podman (rc.podman restart) to apply"
}

cmd_restore_packages() {
  local version="${1:?usage: podman-backup.sh restore-packages <version>}"
  local src="$PODMAN_BACKUP_DIR/packages/$version"

  if [ ! -d "$src" ]; then
    podman_log_error "backup: no package backup found for version $version at $src"
    exit 1
  fi

  podman_require_command upgradepkg

  local txz
  local restored=0
  for txz in "$src"/*.txz; do
    [ -f "$txz" ] || continue
    podman_log "backup: reinstalling $(basename "$txz") from backup (version $version)"
    upgradepkg --reinstall --install-new "$txz"
    restored=$((restored + 1))
  done

  if [ "$restored" -eq 0 ]; then
    podman_log_error "backup: no .txz files found in $src"
    exit 1
  fi

  podman_notify "Podman packages rolled back" \
    "Reinstalled $restored package(s) from the version $version backup. Run 'rc.podman restart' to apply." \
    "warning"
  podman_log "backup: package rollback to version $version complete ($restored package(s))"
}

cmd_list() {
  echo "Config snapshots ($PODMAN_BACKUP_DIR/config/):"
  if [ -d "$PODMAN_BACKUP_DIR/config" ]; then
    find "$PODMAN_BACKUP_DIR/config" -mindepth 1 -maxdepth 1 -type d -printf '  %f\n' 2> /dev/null | sort -r
  fi
  echo
  echo "Package backups ($PODMAN_BACKUP_DIR/packages/):"
  if [ -d "$PODMAN_BACKUP_DIR/packages" ]; then
    find "$PODMAN_BACKUP_DIR/packages" -mindepth 1 -maxdepth 1 -type d -printf '  %f\n' 2> /dev/null | sort -r
  fi
}

cmd_prune() {
  local keep="$DEFAULT_KEEP"
  if [ "${1:-}" = "--keep" ] && [ -n "${2:-}" ]; then
    keep="$2"
  fi

  local kind
  for kind in config packages; do
    local dir="$PODMAN_BACKUP_DIR/$kind"
    [ -d "$dir" ] || continue

    # Sort newest-first by directory name (timestamps and semver both sort
    # correctly lexicographically here — timestamps are zero-padded ISO8601,
    # versions are compared via `sort -V`), then remove everything beyond
    # $keep.
    local sorted
    if [ "$kind" = "config" ]; then
      sorted=$(find "$dir" -mindepth 1 -maxdepth 1 -type d -printf '%f\n' | sort -r)
    else
      sorted=$(find "$dir" -mindepth 1 -maxdepth 1 -type d -printf '%f\n' | sort -rV)
    fi

    local i=0
    local name
    while IFS= read -r name; do
      [ -z "$name" ] && continue
      i=$((i + 1))
      if [ "$i" -gt "$keep" ]; then
        podman_log "backup: pruning old $kind backup: $name"
        rm -rf "${dir:?}/$name"
      fi
    done <<< "$sorted"
  done
}

case "${1:-}" in
  snapshot-config)   cmd_snapshot_config ;;
  restore-config)    shift; cmd_restore_config "$@" ;;
  restore-packages)  shift; cmd_restore_packages "$@" ;;
  list)              cmd_list ;;
  prune)             shift; cmd_prune "$@" ;;
  *)
    echo "usage: $0 {snapshot-config|restore-config <ts>|restore-packages <version>|list|prune [--keep N]}" >&2
    exit 1
    ;;
esac