#!/bin/bash
# List (default) or, with --remove-from-disk, delete the docker volumes that are NOT
# referenced by the current COMPOSE_FILE. Removal also frees the static-file data that was
# offloaded to /slowdisk behind the volume's symlinks (delete_slowdisk_targets_for_key),
# so nothing leaks on /slowdisk.
BASEPATH="$(dirname "$0")"
source $BASEPATH/.env
source $BASEPATH/volume-utils.sh

IFS=':' read -ra parts <<< $COMPOSE_FILE

used_volumes=()

for part in "${parts[@]}"; do
  volumes=$(get_volume_keys "$BASEPATH/$part")

  # Prefix each compose volume key with rpc_ to match docker's volume names.
  prefix="rpc_"
  IFS=$'\n' read -r -d '' -a volumes_array <<< "$(printf "%s\n" "${volumes[@]}" | sed "/^$/! s/^/$prefix/")"

  used_volumes=("${used_volumes[@]}" "${volumes_array[@]}")
done

on_disk=($(docker volume ls --format '{{.Name}}' | grep '^rpc_'))

# A volume counts as "used" only on an EXACT name match. The previous substring test
# ([[ "${used_volumes[@]}" =~ "$element" ]]) could mis-classify a volume whose name is a
# substring of another (e.g. ...-pruned vs ...-pruned-trace) and wrongly purge a live one.
is_used() {
  local v=$1 u
  for u in "${used_volumes[@]}"; do
    [[ "$u" == "$v" ]] && return 0
  done
  return 1
}

unused_volumes=()
for element in "${on_disk[@]}"; do
  is_used "$element" || unused_volumes+=("$element")
done

if [ "$1" = "--remove-from-disk" ]; then
  # Remove each unused volume AND the /slowdisk static data behind its symlinks.
  for volume in "${unused_volumes[@]}"; do
    echo "removing unused volume: $volume"
    delete_slowdisk_targets_for_key "${volume#rpc_}"
    docker volume rm "$volume"
  done
else
  printf '%s\n' "${unused_volumes[@]}"
fi