dsave

#!/usr/bin/env bash

set -euo pipefail
trap 'echo "Interrupted. Killing all jobs..."; kill 0; exit 1' SIGINT

WORKDIR="docker-tars"
mkdir -p "$WORKDIR"

# Get image for container
get_image_for_container() {
  docker inspect --format '{{.Config.Image}}' "$1"
}

# Determine image list
if [[ "$#" -gt 0 ]]; then
  echo "Using images from specified containers: $*"
  mapfile -t IMAGES < <(
    for container in "$@"; do
      if docker ps --format '{{.Names}}' | grep -qx "$container"; then
        get_image_for_container "$container"
      else
        echo "Warning: container '$container' not found or not running" >&2
      fi
    done | sort -u
  )
else
  echo "No container names provided. Using all running containers."
  mapfile -t CONTAINERS < <(docker ps --format '{{.Names}}')
  if [[ ${#CONTAINERS[@]} -eq 0 ]]; then
    echo "No running containers found. Exiting."
    exit 0
  fi
  mapfile -t IMAGES < <(
    for container in "${CONTAINERS[@]}"; do
      get_image_for_container "$container"
    done | sort -u
  )
fi

if [[ ${#IMAGES[@]} -eq 0 ]]; then
  echo "No images to save. Exiting."
  exit 0
fi

echo "Saving ${#IMAGES[@]} unique images to $WORKDIR..."

save_image() {
  local image="$1"
  local safe_name
  safe_name=$(echo "$image" | tr '/:@' '_' | tr -c '[:alnum:]_-' '_')
  local tar_path="$WORKDIR/$safe_name.tar"
  echo "Saving $image to $tar_path"
  docker image save "$image" -o "$tar_path"
}

export -f save_image
export WORKDIR

if command -v parallel &>/dev/null; then
  printf "%s\n" "${IMAGES[@]}" | parallel --will-cite save_image {}
else
  echo "Warning: GNU parallel not found. Falling back to sequential execution." >&2
  for image in "${IMAGES[@]}"; do
    save_image "$image"
  done
fi

echo "Image tars saved in $WORKDIR"