#!/bin/bash
set -e

source ./library
# Entry point of the script.
# If makes sure that the user supplied the right
# amount of arguments (image_name and image_tag)
# and then performs the main workflow:
#       1.      retrieve the image digest
#       2.      retrieve the size of layers for
#               that image.
main() {
  check_args "$@"

  local image=$1
  local tag=$2
  local manifests=$(get_image_tag_layers $image $tag)

  formatOutput "$image" "$tag" "$manifests"
  totalSize "$image" "$tag" "$manifests"
}

# Makes sure that we provided (from the cli) 
# enough arguments.
check_args() {
  if (($# != 2)); then
    echo "Error:
    Two arguments must be provided - $# provided.
    Usage:
      $0 <image> <tag>
Aborting."
    exit 1
  fi
}

totalSize(){
  local image=$1
  local tag=$2
  local manifests=$3

  echo "Calculate the total size of image.
    IMAGE:  $image
    TAG:    $tag
  " >&2
  for manifest in $(jq -r '.[] | @text' <<<"$manifests"); do
    local platform=$(jq -r '.platform | @text' <<< "$manifest")
    local digest=$(jq -r '.digest' <<< "$manifest")
    local layers=$(jq -r '.layers' <<< "$manifest")
    echo "    Digest:  $digest
        Platform: $platform
        TOTAL_SIZE: $(jq -r 'reduce (.[]|.size) as $item (0; . + $item)' <<< "$layers")
    " >&2
  done
  
}

# Run the entry point with the CLI arguments
# as a list of words as supplied.
main "$@"