remove orphan images from markdown files generated by Typora

prune_images.sh

#!/usr/bin/env bash

# does $1 contains $2?
#
# $1: array
# $2: element to test
function array_contains() {
  # local IFS=$'\n'
  local array=($1)
  local i
  for ((i = 0; i < ${#array[@]}; i++)); do
    if [[ "${array[$i]}" == "$2" ]]; then
      return 0
    fi
  done

  return 1
}

function prune() {
  set -euo pipefail

  local root=${1:-.}

  echo "start prune: $root"
  echo "------------------"
  local IFS=$'\n'
  local imageRefs=($(grep --ignore-case -E "[^\/]+\.(png|jpg|jpeg|gif)" -RI "$root" --no-filename --only-matching))
  local images=($(find "$root" -name '*.png' -or -name '*.jpg' -or -name '*.jpeg' -or -name '*.gif'))
  local image
  local imagename
  local i
  for ((i = 0; i < ${#images[@]}; i++)); do
    image="${images[$i]}"
    imagename=${image##*/}
    if ! array_contains "${imageRefs[*]}" "$imagename"; then
      echo "removing: ${image}"
      rm "${image}"
    fi
  done

  echo "------------------"
  echo "done prune: $root"
}

prune "$@"