# <post> : Emit the file download url for a given post
e621_post_to_link() {
  post="${1}"
  [ "${post}" ] || return 1
  wget -qO- "http://www.e621.net/post/show/${post}" | sed -e '/class="original-file-unchanged"/!d; s/^.* href="//g; s/" class=".*$//g'
}

# <post> [filename] : Download the given post, optionally specifying a name
#  if the name lacks an extension, use that of the original url
e621_download_post() {
  post="${1}"
  [ "${post}" ] || return 1
  url="$(e621_post_to_link "${post}")"
  eval $(echo "${url}" | sed -e 's/\?.*$//; s/^.*\///g; s/^\(.*\.\([^.]*\)\)$/file="\1" ext="\2"/')
  file="${2:-${file}}"
  if echo "${file}" | grep -vq "\."
  then
    file="${file}.${ext}"
  fi
  wget -O "${file}" "${url}"
}

# <pool> : Emit a list of posts in this pool
e621_pool_posts() {
  pool="${1}"
  [ "${pool}" ] || return 1
  wget -qO- "http://www.e621.net/pool/show/${pool}" | sed -e '/class="plid"/!d; s/^.*\#pl //g; s/<\/span.*$//g; s/^.*\/\([^\/]*\)$/\1/g'
}

# <pool> [start_count] : Download an entire pool, naming the files sequentially
e621_download_pool() {
  pool="${1}"
  [ "${pool}" ] || return 1
  count="${2:-0}"
  e621_pool_posts "${pool}" | while read post
  do
    name="$(printf "%02u" "${count}")"
  done
}