yt_podoff

#!/bin/bash
# yt_podoff - Create offline caches of YouTube podcast feeds
#
# USAGE: yt_podoff [<youtube-dl_options>... --] <YouTube_url_file> ...
#
# EXAMPLE:
# $ mkdir -p ${HOME}/podcasts/Hak5
# $ echo "https://www.youtube.com/playlist?list=PLW5y1tjAOzI0w_GbtiEbYS5PGJ2pmxAIX" > ${HOME}/podcasts/Hak5/.url
# $ yt_podoff --write-info-json -- ${HOME}/podcasts/Hak5/.url

# Save any youtube-dl options
YOUTUBE_DL_OPTS=()
if [[ "$1" == -* ]]; then

  while [[ "$1" != -- ]]; do

    YOUTUBE_DL_OPTS+=("$1")
    shift

  done

fi

for F in "$@"; do

  if [ -s "$F" ] ; then

    cd "$(dirname "$F")"

    # Read YouTube page URLs...
    FEED_URLS=(); while read U; do

      # ...and transform them into RSS feed URLs (ref: https://stackoverflow.com/a/31535120)
      if [[ "$U" =~ .*youtube\.com/channel/([^/]+).* ]]; then
        FEED_URLS+=("https://www.youtube.com/feeds/videos.xml?channel_id=${BASH_REMATCH[1]}")
      elif [[ "$U" =~ .*youtube\.com/user/([^/]+).* ]]; then
        FEED_URLS+=("https://www.youtube.com/feeds/videos.xml?user=${BASH_REMATCH[1]}")
      elif [[ "$U" =~ .*youtube\.com.*list=([^&]+).* ]]; then
        FEED_URLS+=("https://www.youtube.com/feeds/videos.xml?playlist_id=${BASH_REMATCH[1]}")
      else
        echo "ERROR: Unrecognized URL '$U', skipping." >&2
      fi

    done <"$(basename "$F")"

    # Carve out the video URLs from the RSS feeds...
    curl -s "${FEED_URLS[@]}" | grep 'link rel="alternate"' | sed 's/^.*href="\([^"]*\)".*/\1/' | while read VID_URL; do

      # ...but check if youtube-dl's already downloaded it before
      grep -q "youtube ${VID_URL##*=}" .done.lst || youtube-dl "${YOUTUBE_DL_OPTS[@]}" --download-archive .done.lst "${VID_URL}"

    done

    cd - 2>/dev/null

  fi

done