#!/bin/sh

url="$1"

if [ -z "$url" ]; then
  echo "Usage: yt2rss.sh <youtube_url>" >&2
  exit 1
fi

html=$(curl -Ls "$url")

channel_id=$(printf '%s\n' "$html" | grep -oE 'https://www.youtube.com/channel/UC[[:alnum:]_-]+' | head -n1 | sed 's|.*/||')

if [ -z "$channel_id" ]; then
  echo "Could not find channel ID." >&2
  exit 1
fi

echo "https://www.youtube.com/feeds/videos.xml?channel_id=$channel_id"