#! /bin/bash

LIST=${LIST:?}
curlOpts='-H "User-Agent: topo.tw" --insecure'

ln -sf ${LIST} $(basename $LIST)
ln -sf $0 $(basename $0)

grep '^[^#]' "${LIST}" | while read url interval tags; do
  feed=${url//\//%2F}
  unset next_fetch; declare -i next_fetch=0

  # Get time of next fetch
  if [ -f $feed ]; then
    interval=$(<<<"$interval" sed 's/m/minute/; s/h/hour/; s/d/day/;')
    next_fetch=$(date -d "$(date -r $feed) + $interval" +'%s')
  fi

  # Do not fetch feed if interval covers current time
  [ $(date +'%s') -lt $next_fetch ] && continue

  # Set limit of HTTP connections
  while [ $(jobs -p | wc -l) -ge 10 ]; do
    sleep 0.5;
  done

  curl -s $curlOpts $url -o $feed || echo Fail to fetch $url >&2 &
done