sfeedpath="$HOME/.sfeed/feeds"

: ${SFEEDEFIERS_PATH:=${HOME}/.sfeedefiers}


# order by timestamp (ascending).
# order(name)
order() {
	sort -t '	' -k1n,1
}

# fetch a feed via HTTP/HTTPS etc.
# fetch(name, url, feedfile)
fetch() {
	fetcher=""
	fetcher_options=""

	case "$2" in
	*://*.bandcamp.com/music )
		fetcher=${SFEEDEFIERS_PATH}/bandcamp
		fetcher_options="-n 10"
		;;
	*://mupdf.com/release_history.html )
		fetcher=${SFEEDEFIERS_PATH}/mupdf
		;;
	*://www.mixcloud.com/* | *://soundcloud.com/* )
		fetcher=${SFEEDEFIERS_PATH}/youtube-dl
		fetcher_options="-n 10"
		;;
	* )
		log "${name}" "unsupported URL"
		return 1
		;;
	esac

	${fetcher} ${fetcher_options} "$2" 2>/dev/null
}

# fetch and parse feed.
# feed(name, feedurl)
feed() {
	# wait until ${maxjobs} are finished: will stall the queue if an item
	# is slow, but it is portable.
	[ ${signo} -ne 0 ] && return
	[ $((curjobs % maxjobs)) -eq 0 ] && wait
	[ ${signo} -ne 0 ] && return
	curjobs=$((curjobs + 1))

	(name="$1"
	filename="$(printf '%s' "$1" | tr '/' '_')"
	feedurl="$2"

	sfeedfile="${sfeedpath}/${filename}"
	tmpfeedfile="${sfeedtmpdir}/${filename}"

	if ! fetch "${name}" "${feedurl}" "${sfeedfile}" > "${tmpfeedfile}.tsv"; then
		log "${name}" "FAIL (FETCH)"
		return
	fi

	if ! filter "${name}" < "${tmpfeedfile}.tsv" > "${tmpfeedfile}.filter"; then
		log "${name}" "FAIL (FILTER)"
		return
	fi
	rm -f "${tmpfeedfile}.tsv"

	# new feed data is empty: no need for below stages.
	if [ ! -s "${tmpfeedfile}.filter" ]; then
		log "${name}" "OK"
		return
	fi

	# if file does not exist yet "merge" with /dev/null.
	if [ -e "${sfeedfile}" ]; then
		oldfile="${sfeedfile}"
	else
		oldfile="/dev/null"
	fi

	if ! merge "${name}" "${oldfile}" "${tmpfeedfile}.filter" > "${tmpfeedfile}.merge"; then
		log "${name}" "FAIL (MERGE)"
		return
	fi
	rm -f "${tmpfeedfile}.filter"

	if ! order "${name}" < "${tmpfeedfile}.merge" > "${tmpfeedfile}.order"; then
		log "${name}" "FAIL (ORDER)"
		return
	fi
	rm -f "${tmpfeedfile}.merge"

	# copy
	if ! cp "${tmpfeedfile}.order" "${sfeedfile}"; then
		log "${name}" "FAIL (COPY)"
		return
	fi
	rm -f "${tmpfeedfile}.order"

	# OK
	log "${name}" "OK"
	) &
}


# list of feeds to fetch:
feeds() {
	# feed <name> <feedurl>

	feed 'bandcamp-idlesband' 'https://idlesband.bandcamp.com/music'
	feed 'mupdf' 'https://mupdf.com/release_history.html'
	feed 'soundcloud-filastine' 'https://soundcloud.com/filastine'

}