env/bin/fetch.sh

#!/bin/sh
# fetch
# Written in 2019-2022 by Lucas
# CC0 1.0 Universal/Public domain - No rights reserved
#
# To the extent possible under law, the author(s) have dedicated all
# copyright and related and neighboring rights to this software to the
# public domain worldwide. This software is distributed without any
# warranty. You should have received a copy of the CC0 Public Domain
# Dedication along with this software. If not, see
# <http://creativecommons.org/publicdomain/zero/1.0/>.

usage()
{
	printf "Usage: %s [-T] URL [URL ...]\n" "${0##*/}" >&2
	exit 1
}

fetch_cmd()
{
	# ftp(1) is chatty if stdin is a terminal. It prints its operations to
	# stdout if "-o output" is used. In that case, we'll need to redirect
	# stdout to the tty we're being called from, in order to be able to
	# pipe the output to another command.
	if tty=$(tty) && [ X"$tty" != X"not a tty" ]; then
		$torsocks ftp "$@" >"$tty"
	else
		$torsocks ftp "$@"
	fi
}

torsocks=torsocks
while getopts T flag; do
	case $flag in
	T)	torsocks=
		;;
	*)	usage
		;;
	esac
done
shift $((OPTIND - 1))
[ $# -gt 0 ] || usage

: ${ARCHIVE_BASEDIR:=~/tmp/archive}
mkdir -p "$ARCHIVE_BASEDIR"

rc=0
for url; do
	sha=$(sha256 -qs "$url")

	t=$sha
	h0=${t%${t#??}}
	t=${t#??}
	h1=${t%${t#??}}
	t=${t#??}
	ht=$t

	outdir=$ARCHIVE_BASEDIR/$h0/$h1/$ht

	if [ -f "$outdir/file" ]; then
		printf "%s: already fetched %s\n" "${0##*/}" "$url" >&2
		printf "%s\n" "$outdir/file"
		continue
	fi

	mkdir -p "$outdir"

	{
		fetch_cmd -o "$outdir/file" "$url" &&
		    printf "%s=%s\n" \
		    url "$url" date "$(date +%Y-%m-%d)" >"$outdir/meta" &&
		    printf "%s\n" "$outdir/file"
	} || rc=1
done
exit $rc