#!/usr/bin/env bash
page="$(uriescape "$1")"
cache_file=~/.cache/wikipedia/"${page}.pdf"
mkdir -p ~/.cache/wikipedia
## follow redirects (-L), silent (-s), and no globbing (-g), you can guess what -H does.
last_modified="$(rfc7231date "$(stat -c '%Y' "${cache_file}")")"
if [ "$last_modified" ];then
  curl -H "If-Modified-Since: ${last_modified}" -L -s -g "https://en.wikipedia.org/api/rest_v1/page/pdf/${page}" -o "${cache_file}"
else
  curl -L -s -g "https://en.wikipedia.org/api/rest_v1/page/pdf/${page}" -o "${cache_file}"
fi
fileuri=file://"${cache_file}"
uristart "${fileuri}"