#!/bin/sh -e

# Update /etc/hosts with a well curated blacklist of malware, ads, porn, etc.
# Custom hosts are preserved.

[ "$USER" = root ] || exec sudo "$0" "$@"

cdate=date
case $(uname -s) in
(Darwin) cdate=gdate ;;		# install gdate with 'brew install coreutils'
esac

echo 'Checking from https://github.com/StevenBlack/hosts:'
lsd=$(curl -s 'https://api.github.com/repos/StevenBlack/hosts/commits?path=hosts&page=1&per_page=1' | jq -r '.[0].commit.committer.date')
echo "last source update: $(date -j -f "%FT%TZ" "$lsd")" 
#echo "last source update: $(date --date="$lsd")"  # with BSD date
echo "last local  update: $(date -r /etc/hosts)"
[ $(date -j -f "%FT%TZ" "$lsd" +%s) -lt $(date -r /etc/hosts +%s) ] && echo 'Nothing to do' && exit
# [ $(date --date="$lsd" +%s) -lt $(date -r /etc/hosts +%s) ] && echo 'Nothing to do' && exit # with BSD date # with BSD date

cd /etc
cp -p hosts hosts.old
hosts=$(awk '/^# Custom host/, /^# End of custom host/' hosts.old)
curl -s 'https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts' | awk '
  BEGIN                   { hosts = ARGV[1]; ARGV[1] = "" }
  /^# Custom host/        { print hosts; next }
  /^# End of custom host/ { next }
  { print }
' "$hosts" > hosts.new

mv hosts.new hosts
[ "$(uname -s)" != Darwin ] || { dscacheutil -flushcache; killall -HUP mDNSResponder; }
diff -u /etc/hosts.old /etc/hosts | diffstat