#!/bin/bash

if [ $# -eq 1 ] && [[ "$1" == *".kernel.org/"* ]]
then
  curl "$1" | \
    gpg --verify - "$0" 2>&1 | \
    grep '^gpg: Signature made .* using \S\+ key ID [0-9A-F]\+$' | \
    sed 's|^gpg: Signature made .* using \S\+ key ID \([0-9A-F]\+\)$|0x\1|'
  exit 0
fi

[ $# -eq 1 ] && lvl=$1 || lvl=2

signatures="$(
  curl 'https://kernel.org/' 2>/dev/null | \
    tr '"' '\n' | \
    grep '\.sign$'
)"

alteKeyIds="$(
  echo "${signatures}" | \
    parallel -j0 "$0" "{}" \; 2> /dev/null | \
    sort -u
)"

for ((i=0; i<$lvl; i++))
do
  echo "stage ${i}:" $(echo "${alteKeyIds}" | wc -l) "keys."
  keyIds="$(
    gpg --list-sigs --fast-list-mode --fixed-list-mode --with-colons ${alteKeyIds} | \
      grep '^sig:' | \
      cut -d: -f 5 | \
      sed 's|^|0x|' | \
      sort -u
  )"
  alleKeyIds="$(
    (
      echo "${keyIds}"
      echo "${alteKeyIds}"
    ) | \
      sort -u
  )"

  (
    echo "${alleKeyIds}"
    echo "${alteKeyIds}"
  ) | \
    sort | \
    uniq -u | \
    xargs -n50 gpg --recv-keys

  alteKeyIds="${alleKeyIds}"
done