git cat-file commit HEAD esque

git-cat-file.sh

timezone_offset=$(git log -1 --pretty="%ad" | grep -o "\S\+$")
parents=($(git log -n1 --pretty="%P" HEAD))
gpg_signature=$(git verify-commit HEAD 2>&1 | wc -c)
message=$(cat <<-END
tree $(git write-tree)
$(for parent in $parents; do; echo "parent $parent"; done)
author $(git log -1 --pretty="%an <%ae> %at") $timezone_offset
committer $(git log -1 --pretty="%cn <%ce> %ct") $timezone_offset

$(git log -1 --pretty="%B")
END
)

if (( $gpg_signature )); then
  echo "\nerror: invalid - needs gpg signature" >&2
else
  echo -n "$message"
fi