#!/bin/sh
test ! -r "$1" && echo "Usage: sign <document.pdf> [hoffset [voffset [scale [alt-signature]]]]" && exit 1

signature=$(pass information/signature$(test -n "$5" && echo "-$5"))

# TODO make filenames unique and don't rerun unneccessarily
tmp_base=/tmp/sign
mkdir -p $tmp_base
tmp_signed=$tmp_base/$1_last-signature.pdf
tmp_reversed=$tmp_base/$1_reverse.pdf
sig=$tmp_base/signature_offset.pdf
result="${1%.pdf}_${5:-signed}.pdf"

pdfjam "$signature" --outfile "$sig" --papersize "{595pt, 842pt}" --noautoscale true \
    --offset "${2:-0}pt ${3:-0}pt" --scale "${4:-1}"
pdfjam "$1" last "$sig" --outfile "$tmp_signed" --delta "0 -842pt" --nup "1x2" --fitpaper true

timg "$tmp_signed"

# https://apple.stackexchange.com/questions/198854/shell-command-to-count-pages-in-a-pdf-other-than-pdftk
if test "$(pdftk "$1" dump_data | grep Pages | cut -d' ' -f2)" -gt 1
  then
    pdfjam "$1" last-1 --outfile "$tmp_reversed"
    pdfjam "$tmp_reversed" last-2 "$tmp_signed" --outfile "$result"
  else cp "$tmp_signed" "$result"
fi