#!/usr/bin/env zsh
# Original ps2pdf is just a trivial caller to gs too.
# That ones is lossless, tries to be closer to PDF/A-1.
# It also copies Producer metainformation tag to Creator,
# removes all empty metainformation fields, removed fields
# with uuid:s, removes Format (that is application/pdf).

setopt ERR_EXIT
opts=(
    -dQUIET
    -dBATCH
    -dNOPAUSE
    -dSAFER
    -sDEVICE=pdfwrite
    -dPDFSETTINGS=/default
    -dPDFA=1
    -dCompatibilityLevel=1.4
    -dPDFACompatibilityPolicy=3 # that will skip some errors about XMP
    -dAutoRotatePages=/None
    -dOptimize=true
    -sColorConversionStrategy=RGB # advised for PDF/A
    -sProcessColorModel=DeviceRGB # advised for PDF/A
    -dAutoFilterColorImages=false
    -dAutoFilterGrayImages=false
    -dAutoFilterMonoImages=false
    -dColorImageFilter=/FlateEncode
    -dGrayImageFilter=/FlateEncode
    -dMonoImageFilter=/FlateEncode
    -sOutputFile="$1".pdf
)
gs ${=opts} $1

toremove=(Format)
exiftool $1.pdf | while read l ; do
    f=${${(s/:/)l}[1]:gs/ //}
    [[ "$l" =~ ": " ]] || toremove=($f $toremove)
    [[ "$l" =~ ": uuid:" ]] && toremove=($f $toremove)
done
for i ({1..${#toremove}}) toremove[$i]=-${toremove[$i]}=
exiftool -zip -overwrite_original -quiet \
    -tagsFromFile $1 -Producer\>Creator \
    ${=toremove} $1.pdf
[[ -z $LINEARIZE ]] || LINEARIZE=--linearize
qpdf $LINEARIZE --compress-streams=y $1.pdf $1.pdf.pdf
mv $1.pdf.pdf $1.pdf