Losslessly convert all PNGs in current folder to JPEG-XL preserving EXIF and mtime. (Bash script)

convert_png_to_jxl.sh

#!/bin/bash
if [[ -n $(shopt -s nullglob; echo *.png) ]]; then
    for i in *.png
    do k="${i%.png}.jxl"
      cjxl -q 100 -e 10 "$i" "$k"
    done

    if [[ -n $(shopt -s nullglob; echo *.jxl) ]]; then
        for k in *.jxl
        do i="${k%.jxl}.png"
          exiftool -m -overwrite_original -api compress=1 -tagsfromfile "$i" "$k"
          touch -r "$i" "$k"
          rm "$i"
        done
    fi
fi

if [[ -n $(shopt -s nullglob; echo *.PNG) ]]; then
    for i in *.PNG
    do k="${i%.PNG}.JXL"
      cjxl -q 100 -e 10 "$i" "$k"
    done

    if [[ -n $(shopt -s nullglob; echo *.JXL) ]]; then
        for k in *.JXL
        do i="${k%.JXL}.PNG"
          exiftool -m -overwrite_original -api compress=1 -tagsfromfile "$i" "$k"
          touch -r "$i" "$k"
          rm "$i"
        done
    fi
fi

if [[ -n $(shopt -s nullglob; echo *.png.xmp) ]]; then
    for i in *.png.xmp
    do k="${i%.png.xmp}.jxl.xmp"
      if [[ -f "${i%.png.xmp}.jxl" ]]; then
        mv "$i" "$k"
      fi
    done
fi

if [[ -n $(shopt -s nullglob; echo *.PNG.xmp) ]]; then
    for i in *.PNG.xmp
    do k="${i%.PNG.xmp}.JXL.xmp"
      if [[ -f "${i%.PNG.xmp}.JXL" ]]; then
        mv "$i" "$k"
      fi
    done
fi

find . -empty -delete