ep

#!/usr/bin/env bash

die() { printf %s "${@+$@$'\n'}" 1>&2 ; exit 1 ; }
see() ( { set -x; } 2>/dev/null ; "$@" )

optq=0 force=0

dieifnotinpath() { command -v "$1" >/dev/null || die "$1 not in PATH"; }
dieifnotinpath find_calibre_binary

ecbin="$(find_calibre_binary ebook-convert)" || die

# echo "ecbin=$ecbin"
ecbin_version_2line="$("$ecbin" --version)" ; read -r ecbin_version <<<"$ecbin_version_2line"
[[ "$ecbin_version" ]] || die
# echo "ecbin_version=$ecbin_version"

convert_to_pdf() (
   # https://manual.calibre-ebook.com/generated/en/ebook-convert.html#pdf-output-options
   mpts=3 mpo='--pdf-page-margin-'
   mbotpts="${EP_PDF_PG_MARGIN_BOTTOM:-"$mpts"}"
   echo "$ecbin_version"
   see "$ecbin" "$1" "$2" --output-profile=ipad --use-profile-size "${mpo}bottom=$mbotpts" "${mpo}left=$mpts" "${mpo}right=$mpts" "${mpo}top=$mpts"
   )

do1file() {
   local fnm="$1"
   if [[ ! -f "$fnm" ]]; then
      ((optq!=0)) || echo "$fnm does not name a file"
      return
   fi
   local ext="${fnm##*.}"
   if [[ "$ext" && "${ext^^}" == "PDF" ]]; then  # don't try to convert a PDF to PDF
      ((optq!=0)) || echo "skipping: src is $ext '$fnm'"
   else
      local fpath=""
      if [[ $fnm == */* ]]; then
         fpath="${fnm%/*}/"
      fi                                        # ; echo "fpath=$fpath'"
      local sanspath="${fnm##*/}"               # ; echo "sanspath=$sanspath'"    # https://stackoverflow.com/a/965069
      local sansext="${sanspath%.*}"            # ; echo "sansext=$sansext'"
      local srcfnm="$fnm"                       # ; echo "srcfnm=$srcfnm'"
      local tgtfnm="$fpath$sansext.medtype.pdf" # ; echo "tgtfnm=$tgtfnm'"
      if ((!force)) && [[ -f "$tgtfnm" && "$tgtfnm" -nt "$srcfnm" ]]; then
         ((optq!=0)) || echo "skipping: tgtfnm exists '$tgtfnm'"
      else
         local logfnm="$fpath$sansext.log"      # ; echo "logfnm=$logfnm'"
         if [[ -f "$logfnm"  ]]; then
            local logver ; read -r logver < "$logfnm"
            if ((force)) || [[ "$logver" != "$ecbin_version" ]]; then
               ((optq!=0)) || echo "logver != ecbin_version: $logver != $ecbin_version"
               rm -f "$logfnm"
            fi
         fi
         if [[ -f "$logfnm" && "$logfnm" -nt "$srcfnm" ]]; then
            ((optq!=0)) || echo "skipping: logfile exists '$tgtfnm'"
         else
            echo "creating: $tgtfnm"
            if >"$logfnm" 2>&1 convert_to_pdf "$srcfnm" "$tgtfnm"; then
               # echo "log deleted"
               rm -f "${logfnm:?}"
            else
               echo "FAILED: see '${logfnm}'"
            fi
         fi
      fi
   fi
   }

# parse options
argerr() {  die "usage: $0 [-q] FILE..." ; }
while getopts "fqh" opt; do
  case $opt in
    f) force=1 ;;
    q) optq=1 ;;
    h) argerr;;
    \?) argerr;;
  esac
done
shift "$((OPTIND-1))"  # shift so that $@, $1, etc. refer to the non-option arguments

for fnm in "$@"; do
   do1file "$fnm"
done