#!/usr/bin/env bash

# NAME:         PDFMtEd – Editor
# VERSION:      0.1
# AUTHOR:       (c) 2014 Glutanimate
# DEPENDENCIES: yad exiftool python2.7 (sejda-pdf) (qpdf)
#
# DESCRIPTION:  View and edit PDF metadata using exiftool.
#
# LICENSE:      GNU GPLv3 (http://www.gnu.de/documents/gpl-3.0.en.html)
#
# NOTICE:       THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
#               EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
#               PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR
#               IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
#               AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND
#               PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE,
#               YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
#
#               IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY
#               COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS
#               PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
#               INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
#               THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED
#               INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE
#               PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER
#               PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
#
# USAGE:        pdfmted_editor [-r|-u] <file(s) or directory(ies)>

################ GLOBVAR #################

EXECUTABLE="$(readlink -f "$0")"
PROGDIR="${EXECUTABLE%/*}"
THUMBNAILER="$PROGDIR/pdfmted-thumbnailer.py"
TMPDIR="/tmp/${0##*/}"

############### SETTINGS #################

# Supply password for protected PDF files
PASSWORD=""
# Rename modified files by default?
RENAME_OPT="FALSE"

##############  DIALOGS  #################

# Usage message

USAGE="
Usage: $(basename "$0") [-r|-u|-h] <PDF Files/Directories>

    Title:          PDFMtEd – Editor
    Author:         (c) 2014 Glutanimate
    Description:    View and edit PDF metadata
    Arguments:      This script accepts multiple PDF files and
                    directories as input.

Available options:
    -r rename files by default
    -u arguments are URIs
    -h display this help message\
"

# General settings

YAD_TITLE="PDFMtEd – Editor"
WMCLASS="pdfmtededitor"
ICON="application-pdf"
WIDTH="800"
HEIGHT="650"
PROGWIDTH="400"
PROGHEIGHT="100"

# Descriptions and tooltips

TEXT_INFO_DEPERR="Error: Missing dependencies. Please install the \
following:"

TEXT_MAIN_DESCRP="\
<b>Important note</b>:

Empty fields will <b>delete</b> the associated metadata. \
However, modifications performed by exiftool are <b>reversible</b>. \
To purge the file of all metadata please use PDFMtEd – Inspector
"

TEXT_CHCK_SAVECH="Save changes, file will be skipped if unchecked"
TEXT_CHCK_RENMFL="Rename based on tags"
TEXT_CHCK_DUPLIC="Copy tags over to next/previous file"

TEXT_HOVR_CANCEL="Cancel and exit"
TEXT_HOVR_FNNISH="Save (if option selected) and exit"
TEXT_HOVR_PREVIT="Move back to previous document"
TEXT_HOVR_NEXTIT="Move to next document in line"

TEXT_BTTN_PDFVWR="_Open in PDF viewer"
TEXT_HOVR_PDFVWR="Open document with default PDF viewer"

TEXT_BTTN_SHWFLD="Show in parent _directory"
TEXT_HOVR_SHWFLD="Open parent directory with default file manager"

TEXT_BTTN_CLRALL="C_lear all"
TEXT_HOVR_CLRALL="Clear all fields"

TEXT_INFO_WARNG1="Something went wrong while writing the metadata. Processing the document with \
sejda (recommended) or linearizing it with qpdf helps in these cases. Want to proceed?"
TEXT_NOTI_SUCCE1="Metadata succesfully updated."
TEXT_NOTI_ERROR1="Post-processing failed."

############## FUNCTIONS #################

# dependencies

check_deps() {
    for i in "$@"; do
      type "$i" > /dev/null 2>&1
      if [[ "$?" != "0" ]]; then
        MISSINGDEPS+=" $i"
      fi
    done
}

gui_check_deps(){
    check_deps yad exiftool python2.7
    if [[ -n "$MISSINGDEPS" ]]; then
      gui_show_error "${TEXT_INFO_DEPERR}
      ${MISSINGDEPS}"
      exit 1
    fi
}

# cleanup

var_unset(){
    unset -v KEYWORDS SUBJECT AUTHOR TITLE_FN UPDATED_NAME
}

cleanup(){
  [[ -n "$TMPDIR" && -d "$TMPDIR" ]] && rm -r "$TMPDIR"
}

# evaluate and check arguments

arg_evaluate_options(){
    # grab options if present
    while getopts "ruh" OPTIONS; do
      case $OPTIONS in
        r ) RENAME_OPT="TRUE"
            ;;
        u ) URI_OPT="TRUE"
            ;;
        h ) echo "$USAGE"
            exit 0
            ;;
       \? ) echo "$USAGE"
            exit 1
            ;;
      esac
    done
}

arg_check_correct(){
    # check if arguments aside from options given
    if [[ "$#" = "0" ]]
      then
          error_log 1
    fi

    # check if arguments are files or folders
    for ITEM in "$@"; do
      if [[ ! -d "$ITEM" && ! -f "$ITEM" ]]
        then
            error_log 3
      fi
    done

    # notify user and exit
    if [[ "$ARGERROR" = "1" ]]
      then
          gui_show_error "ERROR: No files/folder selected."
          echo "Exiting..."
          exit 1
    fi
}

arg_uri_to_path(){
  # handle cases where we have to use "pseudo-uris"
  cnt=0
  FILEARGS=()
  for URI in "$@"; do
    # only handles file:// prefix
    # for other uri-specific substitutions we would have to
    # use python+gio-bindings
    FILEARGS[$cnt]="$(echo "$URI" | sed "s/^file:\/\///g")"
    ((cnt++))
  done
}

arg_compose_filearray(){
    # recursively add pdf files and folders in given arguments to array
    unset ARGS
    ARGID="1" # start array at 1
    while IFS= read -r -d $'\0' FILE; do
        if [[ ! "$(file -ib "$FILE")" == *application/pdf* ]]
          then
              echo "Error: '$FILE' is not a pdf file. Ignoring."
              continue
        fi
        ARGS[ARGID++]="$FILE"
    done < <(find "$@" -type f -name '*.pdf' -print0 | sort -z --version-sort)
    # numerical-composite (e.g. 1.1<1.2), zero-delimited sorting
    ARGSTOTAL="${#ARGS[@]}"
    ARGID="1"
    if [[ "$ARGSTOTAL" = "0" ]]; then
      gui_show_error "ERROR: No PDF files found."
      echo "Exiting..."
      exit 1
    fi
}

# Error handling

error_log(){
    if [[ "$1" = "1" ]]; then
      ARGERROR="1"
      echo "ARG ERROR: insufficient arguments given."
    elif [[ "$1" = "2" ]]; then
      ARGERROR="1"
      echo "ARG ERROR: illegal arguments ('$ITEM' is not a file or directory.)"
    elif [[ "$1" = "3" ]]; then
      WRITEERROR="1"
      echo "WRITE ERROR: File not updated. Likely an issue with exiftool"
    elif [[ "$1" = "5" ]]; then
      PSTPRCERROR="1"
      echo "POST PROCESSING ERROR: qpdf/sejda failed."
    fi
}

# Set up environment

setup_filevars(){
    FILE="$(readlink -f "$1")"
    FILE_ESCAPED="${FILE//%/%%}"
    FILENAME="${FILE##*/}"
    BASENAME="${FILENAME%.*}"
    DIRNAME="${FILE%/*}"
    DIRNAME_ESCAPED="${FILE_ESCAPED%/*}"
    PREV_FILE="${ARGS[$ARGID-1]}"
    NEXT_FILE="${ARGS[$ARGID+1]}"
    PREV_FILENAME="${PREV_FILE##*/}"
    NEXT_FILENAME="${NEXT_FILE##*/}"
}

# Set up GUI

setup_geometry(){
  GEOMETRYOPTS=("--center" "--height=$HEIGHT" "--width=$WIDTH")
  PROGGEO=("--center" "--height=$PROGHEIGHT" "--width=$PROGWIDTH")
}

setup_gui(){
    MULTIDOC_TITLE="$YAD_TITLE ($ARGID/$ARGSTOTAL)"
    # we are using arrays to construct and modify YAD dialogs
    # multiple documents - show all elements
    if [[ "$MULTIDOC" = "middle" ]]
      then
          MULTIDOC_FIELDS=(\
          --field="$TEXT_CHCK_DUPLIC":CHK "FALSE" \
          --field="<b>Previous Document</b>:":RO "$PREV_FILENAME" \
          --field="<b>Next Document</b>:":RO "$NEXT_FILENAME")
          MULTIDOC_BUTTONS=(--button="_Previous!go-previous!$TEXT_HOVR_PREVIT:1" \
          --button="_Next!go-next!$TEXT_HOVR_NEXTIT:2")
    # multiple documents, first doc - hide previous
    elif [[ "$MULTIDOC" = "first" ]]
      then
          MULTIDOC_FIELDS=(\
          --field="$TEXT_CHCK_DUPLIC":CHK "FALSE" \
          --field="<b>Next Document</b>:":RO "$NEXT_FILENAME" )
          MULTIDOC_BUTTONS=(--button="_Next!go-next!$TEXT_HOVR_NEXTIT:2")
    # multiple documents, last doc - hide next
    elif [[ "$MULTIDOC" = "last" ]]
      then
          MULTIDOC_FIELDS=(\
          --field="$TEXT_CHCK_DUPLIC":CHK "FALSE" \
          --field="<b>Previous Document</b>:":RO "$PREV_FILENAME")
          MULTIDOC_BUTTONS=(--button="_Previous!go-previous!$TEXT_HOVR_PREVIT:1")
    # single document - hide all elements
    elif [[ "$MULTIDOC" = "single" ]]
      then
          HEIGHT="620"
          MULTIDOC_FIELDS=()
          MULTIDOC_BUTTONS=()
    fi
    setup_geometry
}

# GUIs

gui_notify(){
    notify-send -i "$NOTIFY_ICON" "$YAD_TITLE" "$1"
}

gui_progress(){
    # ampersands in gui elements cause issues in gtk/pango markup
    BASENAME_PANGO="$(echo "$BASENAME" | sed 's/\&/\&amp;/g')"
    yad --progress --pulsate --auto-close \
    "${PROGGEO[@]}" \
    --image="$ICON" --window-icon="$ICON" \
    --class="$WMCLASS" \
    --title="$YAD_TITLE" \
    --text="Processing <b>$BASENAME_PANGO</b> ..." \
    --button='_Cancel!gtk-cancel!':1 \
    2> /dev/null
    PROG_RET="$?"
    if [[ "$PROG_RET" != "0" ]]
      then
          kill -s TERM "$TOP_PID"
    fi
}

gui_show_error(){
    yad --title="$YAD_TITLE" \
      --center --width="400" --height="100" \
      --image=dialog-error \
      --window-icon=dialog-error \
      --class="$WMCLASS" \
      --text="$1" \
      --button="OK":0 2> /dev/null
    echo "$1"
}

gui_metadata_entry_multi(){
    NEW_METADATA="$( \
    yad --form --scroll \
    --always-print-result \
    "${GEOMETRYOPTS[@]}" \
    --image="$IMAGE" --window-icon="$ICON" \
    --class="$WMCLASS" \
    --title="$MULTIDOC_TITLE" \
    --buttons-layout=end \
    --button="_Cancel!gtk-cancel!$TEXT_HOVR_CANCEL:33" \
    "${MULTIDOC_BUTTONS[@]}" \
    --button="_Finish!gtk-ok!$TEXT_HOVR_FNNISH:3" \
    --field="<b>Current Document</b>:":RO "$FILENAME"\
    --field="":LBL "" \
    --field="$TEXT_MAIN_DESCRP":LBL "" \
    --field="Author:" "$AUTHOR_ORIGINAL" \
    --field="Title:" "$TITLE_ORIGINAL" \
    --field="Year:":NUM "$YEAR_ORIGINAL[!0..3000[!1]]" \
    --field="Keywords:" "$KEYWORDS_ORIGINAL" \
    --field="Subject:" "$SUBJECT_ORIGINAL" \
    --field "$TEXT_BTTN_CLRALL!gtk-clear!$TEXT_HOVR_CLRALL":FBTN \
      "@bash -c gui_clear_fields" \
    --field="":LBL "" \
    --field="$TEXT_BTTN_PDFVWR!application-pdf!$TEXT_HOVR_PDFVWR:FBTN" \
      "bash -c \"gui_open '$FILE_ESCAPED'\"" \
    --field="$TEXT_BTTN_SHWFLD!folder!$TEXT_HOVR_SHWFLD:FBTN" \
      "bash -c \"gui_open '$DIRNAME_ESCAPED'\"" \
    --field="":LBL "" \
    --field="$TEXT_CHCK_SAVECH":CHK "TRUE" \
    --field="$TEXT_CHCK_RENMFL":CHK "$RENAME_OPT" \
    "${MULTIDOC_FIELDS[@]}" \
    2> /dev/null)"
    RET_MAIN=$?
    if [[ "$RET_MAIN" = 1 ]]
      then
          PROGRESSION="PREVIOUS"
    elif [[ "$RET_MAIN" = 2 ]]
      then
          PROGRESSION="NEXT"
    elif [[ "$RET_MAIN" = 3 ]]
      then
          PROGRESSION="FINISH"
    else
          echo "Aborted."
          exit 1
    fi
}

gui_postprocess_pdf(){
    yad --title="$YAD_TITLE" \
    --center --width="400" --height="100" \
    --image=dialog-error \
    --window-icon=dialog-error \
    --class="$WMCLASS" \
    --text="$TEXT_INFO_WARNG1" \
    --button="_Process with Sejda!gtk-ok!$TEXT_HOVR_PSTPRC_SEJ:0" \
    --button="_Linearize!gtk-ok!$TEXT_HOVR_PSTPRC_LIN:2" \
    --button="_Cancel!gtk-cancel!$TEXT_HOVR_PSTPRC_CANCEL:1"
    RET_PSTPRC="$?"
    if [[ "$RET_PSTPRC" = "0" ]]; then
      if ! type sejda-console > /dev/null 2>&1; then
        gui_show_error "Error: Sejda not installed."
        gui_postprocess_pdf
        return
      fi
      sejda_process_pdf | gui_progress
      check_modify_success
      error_recheck_write
    elif [[ "$RET_PSTPRC" = "2" ]]; then
      if ! type qpdf > /dev/null 2>&1; then
        gui_show_error "Error: qpdf not installed."
        gui_postprocess_pdf
        return
      fi
      linearize_pdf | gui_progress
      check_modify_success
      error_recheck_write
    else
      return 1
    fi
}


# GUI extensions

# create thumbnail
gui_thumbnail_generate() {
    if [[ -f "$THUMBNAILER" ]]; then
      echo "#Generating preview..."
      $THUMBNAILER "$FILE" > /dev/null 2>&1
    fi
}

# assign thumbnail
gui_thumbnail_assign(){

    PREVIEWIMG="$(python2.7 -c "import gio; import sys; \
    print gio.File(sys.argv[1]).query_info('*').get_attribute_byte_string \
    ('''thumbnail::path''')" "$FILE")"

    if [[ "$(file -ib "$FILE" | cut -d';' -f1)" != "application/pdf" || ! -f "$PREVIEWIMG" ]]
      then
          PREVIEWIMG="$ICON"
    fi

    IMAGE="$PREVIEWIMG"
    NOTIFY_ICON="$PREVIEWIMG"
}

# generic yad xdg-open function
gui_open(){
  PATH_ESCAPED="${1//%/%25}"
  xdg-open "$PATH_ESCAPED" > /dev/null 2>&1 &
}

# clear yad fields
gui_clear_fields(){
    for FIELDNR in {4..8}; do
      echo "$FIELDNR:"
    done
}

# preserve metadata for next document in line
duplicate_metadata () {
    AUTHOR_ORIGINAL="$AUTHOR"
    TITLE_ORIGINAL="$TITLE"
    YEAR_ORIGINAL="$YEAR"
    SUBJECT_ORIGINAL="$SUBJECT"
    KEYWORDS_ORIGINAL="$KEYWORDS"
}


process_yad_formchoices(){
    echo "$NEW_METADATA"
    AUTHOR="$(echo "$NEW_METADATA" | cut -d '|' -f4)"
    TITLE="$(echo "$NEW_METADATA" | cut -d '|' -f5)"
    YEAR="$(echo "$NEW_METADATA" | cut -d '|' -f6 | cut -d ',' -f1 | cut -d '.' -f1)"
    KEYWORDS="$(echo "$NEW_METADATA" | cut -d '|' -f7)"
    SUBJECT="$(echo "$NEW_METADATA" | cut -d '|' -f8)"
    SAVECHOICE="$(echo "$NEW_METADATA" | cut -d '|' -f14)"
    RENAMECHOICE="$(echo "$NEW_METADATA" | cut -d '|' -f15)"
    DUPLICATECHOICE="$(echo "$NEW_METADATA" | cut -d '|' -f16)"
    MODIFYDATE="$(date +"%Y:%m:%d %H:%M:%S")"
    if [[ "$YEAR" = "0" ]]; then
      CREATEDATE=""
    else
      CREATEDATE="$(printf "%04d" "$YEAR"):01:01 00:00:00"
    fi
}

# Metadata input

read_metadata() {
    echo "#Reading embedded metadata..."
    exiftool -e -S -sep ";" -PDF:Title -PDF:Author -PDF:Subject \
    -PDF:Keywords -PDF:CreateDate -PDF:ModifyDate \
    "$FILE" > "$PROGPIPE"
}

print_original_metadata() {
    echo "###Original metadata:"
    echo ""
    echo "Author:               $AUTHOR_ORIGINAL"
    echo "Title:                $TITLE_ORIGINAL"
    echo "Year:                 $YEAR_ORIGINAL"
    echo "Creation date:        $CREATEDATE_ORIGINAL"
    echo "Modification date:    $MODIFYDATE_ORIGINAL"
    echo "Subject:              $SUBJECT_ORIGINAL"
    echo "Keywords:             $KEYWORDS_ORIGINAL"
}

evaluate_original_metadata() {
    METADATA_PDF="$( [[ -f "$PROGPIPE" ]] && cat "$PROGPIPE")"
    AUTHOR_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/Author: //p')"
    TITLE_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/Title: //p')"
    CREATEDATE_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/CreateDate: //p')"
    YEAR_ORIGINAL="${CREATEDATE_ORIGINAL:0:4}"
    MODIFYDATE_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/ModifyDate: //p')"
    SUBJECT_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/Subject: //p')"
    KEYWORDS_ORIGINAL="$(echo "$METADATA_PDF" | sed -n 's/Keywords: //p')"
}

# Metadata output

delete_metadata(){
    echo "#Deleting existing metadata"
    exiftool -e -overwrite_original -all:all="" "$FILE"
}

write_metadata(){
    echo "#Writing new metadata"
    exiftool -e -overwrite_original -password "$PASSWORD" -sep ";" \
    -PDF:Title="$TITLE" -PDF:Author="$AUTHOR" \
    -PDF:Subject="$SUBJECT" -PDF:Keywords="$KEYWORDS" \
    -PDF:ModifyDate="$MODIFYDATE" -PDF:CreateDate="$CREATEDATE" \
    -XMP-dc:Subject="$KEYWORDS" -XMP-dc:Description="$SUBJECT" -XMP-dc:Title="$TITLE" \
    -XMP-dc:Creator="$AUTHOR" -XMP-dc:Date="$CREATEDATE" \
     "$FILE"
    echo "$?" > "$ERRORPIPE1"
}

update_metadata(){
    delete_metadata; write_metadata
    check_modify_success
    error_check_write
}

print_updated_metadata() {
    echo "###Updated metadata:"
    echo ""
    echo "Author:               $AUTHOR"
    echo "Title:                $TITLE"
    echo "Year:                 $YEAR"
    echo "Creation date:        $CREATEDATE"
    echo "Modificaiton date:    $MODIFYDATE"
    echo "Subject:              $SUBJECT"
    echo "Keywords:             $KEYWORDS"
}

update_filename(){
    TARGETFOLDER="$DIRNAME"
    # replace characters in title that might cause issues on some file systems
    TITLE_FN="$(echo "$TITLE" | sed -e 's/\:/\;/g' -e 's/\&/and/g')"
    # Modify the following lines to change the naming scheme:
    # (default naming scheme: ${AUTHOR} - ${TITLE_FN} - ${YEAR})
    if [[ -n "$AUTHOR" ]]; then
      UPDATED_NAME="$AUTHOR"
    fi
    if [[ -n "$TITLE" ]]; then
      if [[ -n "$UPDATED_NAME" ]]; then
        UPDATED_NAME+=" - $TITLE_FN"
      else
        UPDATED_NAME="$TITLE"
      fi
    fi
    if [[ -n "$YEAR" && "$YEAR" != "0" ]]; then
      if [[ -n "$UPDATED_NAME" ]]; then
        UPDATED_NAME+=" - $YEAR"
      else
        UPDATED_NAME="$YEAR"
      fi
    fi
    echo "Updating file name..."
    mv "$FILE" "$TARGETFOLDER/$UPDATED_NAME.pdf"
    ARGS[$ARGID]="$TARGETFOLDER/$UPDATED_NAME.pdf"  # make sure to update file array with
                                                    # new location
}

# Error checks and workarounds

# check if modification was successful
check_modify_success(){
    # if the PDF ModifyDate hasn't been altered we can assume
    # that the exiftool tagging failed
    MODDATE_CHECK="$(exiftool -e -S -sep ";" -PDF:ModifyDate "$FILE"\
    | sed -n 's/ModifyDate: //p')"
    if [[ "$MODDATE_CHECK" != "$MODIFYDATE" ]]
      then
          error_log 3
    fi
}

error_check_write(){
    WRITE_RETURNCODE="$(cat "$ERRORPIPE1")"
    if [[ "$WRITE_RETURNCODE" != "0" || "$WRITEERROR" = "1" ]]
      then
          WRITEERROR="0"
          echo "$TEXT_INFO_WARNG1"
          gui_postprocess_pdf
      else
          gui_notify "$TEXT_NOTI_SUCCE1"
          echo "Success."
    fi
}

error_recheck_write(){
    PSTPRC_RETURNCODE="$(cat "$ERRORPIPE2")"
    if [[ "$PSTPRC_RETURNCODE" != "0" || "$WRITEERROR" = "1" ]]
      then
          error_log 4
          echo "$TEXT_NOTI_ERROR1"
          gui_notify "$TEXT_NOTI_ERROR1"
      else
          gui_notify "$TEXT_NOTI_SUCCE1"
          echo "Success."
    fi
}

sejda_process_pdf(){
    # Sejda does not preserve any document metadata
    # so we have to perform the exiftool actions again;
    # we use delete_metadata() in order to remove sejda-related metadata
    echo "#Running Sejda on $FILENAME..."
    TEMPFILE="$DIRNAME/${BASENAME}_sejda.pdf"
    sejda-console merge --compressed -v 7 -f "$FILE" -o "$TEMPFILE"
    RET_POSTPROC="$?"
    if [[ "$RET_POSTPROC" = "0" ]]; then
      mv "$TEMPFILE" "$DIRNAME/${BASENAME}.pdf"
      delete_metadata
      write_metadata
    fi
    echo "$RET_POSTPROC" > "$ERRORPIPE2"
}

linearize_pdf(){
    # qpdf only preserves metadata that is not marked as
    # obsolete by exiftool; to purge all existing (and potentially
    # corrupted metadata entries) we first delete all metadata,
    # linearize with qpdf, and then rewrite the metadata
    echo "#Linearizing $FILENAME..."
    delete_metadata
    TEMPFILE="$DIRNAME/${BASENAME}_linearized.pdf"
    qpdf --linearize "$FILE" "$TEMPFILE"
    RET_QPDF="$?"
    if [[ "$RET_QPDF" = "0" ]]; then
      mv "$TEMPFILE" "$DIRNAME/${BASENAME}.pdf"
      write_metadata
    fi
    echo "$RET_QPDF" > "$ERRORPIPE2"
}

# Main

main_check_argid(){
    echo "Processing $ARGID of $ARGSTOTAL"
    if [[ "$ARGSTOTAL" = "1" ]]
      then
          MULTIDOC="single"
    elif [[ "$ARGID" = "1" ]]
      then
          MULTIDOC="first"
    elif [[ "$ARGID" = "$ARGSTOTAL" ]]
      then
          MULTIDOC="last"
    else
          MULTIDOC="middle"
    fi
}

main_iteration(){
    var_unset
    setup_filevars "$1"
    setup_gui
    gui_thumbnail_generate; read_metadata
    gui_thumbnail_assign
    evaluate_original_metadata
    [[ "$DUPLICATECHOICE" = "TRUE" ]] && duplicate_metadata
    print_original_metadata
    gui_metadata_entry_multi
    process_yad_formchoices
    print_updated_metadata
    [[ "$SAVECHOICE" = "TRUE" ]] && update_metadata
    [[ "$SAVECHOICE" = "TRUE" && "$RENAMECHOICE" = "TRUE" ]] && update_filename
}

main_check_progression(){
    if [[ "$PROGRESSION" = "NEXT" ]]
      then
          ARGID="$((ARGID+1))"
          main
    elif [[ "$PROGRESSION" = "PREVIOUS" ]]
      then
          ARGID="$((ARGID-1))"
          main
    elif [[ "$PROGRESSION" = "FINISH" ]]
      then
          echo "Finished."
          exit 0
    fi
}

main(){
    main_check_argid
    main_iteration "${ARGS[$ARGID]}"
    main_check_progression
}

############## FCT EXPORT ################

# functions assigned to yad buttons need to be exported

export -f gui_clear_fields
export -f gui_open

############### CLEANUP ##################

trap "cleanup; exit" EXIT

############## PREPWORK ###################

TOP_PID="$$"
mkdir -p "$TMPDIR"
PROGPIPE="$(mktemp -u --tmpdir="$TMPDIR" XXXXXXXX)"
ERRORPIPE1="$(mktemp -u --tmpdir="$TMPDIR" XXXXXXXX)"
ERRORPIPE2="$(mktemp -u --tmpdir="$TMPDIR" XXXXXXXX)"

############## USGCHECKS #################

gui_check_deps
arg_evaluate_options "$@"
shift $((OPTIND-1))
FILEARGS=("$@")
[[ "$URI_OPT" = "TRUE" ]] && arg_uri_to_path "${FILEARGS[@]}"
arg_check_correct "${FILEARGS[@]}"
arg_compose_filearray "${FILEARGS[@]}"

################ MAIN ####################

main