#!/usr/bin/env bash

# option values for the brother DS-740D scanner
simplex_source='Automatic Document Feeder(left aligned)'
duplex_source='Automatic Document Feeder(left aligned,Duplex)'
color_mode='24bit Color[Fast]'
bw_mode='Black & White'
grayscale_mode='True Gray'
valid_resolutions=("100" "150" "200" "300" "400" "600" "1200")

# default options for scanning
sides=$simplex_source
mode='c'
resolution='300'


current_page=$(find "$PWD" -name "out*.pdf" | sort | tail -n 1);
read -r current_pageno <<<"${current_page//[^0-9]/ }"
current_pageno=${current_pageno:-0}
last_out_file="out$current_pageno.pdf"
next_out_file="out$((current_pageno+1)).pdf"

scan() {
  # device="brother5:bus2;dev2"
  device=$(scanimage -f "%d%n" | grep brother5 | head -n 1)
  echo "Selecting scanner '$device'"

  usage() {
    echo "scanbuddy.bash scan -d -r <resolution($resolution)> -b <c|b|g>"
  }

  while getopts "dr:c:" flag; do
    case ${flag} in
     d) 
       echo "Scanning duplex"
       sides=$duplex_source
       ;;
     r)
       if [[ ! " ${valid_resolutions[*]} " =~ [[:space:]]${OPTARG}[[:space:]] ]]; then
         echo "Resolution '$OPTARG' not supported!"
         echo "Supported resolutions: $(printf %s "${valid_resolutions[*]}")"
         exit 1
       fi
       resolution=$OPTARG
       ;;
     c)
       mode=$OPTARG
       ;;
     *)
       ;;
    esac
  done

  case $mode in
    c)
      scanner_mode=$color_mode
      ;;
    b)
      scanner_mode=$bw_mode
      ;;
    g)
      scanner_mode=$grayscale_mode
      ;;
    *)
      echo "Mode '$mode' not supported! Supported modes: (c)olour|(b)lack & white|(g)reyscale"
      ;;
  esac

  echo "Scanning to '$next_out_file'..."
  scanimage \
    --device-name="$device" \
    --format=pdf \
    --output-file="$next_out_file" \
    --mode="$scanner_mode" \
    --resolution="$resolution" \
    --source="$sides" \
    -x 210 -y 297 # A4 
}

if [ "$#" -lt 1 ]; then
  echo "You need an argument!"
  exit 1
fi

case "$1" in
  scan)
    scan "${@:2}"
    ;;
  unscan)
    rm "$last_out_file"
    ;;
  dispatch)
    readarray -d '' out_files < <(find . -regextype posix-awk -regex "\./out[0-9]+\.pdf" -print0 | sort -Vz)
    combined_file=$(mktemp --suff="_scanbuddy.pdf")
    gs -q -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE="$combined_file" -dBATCH "${out_files[@]}"
    echo "Merged pdf written to $combined_file"

    # send to paperless
    PAPERLESS_STATUS=$(curl \
      -H "Authorization: Token $PAPERLESS_TOKEN" \
      -F document=@"$combined_file" \
      "$([ -v PAPERLESS_TAG ] && echo "-F tags=$PAPERLESS_TAG")" \
      "${PAPERLESS_URL}/api/documents/post_document/") || FAILED=1

    if [ -v FAILED ]; then
      echo "Paperless failed with message:\n$PAPERLESS_STATUS"
    else
      echo "Paperless consumption job: '$PAPERLESS_STATUS'"
    fi
    ;;
  *)
    echo "Usage: scanbuddy"
    ;;
esac