#!/usr/bin/env -S bash
# -------------------------------------------------------------------------------------------------------------------- #
# DOVECOT: ATTACHMENT DECODER SCRIPT
# -------------------------------------------------------------------------------------------------------------------- #
# @package    Bash
# @author     Kai Kimera
# @license    MIT
# @version    0.1.0
# @link       https://libsys.ru/ru/2025/03/7d3b9bd5-e43d-52a7-9662-e58a0819c91a/
# -------------------------------------------------------------------------------------------------------------------- #

lib_dir='/usr/lib/dovecot'
content_type="${1}"

# The second parameter is the format's filename extension, which is used when found from a filename of
# application/octet-stream. You can also add more extensions by giving more parameters.
formats='application/pdf pdf
application/x-pdf pdf
application/msword doc
application/mspowerpoint ppt
application/vnd.ms-powerpoint ppt
application/ms-excel xls
application/x-msexcel xls
application/vnd.ms-excel xls
application/vnd.openxmlformats-officedocument.wordprocessingml.document docx
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet xlsx
application/vnd.openxmlformats-officedocument.presentationml.presentation pptx
application/vnd.oasis.opendocument.text odt
application/vnd.oasis.opendocument.spreadsheet ods
application/vnd.oasis.opendocument.presentation odp
'

[[ "${content_type}" == "" ]] && { echo "${formats}"; exit 0; }
fmt="$( echo "${formats}" | grep -w "^${content_type}" | cut -d ' ' -f 2 )"
[[ "${fmt}" == "" ]] && { echo >&2 "Content-Type: ${content_type} not supported"; exit 1; }

# Most decoders can't handle stdin directly, so write the attachment to a temp file.
path="$( mktemp )"; trap 'rm -f "${path}"' 0 1 2 3 14 15; cat > "${path}"

xml_unzip() {
  name="${1}"
  tempdir="$( mktemp -d )"; [[ "${tempdir}" == "" ]] && exit 1

  trap 'rm -rf "${path}" "${tempdir}"' 0 1 2 3 14 15
  cd "${tempdir}" || exit 1
  unzip -q "${path}" 2>/dev/null || exit 0
  find . -name "${name}" -print0 | xargs -0 cat | "${lib_dir}/xml2text"
}

wait_timeout() {
  child_pid=$!
  trap 'kill -9 "${child_pid}"; rm -f "${path}"' 1 2 3 14 15
  wait "${child_pid}"
}

LANG='en_US.UTF-8'; export LANG

if [[ "${fmt}" == "pdf" ]]; then
  /usr/bin/pdftotext "${path}" - 2>/dev/null&
  wait_timeout 2>/dev/null
elif [[ "${fmt}" == "doc" ]]; then
  ( /usr/bin/catdoc "${path}"; true ) 2>/dev/null&
  wait_timeout 2>/dev/null
elif [[ "${fmt}" == "ppt" ]]; then
  ( /usr/bin/catppt "${path}"; true ) 2>/dev/null&
  wait_timeout 2>/dev/null
elif [[ "${fmt}" == "xls" ]]; then
  ( /usr/bin/xls2csv "${path}"; true ) 2>/dev/null&
  wait_timeout 2>/dev/null
elif [[ "${fmt}" == "odt" || "${fmt}" == "ods" || "${fmt}" == "odp" ]]; then
  xml_unzip "content.xml"
elif [[ "${fmt}" == "docx" ]]; then
  xml_unzip "document.xml"
elif [[ "${fmt}" == "xlsx" ]]; then
  xml_unzip "sharedStrings.xml"
elif [[ "${fmt}" == "pptx" ]]; then
  xml_unzip "slide*.xml"
else
  echo "Buggy decoder script: ${fmt} not handled!" >&2; exit 1
fi

exit 0