#!/bin/bash

verwendung() {
  >&2 echo 'sendmailadvanced encrypts emails and generates stamps either in situ or in a pipe. For that it uses hashcash and gnupg.'
  >&2 echo ''
  >&2 echo 'Usage: sendmailadvanced [OPTIONS]'
  >&2 echo '  -h,--hook=hook      activate hook'
  >&2 echo '  -i,--inline=file    enhance email file in situ.'
  >&2 echo '                        "--inline -" has the same effect as "-t".'
  >&2 echo '                        Conflicts with -t|--no-inline.'
  >&2 echo '  -t,--no-inline      enhance email from stdin to stdout.'
  >&2 echo '                        Conflicts with -i|--inline.'
  >&2 echo '  -e,--[no-]encrypt   do (not) encrypt'
  >&2 echo '  -s,--[no-]stamp     do (not) stamp'
  >&2 echo \
'#HELPTEXT#    #'
  exit 1
}

stempeln() {
  oldIFS="${IFS}"

  IFS=','
  for adressat in ${adressatenString}
  do
    if [[ "${adressat}" == *"<"*">"* ]]
    then
      adressat="${adressat#*<}"
      adressat="${adressat%>*}"
    fi
    adressat="$(
      echo "${adressat}" | \
        tr -d "[:space:]"
    )"
    echo "${adressat}" | grep -q "\S" || continue
    hashcash -b ${hashcash_bits} -Xm "${adressat}"
  done

  adressatenString=""

  IFS="${oldIFS}"
}

datei=""
encrypt=true
stamp=true

dForced=false
eForced=false
sForced=false

if [ -r #ETCDIR#/sendmailadvanced.conf ]
then
  . #ETCDIR#/sendmailadvanced.conf
else
  for konfig in $(readlink -f "$0").conf $(find . -name sendmailadvanced.conf 2> /dev/null)
  do
    [ -r "${konfig}" ] || continue
    . "${konfig}"
    break
  done
fi

gpg --list-keys "${gpg_recipient}" &> /dev/null || encrypt=false
which hashcash &> /dev/null || stamp=false

eval set -- "$(getopt -o eh:i:st --long encrypt,no-encrypt,hook:,help,inline:,no-inline,stamp,no-stamp,version -n "$(basename "$0")" -- "$@" || echo verwendung)"

while true
do
  case "$1" in
    -h|--hook)
      shift
      hooks[${#hooks[@]}]="$1"
    ;;
    --help)
      verwendung 0
      ;;
    --version)
      echo '#VERSION#'
      exit 0
      ;;
    -i|--inline)
      ${dForced} && verwendung
      shift
      datei="$1"
      [ "${datei}" == "-" ] && datei=""
      dForced=true
    ;;
    -t|--no-inline)
      ${dForced} && verwendung
      datei=""
      dForced=true
    ;;
    -e|--encrypt)
      ${eForced} && verwendung
      encrypt=true
      eForced=true
    ;;
    --no-encrypt)
      ${eForced} && verwendung
      encrypt=false
      eForced=true
    ;;
    -s|--stamp)
      ${sForced} && verwendung
      stamp=true
      sForced=true
    ;;
    --no-stamp)
      ${sForced} && verwendung
      stamp=false
      sForced=true
    ;;
    --)
      shift
      break
    ;;
    *)
      >&2 echo "FEHLER: Verstehe Option \"$1\" doch nicht! Ich beende."
      verwendung
    ;;
  esac
  shift
done

[ $# -ne 0 ] && verwendung

MAILER="cantfind"
for executable in sendmail msmtp
do
  for prefix in #BINDIR# /usr/bin /usr/sbin /bin /sbin
  do
    [ "${MAILER}" == "cantfind" ] && [ -x ${prefix}/${executable} ] && MAILER="${prefix}/${executable}"
  done
done

if [ -z "${datei}" ] && [ "${MAILER}" == "cantfind" ]
then
  >&2 echo "ERROR: Can't find suitable mailer."
  exit 1
fi

(
  [ -z "${datei}" ] && cat || cat "${datei}"
) | \
(
  IFS=''
  adressatenString=""
  adressatenSammeln=false
  while read -r zeile
  do
    echo "${zeile}" | grep -q "\S" || break
    s="${zeile}"
    if [ "${s:0:3}" == "To:" ] || [ "${s:0:3}" == "Cc:" ]
    then
      adressatenSammeln=true
      s=" ,${s:4}"
    fi
    if [ ! "${s:0:1}" == " " ]
    then
      ${adressatenSammeln} && ${stamp} && stempeln
      adressatenSammeln=false
    fi
    ${adressatenSammeln} && adressatenString="${adressatenString}${s}"
    echo "${zeile}"
  done

  ${stamp} && stempeln
  echo "${zeile}"

  (
    for hookParam in "${hooks[@]}"
    do
      body_header_hook "${hookParam}"
    done
    cat
    for hookParam in "${hooks[@]}"
    do
      body_footer_hook "${hookParam}"
    done
  ) | \
  (
    ${encrypt} && gpg -e -a -s -r ${gpg_recipient} || cat
  )
) | \
(
  if [ -z "${datei}" ]
  then
    ${MAILER} -t
  else
    tmpFile="$(mktemp)"
    cat > "${tmpFile}"
    cat "${tmpFile}" > "${datei}"
    rm -f "${tmpFile}"
  fi
)