#! /bin/sh
#
# mhmail -- simple mail program
#
# This code is Copyright (c) 2012, by the authors of nmh.  See the
# COPYRIGHT file in the root directory of the nmh distribution for
# complete copyright information.
#
# Emulation of compiled mhmail(1), with these differences:
# * Adds -send/-nosend, -headerfield, and -attach options.
# * Adds optional -to switch for recipient addresses.
# * Supports all post(8) (by default, without -profile) or send(1)
#   (with -profile) options.
# * Optionally (with -profile) obeys the users profile, including
#   AliasFile and send entries.
# * Instead of silently not sending an empty message, notifies user
#   "mhmail: empty message not sent, use -body '' to force."
# * The compiled mhmail dropped a trailing newline from the -body argument.
# * Drops support for undocumented -queue option.

usage='Usage: mhmail [-t(o)] addrs ... [switches]
  switches are:
  -at(tach) file [-at(tach) file] ...
  -b(ody) text
  -c(c) addrs ...
  -f(rom) addr
  -hea(derfield) name:value [-hea(derfield) name:value] ...
  -su(bject) text
  -r(esent)
  -pr(ofile)
  -se(nd)
  -nose(nd)
  -v(ersion)
  -hel(p)
  and all post(8)/send(1) switches
  mhmail with no arguments is equivalent to inc'


#### Find directory of this script.  Bourne shell just puts the program
#### name in $0 if it's found from the PATH, so search that if necessary.
finddir() {
  case $0 in
    */*) dirname $1 ;;
    *  ) IFS=:
         for d in $PATH; do
           [ -f "${d:=.}/$1"  -a  -x "$d/$1" ]  &&  printf "$d"  &&  break
         done ;;
  esac
}

bindir=`finddir $0`
nmhbindir=`cd "${bindir}" && pwd`


#### Checks for missing mandatory arguments.
checkforargs() {
  if [ ${attacharg} -eq 1 ]; then
    printf "mhmail: missing argument to -attach\n"; exit 1
  elif [ ${bodyarg} -eq 1 ]; then
    printf "mhmail: missing argument to -body\n"; exit 1
  elif [ ${ccarg} -eq 1  -a  "${cclist}"x = x ]; then
    printf "mhmail: missing argument to -cc\n"; exit 1
  elif [ ${fromarg} -eq 1 ]; then
    printf "mhmail: missing argument to -from\n"; exit 1
  elif [ ${headerfieldarg} -eq 1 ]; then
    printf "mhmail: missing argument to -headerfield\n"; exit 1
  elif [ ${subjectarg} -eq 1 ]; then
    printf "mhmail: missing argument to -subject\n"; exit 1
  elif [ ${toarg} -eq 1 ]; then
    printf "mhmail: missing argument to -to\n"; exit 1
  fi
}

if [ $# -eq 0 ]; then
  #### Emulate mhmail for reading mail.
  exec "${nmhbindir}"/inc
else
  #### Go through all the switches so we can build the draft.
  tolist=                     ## To: addresses
  toarg=0                     ## whether currently handling -to
  attacharg=0                 ## whether currently handling -attach
  attach_send_switch_added=0  ## whether added "-attach Nmh-Attachment" switch
  body=                       ## contents of the message body
  bodyarg=0                   ## whether currently handling -body
  cclist=                     ## Cc: addresses
  ccarg=0                     ## whether currently handling -cc
  from=                       ## From: contents
  fromarg=0                   ## whether currently handling -from
  headerfieldlist=            ## header fields to be added to draft
  headerfieldarg=0            ## whether currently handling -headerfield
  mhmailswitch=0              ## whether currently handling any mhmail switch
  subject=                    ## Subject: contents
  subjectarg=0                ## whether currently handling -subject
  resent=0                    ## whether resending
  postsendargs=               ## switches to pass on to post or send
  post_send_switch_arg=0      ## whether currently handling a post/send switch
  use_send=0                  ## use post (default) or send (-profile)
  sendsw=1                    ## to send (default) or not to send
  for arg in "$@"; do
    case ${arg} in
      #### Post and send won't accept -f -or -s because they'd be
      #### ambiguous, so no conflicts with them.  And they don't have
      #### -b, -c, -r, -t.  For the new switches that compiled mhmail
      #### didn't have:  let -p indicate mhmail -profile, not send
      #### -port.  -send masks the send(1) -send switch.  -attach
      #### masks the send(1) -attach switch.
      -at|-att|-atta|-attac|-attach)
         mhmailswitch=1
         attacharg=1
         use_send=1
         if [ ${attach_send_switch_added} -eq 0 ]; then
           #### Override any send -attach switch in user's profile.
           postsendargs=\
"${postsendargs:+${postsendargs} }-attach Nmh-Attachment"
           attach_send_switch_added=1
         fi ;;
      -b|-bo|-bod|-body) mhmailswitch=1; bodyarg=1 ;;
      -c|-cc) mhmailswitch=1; ccarg=1 ;;
      -f|-fr|-fro|-from) mhmailswitch=1; fromarg=1 ;;
      -hea|-head|-heade|-header|-headerf|-headerfi|-headerfie|-headerfiel|\
-headerfield) mhmailswitch=1; headerfieldarg=1 ;;
      -hel|-help) printf "${usage}\n"; exit ;;
      -nose|-nosen|-nosend) mhmailswitch=1; sendsw=0 ;;
      -p|-pr|-pro|-prof|-profi|-profil|-profile) mhmailswitch=1; use_send=1 ;;
      -resend) printf "mhmail: did you mean -resent instead of -resend?\n" 1>&2
         exit 1 ;;
      -r|-re|-res|-rese|-resen|-resent) mhmailswitch=1; resent=1 ;;
      -se|-sen|-send) mhmailswitch=1; sendsw=1 ;;
      -su|-sub|-subj|-subje|-subjec|-subject) mhmailswitch=1; subjectarg=1 ;;
      -t|-to) toarg=1; ccarg=0 ;;
      -v|-ve|-ver|-vers|-versi|-versio|-version)
         #### Cheat instead of using autoconf and make to fill in the version.
         "${nmhbindir}"/mhpath -v | sed 's/mhpath/mhmail/'; exit ;;
      -*) if [ ${mhmailswitch} -eq 1 ]; then
            checkforargs
            mhmailswitch=0
          fi
          post_send_switch_arg=1
          postsendargs="${postsendargs:+${postsendargs} }${arg}" ;;
      *) mhmailswitch=0
         if [ ${bodyarg} -eq 1 ]; then
           body="${arg}
"
           bodyarg=0
           #### Allow -body "" by using just a newline for the body.
           [ "${body}"x = x ]  &&  body='
'
         elif [ ${fromarg} -eq 1 ]; then
           from="${arg}"
           fromarg=0
         elif [ ${subjectarg} -eq 1 ]; then
           subject="${arg}"
           subjectarg=0
         elif [ ${attacharg} -eq 1 ]; then
           headerfieldlist="${headerfieldlist:+${headerfieldlist}}\
Nmh-Attachment: ${arg}
"
           attacharg=0
         elif [ ${headerfieldarg} -eq 1 ]; then
           #### It's not strictly necessary to have one space after
           #### the : that separates the header field name from the
           #### body, but do it to avoid surprising someone.
           add=`printf "${arg}" | sed -e 's/:/: /' -e 's/:  /: /'`
           headerfieldlist="${headerfieldlist:+${headerfieldlist}}${add}
"
           headerfieldarg=0
         elif [ ${post_send_switch_arg} -eq 1 ]; then
           postsendargs="${postsendargs:+${postsendargs} }${arg}"
         elif [ ${ccarg} -eq 1 ]; then
           #### ccarg can only be reset to 0 by -to.
           cclist="${cclist:+${cclist}, }${arg}"
         else
           #### An address.
           tolist="${tolist:+${tolist}, }${arg}"
           toarg=0
         fi ;;
    esac
  done

  #### Check for at least one address and -from.
  if [ "${tolist}"x = x ]; then
    printf "mhmail: usage: mhmail addrs ... [switches]\n"; exit 1
  fi
  if [ "${from}"x = x ]; then
    nmhlibdir=`${nmhbindir}/mhparam libdir`/
    from=`${nmhlibdir}ap -format '%(localmbox)' 0`
  fi

  #### Check for missing mandatory arguments.
  checkforargs

  #### Build header.
  [ ${resent} -eq 0 ]  &&  prefix=  ||  prefix='Resent-'
  header="${prefix}To: ${tolist}
"
  [ "${cclist}"x = x ]  ||  header="${header}${prefix}Cc: ${cclist}
"
  [ "${subject}"x = x ]  ||  header="${header}${prefix}Subject: ${subject}
"
  [ "${from}"x = x ]  ||  header="${header}${prefix}From: ${from}
"

  if [ "${headerfieldlist}" ]; then
    header="${header}${headerfieldlist}"
  fi

  #### Set up a file to supply as a draft to post/send.  And set a
  #### trap to remove it.  send moves the file to a backup, so it will
  #### remove that, too.
  umask 077
  tmpdir="${MHTMPDIR:-${TMPDIR:-${TMP:-`${nmhbindir}/mhpath +`}}}"
  tmpfile="${tmpdir}/mhmail$$"
  tmpfilebackup="${tmpdir}/[,#]mhmail$$"
  tmpfileresent=

  message_file=
  if [ ${resent} -eq 0 ]; then
    #### Add blank line after header if not resending.
    header="${header}
"
    message_file="${tmpfile}"
  else
    if [ ${use_send} -eq 0 ]; then
      postsendargs="${postsendargs:+${postsendargs} }-dist"
      message_file="${tmpfile}"
    else
      #### When resending with send, tmpfile will just contain the
      #### Resent- header fields.  "${tmpfileresent}" will contain
      #### the message that is being resent.
      tmpfileresent="${tmpdir}/mhmail-resent$$"
      mhdist=1; export mhdist
      mhaltmsg=${tmpfileresent}; export mhaltmsg
      message_file="${tmpfileresent}"
      printf "" >"${message_file}"  || exit 2
    fi
  fi

  trap 'rm -f '"${tmpfile}"' '"${tmpfilebackup}"' '"${tmpfileresent}" EXIT

  if [ "${body}"x = x ]; then
    #### First put message header in the file.
    printf "${header}" >"${tmpfile}" || exit 2

    tmpfile_size_before=`wc -c "${message_file}"`
    #### Now grab the body from stdin.  cat >> handles blank lines
    #### better than body=`cat`.
    cat >>"${message_file}" || exit 2
    tmpfile_size_after=`wc -c "${message_file}"`

    #### Don't allow an empty body (from stdin).  Use string
    #### comparison so we don't have to strip the filename, etc.
    if [ "${tmpfile_size_before}" = "${tmpfile_size_after}" ]; then
      printf "mhmail: empty message not sent, use -body '' to force.\n" 1>&2
      exit 1
    fi

    #### Add trailing newline to body if it doesn't have one.
    if [ `tail -n 1 "${message_file}" | wc -l` -ne 1 ]; then
      printf "\n" >>"${message_file}" || exit 2
    fi
  else
    #### Add trailing newline to body if it doesn't have one.
    [ `printf "${body}" | tail -n 1 | wc -l` -ne 1 ]  &&  body="${body}
"

    if [ "${tmpfileresent}" ]; then
      #### Put just the new message header in the file.
      printf "${header}" >"${tmpfile}" || exit 2
      #### and the body in the file to resend.
      printf "${body}" >"${tmpfileresent}" || exit 2
    else
      #### Put message header and body in the file.
      printf "${header}${body}" >"${tmpfile}" || exit 2
    fi
  fi

  if [ ${sendsw} -eq 0 ]; then
    cat "${tmpfile}"
  else
    if [ ${use_send} -eq 0 ]; then
      post_or_send=`${nmhbindir}/mhparam postproc`
    else
      post_or_send="${nmhbindir}/send"
    fi

    if "${post_or_send}" "${tmpfile}" ${postsendargs}; then
      exit
    else
      status=$?
      mv -f "${tmpfile}" dead.letter
      printf "Letter saved in dead.letter\n"
      exit $status
    fi
  fi
fi