#!/bin/sh
#
# edit-header - helper script to append/replace/remove headers with mutt
#
# Based on an idea by David Champion <dgc at uchicago.edu>
#
# Copyright © 2008 martin f. krafft <madduck@madduck.net>
# Released under the terms of the Artistic Licence 2.0
#
set -eu

if [ ! -x "$(command -v formail)" ]; then
  echo E: formail not installed. >&2
  exit 1
fi

header="${1:-}"
if [ -z "$header" ]; then
  echo "E: no header specified" >&2
  exit 1
fi

get_header_contents()
{
  local contents
  printf "Enter ${1:-header} contents: " >/dev/tty
  read contents </dev/tty
  echo "$contents"
}

script="${0%/*}/${2:-}"
if [ -f "$script" ] && [ -x "$script" ]; then
  if [ -z "${__RLWRAPPED:-}" ] && [ -x $(command -v rlwrap) ]; then
    __RLWRAPPED=true exec rlwrap "$0" "$@"
  fi

  contents_source="$script"
  shift
else
  contents_source=get_header_contents
fi

editor=
case "$0" in
  *append-header|*supersede-header|*replace-header)
    contents="${2:-}"
    [ -n "$contents" ] || contents="$(eval $contents_source $header)"
    case "$0" in
      *append-header) flag=-A;;
      *supersede-header) flag=-i;;
      *replace-header) flag=-I;;
    esac
    editor="${0%/*}/filter-proxy formail $flag \'$header: $contents\'"
    ;;

  *remove-header)
    editor="${0%/*}/filter-proxy formail -I \'$header:\'"
    ;;

  *)
    echo "E: unknown invocation: ${0##*/}" >&2
    exit 1
    ;;

esac

echo "set my_editor=\"\$editor\""
echo "set my_filter=\"$editor\""
echo -n "push '"
echo -n "<enter-command>set editor=\"\$my_filter\"<enter>"
echo -n "<edit>"
echo -n "<enter-command>set editor=\"\$my_editor\"<enter>"
echo -n "<enter-command>unset my_filter<enter>"
echo -n "<enter-command>unset my_editor<enter>"
echo "'"