#!/bin/bash
# Copies first body h1 text into title
#
#  Copyright (C) 2019 Mike Gerwitz
#
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This assumes that an <article> tag exists and assumes that is the main
# content from which the title ought to be derived.
##

set -euo pipefail


main()
{
  local -r placeholder=${1?Missing placeholder}

  local body;
  body=$( cat )

  local title
  title=$(
    <<<"$body" grep -A10 '<main' \
      | grep '<h1' \
      | head -n1 \
      | grep -oP '(?<=>)[^<]+' \
  ) || {
    echo 'error: h12title: failed to locate heading' >&2
    exit 1
  }

  sed "s#$placeholder#${title/&/\\&}#" <<< "$body" || {
    printf "error: h12title: failed title replacement: '%s'\n" "$title" >&2
    exit 1
  }
}

main "$@"