gfixup

#!/usr/bin/env bash
# Usage: {script} PATH
# Construct a commit message for use with rebase --autosquash.
# The commit message will be the subject line from the specified commit with a prefix of "fixup! " and will contain the
# changes on the PATH.
#
#   --help, -h   Displays this help
#
# Report bugs to Henrique Moody <henriquemoody@gmail.com>
#

set -euo pipefail

declare -a HASH_LIST
declare -i HASH_INDEX=1
declare -i HASH_CHOSEN=0
declare -r PATHNAME=${1}

_help()
{
  sed -E 's/^#\s?(.*)/\1/g' "${0}" |
    sed -nE '/^Usage/,/^Report/p' |
    sed "s/{script}/$(basename "${0}")/g"
}

if [[ "${1}" = "--help" ]] || [[ "${1}" = "-h" ]]; then
  _help
  exit
fi

if [[ -z "${1}" ]]; then
  _help 1>&2
  exit 1
fi

if [[ ! -e "${PATHNAME}" ]]; then
  echo "\`${PATHNAME}\` is not a valid path" 1>&2
  exit 2
fi

while read line; do
  echo "${HASH_INDEX}: $(cut -d ' ' -f 2,3- <<< "${line}")"
  HASH_LIST[HASH_INDEX]=$(cut -d ' ' -f 1 <<< "${line}")
  ((++HASH_INDEX))
done < <(git log origin/HEAD...HEAD --format="%H %h %s" "${PATHNAME}")

echo
while [[ -z "${HASH_LIST[HASH_CHOSEN]}" ]]; do
  echo -n "Which commit would you like to fixup? "
  read HASH_CHOSEN
done

echo
set -x
git commit --fixup="${HASH_LIST[HASH_CHOSEN]}" "${PATHNAME}"