#!/usr/bin/env bash
# Library for easier Git hook scripting
# Copyright (C) 2019  Aaron Ball <nullspoon@oper.io>
#
# 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/>.
set -eou pipefail

export OLDREV NEWREV REFNAME
declare -a TAGS
declare -a REFS
declare -a FILES_A
declare -a FILES_M
declare -a FILES_D
declare -a FILES_R

export IFS=$' \n\t'
read OLDREV NEWREV REFNAME
export IFS=$'\n'
[ ${OLDREV} = '0000000000000000000000000000000000000000' ] && OLDREV=${NEWREV}
[ ${NEWREV} = '0000000000000000000000000000000000000000' ] && NEWREV=${OLDREV}


# load_tags:
# Loads any tags into the TAGS array that were created within the changed refs.
load_tags() {
  if [ "${REFNAME:0:10}" = 'refs/tags/' ]; then
    if [ -f "${REFNAME}" ]; then
      printf '[tag] created %s\n' "$(basename ${REFNAME})"
      TAGS+=("$(basename ${REFNAME})")
    elif [ ! -f "${REFNAME}" ]; then
      printf '[tag] deleted %s\n' "$(basename ${REFNAME})"
    else
      printf '[tag] Something went wrong with "%s"\n' "${REFNAME}"
    fi
  fi
}


# load_refs:
# Loads the list of new refs into the REFS array
load_refs() {
  REFS=($(git rev-list "^${OLDREV}" "${NEWREV}"))
}


# load_file_actions:
# Reads the changed refs list and loads file paths into their respective files
# arrays (eg: FILES_A (added), FILES_D (deleted), FILES_M (modified), and
# FILES_R (renamed)).
load_file_actions() {
  local changes=($(git diff --name-status "^${OLDREV}" "${NEWREV}"))
  for change in ${changes[@]}; do
    if [ "${change:0:1}" = 'A' ]; then
      # File is added
      FILES_A+=(${change#*	})
    elif [ "${change:0:1}" = 'M' ]; then
      # File is modified
      FILES_M+=(${change#*	})
    elif [ "${change:0:1}" = 'D' ]; then
      # File is deleted
      FILES_D+=(${change#*	})
    elif [ "${change:0:4}" = 'R100' ]; then
      # File is moved/renamed
      FILES_R+=(${change#*	})
    fi
  done
}


# dump_sess:
# Dumps all gathered info about the git operation to stdout so clients can see
# the changes that were detected. This includes dumping the files arrays, tags
# arrays and the ref information.
dump_sess() {
  printf '\n'
  printf 'OLD:  %s\n' "${OLDREV}"
  printf 'NEW:  %s\n' "${NEWREV}"
  printf 'NAME: %s\n\n' "${REFNAME}"
  printf 'Files added:\n'
  printf '  %s\n' "${FILES_A[@]}"
  printf 'Files modified:\n'
  printf '  %s\n' "${FILES_M[@]}"
  printf 'Files deleted:\n'
  printf '  %s\n' "${FILES_D[@]}"
  printf 'Files renamed:\n'
  printf '  %s\n' "${FILES_R[@]}"
  printf 'Tags created:\n'
  printf '  %s\n' "${TAGS[@]}"
  printf '\n'
}