git-blame-nemesis

#!/usr/bin/env bash

set -eE -o functrace

## Optional, but recommended to find true directory this script resides in
__SOURCE__="${BASH_SOURCE[0]}"
while [[ -h "${__SOURCE__}" ]]; do
    __SOURCE__="$(find "${__SOURCE__}" -type l -ls | sed -n 's@^.* -> \(.*\)@\1@p')"
done
__NAME__="${__SOURCE__##*/}"
__DIR__="$(cd -P "$(dirname "${__SOURCE__}")" && pwd)"
__AUTHOR__='S0AndS0'
__DESCRIPTION__='Find and git blame all files modified by author'

## Source module code within this script
source "${__DIR__}/modules/trap-failure/failure.sh"

trap 'failure "LINENO" "BASH_LINENO" "${BASH_COMMAND}" "${?}"' ERR

##
#
__license__(){
  local __AUTHOR__="${__AUTHOR__:-S0AndS0}"
  local _year
  _year="$(date +'%Y')"
  cat <<EOF
Copyright (C) ${_year} ${__AUTHOR__}

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, version 3 of the License.

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 Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
EOF
}

##
#
__version__() {
  local _version_number
  _version_number="$(git tag --list v* | tail -n1)"
  _version_number="${_version_number:-v0.1.0}"
  _version_number="${_version_number//[^0-9.]/}"

  printf '%s - %s\n' "${__NAME__}" "${_version_number}"
  __license__ "${__AUTHOR__}"
  printf '\nWritten by %s\n' "${__AUTHOR__}"
}

##
#
__usage__() {
  local _message="${1}"
  cat <<EOF
${__DESCRIPTION__}


Usage: ${__NAME__} [OPTIONS]...


Options:
--help
    Prints this message and exits

--license
    Prints copyright for this script and exits

--verbose
    Prints messages about actions

--version
    Prints version for this script and exits

--author "someone"
    Commit author to blame

-- [OPTIONS]
    Arguments to pass through to git blame command

    Utilize following commands for relevant documentation;

      - git help blame

      - man git-blame


Examples:
    ${__NAME__} --verbose --author "${__AUTHOR__}"
EOF

  if (( ${#_message} )); then
    printf >&2 'Error: %s\n' "${_message}"
    return 1
  fi
}

##
# Parse CLI parameters
while (( ${#@} )); do
  case "${1}" in
    --)
      shift 1
      _pass_through_arguments=("${@}")
      break
    ;;
    --version)
      __version__
      exit 0
    ;;
    --license)
      __license__
      exit 0
    ;;
    --help)
      __usage__ ''
      exit 0
    ;;
    --verbose)
      _verbose=1
      shift 1
    ;;
    --author)
      _author="${2:?Undefined value for --author}"
      shift 2
    ;;
  esac
done

##
#
git_log_hashes_by_author() {
  local _author="${1:?Undefined author}"

  git log --author="${_author}" \
    --pretty='format:%h' \
    --ignore-space-change
}

##
#
git_log_paths_by_author() {
  local _author="${1:?Undefined author}"

  git log "${_hash}" --author="${_author}" \
    --pretty='format:' \
    --oneline \
    --name-only
}

##
#
git_is_tracking_hash_path() {
  local _hash="${1:?Undefined hash}"
  local _path="${2:?Undefined path}"

  git show "${_hash}" "${_path}" 1>/dev/null 2>&1
}

##
#
git_blame_hash_path() {
  local _hash="${1:?Undefined hash}"
  local _path="${2:?Undefined path}"

  local _git_opts=(
    "${_pass_through_arguments[@]}"
    "${_hash}"
    "${_path}"
  )

  ## Note: this guard is required due to differences in behavior between
  ##  interactive and non-interactive shell sessions
  if ! git_is_tracking_hash_path "${_hash}" "${_path}"; then
    if (( _verbose )); then
      printf >&2 '[Skipped] git blame %s\n' "${_git_opts[*]}"
    fi
    return
  fi

  read -t 10 -r -p "[Enter] git blame ${_git_opts[*]} "
  if [[ "${REPLY}" =~ ^(n|q) ]]; then
    return 1
  fi
  git blame "${_git_opts[@]}"
}

##
#
while read -r -u 3 _hash; do
  while read -r -u 4 _path; do
    if ! git_blame_hash_path "${_hash}" "${_path}"; then
      break 2
    fi
  done 4< <(git_log_paths_by_author "${_author}")
done 3< <(git_log_hashes_by_author "${_author}")