gist_pull

#!/bin/bash
# Pull all the gists for a given user

user="${1:?No github user defined}"
base_uri="https://api.github.com/users/${user}/gists"
gist_path="${2:-${HOME}/git/gists}"
gist_manifest="${gist_path}/manifest.json"

# Get the top level PID and setup a trap so that we can call die() within subshells
trap "exit 1" TERM
_self_pid="${$}"
export _self_pid

# shellcheck disable=SC2059
die() {
  [ -t 0 ] && _diefmt='\e[31;1m====>%s\e[0m\n'
  printf "${_diefmt:-====>%s\n}" "${0}:(${LINENO}): ${*}" >&2
  # Send a TERM signal to the top level PID, this is trapped and exit 1 is forced
  kill -s TERM "${_self_pid}"
}

requires() {
  local cmd err_count
  err_count=0
  for cmd in "${@}"; do
    if ! command -v "${cmd}" >/dev/null 2>&1; then
      err "${cmd} is required but was not found in PATH"
      (( ++err_count ))
    fi
  done
  (( err_count > 0 )) && exit 1
  return 0
}

# A function to prompt/read an interactive y/n response
# Stops reading after one character, meaning only 'y' or 'Y' will return 0
# Any other character, or an optional timeout (-t|--timeout) will return 1
# Provenance: https://gist.github.com/rawiriblundell/7e8a26d8076ce09b6daa315389f822cd
confirm() {
  local confirm_args
  case "${1}" in
    (-t|--timeout)
      confirm_args=( -t "${2}" )
      set -- "${@:3}"
    ;;
  esac
  
  read "${confirm_args[@]}" -rn 1 -p "${*:-Continue} [y/N]? "
  printf -- '%s\n' ""
  case "${REPLY}" in
    ([yY]) return 0 ;;
    (*)    return 1 ;;
  esac
}

get_url() {
  case "${1}" in
    (--save)  CURL_OPTS=( -O ); shift 1 ;;
  esac
  curl "${CURL_OPTS[@]}" -s "${1:?No URL defined}"
}

generate_insitu_ids() {
  readarray -t insitu_ids < <(
    find . -maxdepth 1 -type d -name "[a-z0-9]*" -printf '%P\n'
  )
}

generate_diff_ids() {
  readarray -t diff_ids < <(
    printf -- '%s\n' "${gist_id_list[@]}" "${insitu_ids[@]}" | sort | uniq -u
  )
}

main() {
  requires curl jq mkdir cd

  # Ensure our gist_path exists
  mkdir -p "${gist_path}" || die "Could not create ${gist_path}"

  # Make our API call and save its output
  get_url "${base_uri}" > "${gist_manifest}"

  # Parse the saved output, plucking out all our gist id's
  readarray -t gist_id_list < <(jq -r '.[].id' "${gist_manifest}")

  (
    cd "${gist_path}" || die "Could not enter ${gist_path}..."
    generate_insitu_ids
    generate_diff_ids
    for gist_id in "${gist_id_list[@]}"; do
      printf -- '%s\n' "Syncing ${gist_id}..."
      gist_uri="https://gist.github.com/${gist_id}.git"
      [[ ! -d "${gist_id}" ]] && git clone "${gist_uri}"
      (
        cd "${gist_id}" || die "Could not enter ${gist_path}/${gist_id}"
        # Get the matching filename from the gist_manifest file
        gist_filename=$(
          jq -r --arg gist_id "${gist_id}" '
            .[] | 
              select(.id==$gist_id) | 
              .files[].filename' "${gist_manifest}"
        )
        ln_target="${gist_path}/${gist_id}/${gist_filename}"
        ln_link="${gist_path}/${gist_filename}"
        ln -s "${ln_target}" "${ln_link}" >/dev/null 2>&1
      )
    done
    if (( "${#diff_ids[@]}" >= 1 )); then
      for old_id in "${diff_ids[@]}"; do
        printf -- '%s\n' "Contents of ${old_id}"
        ls "${old_id}/"
        if confirm "${old_id} appears to be abandoned.  Delete?"; then
          rm -rf "${old_id}"
        fi
      done
    fi
  )
}

main "${@}"