hosts/scripts/hosts-completion

#!/usr/bin/env bash
###############################################################################
# hosts / scripts / hosts-completion
#
# Install and uninstall completions for `hosts`.
#
# https://github.com/xwmx/hosts
###############################################################################

###############################################################################
# Strict Mode
#
# More Information:
#   https://github.com/xwmx/bash-boilerplate#bash-strict-mode
###############################################################################

set -o nounset
set -o errexit
set -o errtrace
set -o pipefail
IFS=$'\n\t'

###############################################################################

export _MY_DIR=
_MY_DIR="$(cd "$(dirname "$0")"; pwd)"
if [[ -z "${_MY_DIR}" ]] || [[ ! -d "${_MY_DIR}" ]]
then
  exit 1
fi

# Usage: _get_bash_completion_path
_get_bash_completion_path() {
  local _bash_completion_path=

  if [[ -n "${BASH_COMPLETION_COMPAT_DIR:-}" ]] &&
     [[ -w "${BASH_COMPLETION_COMPAT_DIR:-}" ]]
  then
    _bash_completion_path="${BASH_COMPLETION_COMPAT_DIR}"
  fi

  if [[ -z "${_bash_completion_path:-}" ]]
  then
    local _maybe_path
    _maybe_path="$(
      pkg-config --variable=completionsdir bash-completion 2>/dev/null || true
    )"

    if [[ -n "${_maybe_path:-}" ]] &&
       [[ -w "${_maybe_path:-}" ]]
    then
      _bash_completion_path="${_maybe_path}"
    fi
  fi

  if [[ -z "${_bash_completion_path:-}"       ]] &&
     [[ -d "/usr/local/etc/bash_completion.d" ]] &&
     [[ -w "/usr/local/etc/bash_completion.d" ]]
  then
    _bash_completion_path="/usr/local/etc/bash_completion.d"
  fi

  if [[ -z "${_bash_completion_path:-}" ]] &&
     [[ -d "/etc/bash_completion.d"     ]] &&
     [[ -w "/etc/bash_completion.d"     ]]
  then
    _bash_completion_path="/etc/bash_completion.d"
  fi

  printf "%s\\n" "${_bash_completion_path:-}"
}

# subcommands ################################################### subcommands #

# Usage: _check
_check() {
  local _bash_completion_path=
  _bash_completion_path="$(_get_bash_completion_path)"

  local _exists=0

  if [[ -n "${_bash_completion_path:-}" ]] &&
     [[ -d "${_bash_completion_path}"   ]] &&
     [[ -w "${_bash_completion_path}"   ]] &&
     [[ -e "${_bash_completion_path}/hosts" ]]
  then
    _exists=1
    printf "Exists: %s\\n" "${_bash_completion_path}/hosts"
  fi

  local _zsh_completion_path="/usr/local/share/zsh/site-functions"

  if [[ -d "${_zsh_completion_path}" ]] &&
     [[ -w "${_zsh_completion_path}" ]] &&
     [[ -e "${_zsh_completion_path}/_hosts" ]]
  then
    _exists=1
    printf "Exists: %s\\n" "${_zsh_completion_path}/_hosts"
  fi

  ((_exists)) || return 1
}

# Usage: _install
_install() {
  local _bash_completion_path=
  _bash_completion_path="$(_get_bash_completion_path)"

  if [[ -n "${_bash_completion_path:-}" ]] &&
     [[ -d "${_bash_completion_path}"   ]] &&
     [[ -w "${_bash_completion_path}"   ]] &&
     [[ ! -e "${_bash_completion_path}/hosts" ]]
  then
    cp \
      "${_MY_DIR}/../etc/hosts-completion.bash" \
      "${_bash_completion_path}/hosts"
    printf "Completion installed: %s\\n" "${_bash_completion_path}/hosts"

    # Cleanup old completion script.
    if [[ -e "${_bash_completion_path}/hosts-completion.bash" ]]
    then
      rm "${_bash_completion_path}/hosts-completion.bash"
    fi
  fi

  local _zsh_completion_path="/usr/local/share/zsh/site-functions"

  if [[ -d "${_zsh_completion_path}" ]] &&
     [[ -w "${_zsh_completion_path}" ]] &&
     [[ ! -e "${_zsh_completion_path}/_hosts" ]]
  then
    cp \
      "${_MY_DIR}/../etc/hosts-completion.zsh" \
      "${_zsh_completion_path}/_hosts"
    printf "Completion installed: %s\\n" "${_zsh_completion_path}/_hosts"
  fi
}

# Usage: _uninstall
_uninstall() {
  local _bash_completion_path=
  _bash_completion_path="$(_get_bash_completion_path)"

  if [[ -n "${_bash_completion_path:-}" ]] &&
     [[ -d "${_bash_completion_path}"   ]] &&
     [[ -w "${_bash_completion_path}"   ]] &&
     [[ -e "${_bash_completion_path}/hosts" ]]
  then
    rm "${_bash_completion_path}/hosts"
    printf "Completion removed: %s\\n" "${_bash_completion_path}/hosts"

    # Cleanup old completion script.
    if [[ -e "${_bash_completion_path}/hosts-completion.bash" ]]
    then
      rm "${_bash_completion_path}/hosts-completion.bash"
    fi
  fi

  local _zsh_completion_path="/usr/local/share/zsh/site-functions"

  if [[ -d "${_zsh_completion_path}" ]] &&
     [[ -w "${_zsh_completion_path}" ]] &&
     [[ -e "${_zsh_completion_path}/_hosts" ]]
  then
    rm "${_zsh_completion_path}/_hosts"
    printf "Completion removed: %s\\n" "${_zsh_completion_path}/_hosts"
  fi
}

# main ################################################################# main #

# Usage: _main <args>...
_main() {
  _subcommand="${1:-}"

  case "${_subcommand}" in
    check)
      _check
      ;;
    install)
      _install
      ;;
    uninstall)
      _uninstall
      ;;
    *)
      cat <<HEREDOC
hosts-completion

Usage:
  hosts-completion [check | install | uninstall]

Description:
  Manage completion scripts for \`hosts\`.
HEREDOC
      ;;
  esac
} && _main "$@"