browse_packages

#!/bin/bash
#
# Browse installed packages along with info about them.
#
# Dependencies: coreutils, fzf, less, pacman, pacman-contrib, sed

set -o nounset -o pipefail

readonly L_OPTS="help,version"
readonly OPTS="hVv"

readonly CMD="${0##*/}"
readonly USAGE="${CMD} [OPTION]..."
readonly USAGE_ERR_MSG=$(
  cat <<END
Usage: ${USAGE}
Try '${CMD} --help' for more information.
END
)
readonly VERSION_INFO=$(
  cat <<END
${CMD} (scripts) 1.0.0

This is free and unencumbered software released into the public domain.
For more information, please refer to <https://unlicense.org/>.
END
)
readonly HELP=$(
  cat <<END
SYNOPSIS
  ${USAGE}

DESCRIPTION
  Browse installed packages along with info about them.
  Press ENTER on any package for a detailed view that includes files.

OPTIONS
  -h, --help
    display this help and exit
  -V, -v, --version
    display version and exit
END
)

#######################################
# Align command according to the 'pacman --info' format
# Arguments:
#  cmd - command to align
#  name - first column of the format (every character before ':')
#######################################
function align_cmd() {
  local -r cmd="$1"
  local -r name="$2"

  echo "${cmd} | sed '1s/^/${name}: /' | sed '2,\$s/^/                  /'"
}

#######################################
# Main function
# Globals:
#   CMD - script basename
#   HELP - help message
#   L_OPTS - long non-positional options (e.g. --help)
#   OPTS - short non-positional options (e.g. --h)
#   USAGE_ERR_MSG - usage error message
#######################################
function main() {
  local opts
  opts=$(
    getopt \
      --options=${OPTS} --longoptions=${L_OPTS} \
      --name "${CMD}" \
      -- "$@"
  )
  if (($? != 0)); then
    echo "${USAGE_ERR_MSG}"
    exit 2
  fi

  eval set -- "${opts}"

  local need_help=false
  local need_version=false

  while true; do
    case "$1" in
      -h | --help)
        need_help=true
        shift
        break
        ;;
      -V | -v | --version)
        need_version=true
        shift
        break
        ;;
      --)
        shift
        break
        ;;
    esac
  done

  if [[ $need_help == true ]]; then
    echo "${HELP}"
    exit 0
  fi

  if [[ $need_version == true ]]; then
    echo "${VERSION_INFO}"
    exit 0
  fi

  if (($# != 0)); then
    echo "${CMD}: expected 0 arguments; got $#"
    echo "${USAGE_ERR_MSG}"
    exit 2
  fi

  local -r files_list_cmd=$(
    align_cmd "pacman --query --list --quiet {}" "Package Files   "
  )
  local -r files_status_cmd=$(
    align_cmd "LC_ALL=C pacman --query --check --check {} 2>&1" \
              "Files Status    "
  )
  local -r package_info_cmd="LC_ALL=C pacman --query --info {} \
                               | head --bytes=-1"
  local -r reversed_tree_cmd=$(
    align_cmd "pactree --optional=-1 --reverse {}" "Reversed Tree   "
  )

  local -r preview_cmd="${package_info_cmd} ; ${reversed_tree_cmd}"

  local -r on_enter_cmd="\
  { \
    ${package_info_cmd}; \
    ${reversed_tree_cmd}; \
    ${files_list_cmd}; \
    ${files_status_cmd}; \
  } | less"

  pacman --query --quiet \
    | fzf --preview "${preview_cmd}" \
      --bind "enter:execute(${on_enter_cmd})" \
      --no-mouse \
      --preview-window=right,70% \
      --reverse

  declare -ir exit_code=$?

  if ((exit_code == 130)); then
    exit 0
  else
    exit ${exit_code}
  fi
}

main "$@"