bin/git-commands

#!/usr/bin/env bash
#
# This script started out as a fork of:
#   https://github.com/hankchanocd/git-commands
#
# Based on `git help -a` provided by `hub`, show all the available git
# commands, both native and custom.
#
# git help -a
#   Ref: https://stackoverflow.com/questions/7866353/git-list-all-available-commands

# -- Ensure Correct git help options ------------------------------------------
help_options='-a'
# https://github.com/git/git/blob/b697d92f/Documentation/RelNotes/2.20.0.txt#L17-L18
git help --no-verbose > /dev/null 2>&1 && help_options='--no-verbose -a'
# Retrieve the git help, only once
# shellcheck disable=SC2086
git_help_all=$(git help $help_options)

# -- Preparation --------------------------------------------------------------
# The line that divides the whole text into two: regular and custom commands
dividing_line_number=$(
  grep -n "git commands available from elsewhere on your \$PATH" \
    <<< "$git_help_all" | sed 's/[^0-9]*//g'
)

whole_line_number=$(
  wc -l <<< "$git_help_all"
)

# shellcheck disable=SC2034
black="$(tput setaf 0)"
red="$(tput setaf 1)"
# shellcheck disable=SC2034
green="$(tput setaf 2)"
# shellcheck disable=SC2034
yellow="$(tput setaf 3)"
blue="$(tput setaf 4)"
# shellcheck disable=SC2034
magenta="$(tput setaf 5)"
# shellcheck disable=SC2034
cyan="$(tput setaf 6)"
white="$(tput setaf 7)"

reset="$(tput sgr0)"

# -- Child Functions ----------------------------------------------------------
function native_commands() {
  while read -r line; do
    echo -e "${white}${line}${reset}"
  done < <(
    head -n "$dividing_line_number" \
      <<< "$git_help_all" | grep "^  [a-z]" | tr ' ' '\n' | grep -v "^$"
  )
}

function custom_commands() {
  while read -r line; do
    echo -e "${blue}${line}${reset}"
  done < <(
    tail -n $((whole_line_number - dividing_line_number)) \
      <<< "$git_help_all" | grep "^  [a-z]" | tr ' ' '\n' | grep -v "^$"
  )
}

function all_commands() {
  native_commands && custom_commands
}

# -- Main ---------------------------------------------------------------------
function main() {
  # If fzf exists
  if command -v fzf > /dev/null 2>&1; then
    while result=$(
      fzf --ansi --reverse --height=90% --cycle \
        --header="Preview: alt-j:↓,alt-k:↑,^f:pg↓,^b:pg↑" \
        --bind "alt-j:preview-down,alt-k:preview-up,ctrl-f:preview-page-down,ctrl-b:preview-page-up" \
        --preview-window=right:75% \
        --preview="COLUMNS=$(( $(tput cols) * 3/4 )) git help git-{} || {
          echo '\n' && (cd /tmp && git-{} -h 2> /dev/null)
        }" <<< "$("${1:-all_commands}" | sort -u -k 1.6)"
        # Ref: https://unix.stackexchange.com/questions/157923/sorting-strings-with-ansi-escape-codes
    ); do
      [[ -n "$result" ]] && git help "$result"
    done
  else
    cat <<EOT

${red}"fzf" is not detected in your \$PATH. Falling back to: "git help $help_options"${reset}

$git_help_all

EOT
  fi
}

# -- Help ---------------------------------------------------------------------
usage() {
  cat <<EOT >&2

  usage: ${0##*/} [<options>]

  List all available git commands with help using fzf.
  Native git commands in white, ${blue}custom git commands in blue${reset}.

  where:
    -h  show this help text
    -n  list only the native git commands
    -c  list only the custom git commands
    -a  list all commands (default)

  Preview window keybindings:
    alt-j:preview-down
    alt-k:preview-up
    ctrl-f:preview-page-down
    ctrl-b:preview-page-up

EOT
}

# -- Parse options ------------------------------------------------------------
while getopts ':hnca:' option; do
  case "$option" in
    h) usage;;
    n) main native_commands;;
    c) main custom_commands;;
    a) main;;
    :) main;;
  \?) printf "Illegal option: -%s\n" "$OPTARG" >&2
      usage && exit 1;;
  esac
done
[[ $OPTIND -eq 1 ]] && main