#!/usr/bin/env bash

MAIN_CMD=${MAIN_CMD:-$(basename "$0")}
PREFIX="${MAIN_CMD}-"

SHORT_DESCRIPTION=${SHORT_DESCRIPTION:-""}
HELP_MAIN=${HELP_MAIN:-"usage: $MAIN_CMD <sub-commands> [options]"}

if [ -n "$SHORT_DESCRIPTION" ];then
HELP=${HELP:-"$MAIN_CMD: $SHORT_DESCRIPTION

$HELP_MAIN"}
else
HELP=${HELP:-"$HELP_MAIN"}
fi

print_help () {
  cat << EOF
$HELP

sub commands: $commands
EOF
}

print_invalid () {
  cat << EOF
Invalid sub command: $1

Sub commands: $commands
EOF
}

get_alias () {
  for cmd in $(alias|grep "alias $PREFIX"|cut -d' ' -f2|cut -d= -f1);do
    c=${cmd/$PREFIX/}
    commands="$commands $c"
  done
}

get_function () {
  for cmd in $(declare -F|grep "declare -f $PREFIX"|cut -d' ' -f3);do
    c=${cmd/$PREFIX/}
    commands="$commands $c"
  done
}

get_exe () {
  local orig_ifs=$IFS
  IFS=":"
  local pathes=($PATH)
  IFS=$orig_ifs
  local p
  local f
  local cmd
  for p in "${pathes[@]}";do
    if [ ! -d "$p" ];then
      continue
    fi
    while read -r f;do
      if [ -x "$f" ];then
        cmd="${f##*/}"
        c=${cmd/$PREFIX/}
        commands="${commands} $c"
      fi
    done < <(find  "$p" -maxdepth 1 -name  "${PREFIX}*")
  done
}

get_commands () {
  commands=""
  get_alias
  get_function
  get_exe
  commands="$(for c in $commands;do echo $c;done |sort -u|tr $'\n' ' ')help"
}

check_command () {
  get_commands
  if [ $# -eq 0 ] || [ "$1" = "-h" ] || [ "$1" = "help" ];then
    print_help
    exit
  fi
  cmd="$1"
  shift
  if ! echo " $commands "|grep -q " $cmd ";then
    print_invalid "$cmd"
    exit 1
  fi
}

execute () {
  check_command "$@"
  shift
  "$PREFIX$cmd" "$@"
}

execute "$@"