#!/bin/bash

# NOTE(crutcher):
# This is a work in progress. Don't pay too mutch attention to it. It has
# the basic functionality that I want, but it has bad naming conventions,
# relies too much on sed, and has some issues with how aliases are stored.


# Components of a subcommand dispatcher's subcommands:
#  * function
#  * aliases
#  * shorthelp
#  * usage
#  * help

function cmd_aliases() {
  local aliases=${1}_aliases;
  echo ${!aliases};
}

function define_aliases() {
  eval "${1}_aliases='$2'";
  for name in $2; do
    if [ -z "$(alias2cmd $name)" ]; then
      eval alias2cmd__${name}=$1;
    else
      echo Error: alias \"$name\" already maps to \"$(alias2cmd $name)\"
      exit 1;
    fi
  done
  local primary_alias=$(echo $2 | sed 's/ .*//');
  primary_alias_list="$primary_alias_list $primary_alias"
}

function alias2cmd() {
  local var=alias2cmd__${1};
  echo ${!var};
}

function dispatch() {
  local name=$1;
  shift;
  args="$@";

  cmd=$(alias2cmd $name);
  if [ ! -z "$cmd" ]; then
    $cmd "$@";
  else
    helpCmd;
  fi
}


function print_cmd_blurb() {
  local cmd=$1;
  local aliases=$(cmd_aliases $cmd);
  local primary_alias=$(echo $aliases | sed 's/ .*//');
  local other_aliases=$(echo $aliases | sed 's/^[^ ]\+ *//');
  echo -n $primary_alias
  if [ ! -z "$other_aliases" ] ; then 
    echo -n ' ('$(echo $other_aliases | sed 's/ \+/, /g')')';
  fi
  local shorthelp=${cmd}_shorthelp;
  echo ' -' ${!shorthelp}
}

function print_cmd_usage() {
  local cmd=$1;
  local cmd_usage=${cmd}_usage;
  if [ ! -z "${!cmd_usage}" ] ; then
    echo 'usage:' ${!cmd_usage}
  fi
}

function print_available_cmds() {
  echo 'Available Commands:';
  for name in $primary_alias_list; do
    echo -n '  ';
    print_cmd_blurb $(alias2cmd $name);
  done
}

define_aliases helpCmd "help"
helpCmd_usage="help [COMMAND]"
helpCmd_shorthelp="display help"
function helpCmd() {
  local cmd=$(alias2cmd $1);
  if [ -z "$cmd" ]; then
    if [ ! -z "$1" ]; then
      echo Error: Unknown Command \"$1\";
    fi
    HELP_PREAMBLE
    echo -ne '\nHelp : '
    print_available_cmds;
  elif [ "$cmd" == helpCmd ]; then
    print_cmd_blurb $cmd;
    print_cmd_usage $cmd;
    cat <<EOF
  Display help on a given command.

EOF
    print_available_cmds;
  else
    echo -n 'Help : '
    print_cmd_blurb $cmd;
    print_cmd_usage $cmd;
    ${cmd}_helpfunc | sed 's/^/  /'
  fi
}

#
# prog specific code goes below this line.
# 

function HELP_PREAMBLE() {
  cat << EOF
Help for the interpreter.
EOF
}


define_aliases helloCmd "hello hi"
helloCmd_usage="hello [TARGET]"
helloCmd_shorthelp="say hello"
function helloCmd_helpfunc() {
  cat << EOF
Say hello to people.
EOF
}
function helloCmd() {
  echo Hello ${1:-World}'!';
}


#
# This must be called _after_ all funcs are defined to run the dispatch
# 
dispatch "$@";