#!/bin/bash
#
# Processes input text and outputs result
#
# This script will return one of two commands with an associated argument, which
# should be interpreted as follows:
#   - MSG - Output the provided message
#   - GO  - Go to the scene matching the provided id
#
#   Copyright (C) 2011 Mike Gerwitz
#
#   This file is part of gsgp. This program is free software: you can
#   redistribute it and/or modify it under the terms of the GNU General Public
#   License as published by the Free Software Foundation, either version 3 of
#   the License, or (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
##

words="$1"
max_words=2
data=$( cat - )

# scene data should be provided via stdin
[ "$data" ] || {
    echo "No scene data provided" >&2
    exit 1
}

# our processing method depends heavily on the word count
count=$( grep -o '\w\+' <<< "$words" | wc -l )

# no use in allowing more words than we're able to interpret
if [ $count -gt $max_words ]; then
    echo "Too many words" >&2
    exit 2
fi

action=$( cut -d' ' -f1 <<< "$words" )
object=$( cut -d' ' -f2 <<< "$words" )

# check for am action on a known object
action_data=$( awk "
    /OBJECT $object/,/^$/ {
        if ( /^[ \t]*ACTION $action / ) {
            print
        }
    }
    " <<< "$data" \
    | sed 's/ *ACTION [^ ]\+ \(.*\)$/\1/'
)

# if we were unable to find the associated object/action, then let the user know
# that they've performed an invalid action
if [ ! "$action_data" ]; then
    echo "MSG Cannot $words"
    exit 0
fi

# what type of command should we execute?
cmd=$( cut -d' ' -f1 <<< "$action_data" )
arg=$( cut -s -d' ' -f2- <<< "$action_data" )

case "$cmd" in
    GO)
        if [ ! "$arg" ]; then
            echo "ERROR: GO command requires target scene" >&2
            exit 4
        fi

        # the action will be to go to the target scene
        echo "GO $arg"
        ;;

    MSG)
        if [ ! "$arg" ]; then
            echo "ERROR: MSG requires an output string" >&2
            exit 4
        fi

        # the MSG action will indicate that a message should be output
        echo "MSG $arg"
        ;;

    *)
        echo "ERROR: Unknown command '$cmd' for action: $words" >&2
        exit 4
        ;;
esac