#!/bin/bash

# game
# Copyright (C) 2009 Thunor <thunorsif@hotmail.com>
# 
# 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/>.

# Object IDs
OBJECT_ROOT=1

# Event IDs
EVENT_INIT=1
EVENT_QUIT=2

# Function IDs
FUNC_INIT=1
FUNC_QUIT=2
FUNC_EXIT=3
FUNC_DO_SOMETHING=4

# Make settings folder if it doesn't already exist
mkdir -p $HOME/.basheng

# Pipe names
PIPEIN=$HOME/.basheng/pipein_$$_$RANDOM
PIPEOUT=$HOME/.basheng/pipeout_$$_$RANDOM

# Start the engine and background it
./engine $PIPEIN $PIPEOUT &
echo "$0: engine pid=$!"

# Force engine shutdown on script exit e.g. ctrl+c
trap "if [ -p $PIPEIN ]; then echo $FUNC_EXIT > $PIPEIN; fi" EXIT

# If necessary, wait a few seconds for both pipes to become available.
# On my PC, most of the time it's instant, but on a hendheld device I
# have experienced a 3 second delay.
if [ ! -p $PIPEIN -o ! -p $PIPEOUT ]; then
	echo "$0: Waiting briefly for both pipes to become available..."
	STARTTIME=$(date "+%s"); ENDTIME=STARTTIME; MAXTIME=9
	until [ $(($ENDTIME-$STARTTIME)) -gt $MAXTIME ]; do
		ENDTIME=$(date "+%s")
		if [ -p $PIPEIN -a -p $PIPEOUT ]; then break; fi
	done
fi

if [ -p $PIPEIN -a -p $PIPEOUT ]; then
	# Sending FUNC_INIT results in the engine unblocking on 
	# "pipein = open(pipein_filename, O_RDONLY);" and eventually
	# sending EVENT_INIT which we'll use to set-up the game/engine
	echo "$0: Sending FUNC_INIT"
	echo $FUNC_INIT > $PIPEIN

	echo "$0: Entering event processing loop"
	while true
	do
		# read will wait until something is received
		if read OBJECT EVENT VALUE1 VALUE2 VALUE3 < $PIPEOUT; then
			if [ $OBJECT == $OBJECT_ROOT ]; then
				if [ $EVENT == $EVENT_INIT ]; then
					echo "$0: Received EVENT_INIT"
					PARAM1=123; PARAM2=456
					echo "$0: Sending FUNC_DO_SOMETHING $PARAM1 $PARAM2"
					# This will result in a reply
					echo $FUNC_DO_SOMETHING $PARAM1 $PARAM2 > $PIPEIN
					read RETVAL < $PIPEOUT
					echo "$0: FUNC_DO_SOMETHING returned $RETVAL"
				elif [ $EVENT == $EVENT_QUIT ]; then
					echo "$0: Received EVENT_QUIT"
					# Shutdown the game
					echo "$0: Sending FUNC_EXIT"
					# This will not result in a reply
					echo $FUNC_EXIT > $PIPEIN
					break
				fi
			fi
		fi
	done

	echo "$0: Goodbye"
	exit 0
else
	echo "$0: Aborting due to unavailable pipes"
	exit 1
fi