#!/usr/bin/env bash
#
# play tic-tac-toe

# parse args
#

export USAGE="usage: $0 [-h] [-e] <command>
	-h  show this help and exit
	-e  show compiler stdout

	commands:
	    ./ttt [move_digit]	    play a place
	    ./ttt quitgame	    quit the game
	    ./ttt clobber	    clean the state of the game
"

export E_FLAG=
while getopts :he flag; do
    case "$flag" in
    h)	echo "$USAGE" 1>&2
	exit 2
	;;
    e)	E_FLAG="1"
	;;
    \?) echo "$0: ERROR: invalid option: -$OPTARG" 1>&2
	exit 3
	;;
    :)	echo "$0: ERROR: option -$OPTARG requires an argument" 1>&2
	exit 3
	;;
   *)
	;;
    esac
done

# check args
#
shift $(( OPTIND - 1 ));
if [[ $# -gt 1 ]]; then
    echo "$USAGE" 1>&2
    exit 1
elif [[ $# -eq 1 ]]; then
    move="$1"
else
    move=
fi

# catch the clobber case
#
if [[ clobber = "$move" ]]; then
    echo "ttt: rm -f ttt_game ttt_game.o ttt_game.c ttt_old.c ttt_new.c" 1>&2
    rm -f ttt_game ttt_game.o ttt_game.c ttt_old.c ttt_new.c
    echo "ttt: rm -f merlyn.c merlyn.o merlyn" 1>&2
    rm -f merlyn.c merlyn.o merlyn
    echo "ttt: removed all but the original source" 1>&2
    exit 0
fi

# catch the quitgame case
#
if [[ quitgame = "$move" ]]; then
    echo "ttt: rm -f ttt_game ttt_game.o ttt_game.c ttt_old.c ttt_new.c" 1>&2
    rm -f ttt_game ttt_game.o ttt_game.c ttt_old.c ttt_new.c
    echo "ttt: current game removed, perhaps you were going to lose? :-)" 1>&2
    exit 0
fi

# watch for bad args
#
if [[ $# -eq 1 ]]; then
    case "$move" in
    1|2|3|4|5|6|7|8|9) ;;
    *)  echo "ttt: bad argument" 1>&2
	echo "usage: ./ttt [move_digit]" 1>&2
	echo "       ./ttt quitgame" 1>&2
	echo "       ./ttt clobber" 1>&2
	exit 2 ;;
    esac
fi

# be sure that we have the merlyn.c source
#
if [[ ! -f merlyn.c ]]; then
    if [[ -f westley.c ]]; then
	echo "ttt: No merlyn.c around these parts, using a copy of westley.c" 1>&2
	cp westley.c merlyn.c
	chmod +w merlyn.c
    else
	echo "ttt: Ouch!  merlyn.c and no westley.c are gone!" 1>&2
	exit 3
    fi
    # check to see if the copy worked
    if [[ ! -f merlyn.c ]]; then
	echo "ttt: Darn, couldn't copy westley.c to merlyn.c" 1>&2
	exit 4
    fi
fi

# be sure we have the merlyn program
#
if [[ ! -f merlyn ]]; then
    export status=0
    if [[ -n $E_FLAG ]]; then
	echo "ttt: make merlyn" 1>&2
	make merlyn
	status=$?
    else
	make merlyn 2>/dev/null
	status=$?
    fi
    if [[ "$status" -ne 0 ]]; then
	echo "ttt: something is wrong, fix merlyn.c and build it yourself!" 1>&2
	echo "     or maybe type:  ./ttt clobber" 1>&2
	exit 5
    fi
    rm -f ttt_game.c
fi

# If we don't have a ttt_game.c, or we cannot write it, make a new ttt_game.c
#
if [[ ! -w ttt_game.c ]]; then
    rm -f ttt_game.c 
    if [[ -z "$move" ]]; then
	./merlyn | tee ttt_game.c
    else
	./merlyn "$move" | tee ttt_game.c
    fi
    chmod +w ttt_game.c

# If we have a ttt_game.c, then assume that we are in the process of playing
#
else
    rm -f ttt_game ttt_new.c
    export status=0
    if [[ -n $E_FLAG ]]; then
	echo "ttt: make ttt_game" 1>&2
	make ttt_game
	status=$?
    else
	make ttt_game 2>/dev/null
	status=$?
    fi
    if [[ "$status" -ne 0 ]]; then
	echo "ttt: something is wrong, fix ttt_game.c and build it yourself!" 1>&2
	echo "     or maybe type:  ./ttt quitgame" 1>&2
	exit 6
    fi
    if [[ -z "$move" ]]; then
	./ttt_game | tee ttt_new.c
    else
	./ttt_game "$move" | tee ttt_new.c
    fi
    chmod +w ttt_new.c
    if [[ -s ttt_new.c ]]; then
	mv ttt_game.c ttt_old.c
	mv ttt_new.c ttt_game.c

# Check for win, lose, or draw
# For a win or draw, copy merlyn.c to ttt_game.c
# For a loss, copy ttt_game.c to merlyn.c, as it is now better
# Also remove the executable for the file replaced
# For anything else, game in progress, do not do anything

	# SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
	# https://www.shellcheck.net/wiki/SC2006
	# shellcheck disable=SC2006
	if [[ -n "`grep ':-(' ttt_game.c`" ]]; then
	    echo
	    echo "ttt: I lose...I won't make THAT mistake again!"
	    chmod +w merlyn.c
	    mv ttt_game.c merlyn.c
	    rm -f merlyn ttt_game
	else
	    # SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
	    # https://www.shellcheck.net/wiki/SC2006
	    # shellcheck disable=SC2006
	    if [[ -n "`grep ':-)' ttt_game.c`" ]]; then
		echo
		echo "ttt: I win!"
		cp merlyn.c ttt_game.c
		rm -f ttt_game
	    else
		# SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
		# https://www.shellcheck.net/wiki/SC2006
		# shellcheck disable=SC2006
		if [[ -z "`grep 'X=-. ' ttt_game.c`" && -z "`grep '^. ' ttt_game.c`" ]]; then
		    echo
		    echo "ttt: It's a draw - play again?"
		    cp merlyn.c ttt_game.c
		    rm -f ttt_game
		fi
	    fi
	fi

    else
	echo "ttt: something is wrong, maybe ttt_old.c will help" 1>&2
	echo "     or maybe type:  ./ttt quitgame" 1>&2
	echo "     or maybe type:  ./ttt clobber" 1>&2
	exit 7
    fi
fi