#!/bin/sh

usage()
{
    echo >&2 "Usage: $(basename $0) [-v] [--tty=<device>] G0|G1 [cp437|iso01|vt100|user|<acm_name>]"
}

usage_exit()
{
    usage
    exit 1
}

tty_out()
{
    /bin/echo -en >&3 $*
}

verbose()
{
    test $VERBOSE = 1 && echo >&2 $*
}

error()
{
    echo >&2 $*
}

activate_charset()
{
    verbose "Switching to $1 charset"
    case $1 in
    G0)
	tty_out "\017"
	;;
    G1)
	tty_out "\016"
	;;
    esac
}

# parse command-line

CHARSET=
ACM=
INTERNAL_ACM=
ACM_NAME=
TTY=/dev/tty

VERBOSE=0

GOT_CHARSET=0
GOT_ACM=0

while [ $# -gt 0 ]
do
    case $1 in
    -v)
	VERBOSE=1
	shift
	;;
    --tty)
	TTY=$2
	shift
	shift
	;;
    --tty=*)
	TTY=${1#--tty=}
	shift
	;;
    G0|G1)
	test ${GOT_CHARSET} = 1 && usage_exit
	CHARSET=$1
	GOT_CHARSET=1
	shift
	;;
    iso01)
	test ${GOT_ACM} = 1 && usage_exit
	INTERNAL_ACM=B
	ACM_NAME=$1
	GOT_ACM=1
	shift
	;;
    vt100)
	test ${GOT_ACM} = 1 && usage_exit
	INTERNAL_ACM=0
	ACM_NAME=$1
	GOT_ACM=1
	shift
	;;
    cp437)
	test ${GOT_ACM} = 1 && usage_exit
	INTERNAL_ACM=U
	ACM_NAME=$1
	GOT_ACM=1
	shift
	;;
    user)
	test ${GOT_ACM} = 1 && usage_exit
	INTERNAL_ACM=K
	ACM_NAME="user-defined"
	GOT_ACM=1
	shift
	;;
    *)
	test ${GOT_ACM} = 1 && usage_exit
	INTERNAL_ACM=K
	ACM_NAME="user-defined"
	ACM=$1
	GOT_ACM=1
	shift
	;;
    esac
done

# open requested tty
test -c "$TTY" && exec 3<>$TTY

# if specified ACM is not available internally, get it from file
if [ "$ACM" != "" ]
then
    case $CHARSET in
    G0)
	OPT=
	;;
    G1)
	OPT=--g1
	;;
    esac
    
    verbose -n "Loading $ACM ACM into user-defined slot..."
    consolechars $OPT --tty=${TTY} -m $ACM && verbose "done."
fi

if [ "$INTERNAL_ACM" -a "$CHARSET" ]
then # make $CHARSET point to $INTERNAL_ACM
    if [ "$TTY" ]
    then
	ONTTY=" on $TTY"
    else
	ONTTY=""
    fi
	
    if [ "$ACM" ]
    then
	verbose "Making ${CHARSET}${ONTTY} point to $ACM_NAME ACM (file $ACM)"
    else
	verbose "Making ${CHARSET}${ONTTY} point to internal ACM $ACM_NAME"
    fi
    case $CHARSET in
    G0)
	tty_out "\033($INTERNAL_ACM"
	;;
    G1)
	tty_out "\033)$INTERNAL_ACM"
	;;
    esac
    activate_charset $CHARSET
elif [ "$CHARSET" -a -z "$INTERNAL_ACM" ]
then # make $CHARSET current
    activate_charset $CHARSET
elif [ "$INTERNAL_ACM" -a -z "$CHARSET" ]
then # set current charset to $ACM
    error "Don't know (yet ?) how to determine current charset."
    error "Please specify G0 or G1"
    exit 1
else
    usage
fi