/*
 *	This is an example of using mrd_read_element_status(3mrd)
 *	to find out what a particular element has media that is
 *	inverted or now.  It will simply print "Inverted" or 
 *	"Not-inverted" based on the result.
 *
 *	Usage:
 *
 *		mrd_inverted robot type element
 *
 *	A quirk of this example, is that if we use an invalid slot
 *	it may print "Not-inverted".  Many medium changers don't
 *	fail Read Element Status for invalid elements, it just
 *	doesn't return any data.  We don't check the data length,
 *	so all we see is the initially clear media byte.
 */
#ifndef	lint
static	char	SccsId[] = "@(#)mrd_inverted.c	1.2 (mrd-example) 3/5/97" ;
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <mrd_common.h>
#include <mrd_message.h>

/*
 *	Given a string, resembling one of the element types,
 *	return the SCSI type code for it.
 */
struct {
	int	code ;
	char	*string ;
} etypes[] = {
	TRANSPORT,	"transport",
	SLOT,		"slot",
	DRIVE,		"drive",
	PORT,		"port",
} ;

convert_type(char *etype)
{
	register i ;

	/*
	 *	For each entry in the array.
	 */
	for(i = 0; i < sizeof(etypes)/sizeof(etypes[0]); i++)
		/*
		 *	Do a case insensitive comparison, allowing
		 *	abbreviations.  Return as soon as a match is
		 *	found.  Return -1 if one isn't found.
		 */
#ifdef	vms
		if( strncmp(etypes[i].string, etype, strlen(etype)) == 0 )
#else
		if( strncasecmp(etypes[i].string, etype, strlen(etype)) == 0 )
#endif
			return etypes[i].code ;

	return -1 ;
}

main(int argc, char *argv[])
{
	int		status ;		/* return status */
	int		type ;			/* Element type */
	int		element ;		/* Element number */
	char		*robot ;		/* Robot to open */
	robot_info_t	robot_info ;		/* Robot data */
	dev_status_t	dev_status ;		/* Device status */
	unsigned char	data[READ_ELEMENT_STATUS_DATA_LENGTH] ;
	char		log_info[MRD_MAX_LOG_STRING+1] ;

	/*
	 *	Check that there are enough arguments.
	 */
	if( argc < 4 ) {
		printf("usage: %s robot type element\n", argv[0]) ;
		exit(1) ;
	}
	else {
		robot   = argv[1] ;
		element = atoi(argv[3]) ;

		if((type  = convert_type(argv[2])) == -1 ) {
			printf("Unrecognized element type: %s\n", argv[2]) ;
			exit(1) ;
		}
	}

	/*
	 *	Initialize the channel field of the robot_info, so
	 *	mrd_startup(3mrd) will actually open the robot.
	 */
	robot_info.channel = BAD_CHANNEL ;

	status = mrd_startup(robot, &robot_info, log_info) ;

	if( status != MRD_STATUS_SUCCESS ) {
		printf("Startup failed: %s: %s.\n", mrd_strstatus(status),
			log_info[0] ? log_info : "none") ;

		exit(1) ;
	}

	switch( type ) {
	case SLOT:
		element += robot_info.slot_start ;
		break ;
	case PORT:
		element += robot_info.port_start ;
		break ;
	case TRANSPORT:
		element += robot_info.transport_start ;
		break ;
	case DRIVE:
		element += robot_info.device_start ;
		break ;
	}

	/*
	 *	Read Element Status commands rarely fail, they just
	 *	succeed, but return no data.  The only byte of
         *	interest is MEDIA_LOC which has the INVERT bit
	 *	in it.  Clear it and check when done.
	 */
	data[MEDIA_LOC] = '\0' ;

	status = mrd_read_element_status(&robot_info, type, element, 1,
			data, READ_ELEMENT_STATUS_DATA_LENGTH, &dev_status) ;

	/*
	 *	But sometimes they do fail.
	 */
	if( status != MRD_STATUS_SUCCESS ) {
		printf("Read Element Status failed on %s: %s.\n", robot,
			mrd_strstatus(status)) ;

		exit(1) ;
	}

	if( data[MEDIA_LOC] & ELEMENT_INVERT )
		printf("Inverted\n") ;
	else
		printf("Not-inverted\n") ;

	(void)mrd_shutdown(&robot_info) ;

	return 0 ;
}