/* ----------------------------------------------------------------
 *   FILE
 *	dest.c
 *	
 *   DESCRIPTION
 *	support for various communication destinations - see lib/H/tcop/dest.h
 *
 *   INTERFACE ROUTINES
 * 	BeginCommand - prepare destination for tuples of the given type
 * 	EndCommand - tell destination that no more tuples will arrive
 * 	NullCommand - tell dest that the last of a query sequence was processed
 *	
 *   NOTES
 *	These routines do the appropriate work before and after
 *	tuples are returned by a query to keep the backend and the
 *	"destination" portals synchronized.
 *
 *   IDENTIFICATION
 *	$Header: RCS/dest.c,v 1.9 91/11/11 22:59:03 hong Exp $
 * ----------------------------------------------------------------
 */

#include "tmp/postgres.h"

RcsId("$Header: RCS/dest.c,v 1.9 91/11/11 22:59:03 hong Exp $");

#include "parser/parse.h"
#include "access/htup.h"
#include "tmp/libpq-be.h"
#include "access/printtup.h"
#include "tmp/portal.h"
#include "utils/log.h"

#include "nodes/pg_lisp.h"
#include "tcop/dest.h"

#include "catalog/pg_type.h"

/* ----------------
 *	output functions
 * ----------------
 */
void
donothing(tuple, attrdesc)
    List tuple;
    List attrdesc;
{
}

void
(*DestToFunction(dest))()
    CommandDest	dest;
{
    switch (dest) {
    case Remote:
	return printtup;
	break;
	
    case Local:
	return be_printtup;
	break;
	
    case Debug:
	return debugtup;
	break;
	
    case None:
    default:
	return donothing;
	break;
    }	

    /*
     * never gets here, but DECstation lint appears to be stupid...
     */

    return donothing;
}

/* ----------------
 * 	EndCommand - tell destination that no more tuples will arrive
 * ----------------
 */
void
EndCommand(commandTag, dest)
    String  	commandTag;
    CommandDest	dest;
{
    switch (dest) {
    case Remote:
	/* ----------------
	 *	tell the fe that the query is over
	 * ----------------
	 */
	pq_putnchar("C", 1);
	pq_putint(0, 4);
	pq_putstr(commandTag);
	pq_flush();
	break;

    case Local:
    case Debug:
	break;
    case CopyEnd:
    pq_putnchar("Z", 1);
	pq_flush();
	break;
    case None:
    default:
	break;
    }
}

/*
 * These are necessary to sync communications between fe/be processes doing
 * COPY rel TO stdout
 * 
 * or 
 *
 * COPY rel FROM stdin
 *
 */

void
SendCopyBegin()
{
	pq_putnchar("B", 1);
	pq_putint(0, 4);
	pq_flush();
}

void
ReceiveCopyBegin()
{
	pq_putnchar("D", 1);
	pq_putint(0, 4);
	pq_flush();
}

/* ----------------
 * 	NullCommand - tell dest that the last of a query sequence was processed
 * 
 * 	Necessary to implement the hacky FE/BE interface to handle
 *	multiple-return queries.
 * ----------------
 */
void
NullCommand(dest)
    CommandDest	dest;
{
    switch (dest) {
    case Remote:
	/* ----------------
	 *	tell the fe that the last of the queries has finished
	 * ----------------
	 */
	pq_putnchar("I", 1);
	pq_putint(0, 4);
	pq_flush();
	break;

    case Local:
    case Debug:
    case None:
    default:
	break;
    }	
}

/* ----------------
 * 	BeginCommand - prepare destination for tuples of the given type
 * ----------------
 */
void
BeginCommand(pname, operation, attinfo, isIntoRel, isIntoPortal, tag, dest)
    char 	*pname;
    int		operation;
    LispValue 	attinfo;
    bool	isIntoRel;
    bool	isIntoPortal;
    char	*tag;
    CommandDest	dest;
{
    PortalEntry	*entry;
    struct attribute **attrs;
    int    natts;
    int    i;
    char   *p;
    
    natts = CInteger(CAR(attinfo));
    attrs  = (struct attribute **) CADR(attinfo);

    switch (dest) {
    case Remote:
	/* ----------------
	 *	if this is a "retrieve portal" query, just return
	 *	because nothing needs to be sent to the fe.
	 * ----------------
	 */
	if (isIntoPortal)
	    return;
	    
	/* ----------------
	 *	if portal name not specified for remote query,
	 *	use the "blank" portal.
	 * ----------------
	 */
	if (pname == NULL)
	    pname = "blank";
	
	/* ----------------
	 *	send fe info on tuples we're about to send
	 * ----------------
	 */
	pq_flush();
	pq_putnchar("P", 1);	/* new portal.. */
	pq_putint(0, 4);	/* xid */
	pq_putstr(pname);	/* portal name */
	
	/* ----------------
	 *	if this is a retrieve, then we send back the tuple
	 *	descriptor of the tuples.  "retrieve into" is an
	 *	exception because no tuples are returned in that case.
	 * ----------------
	 */
	if (operation == RETRIEVE && !isIntoRel) {
	    pq_putnchar("T", 1);	/* type info to follow.. */
	    pq_putint(natts, 2);	/* number of attributes in tuples */
    
	    for (i = 0; i < natts; ++i) {
		pq_putstr(attrs[i]->attname);	/* if 16 char name oops.. */
		pq_putint((int) attrs[i]->atttypid, 4);
		pq_putint(attrs[i]->attlen, 2);
	    }
	}
	pq_flush();
	break;
	
    case Local:
	/* ----------------
	 *	prepare local portal buffer for query results
	 *	and setup result for PQexec()
	 * ----------------
	 */
	entry = be_currentportal();
	if (pname != NULL)
	    pbuf_setportalinfo(entry, pname);
	
	if (operation == RETRIEVE && !isIntoRel) {
	    be_typeinit(entry, attrs, natts);
	    p = (char *) palloc(strlen(entry->name)+2);
	    p[0] = 'P';
	    strcpy(p+1,entry->name);
	} else {
	    p = (char *) palloc(strlen(tag)+2);
	    p[0] = 'C';
	    strcpy(p+1,tag);
	}
	entry->result = p;
	break;
	
    case Debug:
	/* ----------------
	 *	show the return type of the tuples
	 * ----------------
	 */
	if (pname == NULL)
	    pname = "blank";
	
	showatts(pname, natts, attrs);
	break;
	
    case None:
    default:
	break;
    }
}