/*-------------------------------------------------------------------------
 *
 * catalog_utils.c--
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/parser/Attic/catalog_utils.c,v 1.14 1996/12/26 17:47:41 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <string.h>
#include "postgres.h"

#include "lib/dllist.h"
#include "utils/datum.h"

#include "utils/builtins.h"
#include "utils/elog.h"
#include "utils/palloc.h"
#include "fmgr.h"

#include "nodes/pg_list.h"
#include "nodes/parsenodes.h"
#include "utils/syscache.h"
#include "catalog/catname.h"

#include "parser/catalog_utils.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "catalog/pg_proc.h"
#include "catalog/indexing.h"
#include "catalog/catname.h"

#include "access/skey.h"
#include "access/relscan.h"
#include "access/tupdesc.h"
#include "access/htup.h"
#include "access/heapam.h"
#include "access/genam.h"
#include "access/itup.h"
#include "access/tupmacs.h"

#include "storage/buf.h"
#include "storage/bufmgr.h"
#include "utils/lsyscache.h"
#include "storage/lmgr.h"

#include "port-protos.h"              /* strdup() */

struct {
    char *field;
    int code;
} special_attr[] = {
    { "ctid", SelfItemPointerAttributeNumber },
    { "oid", ObjectIdAttributeNumber },
    { "xmin", MinTransactionIdAttributeNumber },
    { "cmin", MinCommandIdAttributeNumber },
    { "xmax", MaxTransactionIdAttributeNumber },
    { "cmax", MaxCommandIdAttributeNumber },
    { "chain", ChainItemPointerAttributeNumber },
    { "anchor", AnchorItemPointerAttributeNumber },
    { "tmin", MinAbsoluteTimeAttributeNumber },
    { "tmax", MaxAbsoluteTimeAttributeNumber },
    { "vtype", VersionTypeAttributeNumber }
};

#define SPECIALS (sizeof(special_attr)/sizeof(*special_attr))
  
static char *attnum_type[SPECIALS] = {
    "tid",
    "oid",
    "xid",
    "cid",
    "xid",
    "cid",
    "tid",
    "tid",
    "abstime",
    "abstime",
    "char"
  };

#define	MAXFARGS 8		/* max # args to a c or postquel function */

/*
 *  This structure is used to explore the inheritance hierarchy above
 *  nodes in the type tree in order to disambiguate among polymorphic
 *  functions.
 */

typedef struct _InhPaths {
    int		nsupers;	/* number of superclasses */
    Oid	self;		/* this class */
    Oid	*supervec;	/* vector of superclasses */
} InhPaths;

/*
 *  This structure holds a list of possible functions or operators that
 *  agree with the known name and argument types of the function/operator.
 */
typedef struct _CandidateList {
    Oid *args;
    struct _CandidateList *next;
} *CandidateList;

static Oid **argtype_inherit(int nargs, Oid *oid_array);
static Oid **genxprod(InhPaths *arginh, int nargs);
static int findsupers(Oid relid, Oid **supervec);

static bool is_lowercase(char *string);
static void make_lowercase(char *string);

/* check to see if a type id is valid,
 * returns true if it is. By using this call before calling 
 * get_id_type or get_id_typname, more meaningful error messages
 * can be produced because the caller typically has more context of
 *  what's going on                 - jolly
 */
bool
check_typeid(Oid id)
{
    return (SearchSysCacheTuple(TYPOID, 
				ObjectIdGetDatum(id),
				0,0,0) != NULL);
}


/* return a Type structure, given an typid */
Type
get_id_type(Oid id)
{
    HeapTuple tup;
    
    if (!(tup = SearchSysCacheTuple(TYPOID, ObjectIdGetDatum(id),
				    0,0,0))) { 
	elog ( WARN, "type id lookup of %ud failed", id);
	return(NULL);
    }
    return((Type) tup);
}

/* return a type name, given a typeid */
char*
get_id_typname(Oid id)
{
    HeapTuple tup;
    TypeTupleForm typetuple;
    
    if (!(tup = SearchSysCacheTuple(TYPOID, ObjectIdGetDatum(id),
				    0,0,0))) {
	elog ( WARN, "type id lookup of %ud failed", id);
	return(NULL);
    }
    typetuple = (TypeTupleForm)GETSTRUCT(tup);
    return (typetuple->typname).data;
}

/* return a Type structure, given type name */
Type
type(char *s)
{
    HeapTuple tup;
    
    if (s == NULL) {
	elog ( WARN , "type(): Null type" );
    }
    
    if (!(tup = SearchSysCacheTuple(TYPNAME, PointerGetDatum(s), 0,0,0))) {
	elog (WARN , "type name lookup of %s failed", s);
    }
    return((Type) tup);
}

/* given attribute id, return type of that attribute */
/* XXX Special case for pseudo-attributes is a hack */
Oid
att_typeid(Relation rd, int attid)
{
    
    if (attid < 0) {
	return(typeid(type(attnum_type[-attid-1])));
    }
    /* -1 because varattno (where attid comes from) returns one
       more than index */
    return(rd->rd_att->attrs[attid-1]->atttypid);
}


int
att_attnelems(Relation rd, int attid)
{
    return(rd->rd_att->attrs[attid-1]->attnelems);
}

/* given type, return the type OID */
Oid
typeid(Type tp)
{
    if (tp == NULL) {
	elog ( WARN , "typeid() called with NULL type struct");
    }
    return(tp->t_oid);
}

/* given type (as type struct), return the length of type */
int16
tlen(Type t)
{
    TypeTupleForm    typ;
    
    typ = (TypeTupleForm)GETSTRUCT(t);
    return(typ->typlen);
}

/* given type (as type struct), return the value of its 'byval' attribute.*/
bool
tbyval(Type t)
{
    TypeTupleForm    typ;
    
    typ = (TypeTupleForm)GETSTRUCT(t);
    return(typ->typbyval);
}

/* given type (as type struct), return the name of type */
char*
tname(Type t)
{
    TypeTupleForm    typ;
    
    typ = (TypeTupleForm)GETSTRUCT(t);
    return (typ->typname).data;
}

/* given type (as type struct), return wether type is passed by value */
int
tbyvalue(Type t)
{
    TypeTupleForm typ;
    
    typ = (TypeTupleForm) GETSTRUCT(t);
    return(typ->typbyval);
}

/* given a type, return its typetype ('c' for 'c'atalog types) */
static char
typetypetype(Type t)
{
    TypeTupleForm typ;
    
    typ = (TypeTupleForm) GETSTRUCT(t);
    return(typ->typtype);
}

/* given operator, return the operator OID */
Oid
oprid(Operator op)
{
    return(op->t_oid);
}

/*
 *  given opname, leftTypeId and rightTypeId,
 *  find all possible (arg1, arg2) pairs for which an operator named
 *  opname exists, such that leftTypeId can be coerced to arg1 and
 *  rightTypeId can be coerced to arg2
 */
static int
binary_oper_get_candidates(char *opname,
			   Oid leftTypeId,
			   Oid rightTypeId,
			   CandidateList *candidates)
{
    CandidateList 	current_candidate;
    Relation            pg_operator_desc;
    HeapScanDesc        pg_operator_scan;
    HeapTuple           tup;
    OperatorTupleForm	oper;
    Buffer              buffer;
    int			nkeys;
    int			ncandidates = 0;
    ScanKeyData  	opKey[3];
    
    *candidates = NULL;

    ScanKeyEntryInitialize(&opKey[0], 0,
			   Anum_pg_operator_oprname,
			   NameEqualRegProcedure,
			   NameGetDatum(opname));

    ScanKeyEntryInitialize(&opKey[1], 0,
			   Anum_pg_operator_oprkind,
			   CharacterEqualRegProcedure,
			   CharGetDatum('b'));

    
    if (leftTypeId == UNKNOWNOID) {
        if (rightTypeId == UNKNOWNOID) {
	    nkeys = 2;
        } else {
	    nkeys = 3;

	    ScanKeyEntryInitialize(&opKey[2], 0,
				   Anum_pg_operator_oprright,
				   ObjectIdEqualRegProcedure,
				   ObjectIdGetDatum(rightTypeId));
        }
    } else if (rightTypeId == UNKNOWNOID) {
	nkeys = 3;
	
	ScanKeyEntryInitialize(&opKey[2], 0,
			       Anum_pg_operator_oprleft,
			       ObjectIdEqualRegProcedure,
			       ObjectIdGetDatum(leftTypeId));
    } else {
	/* currently only "unknown" can be coerced */
        return 0;
    }
    
    pg_operator_desc = heap_openr(OperatorRelationName);
    pg_operator_scan = heap_beginscan(pg_operator_desc,
				      0,
				      SelfTimeQual,
				      nkeys,
				      opKey);
    
    do {
        tup = heap_getnext(pg_operator_scan, 0, &buffer);
	if (HeapTupleIsValid(tup)) {
	    current_candidate = (CandidateList)palloc(sizeof(struct _CandidateList));
	    current_candidate->args = (Oid *)palloc(2 * sizeof(Oid));
	    
	    oper = (OperatorTupleForm)GETSTRUCT(tup);
	    current_candidate->args[0] = oper->oprleft;
	    current_candidate->args[1] = oper->oprright;
	    current_candidate->next = *candidates;
	    *candidates = current_candidate;
	    ncandidates++;
	    ReleaseBuffer(buffer);
	}
    } while(HeapTupleIsValid(tup));
    
    heap_endscan(pg_operator_scan);
    heap_close(pg_operator_desc);
    
    return ncandidates;
}

/*
 * equivalentOpersAfterPromotion -
 *    checks if a list of candidate operators obtained from
 *    binary_oper_get_candidates() contain equivalent operators. If
 *    this routine is called, we have more than 1 candidate and need to
 *    decided whether to pick one of them. This routine returns true if
 *    the all the candidates operate on the same data types after
 *    promotion (int2, int4, float4 -> float8).
 */
static bool
equivalentOpersAfterPromotion(CandidateList candidates)
{
    CandidateList result;
    CandidateList promotedCandidates = NULL;
    Oid leftarg, rightarg;

    for (result = candidates; result != NULL; result = result->next) {
	CandidateList c;
	c = (CandidateList)palloc(sizeof(*c));
	c->args = (Oid *)palloc(2 * sizeof(Oid));
	switch (result->args[0]) {
	case FLOAT4OID:
	case INT4OID:
	case INT2OID:
	    c->args[0] = FLOAT8OID;
	    break;
	default:
	    c->args[0] = result->args[0];
	    break;
	}
	switch (result->args[1]) {
	case FLOAT4OID:
	case INT4OID:
	case INT2OID:
	    c->args[1] = FLOAT8OID;
	    break;
	default:
	    c->args[1] = result->args[1];
	    break;
	}
	c->next = promotedCandidates;
	promotedCandidates = c;
    }

    /* if we get called, we have more than 1 candidates so we can do the
       following safely */
    leftarg = promotedCandidates->args[0];
    rightarg = promotedCandidates->args[1];

    for (result=promotedCandidates->next; result!=NULL; result=result->next) {
	if (result->args[0]!=leftarg || result->args[1]!=rightarg)
	    /*
	     * this list contains operators that operate on different
	     * data types even after promotion. Hence we can't decide on
	     * which one to pick. The user must do explicit type casting.
	     */
	    return FALSE;
    }

    /* all the candidates are equivalent in the following sense: they operate
       on equivalent data types and picking any one of them is as good. */
    return TRUE;
}
	

/*
 *  given a choice of argument type pairs for a binary operator,
 *  try to choose a default pair
 */
static CandidateList
binary_oper_select_candidate(Oid arg1,
			     Oid arg2,
			     CandidateList candidates)
{
    CandidateList result;

    /*
     * if both are "unknown", there is no way to select a candidate
     *
     * current wisdom holds that the default operator should be one
     * in which both operands have the same type (there will only
     * be one such operator)
     *
     * 7.27.93 - I have decided not to do this; it's too hard to
     * justify, and it's easy enough to typecast explicitly -avi
     * [the rest of this routine were commented out since then -ay]
     */
    
    if (arg1 == UNKNOWNOID && arg2 == UNKNOWNOID)
	return (NULL);

    /*
     * 6/23/95 - I don't complete agree with avi. In particular, casting
     *    floats is a pain for users. Whatever the rationale behind not doing
     *    this is, I need the following special case to work.
     *
     *    In the WHERE clause of a query, if a float is specified without
     *    quotes, we treat it as float8. I added the float48* operators so
     *    that we can operate on float4 and float8. But now we have more
     *    than one matching operator if the right arg is unknown (eg. float
     *    specified with quotes). This break some stuff in the regression
     *    test where there are floats in quotes not properly casted. Below
     *    is the solution. In addition to requiring the operator operates
     *    on the same type for both operands [as in the code Avi originally
     *    commented out], we also require that the operators be equivalent
     *    in some sense. (see equivalentOpersAfterPromotion for details.)
     *                                                  - ay 6/95
     */
    if (!equivalentOpersAfterPromotion(candidates))
	return NULL;

    /* if we get here, any one will do but we're more picky and require
       both operands be the same. */
    for (result = candidates; result != NULL; result = result->next) {
	if (result->args[0] == result->args[1])
	    return result;
    }

    return (NULL);
}

/* Given operator, types of arg1, and arg2, return oper struct */
/* arg1, arg2 --typeids */
Operator
oper(char *op, Oid arg1, Oid arg2)
{
    HeapTuple tup;
    CandidateList candidates;
    int ncandidates;

    if (!arg2) arg2=arg1;
    if (!arg1) arg1=arg2;

    if (!(tup = SearchSysCacheTuple(OPRNAME,
				    PointerGetDatum(op),
				    ObjectIdGetDatum(arg1),
				    ObjectIdGetDatum(arg2),
				    Int8GetDatum('b')))) {
	ncandidates = binary_oper_get_candidates(op, arg1, arg2, &candidates);
	if (ncandidates == 0) {
	    /*
	     * no operators of the desired types found
	     */
	    op_error(op, arg1, arg2);
	    return(NULL);
	} else if (ncandidates == 1) {
	    /*
	     * exactly one operator of the desired types found
	     */
	    tup = SearchSysCacheTuple(OPRNAME,
				      PointerGetDatum(op),
				      ObjectIdGetDatum(candidates->args[0]),
				      ObjectIdGetDatum(candidates->args[1]),
				      Int8GetDatum('b'));
	    Assert(HeapTupleIsValid(tup));
	} else {
	    /*
	     * multiple operators of the desired types found
	     */
	    candidates = binary_oper_select_candidate(arg1, arg2, candidates);
	    if (candidates != NULL) {
		/* we chose one of them */
		tup = SearchSysCacheTuple(OPRNAME,
					  PointerGetDatum(op),
					  ObjectIdGetDatum(candidates->args[0]),
					  ObjectIdGetDatum(candidates->args[1]),
					  Int8GetDatum('b'));
		Assert(HeapTupleIsValid(tup));
	    } else {
		Type tp1, tp2;
		
		/* we chose none of them */
		tp1 = get_id_type(arg1);
		tp2 = get_id_type(arg2);
		elog(NOTICE, "there is more than one operator %s for types", op);
		elog(NOTICE, "%s and %s. You will have to retype this query",
		     tname(tp1), tname(tp2));
		elog(WARN, "using an explicit cast");
		
		return(NULL);
	    }
	}
    }
    return((Operator) tup);
}

/*
 *  given opname and typeId, find all possible types for which 
 *  a right/left unary operator named opname exists,
 *  such that typeId can be coerced to it
 */
static int
unary_oper_get_candidates(char *op,
			  Oid typeId,
			  CandidateList *candidates,
			  char rightleft)
{
    CandidateList 	current_candidate;
    Relation            pg_operator_desc;
    HeapScanDesc        pg_operator_scan;
    HeapTuple           tup;
    OperatorTupleForm	oper;
    Buffer              buffer;
    int			ncandidates = 0;
    
    static ScanKeyData opKey[2] = {
	{ 0, Anum_pg_operator_oprname, NameEqualRegProcedure },
	{ 0, Anum_pg_operator_oprkind, CharacterEqualRegProcedure } };
    
    *candidates = NULL;
    
    fmgr_info(NameEqualRegProcedure, (func_ptr *) &opKey[0].sk_func,
	      &opKey[0].sk_nargs);
    opKey[0].sk_argument = NameGetDatum(op);
    fmgr_info(CharacterEqualRegProcedure, (func_ptr *) &opKey[1].sk_func,
	      &opKey[1].sk_nargs);
    opKey[1].sk_argument = CharGetDatum(rightleft);
    
    /* currently, only "unknown" can be coerced */
    if (typeId != UNKNOWNOID) {
        return 0;
    }
    
    pg_operator_desc = heap_openr(OperatorRelationName);
    pg_operator_scan = heap_beginscan(pg_operator_desc,
				      0,
				      SelfTimeQual,
				      2,
				      opKey);
    
    do {
        tup = heap_getnext(pg_operator_scan, 0, &buffer);
	if (HeapTupleIsValid(tup)) {
	    current_candidate = (CandidateList)palloc(sizeof(struct _CandidateList));
	    current_candidate->args = (Oid *)palloc(sizeof(Oid));
	    
	    oper = (OperatorTupleForm)GETSTRUCT(tup);
	    if (rightleft == 'r')
		current_candidate->args[0] = oper->oprleft;
	    else
		current_candidate->args[0] = oper->oprright;
	    current_candidate->next = *candidates;
	    *candidates = current_candidate;
	    ncandidates++;
	    ReleaseBuffer(buffer);
	}
    } while(HeapTupleIsValid(tup));
    
    heap_endscan(pg_operator_scan);
    heap_close(pg_operator_desc);
    
    return ncandidates;
}

/* Given unary right-side operator (operator on right), return oper struct */
/* arg-- type id */
Operator
right_oper(char *op, Oid arg)
{
    HeapTuple tup;
    CandidateList candidates;
    int ncandidates;
    
    /*
      if (!OpCache) {
      init_op_cache();
      }
      */
    if (!(tup = SearchSysCacheTuple(OPRNAME,
				    PointerGetDatum(op),
				    ObjectIdGetDatum(arg),
				    ObjectIdGetDatum(InvalidOid),
				    Int8GetDatum('r')))) {
	ncandidates = unary_oper_get_candidates(op, arg, &candidates, 'r');
	if (ncandidates == 0) {
	    elog ( WARN ,
		  "Can't find right op: %s for type %d", op, arg );
	    return(NULL);
	}
	else if (ncandidates == 1) {
	    tup = SearchSysCacheTuple(OPRNAME,
				      PointerGetDatum(op),
				      ObjectIdGetDatum(candidates->args[0]),
				      ObjectIdGetDatum(InvalidOid),
				      Int8GetDatum('r'));
	    Assert(HeapTupleIsValid(tup));
	}
	else {
	    elog(NOTICE, "there is more than one right operator %s", op);
	    elog(NOTICE, "you will have to retype this query");
	    elog(WARN, "using an explicit cast");
	    return(NULL);
	}
    }
    return((Operator) tup);
}

/* Given unary left-side operator (operator on left), return oper struct */
/* arg--type id */
Operator
left_oper(char *op, Oid arg)
{
    HeapTuple tup;
    CandidateList candidates;
    int ncandidates;
    
    /*
      if (!OpCache) {
      init_op_cache();
      }
      */
    if (!(tup = SearchSysCacheTuple(OPRNAME,
				    PointerGetDatum(op),
				    ObjectIdGetDatum(InvalidOid),
				    ObjectIdGetDatum(arg),
				    Int8GetDatum('l')))) {
	ncandidates = unary_oper_get_candidates(op, arg, &candidates, 'l');
	if (ncandidates == 0) {
	    elog ( WARN ,
		  "Can't find left op: %s for type %d", op, arg );
	    return(NULL);
	}
	else if (ncandidates == 1) {
	    tup = SearchSysCacheTuple(OPRNAME,
				      PointerGetDatum(op),
				      ObjectIdGetDatum(InvalidOid),
				      ObjectIdGetDatum(candidates->args[0]),
				      Int8GetDatum('l'));
	    Assert(HeapTupleIsValid(tup));
	}
	else {
	    elog(NOTICE, "there is more than one left operator %s", op);
	    elog(NOTICE, "you will have to retype this query");
	    elog(WARN, "using an explicit cast");
	    return(NULL);
	}
    }
    return((Operator) tup);
}

/* given range variable, return id of variable */

int
varattno(Relation rd, char *a)
{
    int i;
    
    for (i = 0; i < rd->rd_rel->relnatts; i++) {
	if (!namestrcmp(&(rd->rd_att->attrs[i]->attname), a)) {
	    return(i+1);
	}
    }
    for (i = 0; i < SPECIALS; i++) {
	if (!strcmp(special_attr[i].field, a)) {
	    return(special_attr[i].code);
	}
    }
    
    elog(WARN,"Relation %s does not have attribute %s\n", 
	 RelationGetRelationName(rd), a );
    return(-1);
}

/* Given range variable, return whether attribute of this name
 * is a set.
 * NOTE the ASSUMPTION here that no system attributes are, or ever
 * will be, sets.
 */
bool
varisset(Relation rd, char *name)
{
    int i;
    
    /* First check if this is a system attribute */
    for (i = 0; i < SPECIALS; i++) {
	if (! strcmp(special_attr[i].field, name)) {
	    return(false);   /* no sys attr is a set */
	}
    }
    return (get_attisset(rd->rd_id, name));
}

/* given range variable, return id of variable */
int
nf_varattno(Relation rd, char *a)
{
    int i;
    
    for (i = 0; i < rd->rd_rel->relnatts; i++) {
	if (!namestrcmp(&(rd->rd_att->attrs[i]->attname), a)) {
	    return(i+1);
	}
    }
    for (i = 0; i < SPECIALS; i++) {
	if (!strcmp(special_attr[i].field, a)) {
	    return(special_attr[i].code);
	}
    }
    return InvalidAttrNumber;
}

/*-------------
 * given an attribute number and a relation, return its relation name
 */
char*
getAttrName(Relation rd, int attrno)
{
    char *name;
    int i;
    
    if (attrno<0) {
	for (i = 0; i < SPECIALS; i++) {
	    if (special_attr[i].code == attrno) {
		name = special_attr[i].field;
		return(name);
	    }
	}
	elog(WARN, "Illegal attr no %d for relation %s\n",
	     attrno, RelationGetRelationName(rd));
    } else if (attrno >=1 && attrno<= RelationGetNumberOfAttributes(rd)) {
	name = (rd->rd_att->attrs[attrno-1]->attname).data;
	return(name);
    } else {
	elog(WARN, "Illegal attr no %d for relation %s\n",
	     attrno, RelationGetRelationName(rd));
    }
    
    /*
     * Shouldn't get here, but we want lint to be happy...
     */
    
    return(NULL);
}

/* Given a typename and value, returns the ascii form of the value */

char *
outstr(char *typename,	/* Name of type of value */
       char *value)	/* Could be of any type */
{
    TypeTupleForm tp;
    Oid op;
    
    tp = (TypeTupleForm ) GETSTRUCT(type(typename));
    op = tp->typoutput;
    return((char *) fmgr(op, value));
}

/* Given a Type and a string, return the internal form of that string */
char *
instr2(Type tp, char *string, int typlen)
{
    return(instr1((TypeTupleForm ) GETSTRUCT(tp), string, typlen));
}

/* Given a type structure and a string, returns the internal form of
   that string */
char *
instr1(TypeTupleForm tp, char *string, int typlen)
{
    Oid op;
    Oid typelem;
    
    op = tp->typinput;
    typelem = tp->typelem; /* XXX - used for array_in */
    /* typlen is for bpcharin() and varcharin() */
    return((char *) fmgr(op, string, typelem, typlen));
}

/* Given the attribute type of an array return the arrtribute type of
   an element of the array */

Oid
GetArrayElementType(Oid typearray)
{
    HeapTuple type_tuple;
    TypeTupleForm type_struct_array;
    
    type_tuple = SearchSysCacheTuple(TYPOID,
				     ObjectIdGetDatum(typearray),
				     0,0,0);
    
    if (!HeapTupleIsValid(type_tuple))
	elog(WARN, "GetArrayElementType: Cache lookup failed for type %d\n",
	     typearray);
    
    /* get the array type struct from the type tuple */
    type_struct_array = (TypeTupleForm) GETSTRUCT(type_tuple);
    
    if (type_struct_array->typelem == InvalidOid) {
	elog(WARN, "GetArrayElementType: type %s is not an array",
	     (Name)&(type_struct_array->typname.data[0]));
    }
    
    return(type_struct_array->typelem);
}

Oid
funcid_get_rettype(Oid funcid)
{
    HeapTuple func_tuple = NULL;
    Oid funcrettype = (Oid)0;
    
    func_tuple = SearchSysCacheTuple(PROOID, ObjectIdGetDatum(funcid),
				     0,0,0);
    
    if ( !HeapTupleIsValid ( func_tuple )) 
	elog (WARN, "function  %d does not exist", funcid);
    
    funcrettype = (Oid)
	((Form_pg_proc)GETSTRUCT(func_tuple))->prorettype ;
    
    return (funcrettype);
}

/*
 * get a list of all argument type vectors for which a function named
 * funcname taking nargs arguments exists
 */
static CandidateList
func_get_candidates(char *funcname, int nargs)
{
    Relation heapRelation;
    Relation idesc;
    ScanKeyData skey;
    HeapTuple tuple;
    IndexScanDesc sd;
    RetrieveIndexResult indexRes;
    Buffer buffer;
    Form_pg_proc pgProcP;
    bool bufferUsed = FALSE;
    CandidateList candidates = NULL;
    CandidateList current_candidate;
    int i;
    
    heapRelation = heap_openr(ProcedureRelationName);
    ScanKeyEntryInitialize(&skey,
                           (bits16)0x0,
                           (AttrNumber)1,
                           (RegProcedure)NameEqualRegProcedure,
                           (Datum)funcname);
    
    idesc = index_openr(ProcedureNameIndex);
    
    sd = index_beginscan(idesc, false, 1, &skey);
    
    do {  
        tuple = (HeapTuple)NULL;
        if (bufferUsed) {
            ReleaseBuffer(buffer);
            bufferUsed = FALSE;
        }
	
        indexRes = index_getnext(sd, ForwardScanDirection);
        if (indexRes) {
            ItemPointer iptr;
	    
            iptr = &indexRes->heap_iptr;
            tuple = heap_fetch(heapRelation, NowTimeQual, iptr, &buffer);
            pfree(indexRes);
            if (HeapTupleIsValid(tuple)) {
                pgProcP = (Form_pg_proc)GETSTRUCT(tuple);
                bufferUsed = TRUE;
		if (pgProcP->pronargs == nargs) {
		    current_candidate = (CandidateList)
			palloc(sizeof(struct _CandidateList));
		    current_candidate->args = (Oid *)
			palloc(8 * sizeof(Oid));
		    memset(current_candidate->args, 0, 8 * sizeof(Oid)); 
		    for (i=0; i<nargs; i++) {
			current_candidate->args[i] = 
			    pgProcP->proargtypes[i];
		    }
		    
		    current_candidate->next = candidates;
		    candidates = current_candidate;
		}
            }
	}
    } while (indexRes);
    
    index_endscan(sd);
    index_close(idesc);
    heap_close(heapRelation);		 
    
    return candidates;
}

/*
 * can input_typeids be coerced to func_typeids?
 */
static bool
can_coerce(int nargs, Oid *input_typeids, Oid *func_typeids)
{
    int i;
    Type tp;
    
    /*
     * right now, we only coerce "unknown", and we cannot coerce it to a
     * relation type
     */
    for (i=0; i<nargs; i++) {
	if (input_typeids[i] != func_typeids[i]) {
	    if (input_typeids[i] != UNKNOWNOID || func_typeids[i] == 0)
		return false;
	    
	    tp = get_id_type(input_typeids[i]);
	    if (typetypetype(tp) == 'c' )
		return false;
	}
    }
    
    return true;
}

/*
 * given a list of possible typeid arrays to a function and an array of
 * input typeids, produce a shortlist of those function typeid arrays
 * that match the input typeids (either exactly or by coercion), and
 * return the number of such arrays
 */
static int
match_argtypes(int nargs,
	       Oid *input_typeids,
	       CandidateList function_typeids,
	       CandidateList *candidates) /* return value */
{
    CandidateList current_candidate;
    CandidateList matching_candidate;
    Oid *current_typeids;
    int ncandidates = 0;
    
    *candidates = NULL;
    
    for (current_candidate = function_typeids;
	 current_candidate != NULL;
	 current_candidate = current_candidate->next) {
	current_typeids = current_candidate->args;
	if (can_coerce(nargs, input_typeids, current_typeids)) {
	    matching_candidate = (CandidateList)
		palloc(sizeof(struct _CandidateList));
	    matching_candidate->args = current_typeids;
	    matching_candidate->next = *candidates;
	    *candidates = matching_candidate;
	    ncandidates++;
	}
    }
    
    return ncandidates;
}

/*
 * given the input argtype array and more than one candidate
 * for the function argtype array, attempt to resolve the conflict.
 * returns the selected argtype array if the conflict can be resolved,
 * otherwise returns NULL
 */
static Oid *
func_select_candidate(int nargs,
		      Oid *input_typeids,
		      CandidateList candidates)
{
    /* XXX no conflict resolution implemeneted yet */
    return (NULL);
}

static
bool is_lowercase(char *string)
{
    int i;

    for(i = 0; i < strlen(string); i++) {
	if(string[i] >= 'A' && string[i] <= 'Z') {
	    return false;
	}
    }

    return true;
}

static
void make_lowercase(char *string)
{
    int i;

    for(i = 0; i < strlen(string); i++) {
	if(string[i] >= 'A' && string[i] <= 'Z') {
	    string[i] = (string[i] - 'A') + 'a';
	}
    }
}

bool
func_get_detail(char *funcname,
		int nargs,
		Oid *oid_array,
		Oid *funcid,	/* return value */
		Oid *rettype,	/* return value */
		bool *retset,	/* return value */
		Oid **true_typeids) /* return value */
{
    Oid **input_typeid_vector;
    Oid *current_input_typeids;
    CandidateList function_typeids;
    CandidateList current_function_typeids;
    HeapTuple ftup;
    Form_pg_proc pform;
    
    /*
     * attempt to find named function in the system catalogs
     * with arguments exactly as specified - so that the normal
     * case is just as quick as before
     */
    ftup = SearchSysCacheTuple(PRONAME, 
			       PointerGetDatum(funcname),
			       Int32GetDatum(nargs),
			       PointerGetDatum(oid_array),
			       0);
    *true_typeids = oid_array;
    
    /*
     * If an exact match isn't found :
     * 1) get a vector of all possible input arg type arrays constructed
     *    from the superclasses of the original input arg types
     * 2) get a list of all possible argument type arrays to the
     *	  function with given name and number of arguments
     * 3) for each input arg type array from vector #1 :
     *	  a) find how many of the function arg type arrays from list #2
     *	     it can be coerced to
     *	  b) - if the answer is one, we have our function
     *	     - if the answer is more than one, attempt to resolve the
     *	       conflict
     *	     - if the answer is zero, try the next array from vector #1
     */
    if (!HeapTupleIsValid(ftup)) {
	function_typeids = func_get_candidates(funcname, nargs);
	
	if (function_typeids != NULL) {
	    int ncandidates = 0;
	    
	    input_typeid_vector = argtype_inherit(nargs, oid_array);
	    current_input_typeids = oid_array;
	    
	    do {
		ncandidates = match_argtypes(nargs, current_input_typeids,
					     function_typeids,
					     &current_function_typeids);
		if (ncandidates == 1) {
		    *true_typeids = current_function_typeids->args;
		    ftup = SearchSysCacheTuple(PRONAME, 
					       PointerGetDatum(funcname),
					       Int32GetDatum(nargs),
					       PointerGetDatum(*true_typeids),
					       0);
		    Assert(HeapTupleIsValid(ftup));
		}
		else if (ncandidates > 1) {
		    *true_typeids =
			func_select_candidate(nargs,
					      current_input_typeids,
					      current_function_typeids);
		    if (*true_typeids == NULL) {
			elog(NOTICE, "there is more than one function named \"%s\"",
			     funcname);
			elog(NOTICE, "that satisfies the given argument types. you will have to");
			elog(NOTICE, "retype your query using explicit typecasts.");
			func_error("func_get_detail", funcname, nargs, oid_array);
		    }
		    else {
			ftup = SearchSysCacheTuple(PRONAME, 
						   PointerGetDatum(funcname),
						   Int32GetDatum(nargs),
						   PointerGetDatum(*true_typeids),
						   0);
			Assert(HeapTupleIsValid(ftup));
		    }
		}
		current_input_typeids = *input_typeid_vector++;
	    } 
	    while (current_input_typeids !=
		   InvalidOid && ncandidates == 0);
	}
    }
    
    if (!HeapTupleIsValid(ftup)) {
	Type tp;

	/*
	 * everything else has failed--try converting the function
	 * name to lowercase, and do everything one more time
	 * (if it's not already lowercase).  so ODBC applications
	 * that expect uppercase names to work can work.  --djm 8/17/96
	 */
	if(!is_lowercase(funcname)) {
	    char *lowercase_funcname = strdup(funcname);
	    bool result;

	    make_lowercase(lowercase_funcname);
	    result = func_get_detail(lowercase_funcname, nargs, oid_array,
				     funcid, rettype, retset,	
				     true_typeids);
	    
	    free(lowercase_funcname);
	    return result;
	} else {
	if (nargs == 1) {
	    tp = get_id_type(oid_array[0]);
	    if (typetypetype(tp) == 'c')
		elog(WARN, "no such attribute or function \"%s\"",
		     funcname);
	}
	func_error("func_get_detail", funcname, nargs, oid_array);
	}
    } else {
	pform = (Form_pg_proc) GETSTRUCT(ftup);
	*funcid = ftup->t_oid;
	*rettype = pform->prorettype;
	*retset = pform->proretset;
	
	return (true);
    }
/* shouldn't reach here */
 return (false);

}

/*
 *  argtype_inherit() -- Construct an argtype vector reflecting the
 *			 inheritance properties of the supplied argv.
 *
 *	This function is used to disambiguate among functions with the
 *	same name but different signatures.  It takes an array of eight
 *	type ids.  For each type id in the array that's a complex type
 *	(a class), it walks up the inheritance tree, finding all
 *	superclasses of that type.  A vector of new Oid type arrays
 *	is returned to the caller, reflecting the structure of the
 *	inheritance tree above the supplied arguments.
 *
 *	The order of this vector is as follows:  all superclasses of the
 *	rightmost complex class are explored first.  The exploration
 *	continues from right to left.  This policy means that we favor
 *	keeping the leftmost argument type as low in the inheritance tree
 *	as possible.  This is intentional; it is exactly what we need to
 *	do for method dispatch.  The last type array we return is all
 *	zeroes.  This will match any functions for which return types are
 *	not defined.  There are lots of these (mostly builtins) in the
 *	catalogs.
 */
static Oid **
argtype_inherit(int nargs, Oid *oid_array)
{
    Oid relid;
    int i;
    InhPaths arginh[MAXFARGS];
    
    for (i = 0; i < MAXFARGS; i++) {
	if (i < nargs) {
	    arginh[i].self = oid_array[i];
	    if ((relid = typeid_get_relid(oid_array[i])) != InvalidOid) {
		arginh[i].nsupers = findsupers(relid, &(arginh[i].supervec));
	    } else {
		arginh[i].nsupers = 0;
		arginh[i].supervec = (Oid *) NULL;
	    }
	} else {
	    arginh[i].self = InvalidOid;
	    arginh[i].nsupers = 0;
	    arginh[i].supervec = (Oid *) NULL;
	}
    }
    
    /* return an ordered cross-product of the classes involved */
    return (genxprod(arginh, nargs));
}

typedef struct _SuperQE {
    Oid	sqe_relid;
} SuperQE;

static int
findsupers(Oid relid, Oid **supervec)
{
    Oid *relidvec;
    Relation inhrel;
    HeapScanDesc inhscan;
    ScanKeyData skey;
    HeapTuple inhtup;
    TupleDesc inhtupdesc;
    int nvisited;
    SuperQE *qentry, *vnode;
    Dllist *visited, *queue;
    Dlelem *qe, *elt;

    Relation rd;
    Buffer buf;
    Datum d;
    bool newrelid;
    char isNull;
    
    nvisited = 0;
    queue = DLNewList();
    visited = DLNewList();


    inhrel = heap_openr(InheritsRelationName);
    RelationSetLockForRead(inhrel);
    inhtupdesc = RelationGetTupleDescriptor(inhrel);
    
    /*
     *  Use queue to do a breadth-first traversal of the inheritance
     *  graph from the relid supplied up to the root.
     */
    do {
	ScanKeyEntryInitialize(&skey, 0x0, Anum_pg_inherits_inhrel,
			       ObjectIdEqualRegProcedure,
			       ObjectIdGetDatum(relid));
	
	inhscan = heap_beginscan(inhrel, 0, NowTimeQual, 1, &skey);
	
	while (HeapTupleIsValid(inhtup = heap_getnext(inhscan, 0, &buf))) {
	    qentry = (SuperQE *) palloc(sizeof(SuperQE));
	    
	    d = (Datum) fastgetattr(inhtup, Anum_pg_inherits_inhparent,
				    inhtupdesc, &isNull);
	    qentry->sqe_relid = DatumGetObjectId(d);
	    
	    /* put this one on the queue */
	    DLAddTail(queue, DLNewElem(qentry));
	    
	    ReleaseBuffer(buf);
	}
	
	heap_endscan(inhscan);
	
	/* pull next unvisited relid off the queue */
	do {
	  qe = DLRemHead(queue);
	  qentry = qe ? (SuperQE*)DLE_VAL(qe) : NULL;

	    if (qentry == (SuperQE *) NULL)
		break;
	    
	    relid = qentry->sqe_relid;
	    newrelid = true;
	    
	   for (elt = DLGetHead(visited); elt; elt = DLGetSucc(elt)) {
	     vnode = (SuperQE*)DLE_VAL(elt);
	     if (vnode && (qentry->sqe_relid == vnode->sqe_relid)) {
	       newrelid = false;
	       break;
	     }
	   }
	} while (!newrelid);
	
	if (qentry != (SuperQE *) NULL) {
	    
	    /* save the type id, rather than the relation id */
	    if ((rd = heap_open(qentry->sqe_relid)) == (Relation) NULL)
		elog(WARN, "relid %d does not exist", qentry->sqe_relid);
	    qentry->sqe_relid = typeid(type(RelationGetRelationName(rd)->data));
	    heap_close(rd);
	    
	    DLAddTail(visited, qe);

	    nvisited++;
	}
    } while (qentry != (SuperQE *) NULL);
    
    RelationUnsetLockForRead(inhrel);
    heap_close(inhrel);
    
    if (nvisited > 0) {
	relidvec = (Oid *) palloc(nvisited * sizeof(Oid));
	*supervec = relidvec;

	for (elt = DLGetHead(visited); elt; elt = DLGetSucc(elt)) {
	     vnode = (SuperQE*)DLE_VAL(elt);
	     *relidvec++ = vnode->sqe_relid;
	   }
	  
    } else {
	*supervec = (Oid *) NULL;
      }

    return (nvisited);
}

static Oid **
genxprod(InhPaths *arginh, int nargs)
{
    int nanswers;
    Oid **result, **iter;
    Oid *oneres;
    int i, j;
    int cur[MAXFARGS];
    
    nanswers = 1;
    for (i = 0; i < nargs; i++) {
	nanswers *= (arginh[i].nsupers + 2);
	cur[i] = 0;
    }
    
    iter = result = (Oid **) palloc(sizeof(Oid *) * nanswers);
    
    /* compute the cross product from right to left */
    for (;;) {
	oneres = (Oid *) palloc(MAXFARGS * sizeof(Oid));
	memset(oneres, 0, MAXFARGS * sizeof(Oid));
	
	for (i = nargs - 1; i >= 0 && cur[i] > arginh[i].nsupers; i--)
	    continue;
	
	/* if we're done, terminate with NULL pointer */
	if (i < 0) {
	    *iter = NULL;
	    return (result);
	}
	
	/* no, increment this column and zero the ones after it */
	cur[i] = cur[i] + 1;
	for (j = nargs - 1; j > i; j--)
	    cur[j] = 0;
	
	for (i = 0; i < nargs; i++) {
	    if (cur[i] == 0)
		oneres[i] = arginh[i].self;
	    else if (cur[i] > arginh[i].nsupers)
		oneres[i] = 0;	/* wild card */
	    else
		oneres[i] = arginh[i].supervec[cur[i] - 1];
	}
	
	*iter++ = oneres;
    }
}

/* Given a type id, returns the in-conversion function of the type */
Oid
typeid_get_retinfunc(Oid type_id)
{
    HeapTuple       typeTuple;
    TypeTupleForm   type;
    Oid             infunc;
    typeTuple = SearchSysCacheTuple(TYPOID,
				    ObjectIdGetDatum(type_id),
				    0,0,0);
    if ( !HeapTupleIsValid ( typeTuple ))
	elog(WARN,
	     "typeid_get_retinfunc: Invalid type - oid = %u",
	     type_id);
    
    type = (TypeTupleForm) GETSTRUCT(typeTuple);
    infunc = type->typinput;
    return(infunc);
}

Oid
typeid_get_relid(Oid type_id)
{
    HeapTuple       typeTuple;
    TypeTupleForm   type;
    Oid             infunc;
    typeTuple = SearchSysCacheTuple(TYPOID,
				    ObjectIdGetDatum(type_id),
				    0,0,0);
    if ( !HeapTupleIsValid ( typeTuple ))
	elog(WARN, "typeid_get_relid: Invalid type - oid = %u ", type_id);
    
    type = (TypeTupleForm) GETSTRUCT(typeTuple);
    infunc = type->typrelid;
    return(infunc);
}

Oid
get_typrelid(Type typ)
{
    TypeTupleForm typtup;
    
    typtup = (TypeTupleForm) GETSTRUCT(typ);
    
    return (typtup->typrelid);
}

Oid
get_typelem(Oid type_id)
{
    HeapTuple       typeTuple;
    TypeTupleForm   type;
    
    if (!(typeTuple = SearchSysCacheTuple(TYPOID,
					  ObjectIdGetDatum(type_id),
					  0,0,0))) {
	elog (WARN , "type id lookup of %u failed", type_id);
    }
    type = (TypeTupleForm) GETSTRUCT(typeTuple);
    
    return (type->typelem);
}

char
FindDelimiter(char *typename)
{
    char            delim;
    HeapTuple       typeTuple;
    TypeTupleForm   type;
    
    
    if (!(typeTuple = SearchSysCacheTuple(TYPNAME, 
					  PointerGetDatum(typename),
					  0,0,0))) {
        elog (WARN , "type name lookup of %s failed", typename);
    }
    type = (TypeTupleForm) GETSTRUCT(typeTuple);
    
    delim = type->typdelim;
    return (delim);
}

/*
 * Give a somewhat useful error message when the operator for two types
 * is not found.
 */
void
op_error(char *op, Oid arg1, Oid arg2)
{
    Type tp1 = NULL, tp2 = NULL;

    if (check_typeid(arg1)) {
	tp1 = get_id_type(arg1);
    } else {
	elog(WARN, "left hand side of operator %s has an unknown type, probably a bad attribute name", op);
    }

    if (check_typeid(arg2)) {
	tp2 = get_id_type(arg2);
    } else {
	elog(WARN, "right hand side of operator %s has an unknown type, probably a bad attribute name", op);
    }
    
    elog(NOTICE, "there is no operator %s for types %s and %s",
	 op, tname(tp1),tname(tp2));
    elog(NOTICE, "You will either have to retype this query using an");
    elog(NOTICE, "explicit cast, or you will have to define the operator");
    elog(WARN, "%s for %s and %s using CREATE OPERATOR", 
	 op, tname(tp1),tname(tp2));
}

/*
 * Error message when function lookup fails that gives details of the
 * argument types
 */
void
func_error(char *caller, char *funcname, int nargs, Oid *argtypes)
{
    Type get_id_type();
    char p[(NAMEDATALEN+2)*MAXFMGRARGS], *ptr;
    int i;
	
    ptr = p;
    *ptr = '\0';
    for (i=0; i<nargs; i++) {
	if (i) {
	    *ptr++ = ',';
	    *ptr++ = ' ';
	}
	if (argtypes[i] != 0) {
	    (void) strcpy(ptr, tname(get_id_type(argtypes[i])));
	    *(ptr + NAMEDATALEN) = '\0';
	} else
	    strcpy(ptr, "opaque");
	ptr += strlen(ptr);
    }
	
    elog(WARN, "%s: function %s(%s) does not exist", caller, funcname, p);
}

