/*-------------------------------------------------------------------------
 *
 * clauses.c--
 *    routines to manipulate qualification clauses
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.5 1996/11/30 17:48:52 momjian Exp $
 *
 * HISTORY
 *    AUTHOR		DATE		MAJOR EVENT
 *    Andrew Yu		Nov 3, 1994	clause.c and clauses.c combined
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <catalog/pg_operator.h>
#include "nodes/primnodes.h"
#include "nodes/relation.h"
#include "nodes/parsenodes.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"

#include "catalog/pg_aggregate.h"

#include "utils/syscache.h"
#include "utils/lsyscache.h"

#include "optimizer/clauses.h"
#include "optimizer/internal.h"
#include "optimizer/var.h"


Expr *
make_clause(int type, Node *oper, List *args)
{
    if (type == AND_EXPR || type == OR_EXPR || type == NOT_EXPR ||
	type == OP_EXPR || type == FUNC_EXPR) {
	Expr *expr = makeNode(Expr);

	/*
	 * assume type checking already done and we don't need the type of
	 * the expr any more.
	 */
	expr->typeOid = InvalidOid;
	expr->opType = type;
	expr->oper = oper;	/* ignored for AND, OR, NOT */
	expr->args = args;
	return expr;
    }else {
	/* will this ever happen? translated from lispy C code - ay 10/94 */
	return((Expr*)args);
    }
}


/*****************************************************************************
 *	OPERATOR clause functions
 *****************************************************************************/


/*    
 * is_opclause--
 *    
 * Returns t iff the clause is an operator clause:
 *    		(op expr expr) or (op expr).
 *
 * [historical note: is_clause has the exact functionality and is used
 *	throughout the code. They're renamed to is_opclause for clarity.
 *						- ay 10/94.]
 */
bool
is_opclause(Node *clause)
{
    return 
	(clause!=NULL &&
	 nodeTag(clause)==T_Expr && ((Expr*)clause)->opType==OP_EXPR);
}

/*    
 * make_opclause--
 *    Creates a clause given its operator left operand and right
 *    operand (if it is non-null).
 *    
 */
Expr *
make_opclause(Oper *op, Var *leftop, Var *rightop)
{
    Expr *expr = makeNode(Expr);

    expr->typeOid = InvalidOid;	/* assume type checking done */
    expr->opType = OP_EXPR;
    expr->oper = (Node*)op;
    expr->args = makeList(leftop, rightop, -1);
    return expr;
}

/*    
 * get_leftop--
 *    
 * Returns the left operand of a clause of the form (op expr expr)
 *   	or (op expr)
 * NB: it is assumed (for now) that all expr must be Var nodes    
 */
Var *
get_leftop(Expr *clause)
{
    if (clause->args!=NULL)
	return(lfirst(clause->args));
    else
	return NULL;
}

/*    
 * get_rightop
 *    
 * Returns the right operand in a clause of the form (op expr expr).
 *    
 */
Var *
get_rightop(Expr *clause)
{
    if (clause->args!=NULL && lnext(clause->args)!=NULL)
	return (lfirst(lnext(clause->args)));
    else
	return NULL;
}

/*****************************************************************************
 *    	AGG clause functions
 *****************************************************************************/

bool
agg_clause(Node *clause)
{
    return
	(clause!=NULL && nodeTag(clause)==T_Aggreg);
}

/*****************************************************************************
 *    	FUNC clause functions
 *****************************************************************************/

/*    
 * is_funcclause--
 *    
 * Returns t iff the clause is a function clause: (func { expr }).
 *    
 */
bool
is_funcclause(Node *clause)
{
    return
	(clause!=NULL &&
	 nodeTag(clause)==T_Expr && ((Expr*)clause)->opType==FUNC_EXPR);
}

/*    
 * make_funcclause--
 *    
 * Creates a function clause given the FUNC node and the functional
 * arguments.
 *    
 */
Expr *
make_funcclause(Func *func, List *funcargs)
{
    Expr *expr = makeNode(Expr);

    expr->typeOid = InvalidOid;	/* assume type checking done */
    expr->opType = FUNC_EXPR;
    expr->oper = (Node*)func;
    expr->args = funcargs;
    return expr;
}

/*****************************************************************************
 *    	OR clause functions
 *****************************************************************************/

/*    
 * or_clause--
 *    
 * Returns t iff the clause is an 'or' clause: (OR { expr }).
 *    
 */
bool
or_clause(Node *clause)
{
    return
	(clause!=NULL &&
	 nodeTag(clause)==T_Expr && ((Expr*)clause)->opType==OR_EXPR);
}

/*    
 * make_orclause--
 *    
 * Creates an 'or' clause given a list of its subclauses.
 *    
 */
Expr *
make_orclause(List *orclauses)
{
    Expr *expr = makeNode(Expr);

    expr->typeOid = InvalidOid;	/* assume type checking done */
    expr->opType = OR_EXPR;
    expr->oper = NULL;
    expr->args = orclauses;
    return expr;
}

/*****************************************************************************
 *    	NOT clause functions
 *****************************************************************************/

/*    
 * not_clause--
 *    
 * Returns t iff this is a 'not' clause: (NOT expr).
 *    
 */
bool
not_clause(Node *clause)
{
    return
	(clause!=NULL &&
	 nodeTag(clause)==T_Expr && ((Expr*)clause)->opType == NOT_EXPR);
}

/*    
 * make_notclause--
 *    
 * Create a 'not' clause given the expression to be negated.
 *    
 */
Expr *
make_notclause(Expr *notclause)
{
    Expr *expr = makeNode(Expr);

    expr->typeOid = InvalidOid;	/* assume type checking done */
    expr->opType = NOT_EXPR;
    expr->oper = NULL;
    expr->args = lcons(notclause, NIL);
    return expr;
}

/*    
 * get_notclausearg--
 *    
 * Retrieve the clause within a 'not' clause
 *    
 */
Expr *
get_notclausearg(Expr *notclause)
{
     return(lfirst(notclause->args));
}

/*****************************************************************************
 *    	AND clause functions
 *****************************************************************************/


/*    
 * and_clause--
 *    
 * Returns t iff its argument is an 'and' clause: (AND { expr }).
 *    
 */
bool
and_clause(Node *clause)
{
    return
	(clause!=NULL &&
	 nodeTag(clause)==T_Expr && ((Expr*)clause)->opType == AND_EXPR);
}
/*    		 
 * make_andclause--
 *    
 * Create an 'and' clause given its arguments in a list.
 *    
 */
Expr *
make_andclause(List *andclauses)
{
    Expr *expr = makeNode(Expr);

    expr->typeOid = InvalidOid;	/* assume type checking done */
    expr->opType = AND_EXPR;
    expr->oper = NULL;
    expr->args = andclauses;
    return expr;
}

/*****************************************************************************
 *                                                                           *
 *                                                                           *
 *                                                                           *
 *****************************************************************************/


/*    
 * pull-constant-clauses--
 *    Scans through a list of qualifications and find those that
 *    contain no variables.
 *    
 * Returns a list of the constant clauses in constantQual and the remaining
 * quals as the return value.
 *    
 */
List *
pull_constant_clauses(List *quals, List **constantQual)
{
    List *q;
    List *constqual=NIL;
    List *restqual=NIL;

    foreach(q, quals) {
	if (!contain_var_clause(lfirst(q))) {
	    constqual = lcons(lfirst(q), constqual);
	}else {
	    restqual = lcons(lfirst(q), restqual);
	}
    }
    freeList(quals);
    *constantQual = constqual;
    return restqual;
}

/*    
 * clause-relids-vars--
 *    Retrieves relids and vars appearing within a clause.
 *    Returns ((relid1 relid2 ... relidn) (var1 var2 ... varm)) where 
 *    vars appear in the clause  this is done by recursively searching
 *    through the left and right operands of a clause.
 *    
 * Returns the list of relids and vars.
 *    
 * XXX take the nreverse's out later
 *    
 */
void
clause_relids_vars(Node *clause, List **relids, List **vars)
{
    List *clvars = pull_var_clause(clause);
    List *var_list = NIL;
    List *varno_list = NIL;
    List *i = NIL;

    foreach (i, clvars) {
	Var *var = (Var *)lfirst(i);
	List *vi;

	if (!intMember(var->varno, varno_list)) {
	    varno_list = lappendi(varno_list, var->varno);
	}
	foreach (vi, var_list)
	{
	    Var *in_list = (Var *)lfirst(vi);
	    
	    if ( in_list->varno == var->varno && 
	    		in_list->varattno == var->varattno )
	    	break;
	}
	if ( vi == NIL )
	    var_list = lappend(var_list, var);
    }

    *relids = varno_list;
    *vars = var_list;
    return;
}

/*    
 * NumRelids--
 *    	(formerly clause-relids)
 *    
 * Returns the number of different relations referenced in 'clause'.
 */
int
NumRelids(Node *clause)
{
    List *vars = pull_var_clause(clause);
    List *i = NIL;
    List *var_list = NIL;

    foreach (i, vars) {
	Var *var = (Var *)lfirst(i);

	if (!intMember(var->varno, var_list)) {
	    var_list = lconsi(var->varno, var_list);
	}
    }

    return(length(var_list));
}

/*    
 * contains-not--
 *
 * Returns t iff the clause is a 'not' clause or if any of the
 * subclauses within an 'or' clause contain 'not's.
 *    
 */
bool
contains_not(Node *clause)
{
    if (single_node(clause))
	return (false);

    if (not_clause(clause))
	return (true);

    if (or_clause(clause)) {
	List *a;
	foreach(a, ((Expr*)clause)->args) {
	    if (contains_not(lfirst(a)))
		return (true);
	}
    }
	
    return(false);
}

/*    
 * join-clause-p--
 *    
 * Returns t iff 'clause' is a valid join clause.
 *    
 */
bool
join_clause_p(Node *clause)
{
    Node *leftop, *rightop;

    if (!is_opclause(clause))
	return false;

    leftop = (Node*)get_leftop((Expr*)clause);
    rightop = (Node*)get_rightop((Expr*)clause);

    /*
     * One side of the clause (i.e. left or right operands)
     * must either be a var node ...
     */
    if (IsA(leftop,Var) || IsA(rightop,Var))
	return true;

    /*
     * ... or a func node.
     */
    if (is_funcclause(leftop) || is_funcclause(rightop))
	return(true);

    return(false);
}

/*    
 * qual-clause-p--
 *    
 * Returns t iff 'clause' is a valid qualification clause.
 *    
 */
bool
qual_clause_p(Node *clause)
{
    if (!is_opclause(clause))
	return false;

    if (IsA (get_leftop((Expr*)clause),Var) &&
	IsA (get_rightop((Expr*)clause),Const))
	{
	    return(true);
	}
    else if (IsA (get_rightop((Expr*)clause),Var) &&
	     IsA (get_leftop((Expr*)clause),Const))
	{
	    return(true);
	}
    return(false);
}

/*    
 * fix-opid--
 *    Calculate the opfid from the opno...
 *    
 * Returns nothing.
 *    
 */
void
fix_opid(Node *clause)
{
    if (clause==NULL || single_node(clause)) {
	;
    } 
    else if (or_clause (clause)) {
	fix_opids(((Expr*)clause)->args);
    } 
    else if (is_funcclause (clause)) {
	fix_opids(((Expr*)clause)->args);
    } 
    else if (IsA(clause,ArrayRef)) {
	ArrayRef *aref = (ArrayRef *)clause;
	
	fix_opids(aref->refupperindexpr);
	fix_opids(aref->reflowerindexpr);
	fix_opid(aref->refexpr);
	fix_opid(aref->refassgnexpr);
    }
    else if (not_clause(clause)) {
	fix_opid((Node*)get_notclausearg((Expr*)clause));
    } 
    else if (is_opclause (clause)) {
	replace_opid((Oper*)((Expr*)clause)->oper);
	fix_opid((Node*)get_leftop((Expr*)clause));
	fix_opid((Node*)get_rightop((Expr*)clause));
    }
    else if (agg_clause (clause)) {
    	fix_opid (((Aggreg*)clause)->target);
    }

}

/*    
 * fix-opids--
 *    Calculate the opfid from the opno for all the clauses...
 *    
 * Returns its argument.
 *    
 */
List *
fix_opids(List *clauses)
{
    List *clause;

    foreach(clause, clauses)
	fix_opid(lfirst(clause));

    return(clauses);
}

/*    
 * get_relattval--
 *    	For a non-join clause, returns a list consisting of the 
 *    		relid,
 *    		attno,
 *    		value of the CONST node (if any), and a
 *    		flag indicating whether the value appears on the left or right
 *    			of the operator and whether the value varied.
 *
 * OLD OBSOLETE COMMENT FOLLOWS:
 *    	If 'clause' is not of the format (op var node) or (op node var),
 *    	or if the var refers to a nested attribute, then -1's are returned for
 *    	everything but the value  a blank string "" (pointer to \0) is
 *    	returned for the value if it is unknown or null.
 * END OF OLD OBSOLETE COMMENT.
 * NEW COMMENT:
 * when defining rules one of the attibutes of the operator can
 * be a Param node (which is supposed to be treated as a constant).
 * However as there is no value specified for a parameter until run time
 * this routine used to return "" as value, which made 'compute_selec'
 * to bomb (because it was expecting a lisp integer and got back a lisp
 * string). Now the code returns a plain old good "lispInteger(0)".
 *    
 */
void
get_relattval(Node *clause,
	      int *relid,
	      AttrNumber *attno,
	      Datum *constval,
	      int *flag)
{
    Var *left = get_leftop((Expr*)clause);
    Var *right = get_rightop((Expr*)clause);
    
    if(is_opclause(clause) && IsA(left,Var) && 
       IsA(right,Const)) {

	if(right!=NULL) {

	    *relid = left->varno;
	    *attno = left->varattno;
	    *constval = ((Const *)right)->constvalue;
	    *flag = (_SELEC_CONSTANT_RIGHT_ | _SELEC_IS_CONSTANT_);

	} else {

	    *relid = left->varno;
	    *attno = left->varattno;
	    *constval = 0;
	    *flag = (_SELEC_CONSTANT_RIGHT_ | _SELEC_NOT_CONSTANT_);
	
	} 
#ifdef INDEXSCAN_PATCH
    } else if (is_opclause(clause) && IsA(left,Var) && IsA(right,Param)) {
	/* Function parameter used as index scan arg.  DZ - 27-8-1996 */ 
	*relid = left->varno;
	*attno = left->varattno;
	*constval = 0;
	*flag = (_SELEC_NOT_CONSTANT_);
#endif
    }else if (is_opclause(clause) &&
	      is_funcclause((Node*)left) &&
	      IsA(right,Const)) {
	List *args = ((Expr*)left)->args;


	*relid = ((Var*)lfirst(args))->varno;
	*attno = InvalidAttrNumber;
	*constval = ((Const*)right)->constvalue;
	*flag = (_SELEC_CONSTANT_RIGHT_ | _SELEC_IS_CONSTANT_);
    
	/*
	 * XXX both of these func clause handling if's seem wrong to me.
	 *     they assume that the first argument is the Var.  It could
	 *     not handle (for example) f(1, emp.name).  I think I may have
	 *     been assuming no constants in functional index scans when I
	 *     implemented this originally (still currently true).
	 *     -mer 10 Aug 1992
	 */
    } else if (is_opclause(clause) &&
	     is_funcclause((Node*)right) &&
	       IsA(left,Const)) {
	List *args = ((Expr*)right)->args;

	*relid = ((Var*)lfirst(args))->varno;
	*attno = InvalidAttrNumber;
	*constval = ((Const*)left)->constvalue;
	*flag = ( _SELEC_IS_CONSTANT_);
    
    } else if (is_opclause (clause) && IsA (right,Var) &&
	      IsA (left,Const)) {
	if (left!=NULL) {

	    *relid = right->varno;
	    *attno = right->varattno;
	    *constval = ((Const*)left)->constvalue;
	    *flag = (_SELEC_IS_CONSTANT_);
	} else {

	    *relid = right->varno;
	    *attno = right->varattno;
	    *constval = 0;
	    *flag = (_SELEC_NOT_CONSTANT_);
	} 
    } else {
	/* One or more of the operands are expressions 
	 * (e.g., oper clauses)
	 */
	*relid = _SELEC_VALUE_UNKNOWN_;
	*attno = _SELEC_VALUE_UNKNOWN_;
	*constval = 0;
	*flag = (_SELEC_NOT_CONSTANT_);
    }		       
}

/*    
 * get_relsatts--
 *    
 * Returns a list 
 *    		( relid1 attno1 relid2 attno2 )
 *    	for a joinclause.
 *    
 * If the clause is not of the form (op var var) or if any of the vars
 * refer to nested attributes, then -1's are returned.
 *    
 */
void
get_rels_atts(Node *clause,
	      int *relid1,
	      AttrNumber *attno1,
	      int *relid2,
	      AttrNumber *attno2)
{
    Var *left = get_leftop((Expr*)clause);
    Var *right = get_rightop((Expr*)clause);
    bool var_left = (IsA(left,Var));
    bool var_right = (IsA(right,Var));
    bool varexpr_left = (bool)((IsA(left,Func) || IsA (left,Oper)) &&
			       contain_var_clause((Node*)left));
    bool varexpr_right = (bool)(( IsA(right,Func) || IsA (right,Oper)) &&
				contain_var_clause((Node*)right));
    
    if (is_opclause(clause)) {
	if(var_left && var_right) {

	    *relid1 = left->varno;
	    *attno1 = left->varoattno;
	    *relid2 = right->varno;
	    *attno2 = right->varoattno;
	    return;
	} else if (var_left && varexpr_right ) {

	    *relid1 = left->varno;
	    *attno1 = left->varoattno;
	    *relid2 = _SELEC_VALUE_UNKNOWN_;
	    *attno2 = _SELEC_VALUE_UNKNOWN_;
	    return;
	} else if (varexpr_left && var_right) {

	    *relid1 = _SELEC_VALUE_UNKNOWN_;
	    *attno1 = _SELEC_VALUE_UNKNOWN_;
	    *relid2 = right->varno;
	    *attno2 = right->varoattno;
	    return;
	}
    }

    *relid1 = _SELEC_VALUE_UNKNOWN_;
    *attno1 = _SELEC_VALUE_UNKNOWN_;
    *relid2 = _SELEC_VALUE_UNKNOWN_;
    *attno2 = _SELEC_VALUE_UNKNOWN_;
    return;
}

void
CommuteClause(Node *clause)
{
    Node *temp;
    Oper *commu;
    OperatorTupleForm commuTup;
    HeapTuple heapTup;

    if (!is_opclause(clause))
	return;

    heapTup = (HeapTuple)
	get_operator_tuple(get_commutator(((Oper*)((Expr*)clause)->oper)->opno));

    if (heapTup == (HeapTuple)NULL)
	return;

    commuTup = (OperatorTupleForm)GETSTRUCT(heapTup);

    commu = makeOper(heapTup->t_oid,
		     InvalidOid,
		     commuTup->oprresult,
		     ((Oper*)((Expr*)clause)->oper)->opsize,
		     NULL);

    /*
     * reform the clause -> (operator func/var constant)
     */
    ((Expr*)clause)->oper = (Node*)commu;
    temp = lfirst(((Expr*)clause)->args);
    lfirst(((Expr*)clause)->args) = lsecond(((Expr*)clause)->args);
    lsecond(((Expr*)clause)->args) = temp;
}


