/*
 * array_iterator.c --
 *
 * This file defines a new group of operators which take an
 * array and a scalar value, iterate a scalar operator over the
 * elements of the array and the value and compute a result as
 * the logical OR or AND of the results.
 * For example array_int4eq returns true if some of the elements
 * of an array of int4 is equal to the given value:
 *
 *		array_int4eq({1,2,3}, 1)  -->  true
 *		array_int4eq({1,2,3}, 4)  -->  false
 *
 * If we have defined T array types and O scalar operators
 * we can define T x O array operators, each of them has a name
 * like "array_<basetype><operation>" and takes an array of type T
 * iterating the operator O over all the elements. Note however
 * that some of the possible combination are invalid, for example
 * the array_int4_like because there is no like operator for int4.
 * It is now possible to write queries which look inside the arrays:
 *
 *		create table t(id int4[], txt text[]);
 *		select * from t where t.id *= 123;
 *		select * from t where t.txt *~ '[a-z]';
 *		select * from t where t.txt[1:3] **~ '[a-z]';
 *
 * Copyright (c) 1996, Massimo Dal Zotto <dz@cs.unitn.it>
 */

#include <ctype.h>
#include <stdio.h>
#include <sys/types.h>
#include <string.h>

#include "postgres.h"
#include "pg_type.h"
#include "miscadmin.h"
#include "syscache.h"
#include "access/xact.h"
#include "utils/builtins.h"
#include "utils/elog.h"

static int32
array_iterator(Oid elemtype, Oid proc, int and, ArrayType *array, Datum value)
{
	HeapTuple	typ_tuple;
	TypeTupleForm typ_struct;
	bool		typbyval;
	int			typlen;
	func_ptr	proc_fn;
	int			pronargs;
	int			nitems,
				i,
				result;
	int			ndim,
			   *dim;
	char	   *p;

	/* Sanity checks */
	if ((array == (ArrayType *) NULL)
		|| (ARR_IS_LO(array) == true))
	{
		/* elog(NOTICE, "array_iterator: array is null"); */
		return (0);
	}
	ndim = ARR_NDIM(array);
	dim = ARR_DIMS(array);
	nitems = getNitems(ndim, dim);
	if (nitems == 0)
	{
		/* elog(NOTICE, "array_iterator: nitems = 0"); */
		return (0);
	}

	/* Lookup element type information */
	typ_tuple = SearchSysCacheTuple(TYPOID, ObjectIdGetDatum(elemtype), 0, 0, 0);
	if (!HeapTupleIsValid(typ_tuple))
	{
		elog(WARN, "array_iterator: cache lookup failed for type %d", elemtype);
		return 0;
	}
	typ_struct = (TypeTupleForm) GETSTRUCT(typ_tuple);
	typlen = typ_struct->typlen;
	typbyval = typ_struct->typbyval;

	/* Lookup the function entry point */
	proc_fn == (func_ptr) NULL;
	fmgr_info(proc, &proc_fn, &pronargs);
	if ((proc_fn == NULL) || (pronargs != 2))
	{
		elog(WARN, "array_iterator: fmgr_info lookup failed for oid %d", proc);
		return (0);
	}

	/* Scan the array and apply the operator to each element */
	result = 0;
	p = ARR_DATA_PTR(array);
	for (i = 0; i < nitems; i++)
	{
		if (typbyval)
		{
			switch (typlen)
			{
				case 1:
					result = (int) (*proc_fn) (*p, value);
					break;
				case 2:
					result = (int) (*proc_fn) (*(int16 *) p, value);
					break;
				case 3:
				case 4:
					result = (int) (*proc_fn) (*(int32 *) p, value);
					break;
			}
			p += typlen;
		}
		else
		{
			result = (int) (*proc_fn) (p, value);
			if (typlen > 0)
			{
				p += typlen;
			}
			else
			{
				p += INTALIGN(*(int32 *) p);
			}
		}
		if (result)
		{
			if (!and)
			{
				return (1);
			}
		}
		else
		{
			if (and)
			{
				return (0);
			}
		}
	}

	if (and && result)
	{
		return (1);
	}
	else
	{
		return (0);
	}
}

/*
 * Iterators for type _text
 */

int32
array_texteq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 25,		/* text */
						  (Oid) 67,		/* texteq */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_texteq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 25,		/* text */
						  (Oid) 67,		/* texteq */
						  1,	/* logical and */
						  array, (Datum) value);
}

int32
array_textregexeq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 25,		/* text */
						  (Oid) 81,		/* textregexeq */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_textregexeq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 25,		/* text */
						  (Oid) 81,		/* textregexeq */
						  1,	/* logical and */
						  array, (Datum) value);
}

/*
 * Iterators for type _char16. Note that the regexp operators
 * take the second argument of type text.
 */

int32
array_char16eq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 20,		/* char16 */
						  (Oid) 490,	/* char16eq */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_char16eq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 20,		/* char16 */
						  (Oid) 490,	/* char16eq */
						  1,	/* logical and */
						  array, (Datum) value);
}

int32
array_char16regexeq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 20,		/* char16 */
						  (Oid) 700,	/* char16regexeq */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_char16regexeq(ArrayType *array, char *value)
{
	return array_iterator((Oid) 20,		/* char16 */
						  (Oid) 700,	/* char16regexeq */
						  1,	/* logical and */
						  array, (Datum) value);
}

/*
 * Iterators for type _int4
 */

int32
array_int4eq(ArrayType *array, int4 value)
{
	return array_iterator((Oid) 23,		/* int4 */
						  (Oid) 65,		/* int4eq */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_int4eq(ArrayType *array, int4 value)
{
	return array_iterator((Oid) 23,		/* int4 */
						  (Oid) 65,		/* int4eq */
						  1,	/* logical and */
						  array, (Datum) value);
}

int32
array_int4gt(ArrayType *array, int4 value)
{
	return array_iterator((Oid) 23,		/* int4 */
						  (Oid) 147,	/* int4gt */
						  0,	/* logical or */
						  array, (Datum) value);
}

int32
array_all_int4gt(ArrayType *array, int4 value)
{
	return array_iterator((Oid) 23,		/* int4 */
						  (Oid) 147,	/* int4gt */
						  1,	/* logical and */
						  array, (Datum) value);
}
