/*
 * Copyright 2018-2020 Bytes & Brains
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <postgres.h>		 // Datum, etc.
#include <fmgr.h>			 // PG_FUNCTION_ARGS, etc.
#include <utils/geo_decls.h> // making native points
#include <access/hash.h>	 // hash_any

#include <h3api.h> // Main H3 include
#include "extension.h"

/* conversion */
PG_FUNCTION_INFO_V1(h3index_in);
PG_FUNCTION_INFO_V1(h3index_out);
PG_FUNCTION_INFO_V1(h3index_to_bigint);
PG_FUNCTION_INFO_V1(bigint_to_h3index);

/* b-tree */
PG_FUNCTION_INFO_V1(h3index_eq);
PG_FUNCTION_INFO_V1(h3index_ne);
PG_FUNCTION_INFO_V1(h3index_lt);
PG_FUNCTION_INFO_V1(h3index_le);
PG_FUNCTION_INFO_V1(h3index_gt);
PG_FUNCTION_INFO_V1(h3index_ge);

/* r-tree */
PG_FUNCTION_INFO_V1(h3index_overlaps);
PG_FUNCTION_INFO_V1(h3index_contains);
PG_FUNCTION_INFO_V1(h3index_contained_by);

/* static helpers */
static int
containment(H3Index a, H3Index b)
{
	int			aRes = h3GetResolution(a);
	int			bRes = h3GetResolution(b);
	H3Index		aParent = h3ToParent(a, bRes);
	H3Index		bParent = h3ToParent(b, aRes);

	/* a contains b */
	if (a == bParent)
		return 1;

	/* a contained by b */
	if (b == aParent)
		return -1;

	/* no overlap */
	return 0;
}

/* textual input/output functions */
Datum
h3index_in(PG_FUNCTION_ARGS)
{
	char	   *str = PG_GETARG_CSTRING(0);
	H3Index		hex = stringToH3(str);

	PG_RETURN_H3INDEX(hex);
}

Datum
h3index_out(PG_FUNCTION_ARGS)
{
	H3Index		hex = PG_GETARG_H3INDEX(0);
	char	   *str = palloc(17 * sizeof(char));

	h3ToString(hex, str, 17);
	PG_RETURN_CSTRING(str);
}

/* bigint conversion functions */
Datum
h3index_to_bigint(PG_FUNCTION_ARGS)
{
	H3Index		h3index = PG_GETARG_H3INDEX(0);

	PG_RETURN_INT64(h3index);
}

Datum
bigint_to_h3index(PG_FUNCTION_ARGS)
{
	int64		bigint = PG_GETARG_INT64(0);

	PG_RETURN_H3INDEX(bigint);
}

/* b-tree operators */
Datum
h3index_eq(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a == b;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_ne(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a != b;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_lt(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a < b;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_le(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a <= b;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_gt(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a > b;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_ge(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = a >= b;

	PG_RETURN_BOOL(ret);
}

/* r-tree operators */
Datum
h3index_overlaps(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = containment(a, b) != 0;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_contains(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = containment(a, b) > 0;

	PG_RETURN_BOOL(ret);
}

Datum
h3index_contained_by(PG_FUNCTION_ARGS)
{
	H3Index		a = PG_GETARG_H3INDEX(0);
	H3Index		b = PG_GETARG_H3INDEX(1);
	bool		ret = containment(a, b) < 0;

	PG_RETURN_BOOL(ret);
}