#include "postgres.h"
#include "catalog/pg_type.h"
#include "fmgr.h"
#include "utils/builtins.h"
#include "utils/jsonb.h"
PG_MODULE_MAGIC;

static int	lengthCompareJsonbStringValue(const void *a, const void *b);

PG_FUNCTION_INFO_V1(jsonb_deep_add);
Datum
jsonb_deep_add(PG_FUNCTION_ARGS)
{
 	// https://trac.osgeo.org/postgis/ticket/3867
	#ifdef PG_GETARG_JSONB_P
		Jsonb	   *jb1 = PG_GETARG_JSONB_P(0);
		Jsonb	   *jb2 = PG_GETARG_JSONB_P(1);
	#else
		Jsonb	   *jb1 = PG_GETARG_JSONB(0);
		Jsonb	   *jb2 = PG_GETARG_JSONB(1);
	#endif
	JsonbIterator *it1,
			   *it2;
	JsonbValue	v1,
				v2;
	JsonbIteratorToken r1,
				r2;
	JsonbValue *res;
	JsonbParseState *state = NULL;

	/* Here we create the new jsonb */
	int			nestedLevel = 0;

	if (jb1 == NULL)
		#ifdef PG_RETURN_JSONB_P
			PG_RETURN_JSONB_P(jb2);
		#else
			PG_RETURN_JSONB(jb2);
		#endif
	if (jb2 == NULL)
		#ifdef PG_RETURN_JSONB_P
			PG_RETURN_JSONB_P(jb1);
		#else
			PG_RETURN_JSONB(jb1);
		#endif
	if (!JB_ROOT_IS_OBJECT(jb1) || !JB_ROOT_IS_OBJECT(jb2))
		ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Can only sum objects")));


	it1 = JsonbIteratorInit(&jb1->root);
	it2 = JsonbIteratorInit(&jb2->root);

	r1 = JsonbIteratorNext(&it1, &v1, false);
	r2 = JsonbIteratorNext(&it2, &v2, false);

	if (r1 != WJB_BEGIN_OBJECT || r2 != WJB_BEGIN_OBJECT)
		ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Iterator was not an object")));

	pushJsonbValue(&state, r1, NULL);
	/* Start object */
	r1 = JsonbIteratorNext(&it1, &v1, false);
	r2 = JsonbIteratorNext(&it2, &v2, false);

	while (!(r1 == WJB_END_OBJECT && r2 == WJB_END_OBJECT && nestedLevel == 0))
	{
		int			difference;

		/* Datum sum; */
		JsonbValue	newValue;

		if (r1 == WJB_END_OBJECT && r2 == WJB_END_OBJECT && nestedLevel > 0)
		{
			pushJsonbValue(&state, WJB_END_OBJECT, NULL);
			r1 = JsonbIteratorNext(&it1, &v1, false);
			r2 = JsonbIteratorNext(&it2, &v2, false);
			nestedLevel--;
			continue;
		}
		if (r1 == WJB_END_OBJECT)
		{
			pushJsonbValue(&state, r2, &v2);
			r2 = JsonbIteratorNext(&it2, &v2, true);
			continue;
		}
		if (r2 == WJB_END_OBJECT)
		{
			pushJsonbValue(&state, r1, &v1);
			r1 = JsonbIteratorNext(&it1, &v1, true);
			continue;
		}
		difference = lengthCompareJsonbStringValue(&v1, &v2);
		/* first key is smaller */
		if (difference < 0)
		{
			pushJsonbValue(&state, r1, &v1);
			r1 = JsonbIteratorNext(&it1, &v1, true);
			/* jbvBinary is returned in skipNested mode */
			if ((&v1)->type == jbvNumeric || (&v1)->type == jbvBinary)
			{
				pushJsonbValue(&state, r1, &v1);
			}
			else
			{
				ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Only numeric values allowed")));
			}
			r1 = JsonbIteratorNext(&it1, &v1, true);
			continue;
		}
		else if (difference > 0)
		{
			pushJsonbValue(&state, r2, &v2);
			r2 = JsonbIteratorNext(&it2, &v2, true);

			if ((&v2)->type == jbvNumeric || (&v2)->type == jbvBinary)
			{
				pushJsonbValue(&state, r2, &v2);
			}
			else
			{
				ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Only numeric values allowed")));
			}
			r2 = JsonbIteratorNext(&it2, &v2, true);
			continue;
		}
		pushJsonbValue(&state, r1, &v1);
		r2 = JsonbIteratorNext(&it2, &v2, false);
		r1 = JsonbIteratorNext(&it1, &v1, false);
		if ((&v1)->type == jbvNumeric && (&v2)->type == jbvNumeric)
		{
			/* TODO jbvString, jbvNull and jbvBool */
			newValue.type = jbvNumeric;

			newValue.val.numeric = DatumGetNumeric((DirectFunctionCall2(numeric_add, PointerGetDatum(
																									 (&v1)->val.numeric), PointerGetDatum((&v2)->val.numeric))));

			pushJsonbValue(&state, WJB_VALUE, &newValue);
		}
		else if ((&v1)->type == jbvObject && (&v2)->type == jbvObject)
		{
			pushJsonbValue(&state, WJB_BEGIN_OBJECT, NULL);
			nestedLevel++;
		}
		else
		{
			ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Incompatible types")));
		}
		r2 = JsonbIteratorNext(&it2, &v2, false);
		r1 = JsonbIteratorNext(&it1, &v1, false);

	}

	res = pushJsonbValue(&state, WJB_END_OBJECT, NULL);

	Assert(res != NULL);

	#ifdef PG_RETURN_JSONB_P
		PG_RETURN_JSONB_P(JsonbValueToJsonb(res));
	#else
		PG_RETURN_JSONB(JsonbValueToJsonb(res));
	#endif
}

/* Taken from src/backend/adt/jsonb_utils.c
 * Compare two jbvString JsonbValue values, a and b.
 *
 * This is a special qsort() comparator used to sort strings in certain
 * internal contexts where it is sufficient to have a well-defined sort order.
 * In particular, object pair keys are sorted according to this criteria to
 * facilitate cheap binary searches where we don't care about lexical sort
 * order.
 *
 * a and b are first sorted based on their length.  If a tie-breaker is
 * required, only then do we consider string binary equality.
 */
static int
lengthCompareJsonbStringValue(const void *a, const void *b)
{
	const JsonbValue *va = (const JsonbValue *) a;
	const JsonbValue *vb = (const JsonbValue *) b;
	int			res;

	Assert(va->type == jbvString);
	Assert(vb->type == jbvString);

	if (va->val.string.len == vb->val.string.len)
	{
		res = memcmp(va->val.string.val, vb->val.string.val, va->val.string.len);
	}
	else
	{
		res = (va->val.string.len > vb->val.string.len) ? 1 : -1;
	}

	return res;
}