/**
*******************************************************************************
* @file json_object_iterator.c
*
* Copyright (c) 2009-2012 Hewlett-Packard Development Company, L.P.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See COPYING for details.
*
* @brief  json-c forces clients to use its private data
*         structures for JSON Object iteration.  This API
*         implementation corrects that by abstracting the
*         private json-c details.
*
*******************************************************************************
*/

#include <stddef.h>

#include "json.h"
#include "json_object_private.h"

#include "json_object_iterator.h"

/**
* How It Works
*
* For each JSON Object, json-c maintains a linked list of zero
* or more lh_entry (link-hash entry) structures inside the
* Object's link-hash table (lh_table).
*
* Each lh_entry structure on the JSON Object's linked list
* represents a single name/value pair.  The "next" field of the
* last lh_entry in the list is set to NULL, which terminates
* the list.
*
* We represent a valid iterator that refers to an actual
* name/value pair via a pointer to the pair's lh_entry
* structure set as the iterator's opaque_ field.
*
* We follow json-c's current pair list representation by
* representing a valid "end" iterator (one that refers past the
* last pair) with a NULL value in the iterator's opaque_ field.
*
* A JSON Object without any pairs in it will have the "head"
* field of its lh_table structure set to NULL.  For such an
* object, json_object_iter_begin will return an iterator with
* the opaque_ field set to NULL, which is equivalent to the
* "end" iterator.
*
* When iterating, we simply update the iterator's opaque_ field
* to point to the next lh_entry structure in the linked list.
* opaque_ will become NULL once we iterate past the last pair
* in the list, which makes the iterator equivalent to the "end"
* iterator.
*/

/// Our current representation of the "end" iterator;
///
/// @note May not always be NULL
//static const void* kObjectEndIterValue = NULL;

/**
* ****************************************************************************
*/
struct json_object_iterator json_object_iter_begin(struct json_object* obj)
{
	struct json_object_iterator iter;
	struct lh_table* pTable;

	/// @note json_object_get_object will return NULL if passed NULL
	///       or a non-json_type_object instance
	pTable = json_object_get_object(obj);
	//JASSERT(NULL != pTable);

	/// @note For a pair-less Object, head is NULL, which matches our
	///       definition of the "end" iterator
	iter.opaque_ = pTable->head;
	return iter;
}

/**
* ****************************************************************************
*/
struct json_object_iterator json_object_iter_end(PRUNTIME pRuntime, const struct json_object* obj)
{
	struct json_object_iterator iter;

	PVARIABLES_CONFIGURATION pVariables = (PVARIABLES_CONFIGURATION)(pRuntime->pModuleSpecificData[INDEX_CONFIGURATION]->lpVariables);

	//JASSERT(NULL != obj);
	//JASSERT(json_object_is_type(obj, json_type_object));

	iter.opaque_ = pVariables->kObjectEndIterValue;

	return iter;
}

/**
* ****************************************************************************
*/
void
json_object_iter_next(struct json_object_iterator* iter)
{
	//JASSERT(NULL != iter);
	//JASSERT(kObjectEndIterValue != iter->opaque_);

	iter->opaque_ = ((struct lh_entry *)iter->opaque_)->next;
}


/**
* ****************************************************************************
*/
const char* json_object_iter_peek_name(const struct json_object_iterator* iter)
{
	//JASSERT(NULL != iter);
	//JASSERT(kObjectEndIterValue != iter->opaque_);

	return (const char*)(((struct lh_entry *)iter->opaque_)->k);
}


/**
* ****************************************************************************
*/
struct json_object*	json_object_iter_peek_value(const struct json_object_iterator* iter)
{
	//JASSERT(NULL != iter);
	//JASSERT(kObjectEndIterValue != iter->opaque_);

	return (struct json_object*)(((struct lh_entry *)iter->opaque_)->v);
}


/**
* ****************************************************************************
*/
json_bool json_object_iter_equal(const struct json_object_iterator* iter1, const struct json_object_iterator* iter2)
{
	//JASSERT(NULL != iter1);
	//JASSERT(NULL != iter2);

	return (iter1->opaque_ == iter2->opaque_);
}


/**
* ****************************************************************************
*/
struct json_object_iterator	json_object_iter_init_default(void)
{
	struct json_object_iterator iter;

	/**
	* @note Make this a negative, invalid value, such that
	*       accidental access to it would likely be trapped by the
	*       hardware as an invalid address.
	*/
	iter.opaque_ = NULL;

	return iter;
}
