/*
Copyright 2022 Embedded Artistry LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef LL_H__
#define LL_H__

#include <stdint.h>
#include <stdlib.h> //size_t, NULL

/** @defgroup linkedlist-C C Linked List Interface
 * A linked list library for C modules
 *
 * @ingroup FrameworkUtils
 * @{
 */

/**
 * Define offsetof if we don't have it already
 */
#ifndef offsetof
#ifdef __compiler_offsetof
#define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER)
#else
#define offsetof(TYPE, MEMBER) ((size_t) & ((TYPE*)0)->MEMBER)
#endif
#endif // offsetof

/**
 * Define container_of if we don't have it already
 */
#ifndef container_of
#ifdef __GNUC__
#ifndef __clang__
// Isolate the GNU-specific expression
#define container_of(ptr, type, member)                       \
	({                                                        \
		const __typeof__(((type*)0)->member)* __mptr = (ptr); \
		(type*)((uintptr_t)__mptr - offsetof(type, member));  \
	})
#else // we are clang - avoid GNU expression
#define container_of(ptr, type, member) ((type*)((uintptr_t)(ptr)-offsetof(type, member)))
#endif // GNU and not clang
#else
#define container_of(ptr, type, member) ((type*)((uintptr_t)(ptr)-offsetof(type, member)))
#endif // not GNU
#endif // container_of

#ifdef __cplusplus
extern "C" {
#endif //__cplusplus

/** Linked list struct
 *
 * This is a doubly linked list structure.
 * The ll_t structure should be embedded in a container structure that you want to list.
 *
 * Example:
 *
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 */
typedef struct ll_head
{
	/// Pointer to the next element in the list.
	struct ll_head* next;
	/// Pointer to the previous element in the list.
	struct ll_head* prev;
} ll_t;

//#pragma mark - List Manipulation -

/// @name Get Containers
/// @{

/** Get the container for a list entry
 *
 * @param[in] ptr The pointer to the target ll_t node.
 * @param[in] type The struct type which contains the ll_t node. For this example struct,
 * type would refer to alloc_node_t:
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 *
 * @param[in] member The member which corresponds to the member name of the ll_t entry. For this
 * example struct, member would refer to `node`.
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 *
 * @returns a pointer to the struct containing the linked list node at `ptr`, cast to type `type`.
 */
#define list_entry(ptr, type, member) container_of(ptr, type, member)

/** Get the container for the first item in the list
 *
 * @param[in] head The pointer to the head of the list.
 * @param[in] type The struct type which contains the ll_t node. For this example struct,
 * type would refer to alloc_node_t:
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode

 * @param[in] member The member which corresponds to the member name of the ll_t entry. For this
 * example struct, member would refer to `node`.
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 *
 * @returns a pointer to the struct containing the linked list node at `ptr`, cast to type `type`.
 */
#define list_first_entry(head, type, member) list_entry((head)->next, type, member)

/// @}
// Get containers

//#pragma mark - Foreach -

/// @name Foreach Operations
/// @{

/** Declare a foreach loop which iterates over the list
 *
 * list_for_each() will run as long as the current object's next pointer is not equal to the
 * head of the list. It's possible for a malformed list to loop forever.
 *
 * @param[in] pos The variable which will hold the current iteration's position value.
 *	This variable must be a pointer and should be pre-declared before instantiating the loop.
 *	@code
 *	ll_t *b;
 *	list_for_each(b, &free_list)
 *   {
 *	...
 * 	}
 *   @endcode
 * @param[in] head The head of the linked list. Input should be a pointer.
 */
#define list_for_each(pos, head) for(pos = (head)->next; pos != (head); pos = pos->next)

/** Declare a foreach loop which iterates over the list, copy current node pointer.
 *
 * list_for_each_safe() will run as long as the current object's next pointer is not equal to the
 * head of the list. It's possible for a malformed list to loop forever.
 *
 * The list_for_each_safe() variant makes a copy of the current node pointer, enabling the loop
 * to get to the next pointer if there is a deletion.
 *
 * @param[in] pos The variable which will hold the current iteration's position value.
 *	This variable must be a pointer should be pre-declared before instantiating the loop.
 *	@code
 *	ll_t *b, *t;
 *	list_for_each_safe(b, t, &free_list)
 *   {
 *	...
 * 	}
 *  @endcode
 * @param[in] n The variable which will hold the current iteration's position value **copy**.
 *	This variable must be a pointer and should be pre-declared before instantiating the loop.
 *	@code
 *	alloc_node_t *b, *t;
 *	list_for_each_safe(b, t, &free_list)
 *   {
 *	...
 * 	}
 *	@endcode
 * @param[in] head The head of the linked list. Input should be a pointer.
 */
#define list_for_each_safe(pos, n, head) \
	for(pos = (head)->next, n = pos->next; pos != (head); pos = n, n = pos->next)

/** Declare a for loop which operates on each node in the list using the container value.
 *
 * @param[in] pos The variable which will hold the current iteration's position value.
 *	This variable must be a pointer and should be pre-declared before instantiating the loop.
 *  The `pos` variable must be the container type.
 *	@code
 *	alloc_node_t *b, *t;
 *	list_for_each_entry(b, &free_list, node)
 *   {
 *	...
 * 	}
 *  @endcode
 *
 * @param[in] head The head of the linked list. Input should be a pointer.
 *
 * @param[in] member The member which corresponds to the member name of the ll_t entry. For this
 * example struct, member would refer to `node`.
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 */
#define list_for_each_entry(pos, head, member)                                            \
	for(pos = list_entry((head)->next, __typeof__(*pos), member); &pos->member != (head); \
		pos = list_entry(pos->member.next, __typeof__(*pos), member))

/** Declare a for loop which operates on each node in the list using a copy of the container value.
 *
 * @param[in] pos The variable which will hold the current iteration's position value.
 *	This variable must be a pointer and should be pre-declared before instantiating the loop.
 *  The `pos` variable must be the container type.
 *	@code
 *	alloc_node_t *b, *t;
 *	list_for_each_entry(b, &free_list, node)
 *   {
 *	...
 * 	}
 *  @endcode
 * @param[in] n The variable which will hold the current iteration's position value **copy**.
 *	This variable must be a pointer and should be pre-declared before instantiating the loop.
 *  The `n` variable must be the container type.
 *	@code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 *
 *	alloc_node_t *b, *t;
 *	list_for_each_entrysafe(b, t, &free_list, node)
 *   {
 *	...
 * 	}
 *   @endcode
 * @param[in] head The head of the linked list. Input should be a pointer.
 * @param[in] member The member which corresponds to the member name of the ll_t entry. For this
 * example struct, member would refer to `node`.
 * @code
 * typedef struct
 * {
 * 	ll_t node;
 * 	size_t size;
 * 	char* block;
 * } alloc_node_t;
 * @endcode
 */
#define ll_for_each_entry_safe(pos, n, head, member)            \
	for(pos = list_entry((head)->next, __typeof__(*pos), member), \
	n = list_entry(pos->member.next, __typeof__(*pos), member);   \
		&pos->member != (head); pos = n, n = list_entry(n->member.next, __typeof__(*n), member))

/// @}
// End foreach

//#pragma mark - Init -

/// @name Initialization
/// @{

/// Initialize a linked list so it points to itself
/// @param[in] name of the linked list object
#define ll_head_INIT(name) \
	{                      \
		&(name), &(name)   \
	}

/** Initialize a linked list
 *
 * @code
 * // This macro declares and initializes our linked list
 * static LIST_INIT(free_list);
 * @endcode
 * @param[in] name The name of the linked list object to declare
 */
#define LIST_INIT(name) struct ll_head name = ll_head_INIT(name)

/// Initialize an existing linked list head pointer
/// @param[in] ptr Pointer to the ll_head structure to initialize
static inline void INIT_LIST_HEAD(struct ll_head* ptr)
{
	ptr->next = ptr;
	ptr->prev = ptr;
}

/// Check if a list is empty
/// @param[in] head Pointer to the list head
/// @return 1 if the list is empty, 0 otherwise
static inline int list_empty(const struct ll_head* head)
{
	return head->next == head;
}

/// @}

//#pragma mark - Add -

/// @name Addition
/// @{

/// Insert a new element between two existing elements.
/// @param[in] n The node to add to the list.
/// @param[in] prev The pointer to the node before where the new node will be inserted.
/// @param[in] next The pointer to the new node after where the new node will be inserted.
static inline void list_insert(struct ll_head* n, struct ll_head* prev, struct ll_head* next)
{
	next->prev = n;
	n->next = next;
	n->prev = prev;
	prev->next = n;
}

/// Add a node to the front of the list
/// @param[in] n The node to add to the list.
/// @param[in] head The head of the list.
static inline void list_add(struct ll_head* n, struct ll_head* head)
{
	list_insert(n, head, head->next);
}

/// Add a node to the end of the list
/// @param[in] n The node to add to the list.
/// @param[in] head The head of the list.
static inline void list_add_tail(struct ll_head* n, struct ll_head* head)
{
	list_insert(n, head->prev, head);
}

/// @}

//#pragma mark - Delete -

/// @name Deletion
/// @{

/// Remove the node between two element pointers.
///
/// Joins the `prev` and `next` elements together, effectively removing
/// the element in the middle.
///
/// @param[in] prev The previous element in the list, which will now be joined to next.
/// @param[in] next The next element in the list, which will now be joined to prev.
static inline void list_join_nodes(struct ll_head* prev, struct ll_head* next)
{
	next->prev = prev;
	prev->next = next;
}

/// Remove an entry from the list
/// @param[in] entry The pointer to the entry to remove from the list.
static inline void list_del(struct ll_head* entry)
{
	list_join_nodes(entry->prev, entry->next);
	entry->next = NULL;
	entry->prev = NULL;
}

/// @}

/// @}
// end group

#ifdef __cplusplus
}
#endif //__cplusplus

#endif // LL_H__
