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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * @file linked_list.h
 * @brief Linked list implementation.
 * @author Mike Becker
 * @author Olaf Wintermann
 * @copyright 2-Clause BSD License
 */

#ifndef UCX_LINKED_LIST_H
#define UCX_LINKED_LIST_H

#include "common.h"
#include "list.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Metadata for a linked list.
 */
typedef struct cx_linked_list_s {
    /** Base members. */
    struct cx_list_s base;
    /**
     * Location of the prev pointer (mandatory).
     */
    off_t loc_prev;
    /**
     * Location of the next pointer (mandatory).
     */
    off_t loc_next;
    /**
     * Location of the payload (mandatory).
     */
    off_t loc_data;
    /**
     * Additional bytes to allocate @em behind the payload (e.g. for metadata).
     */
    size_t extra_data_len;
    /**
     * Pointer to the first node.
     */
    void *begin;
    /**
     * Pointer to the last node.
     */
    void *end;
} cx_linked_list;

/**
 * Allocates a linked list for storing elements with @p elem_size bytes each.
 *
 * If @p elem_size is #CX_STORE_POINTERS, the created list stores pointers instead of
 * copies of the added elements, and the compare function will be automatically set
 * to cx_cmp_ptr() if none is given.
 *
 * @param allocator the allocator for allocating the list nodes
 * (if @c NULL, the cxDefaultAllocator will be used)
 * @param comparator the comparator for the elements
 * (if @c NULL, and the list is not storing pointers, sort and find
 * functions will not work)
 * @param elem_size the size of each element in bytes
 * @return the created list
 */
cx_attr_nodiscard cx_attr_malloc cx_attr_dealloc(cxListFree, 1)
CX_EXPORT CxList *cxLinkedListCreate(const CxAllocator *allocator,
        cx_compare_func comparator, size_t elem_size);

/**
 * Allocates a linked list for storing elements with @p elem_size bytes each.
 *
 * The list will use cxDefaultAllocator and no comparator function. If you want
 * to call functions that need a comparator, you must either set one immediately
 * after list creation or use cxLinkedListCreate().
 *
 * If @p elem_size is #CX_STORE_POINTERS, the created list stores pointers instead of
 * copies of the added elements, and the compare function will be automatically set
 * to cx_cmp_ptr().
 *
 * @param elem_size (@c size_t) the size of each element in bytes
 * @return (@c CxList*) the created list
 */
#define cxLinkedListCreateSimple(elem_size) \
        cxLinkedListCreate(NULL, NULL, elem_size)

/**
 * Finds the node at a certain index.
 *
 * This function can be used to start at an arbitrary position within the list.
 * If the search index is larger than the start index, @p loc_advance must denote
 * the location of a @c next pointer (i.e., a pointer to the next node).
 * But it is also possible that the search index is smaller than the start index
 * (e.g., in cases where traversing a list backwards is faster).
 * In that case @p loc_advance must denote the location of a @c prev pointer
 * (i.e., a pointer to the previous node).
 *
 * @param start a pointer to the start node
 * @param start_index the start index
 * @param loc_advance the location of the pointer to advance
 * @param index the search index
 * @return the node found at the specified index
 */
cx_attr_nonnull cx_attr_nodiscard
CX_EXPORT void *cx_linked_list_at(const void *start,size_t start_index,
        ptrdiff_t loc_advance, size_t index);

/**
 * Finds the node containing an element within a linked list.
 *
 * @param start a pointer to the start node
 * @param loc_advance the location of the pointer to advance
 * @param loc_data the location of the @c data pointer within your node struct
 * @param cmp_func a compare function to compare @p elem against the node data
 * @param elem a pointer to the element to find
 * @param found_index an optional pointer where the index of the found node
 * (given that @p start has index 0) is stored
 * @return a pointer to the found node or @c NULL if no matching node was found
 */
cx_attr_nonnull_arg(1, 4, 5)
CX_EXPORT void *cx_linked_list_find(const void *start, ptrdiff_t loc_advance,
        ptrdiff_t loc_data, cx_compare_func cmp_func, const void *elem,
        size_t *found_index);

/**
 * Finds the first node in a linked list.
 *
 * The function starts with the pointer denoted by @p node and traverses the list
 * along a prev pointer whose location within the node struct is
 * denoted by @p loc_prev.
 *
 * @param node a pointer to a node in the list
 * @param loc_prev the location of the @c prev pointer
 * @return a pointer to the first node
 */
cx_attr_nonnull cx_attr_returns_nonnull
CX_EXPORT void *cx_linked_list_first(const void *node, ptrdiff_t loc_prev);

/**
 * Finds the last node in a linked list.
 *
 * The function starts with the pointer denoted by @p node and traverses the list
 * along a next pointer whose location within the node struct is
 * denoted by @p loc_next.
 *
 * @param node a pointer to a node in the list
 * @param loc_next the location of the @c next pointer
 * @return a pointer to the last node
 */
cx_attr_nonnull cx_attr_returns_nonnull
CX_EXPORT void *cx_linked_list_last(const void *node, ptrdiff_t loc_next);

/**
 * Finds the predecessor of a node in case it is not linked.
 *
 * @remark If @p node is not contained in the list starting with @p begin, the behavior is undefined.
 *
 * @param begin the node where to start the search
 * @param loc_next the location of the @c next pointer
 * @param node the successor of the node to find
 * @return the node or @c NULL if @p node has no predecessor
 */
cx_attr_nonnull
CX_EXPORT void *cx_linked_list_prev(const void *begin, ptrdiff_t loc_next, const void *node);

/**
 * Adds a new node to a linked list.
 * The node must not be part of any list yet.
 *
 * @remark One of the pointers @p begin or @p end may be @c NULL, but not both.
 *
 * @param begin a pointer to the beginning node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be appended
 */
cx_attr_nonnull_arg(5)
CX_EXPORT void cx_linked_list_add(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node);

/**
 * Prepends a new node to a linked list.
 * The node must not be part of any list yet.
 *
 * @remark One of the pointers @p begin or @p end may be @c NULL, but not both.
 *
 * @param begin a pointer to the beginning node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be prepended
 */
cx_attr_nonnull_arg(5)
CX_EXPORT void cx_linked_list_prepend(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node);

/**
 * Links two nodes.
 *
 * @param left the new predecessor of @p right
 * @param right the new successor of @p left
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 */
cx_attr_nonnull
CX_EXPORT void cx_linked_list_link(void *left, void *right, ptrdiff_t loc_prev, ptrdiff_t loc_next);

/**
 * Unlinks two nodes.
 *
 * If right is not the successor of left, the behavior is undefined.
 *
 * @param left the predecessor of @p right
 * @param right the successor of @p left
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 */
cx_attr_nonnull
CX_EXPORT void cx_linked_list_unlink(void *left, void *right, ptrdiff_t loc_prev, ptrdiff_t loc_next);

/**
 * Inserts a new node after a given node of a linked list.
 * The new node must not be part of any list yet.
 *
 * @note If you specify @c NULL as the @p node to insert after, this function needs either the @p begin or
 * the @p end pointer to determine the start of the list. Then the new node will be prepended to the list.
 *
 * @param begin a pointer to the beginning node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param node the node after which to insert (@c NULL if you want to prepend the node to the list)
 * @param new_node a pointer to the node that shall be inserted
 */
cx_attr_nonnull_arg(6)
CX_EXPORT void cx_linked_list_insert(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *node, void *new_node);

/**
 * Inserts a chain of nodes after a given node of a linked list.
 * The chain must not be part of any list yet.
 *
 * If you do not explicitly specify the end of the chain, it will be determined by traversing
 * the @c next pointer.
 *
 * @note If you specify @c NULL as the @p node to insert after, this function needs either the @p begin or
 * the @p end pointer to determine the start of the list. If only the @p end pointer is specified, you also need
 * to provide a valid @p loc_prev location.
 * Then the chain will be prepended to the list.
 *
 * @param begin a pointer to the beginning node pointer (if your list has one)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param node the node after which to insert (@c NULL to prepend the chain to the list)
 * @param insert_begin a pointer to the first node of the chain that shall be inserted
 * @param insert_end a pointer to the last node of the chain (or NULL if the last node shall be determined)
 */
cx_attr_nonnull_arg(6)
CX_EXPORT void cx_linked_list_insert_chain(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *node, void *insert_begin, void *insert_end);

/**
 * Inserts a node into a sorted linked list.
 * The new node must not be part of any list yet.
 *
 * If the list starting with the node pointed to by @p begin is not sorted
 * already, the behavior is undefined.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be inserted
 * @param cmp_func a compare function that will receive the node pointers
 */
cx_attr_nonnull_arg(1, 5, 6)
CX_EXPORT void cx_linked_list_insert_sorted(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node, cx_compare_func cmp_func);

/**
 * Inserts a chain of nodes into a sorted linked list.
 * The chain must not be part of any list yet.
 *
 * If either the list starting with the node pointed to by @p begin or the list
 * starting with @p insert_begin is not sorted, the behavior is undefined.
 *
 * @attention In contrast to cx_linked_list_insert_chain(), the source chain
 * will be broken and inserted into the target list so that the resulting list
 * will be sorted according to @p cmp_func. That means each node in the source
 * chain may be re-linked with nodes from the target list.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param insert_begin a pointer to the first node of the chain that shall be inserted
 * @param cmp_func a compare function that will receive the node pointers
 */
cx_attr_nonnull_arg(1, 5, 6)
CX_EXPORT void cx_linked_list_insert_sorted_chain(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *insert_begin, cx_compare_func cmp_func);

/**
 * Inserts a node into a sorted linked list if no other node with the same value already exists.
 * The new node must not be part of any list yet.
 *
 * If the list starting with the node pointed to by @p begin is not sorted
 * already, the behavior is undefined.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param new_node a pointer to the node that shall be inserted
 * @param cmp_func a compare function that will receive the node pointers
 * @retval zero when the node was inserted
 * @retval non-zero when a node with the same value already exists
 */
cx_attr_nonnull_arg(1, 5, 6)
CX_EXPORT int cx_linked_list_insert_unique(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *new_node, cx_compare_func cmp_func);

/**
 * Inserts a chain of nodes into a sorted linked list, avoiding duplicates.
 * The chain must not be part of any list yet.
 *
 * If either the list starting with the node pointed to by @p begin or the list
 * starting with @p insert_begin is not sorted, the behavior is undefined.
 *
 * @attention In contrast to cx_linked_list_insert_sorted(), not all nodes of the
 * chain might be added. This function returns a new chain consisting of all the duplicates.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (if your list has one)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param insert_begin a pointer to the first node of the chain that shall be inserted
 * @param cmp_func a compare function that will receive the node pointers
 * @return a pointer to a new chain with all duplicates that were not inserted (or @c NULL when there were no duplicates)
 */
cx_attr_nonnull_arg(1, 5, 6) cx_attr_nodiscard
CX_EXPORT void *cx_linked_list_insert_unique_chain(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *insert_begin, cx_compare_func cmp_func);

/**
 * Removes a chain of nodes from the linked list.
 *
 * If one of the nodes to remove is the beginning (resp. end) node of the list, and if @p begin (resp. @p end)
 * addresses are provided, the pointers are adjusted accordingly.
 *
 * The following combinations of arguments are valid (more arguments are optional):
 * @li @p loc_next and @p loc_prev (ancestor node is determined by using the prev pointer, overall O(1) performance)
 * @li @p loc_next and @p begin (ancestor node is determined by list traversal, overall O(n) performance)
 *
 * @remark The @c next and @c prev pointers of the removed chain are not cleared by this function and may still be used
 * to traverse to a former adjacent node in the list, or within the chain.
 *
 * @param begin a pointer to the beginning node pointer (optional)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param node the start node of the chain
 * @param num the number of nodes to remove
 * @return the actual number of nodes that were removed (can be less when the list did not have enough nodes)
 */
cx_attr_nonnull_arg(5)
CX_EXPORT size_t cx_linked_list_remove_chain(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *node, size_t num);

/**
 * Removes a node from the linked list.
 *
 * If the node to remove is the beginning (resp. end) node of the list, and if @p begin (resp. @p end)
 * addresses are provided, the pointers are adjusted accordingly.
 *
 * The following combinations of arguments are valid (more arguments are optional):
 * @li @p loc_next and @p loc_prev (ancestor node is determined by using the prev pointer, overall O(1) performance)
 * @li @p loc_next and @p begin (ancestor node is determined by list traversal, overall O(n) performance)
 *
 * @remark The @c next and @c prev pointers of the removed node are not cleared by this function and may still be used
 * to traverse to a former adjacent node in the list.
 *
 * @param begin a pointer to the beginning node pointer (optional)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param node the node to remove
 */
cx_attr_nonnull_arg(5)
CX_EXPORT void cx_linked_list_remove(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, void *node);

/**
 * Determines the size of a linked list starting with @p node.
 *
 * @param node the first node
 * @param loc_next the location of the @c next pointer within the node struct
 * @return the size of the list or zero if @p node is @c NULL
 */
cx_attr_nodiscard
CX_EXPORT size_t cx_linked_list_size(const void *node, ptrdiff_t loc_next);

/**
 * Sorts a linked list based on a comparison function.
 *
 * This function can work with linked lists of the following structure:
 * @code
 * typedef struct node node;
 * struct node {
 *   node* prev;
 *   node* next;
 *   my_payload data;
 * }
 * @endcode
 *
 * @note This is a recursive function with at most logarithmic recursion depth.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if not present)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 * @param loc_data the location of the @c data pointer within your node struct
 * @param cmp_func the compare function defining the sort order
 */
cx_attr_nonnull_arg(1, 6)
CX_EXPORT void cx_linked_list_sort(void **begin, void **end,
        ptrdiff_t loc_prev, ptrdiff_t loc_next, ptrdiff_t loc_data, cx_compare_func cmp_func);


/**
 * Compares two lists element wise.
 *
 * @attention Both lists must have the same structure.
 *
 * @param begin_left the beginning of the left list (@c NULL denotes an empty list)
 * @param begin_right the beginning of the right list  (@c NULL denotes an empty list)
 * @param loc_advance the location of the pointer to advance
 * @param loc_data the location of the @c data pointer within your node struct
 * @param cmp_func the function to compare the elements
 * @return the first non-zero result of invoking @p cmp_func or: negative if the left list is smaller than the
 * right list, positive if the left list is larger than the right list, zero if both lists are equal.
 */
cx_attr_nonnull_arg(5)
CX_EXPORT int cx_linked_list_compare(const void *begin_left, const void *begin_right,
        ptrdiff_t loc_advance, ptrdiff_t loc_data, cx_compare_func cmp_func);

/**
 * Reverses the order of the nodes in a linked list.
 *
 * @param begin a pointer to the beginning node pointer (required)
 * @param end a pointer to the end node pointer (optional)
 * @param loc_prev the location of a @c prev pointer within your node struct (negative if your struct does not have one)
 * @param loc_next the location of a @c next pointer within your node struct (required)
 */
cx_attr_nonnull_arg(1)
CX_EXPORT void cx_linked_list_reverse(void **begin, void **end, ptrdiff_t loc_prev, ptrdiff_t loc_next);

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

#endif // UCX_LINKED_LIST_H