/* -*- Mode: c; c-basic-offset: 4; indent-tabs-mode: t; tab-width: 8; -*- */
/*
 * Copyright 2013 Andrea Canciani
 *
 * 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.
 *
 * Author(s): Andrea Canciani <ranma42@gmail.com>
 */

#ifndef SIMPLEDATA_LIST_H
#define SIMPLEDATA_LIST_H

#include "simpleops/compiler.h"

typedef struct _simpledata_list {
    struct _simpledata_list *next;
    struct _simpledata_list *prev;
} simpledata_list_t;

static simpleops_inline void
simpledata_list_init_head (simpledata_list_t *head)
{
    head->next = head->prev = head;
}

static simpleops_inline simpleops_bool_t
simpledata_list_is_empty (const simpledata_list_t *head)
{
    return head == head->next;
}

static simpleops_inline void
_simpledata_list_insert_helper (simpledata_list_t *prev,
				simpledata_list_t *next,
				simpledata_list_t *el)
{
    next->prev = el;
    el->next = next;
    el->prev = prev;
    prev->next = el;
}

static simpleops_inline void
_simpledata_list_remove_helper (simpledata_list_t *prev,
				simpledata_list_t *next)
{
    next->prev = prev;
    prev->next = next;
}

static simpleops_inline void
simpledata_list_remove (simpledata_list_t *el)
{
    _simpledata_list_remove_helper (el->prev, el->next);
}

static simpleops_inline void
simpledata_list_insert (simpledata_list_t *pos,
			simpledata_list_t *el)
{
    _simpledata_list_insert_helper (pos, pos->next, el);
}

static simpleops_inline void
simpledata_list_prepend (simpledata_list_t *head,
			 simpledata_list_t *el)
{
    simpledata_list_insert (head, el);
}

static simpleops_inline void
simpledata_list_append (simpledata_list_t *head,
			simpledata_list_t *el)
{
    _simpledata_list_insert_helper (head->prev, head, el);
}

static simpleops_inline simpledata_list_t *
simpledata_list_first (simpledata_list_t *head)
{
    /* This assumes that the list is not empty */
    return head->next;
}

static simpleops_inline simpledata_list_t *
simpledata_list_last (simpledata_list_t *head)
{
    /* This assumes that the list is not empty */
    return head->prev;
}

static simpleops_inline void
simpledata_list_foreach (const simpledata_list_t *head,
			 void (*f) (const simpledata_list_t *el, void *arg),
			 void *arg)
{
    const simpledata_list_t *el;

    for (el = head->next; el != head; el = el->next)
	f (el, arg);
}

static simpleops_inline void
_simpledata_list_merge (simpledata_list_t *head_a,
			simpledata_list_t *head_b,
			int (*cmp) (const simpledata_list_t *a,
				    const simpledata_list_t *b,
				    void *arg),
			void *arg)
{
    simpledata_list_t *head, *tmp, *curr_a, *curr_b;

    head = head_a;
    curr_a = simpledata_list_first(head_a);
    curr_b = simpledata_list_first(head_b);

    do {
	while (curr_a != head_a && cmp(curr_a, curr_b, arg) <= 0)
	    curr_a = curr_a->next;

	curr_b->prev = curr_a->prev;
	curr_a->prev->next = curr_b;
	if (curr_a == head_a)
	    break;

	tmp = head_a;
	head_a = head_b;
	head_b = tmp;

	tmp = curr_a;
	curr_a = curr_b;
	curr_b = tmp;
    } while (1);

    head->prev = head_b->prev;
    head->prev->next = head;
}

static simpleops_inline void
simpledata_list_merge (simpledata_list_t *head_a,
		       simpledata_list_t *head_b,
		       int (*cmp) (const simpledata_list_t *a,
				   const simpledata_list_t *b,
				   void *arg),
		       void *arg)
{
    if (simpledata_list_is_empty(head_b))
	return;

    if (simpledata_list_is_empty(head_a)) {
	*head_a = *head_b;
	head_a->prev->next = head_a;
	head_a->next->prev = head_a;
	return;
    }

    _simpledata_list_merge(head_a, head_b, cmp, arg);
}

static simpleops_inline void
_simpledata_list_sort (simpledata_list_t *head,
		       simpledata_list_t *remaining_head,
		       size_t level,
		       int (*cmp) (const simpledata_list_t *a,
				   const simpledata_list_t *b,
				   void *arg),
		       void *arg)
{
    simpledata_list_t head_other, *first, *curr;
    size_t i;

    first = simpledata_list_first(head);
    curr = first->next;

    /* Single element */
    if (curr == head)
	return;

    head_other.next = curr->next;
    head_other.prev = head->prev;

    if (cmp(first, curr, arg) <= 0) {
	/* Two elements, already sorted */
	if (head_other.next == head)
	    return;
    } else {
	/* Two elements, inverted */
	head->next = curr;
	curr->next = first;
	first->next = head;

	head->prev = first;
	curr->prev = head;
	first->prev = curr;

	/* Two elements, manually sorted */
	if (head_other.next == head)
	    return;

	curr = first;
    }

    head->prev = curr;
    curr->next = head;

    for (i = 0; i < level; i++) {
	head_other.prev->next = &head_other;
	head_other.next->prev = &head_other;
	simpledata_list_init_head (remaining_head);

	_simpledata_list_sort (&head_other, remaining_head, i, cmp, arg);
	_simpledata_list_merge (head, &head_other, cmp, arg);

	if (simpledata_list_is_empty(remaining_head))
	    return;

	head_other = *remaining_head;
    }

    *remaining_head = head_other;
    remaining_head->prev->next = remaining_head;
    remaining_head->next->prev = remaining_head;
}

static simpleops_inline void
simpledata_list_sort (simpledata_list_t *head,
		      int (*cmp) (const simpledata_list_t *a,
				  const simpledata_list_t *b,
				  void *arg),
		      void *arg)
{
    simpledata_list_t tmp;

    if (!simpledata_list_is_empty(head))
	_simpledata_list_sort(head, &tmp, (size_t)-1, cmp, arg);
}

#endif