/*
   Copyright (c) 2014 Anton Titov.

   Copyright (c) 2014 pCloud Ltd.  All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met: Redistributions of source code must retain the above
   copyright notice, this list of conditions and the following
   disclaimer.  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.  Neither the name of pCloud Ltd nor the
   names of its contributors may be used to endorse or promote
   products derived from this software without specific prior written
   permission.

   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 pCloud
   Ltd 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.
*/

#ifndef _PSYNC_TREE_H
#define _PSYNC_TREE_H

#include <stddef.h>
#include <stdlib.h>

typedef struct _psync_tree {
  struct _psync_tree *left;
  struct _psync_tree *right;
  struct _psync_tree *parent;
  long int height;
} psync_tree;

#define PSYNC_TREE_EMPTY NULL

#define ptree_isempty(l) ((l) == NULL)
#define ptree_element(a, t, n) ((t *)((char *)(a)-offsetof(t, n)))
#define ptree_for_each(a, l)                                              \
  for (a = ptree_get_first(l); a != NULL; a = ptree_get_next(a))
#define ptree_for_each_element(a, l, t, n)                                \
  for (a = (ptree_get_first(l) ? ptree_element(ptree_get_first(l), t, n) : NULL); \
       a != NULL;                                                              \
       a = (ptree_get_next(&a->n) ? ptree_element(ptree_get_next(&a->n), t, n) : NULL))

#define ptree_for_each_element_call(l, t, n, c)                           \
  do {                                                                         \
    psync_tree *___tmpa;                                                       \
    ___tmpa = ptree_get_first(l);                                         \
    while (___tmpa) {                                                          \
      c(ptree_element(___tmpa, t, n));                                    \
      ___tmpa = ptree_get_next(___tmpa);                                  \
    }                                                                          \
  } while (0)

#define ptree_for_each_element_call_safe(l, t, n, c)                      \
  do {                                                                         \
    psync_tree *___tmpa, *___tmpb;                                             \
    ___tmpa = ptree_get_first_safe(l);                                    \
    while (___tmpa) {                                                          \
      ___tmpb = ptree_get_next_safe(___tmpa);                             \
      c(ptree_element(___tmpa, t, n));                                    \
      ___tmpa = ___tmpb;                                                       \
    }                                                                          \
  } while (0)

typedef int (*ptree_compare)(const psync_tree *, const psync_tree *);

static inline long int ptree_height(psync_tree *tree) {
  return tree ? tree->height : 0;
}

static inline psync_tree *ptree_get_first(psync_tree *tree) {
  if (!tree)
    return tree;
  while (tree->left)
    tree = tree->left;
  return tree;
}

static inline psync_tree *ptree_get_last(psync_tree *tree) {
  if (!tree)
    return tree;
  while (tree->right)
    tree = tree->right;
  return tree;
}

static inline psync_tree *ptree_get_next(psync_tree *tree) {
  if (tree->right) {
    tree = tree->right;
    while (tree->left)
      tree = tree->left;
    return tree;
  } else {
    while (tree->parent && tree == tree->parent->right)
      tree = tree->parent;
    return tree->parent;
  }
}

static inline psync_tree *ptree_get_prev(psync_tree *tree) {
  if (tree->left) {
    tree = tree->left;
    while (tree->right)
      tree = tree->right;
    return tree;
  } else {
    while (tree->parent && tree == tree->parent->left)
      tree = tree->parent;
    return tree->parent;
  }
}

static inline psync_tree *ptree_get_first_safe(psync_tree *tree) {
  if (!tree)
    return tree;
  while (1) {
    if (tree->left)
      tree = tree->left;
    else if (tree->right)
      tree = tree->right;
    else
      break;
  }
  return tree;
}

static inline psync_tree *ptree_get_next_safe(psync_tree *tree) {
  if (!tree->parent)
    return NULL;
  if (tree->parent->right == tree || tree->parent->right == NULL)
    return tree->parent;
  tree = tree->parent->right;
  while (1) {
    if (tree->left)
      tree = tree->left;
    else if (tree->right)
      tree = tree->right;
    else
      break;
  }
  return tree;
}

psync_tree *ptree_get_add_after(psync_tree *tree, psync_tree *node,
                                     psync_tree *newnode);
psync_tree *ptree_get_add_before(psync_tree *tree, psync_tree *node,
                                      psync_tree *newnode);
psync_tree *ptree_get_added_at(psync_tree *tree, psync_tree *parent,
                                    psync_tree *newnode);

psync_tree *ptree_get_del(psync_tree *tree, psync_tree *node);

static inline psync_tree *ptree_get_add(psync_tree *tree,
                                             psync_tree *newnode,
                                             ptree_compare comp) {
  psync_tree *el;
  if (!tree)
    return ptree_get_add_after(tree, NULL, newnode);
  el = tree;
  while (1) {
    if (comp(newnode, el) < 0) {
      if (el->left)
        el = el->left;
      else
        return ptree_get_add_before(tree, el, newnode);
    } else {
      if (el->right)
        el = el->right;
      else
        return ptree_get_add_after(tree, el, newnode);
    }
  }
}

static inline void ptree_add_after(psync_tree **tree, psync_tree *node,
                                        psync_tree *newnode) {
  *tree = ptree_get_add_after(*tree, node, newnode);
}

static inline void ptree_add_before(psync_tree **tree, psync_tree *node,
                                         psync_tree *newnode) {
  *tree = ptree_get_add_before(*tree, node, newnode);
}

static inline void ptree_added_at(psync_tree **tree, psync_tree *parent,
                                       psync_tree *newnode) {
  *tree = ptree_get_added_at(*tree, parent, newnode);
}

static inline void ptree_del(psync_tree **tree, psync_tree *node) {
  *tree = ptree_get_del(*tree, node);
}

static inline void ptree_add(psync_tree **tree, psync_tree *newnode,
                                  ptree_compare comp) {
  *tree = ptree_get_add(*tree, newnode, comp);
}

#endif