// Copyright (C) 2023 Mistivia <i@mistivia.com>
// Licensed under GPLv3. See LICENSE for details.

/*
 * Copyright 2002 Niels Provos <provos@citi.umich.edu>
 * 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 AUTHOR ``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 AUTHOR 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.
 */

#include "rb_tree.h"

#define RED 1
#define BLACK 0

static rb_node_t *rb_tree_minmax(rb_tree_t *, int);
void *rb_tree_min(rb_tree_t *head) { return rb_tree_minmax(head, -1); }
void *rb_tree_max(rb_tree_t *head) { return rb_tree_minmax(head, 1); }

void *rb_tree_left(void *node) {
    rb_node_t *elm = node;
    if (node == NULL) return NULL;
    return elm->entry.rbe_left;
}
void *rb_tree_right(void *node) {
    rb_node_t *elm = node;
    if (node == NULL) return NULL;
    return elm->entry.rbe_right;
}
void *rb_tree_parent(void *node) {
    rb_node_t *elm = node;
    if (node == NULL) return NULL;
    return elm->entry.rbe_parent;
}

static void augment(rb_tree_t *head, rb_node_t *elm) {
    if (head->augment != NULL) head->augment(elm);
}

static void rb_tree_insert_color(rb_tree_t *head, rb_node_t *elm);
static void rb_tree_remove_color(rb_tree_t *head, rb_node_t *parent,
                                 rb_node_t *elm);

static void rotate_left(rb_tree_t *head, rb_node_t *elm) {
    rb_node_t *tmp = elm->entry.rbe_right;
    if ((elm->entry.rbe_right = tmp->entry.rbe_left)) {
        tmp->entry.rbe_left->entry.rbe_parent = elm;
    }
    augment(head, elm);
    if ((tmp->entry.rbe_parent = elm->entry.rbe_parent)) {
        if (elm == elm->entry.rbe_parent->entry.rbe_left)
            elm->entry.rbe_parent->entry.rbe_left = tmp;
        else
            elm->entry.rbe_parent->entry.rbe_right = tmp;
    } else {
        head->rbh_root = tmp;
    }
    tmp->entry.rbe_left = elm;
    elm->entry.rbe_parent = tmp;
    augment(head, tmp);
    if (tmp->entry.rbe_parent) {
        augment(head, tmp->entry.rbe_parent);
    }
}

static void rotate_right(rb_tree_t *head, rb_node_t *elm) {
    rb_node_t *tmp = elm->entry.rbe_left;
    if ((elm->entry.rbe_left = tmp->entry.rbe_right)) {
        tmp->entry.rbe_right->entry.rbe_parent = elm;
    }
    augment(head, elm);
    if ((tmp->entry.rbe_parent = elm->entry.rbe_parent)) {
        if (elm == elm->entry.rbe_parent->entry.rbe_left)
            elm->entry.rbe_parent->entry.rbe_left = tmp;
        else
            elm->entry.rbe_parent->entry.rbe_right = tmp;
    } else {
        head->rbh_root = tmp;
    }
    tmp->entry.rbe_right = elm;
    elm->entry.rbe_parent = tmp;
    augment(head, tmp);
    if (tmp->entry.rbe_parent) {
        augment(head, tmp->entry.rbe_parent);
    }
}

static void rb_tree_insert_color(rb_tree_t *head, rb_node_t *elm) {
    rb_node_t *parent, *gparent, *tmp;
    while ((parent = elm->entry.rbe_parent) && parent->entry.rbe_color == 1) {
        gparent = parent->entry.rbe_parent;
        if (parent == gparent->entry.rbe_left) {
            tmp = gparent->entry.rbe_right;
            if (tmp && tmp->entry.rbe_color == 1) {
                tmp->entry.rbe_color = BLACK;
                parent->entry.rbe_color = BLACK;
                gparent->entry.rbe_color = RED;
                elm = gparent;
                continue;
            }
            if (parent->entry.rbe_right == elm) {
                rotate_left(head, parent);
                tmp = parent;
                parent = elm;
                elm = tmp;
            }
            parent->entry.rbe_color = BLACK;
            gparent->entry.rbe_color = RED;
            rotate_right(head, gparent);
        } else {
            tmp = gparent->entry.rbe_left;
            if (tmp && tmp->entry.rbe_color == 1) {
                tmp->entry.rbe_color = BLACK;
                parent->entry.rbe_color = BLACK;
                gparent->entry.rbe_color = RED;
                ;
                elm = gparent;
                continue;
            }
            if (parent->entry.rbe_left == elm) {
                rotate_right(head, parent);
                tmp = parent;
                parent = elm;
                elm = tmp;
            }
            parent->entry.rbe_color = BLACK;
            gparent->entry.rbe_color = RED;
            rotate_left(head, gparent);
        }
    }
    head->rbh_root->entry.rbe_color = BLACK;
}

static void rb_tree_remove_color(rb_tree_t *head, rb_node_t *parent,
                                 rb_node_t *elm) {
    rb_node_t *tmp;
    while ((elm == NULL || elm->entry.rbe_color == 0) &&
           elm != head->rbh_root) {
        if (parent->entry.rbe_left == elm) {
            tmp = parent->entry.rbe_right;
            if (tmp->entry.rbe_color == 1) {
                tmp->entry.rbe_color = BLACK;
                parent->entry.rbe_color = RED;
                rotate_left(head, parent);
                tmp = parent->entry.rbe_right;
            }
            if ((tmp->entry.rbe_left == NULL ||
                 tmp->entry.rbe_left->entry.rbe_color == 0) &&
                (tmp->entry.rbe_right == NULL ||
                 tmp->entry.rbe_right->entry.rbe_color == 0)) {
                tmp->entry.rbe_color = RED;
                elm = parent;
                parent = elm->entry.rbe_parent;
            } else {
                if (tmp->entry.rbe_right == NULL ||
                    tmp->entry.rbe_right->entry.rbe_color == 0) {
                    rb_node_t *oleft;
                    if ((oleft = tmp->entry.rbe_left))
                        oleft->entry.rbe_color = BLACK;
                    tmp->entry.rbe_color = RED;
                    rotate_right(head, tmp);
                    tmp = parent->entry.rbe_right;
                }
                tmp->entry.rbe_color = parent->entry.rbe_color;
                parent->entry.rbe_color = BLACK;
                if (tmp->entry.rbe_right)
                    tmp->entry.rbe_right->entry.rbe_color = BLACK;
                rotate_left(head, parent);
                elm = head->rbh_root;
                break;
            }
        } else {
            tmp = parent->entry.rbe_left;
            if (tmp->entry.rbe_color == 1) {
                tmp->entry.rbe_color = BLACK;
                parent->entry.rbe_color = RED;
                rotate_right(head, parent);
                tmp = parent->entry.rbe_left;
            }
            if ((tmp->entry.rbe_left == NULL ||
                 tmp->entry.rbe_left->entry.rbe_color == 0) &&
                (tmp->entry.rbe_right == NULL ||
                 tmp->entry.rbe_right->entry.rbe_color == 0)) {
                tmp->entry.rbe_color = RED;
                elm = parent;
                parent = elm->entry.rbe_parent;
            } else {
                if (tmp->entry.rbe_left == NULL ||
                    tmp->entry.rbe_left->entry.rbe_color == 0) {
                    rb_node_t *oright;
                    if ((oright = tmp->entry.rbe_right))
                        oright->entry.rbe_color = BLACK;
                    tmp->entry.rbe_color = RED;
                    rotate_left(head, tmp);
                    tmp = parent->entry.rbe_left;
                }
                tmp->entry.rbe_color = parent->entry.rbe_color;
                parent->entry.rbe_color = BLACK;
                if (tmp->entry.rbe_left)
                    tmp->entry.rbe_left->entry.rbe_color = BLACK;
                rotate_right(head, parent);
                elm = head->rbh_root;
                break;
            }
        }
    }
    if (elm) elm->entry.rbe_color = BLACK;
}

void rb_tree_remove(rb_tree_t *head, void *elmv) {
    rb_node_t *elm = elmv;
    rb_node_t *child, *parent;
    int color;
    if (elm->entry.rbe_left == NULL)
        child = elm->entry.rbe_right;
    else if (elm->entry.rbe_right == NULL)
        child = elm->entry.rbe_left;
    else {
        rb_node_t *old = elm, *left;
        elm = elm->entry.rbe_right;
        while ((left = elm->entry.rbe_left))
            elm = left;
        child = elm->entry.rbe_right;
        parent = elm->entry.rbe_parent;
        color = elm->entry.rbe_color;
        if (child) child->entry.rbe_parent = parent;
        if (parent) {
            if (parent->entry.rbe_left == elm)
                parent->entry.rbe_left = child;
            else
                parent->entry.rbe_right = child;
            augment(head, parent);
        } else
            head->rbh_root = child;
        if (elm->entry.rbe_parent == old) parent = elm;
        elm->entry = old->entry;
        if (old->entry.rbe_parent) {
            if ((old->entry.rbe_parent)->entry.rbe_left == old)
                (old->entry.rbe_parent)->entry.rbe_left = elm;
            else
                (old->entry.rbe_parent)->entry.rbe_right = elm;
            augment(head, old->entry.rbe_parent);
        } else
            head->rbh_root = elm;
        old->entry.rbe_left->entry.rbe_parent = elm;
        if (old->entry.rbe_right) old->entry.rbe_right->entry.rbe_parent = elm;
        if (parent) {
            left = parent;
            if (head->augment != NULL) {
                do {
                    augment(head, left);
                } while ((left = left->entry.rbe_parent));
            }
        }
        goto color;
    }
    parent = elm->entry.rbe_parent;
    color = elm->entry.rbe_color;
    if (child) child->entry.rbe_parent = parent;
    if (parent) {
        if (parent->entry.rbe_left == elm)
            parent->entry.rbe_left = child;
        else
            parent->entry.rbe_right = child;
        rb_node_t *goback = parent;
        if (head->augment != NULL) {
            do {
                augment(head, goback);
            } while ((goback = goback->entry.rbe_parent));
        }
    } else
        head->rbh_root = child;
color:
    if (color == 0) rb_tree_remove_color(head, parent, child);
}

void *rb_tree_insert(rb_tree_t *head, void *elmv) {
    rb_node_t *elm = elmv;
    rb_node_t *tmp;
    rb_node_t *parent = NULL;
    int comp = 0;
    tmp = head->rbh_root;
    while (tmp) {
        parent = tmp;
        comp = head->cmp((void *)elm->content, (void *)parent->content);
        if (comp < 0)
            tmp = tmp->entry.rbe_left;
        else if (comp > 0)
            tmp = tmp->entry.rbe_right;
        else
            return tmp;
    }
    elm->entry.rbe_parent = parent;
    elm->entry.rbe_left = elm->entry.rbe_right = NULL;
    elm->entry.rbe_color = RED;
    if (parent != NULL) {
        if (comp < 0)
            parent->entry.rbe_left = elm;
        else
            parent->entry.rbe_right = elm;
        rb_node_t *goback = parent;
        if (head->augment != NULL) {
            do {
                augment(head, goback);
            } while ((goback = goback->entry.rbe_parent));
        }
    } else
        head->rbh_root = elm;
    rb_tree_insert_color(head, elm);
    return (NULL);
}

void *rb_tree_find(rb_tree_t *head, void *key) {
    rb_node_t *tmp = head->rbh_root;
    int comp;
    while (tmp) {
        comp = head->cmp(key, (void *)tmp->content);
        if (comp < 0)
            tmp = tmp->entry.rbe_left;
        else if (comp > 0)
            tmp = tmp->entry.rbe_right;
        else
            return tmp;
    }
    return (NULL);
}

void *rb_tree_next(rb_tree_t *head, void *elmv) {
    rb_node_t *elm = elmv;
    if (elm->entry.rbe_right) {
        elm = elm->entry.rbe_right;
        while (elm->entry.rbe_left)
            elm = elm->entry.rbe_left;
    } else {
        if (elm->entry.rbe_parent &&
            (elm == (elm->entry.rbe_parent)->entry.rbe_left))
            elm = elm->entry.rbe_parent;
        else {
            while (elm->entry.rbe_parent &&
                   (elm == (elm->entry.rbe_parent)->entry.rbe_right))
                elm = elm->entry.rbe_parent;
            elm = elm->entry.rbe_parent;
        }
    }
    return elm;
}

static rb_node_t *rb_tree_minmax(rb_tree_t *head, int val) {
    rb_node_t *tmp = head->rbh_root;
    rb_node_t *parent = NULL;
    while (tmp) {
        parent = tmp;
        if (val < 0)
            tmp = tmp->entry.rbe_left;
        else
            tmp = tmp->entry.rbe_right;
    }
    return parent;
};