/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details.
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/* avl.c - routines to implement an avl tree */
/*
 * Copyright (c) 1993 Regents of the University of Michigan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of Michigan at Ann Arbor. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#if 0
static char copyright[] = "@(#) Copyright (c) 1993 Regents of the University of Michigan.\nAll rights reserved.\n";
static char avl_version[] = "AVL library version 1.0\n";
#endif

#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include "avl.h"

#define ROTATERIGHT(x)                              \
    {                                               \
        Avlnode *tmp;                               \
        if (*x == NULL || (*x)->avl_left == NULL) { \
            (void)printf("RR error\n");             \
            exit(1);                                \
        }                                           \
        tmp = (*x)->avl_left;                       \
        (*x)->avl_left = tmp->avl_right;            \
        tmp->avl_right = *x;                        \
        *x = tmp;                                   \
    }
#define ROTATELEFT(x)                                \
    {                                                \
        Avlnode *tmp;                                \
        if (*x == NULL || (*x)->avl_right == NULL) { \
            (void)printf("RL error\n");              \
            exit(1);                                 \
        }                                            \
        tmp = (*x)->avl_right;                       \
        (*x)->avl_right = tmp->avl_left;             \
        tmp->avl_left = *x;                          \
        *x = tmp;                                    \
    }

/*
 * ravl_insert - called from avl_insert() to do a recursive insert into
 * and balance of an avl tree.
 */

static int
ravl_insert(
    Avlnode **iroot,
    caddr_t data,
    int *taller,
    IFP fcmp, /* comparison function */
    IFP fdup, /* function to call for duplicates */
    int depth)
{
    int rc, cmp, tallersub;
    Avlnode *l, *r;

    if (*iroot == 0) {
        if ((*iroot = (Avlnode *)malloc(sizeof(Avlnode))) == NULL) {
            return (-1);
        }
        (*iroot)->avl_left = 0;
        (*iroot)->avl_right = 0;
        (*iroot)->avl_bf = 0;
        (*iroot)->avl_data = data;
        *taller = 1;
        return (0);
    }

    cmp = (*fcmp)(data, (*iroot)->avl_data);

    /* equal - duplicate name */
    if (cmp == 0) {
        *taller = 0;
        return ((*fdup)((*iroot)->avl_data, data));
    }

    /* go right */
    else if (cmp > 0) {
        rc = ravl_insert(&((*iroot)->avl_right), data, &tallersub,
                         fcmp, fdup, depth);
        if (tallersub)
            switch ((*iroot)->avl_bf) {
            case LH: /* left high - balance is restored */
                (*iroot)->avl_bf = EH;
                *taller = 0;
                break;
            case EH: /* equal height - now right heavy */
                (*iroot)->avl_bf = RH;
                *taller = 1;
                break;
            case RH: /* right heavy to start - right balance */
                r = (*iroot)->avl_right;
                switch (r->avl_bf) {
                case LH: /* double rotation left */
                    l = r->avl_left;
                    switch (l->avl_bf) {
                    case LH:
                        (*iroot)->avl_bf = EH;
                        r->avl_bf = RH;
                        break;
                    case EH:
                        (*iroot)->avl_bf = EH;
                        r->avl_bf = EH;
                        break;
                    case RH:
                        (*iroot)->avl_bf = LH;
                        r->avl_bf = EH;
                        break;
                    }
                    l->avl_bf = EH;
                    ROTATERIGHT((&r))
                    (*iroot)->avl_right = r;
                    ROTATELEFT(iroot)
                    *taller = 0;
                    break;
                case EH: /* This should never happen */
                    break;
                case RH: /* single rotation left */
                    (*iroot)->avl_bf = EH;
                    r->avl_bf = EH;
                    ROTATELEFT(iroot)
                    *taller = 0;
                    break;
                }
                break;
            }
        else
            *taller = 0;
    }

    /* go left */
    else {
        rc = ravl_insert(&((*iroot)->avl_left), data, &tallersub,
                         fcmp, fdup, depth);
        if (tallersub)
            switch ((*iroot)->avl_bf) {
            case LH: /* left high to start - left balance */
                l = (*iroot)->avl_left;
                switch (l->avl_bf) {
                case LH: /* single rotation right */
                    (*iroot)->avl_bf = EH;
                    l->avl_bf = EH;
                    ROTATERIGHT(iroot)
                    *taller = 0;
                    break;
                case EH: /* this should never happen */
                    break;
                case RH: /* double rotation right */
                    r = l->avl_right;
                    switch (r->avl_bf) {
                    case LH:
                        (*iroot)->avl_bf = RH;
                        l->avl_bf = EH;
                        break;
                    case EH:
                        (*iroot)->avl_bf = EH;
                        l->avl_bf = EH;
                        break;
                    case RH:
                        (*iroot)->avl_bf = EH;
                        l->avl_bf = LH;
                        break;
                    }
                    r->avl_bf = EH;
                    ROTATELEFT((&l))
                    (*iroot)->avl_left = l;
                    ROTATERIGHT(iroot)
                    *taller = 0;
                    break;
                }
                break;
            case EH: /* equal height - now left heavy */
                (*iroot)->avl_bf = LH;
                *taller = 1;
                break;
            case RH: /* right high - balance is restored */
                (*iroot)->avl_bf = EH;
                *taller = 0;
                break;
            }
        else
            *taller = 0;
    }

    return (rc);
}

/*
 * avl_insert -- insert a node containing data data into the avl tree
 * with root root.  fcmp is a function to call to compare the data portion
 * of two nodes.  it should take two arguments and return <, >, or == 0,
 * depending on whether its first argument is <, >, or == its second
 * argument (like strcmp, e.g.).  fdup is a function to call when a duplicate
 * node is inserted.  it should return 0, or -1 and its return value
 * will be the return value from avl_insert in the case of a duplicate node.
 * the function will be called with the original node's data as its first
 * argument and with the incoming duplicate node's data as its second
 * argument.  this could be used, for example, to keep a count with each
 * node.
 *
 * NOTE: this routine may malloc memory
 */

int
avl_insert(
    Avlnode **root,
    void *data,
    IFP fcmp,
    IFP fdup)
{
    int taller;

    return ravl_insert(root, (caddr_t)data, &taller, fcmp, fdup, 0);
}

/*
 * right_balance() - called from delete when root's right subtree has
 * been shortened because of a deletion.
 */

static int
right_balance(Avlnode **root)
{
    int shorter = 0;
    Avlnode *r, *l;

    switch ((*root)->avl_bf) {
    case RH: /* was right high - equal now */
        (*root)->avl_bf = EH;
        shorter = 1;
        break;
    case EH: /* was equal - left high now */
        (*root)->avl_bf = LH;
        shorter = 0;
        break;
    case LH: /* was right high - balance */
        l = (*root)->avl_left;
        switch (l->avl_bf) {
        case RH: /* double rotation left */
            r = l->avl_right;
            switch (r->avl_bf) {
            case RH:
                (*root)->avl_bf = EH;
                l->avl_bf = LH;
                break;
            case EH:
                (*root)->avl_bf = EH;
                l->avl_bf = EH;
                break;
            case LH:
                (*root)->avl_bf = RH;
                l->avl_bf = EH;
                break;
            }
            r->avl_bf = EH;
            ROTATELEFT((&l))
            (*root)->avl_left = l;
            ROTATERIGHT(root)
            shorter = 1;
            break;
        case EH: /* right rotation */
            (*root)->avl_bf = LH;
            l->avl_bf = RH;
            ROTATERIGHT(root);
            shorter = 0;
            break;
        case LH: /* single rotation right */
            (*root)->avl_bf = EH;
            l->avl_bf = EH;
            ROTATERIGHT(root)
            shorter = 1;
            break;
        }
        break;
    }

    return (shorter);
}

/*
 * left_balance() - called from delete when root's left subtree has
 * been shortened because of a deletion.
 */

static int
left_balance(Avlnode **root)
{
    int shorter = 0;
    Avlnode *r, *l;

    switch ((*root)->avl_bf) {
    case LH: /* was left high - equal now */
        (*root)->avl_bf = EH;
        shorter = 1;
        break;
    case EH: /* was equal - right high now */
        (*root)->avl_bf = RH;
        shorter = 0;
        break;
    case RH: /* was right high - balance */
        r = (*root)->avl_right;
        switch (r->avl_bf) {
        case LH: /* double rotation left */
            l = r->avl_left;
            switch (l->avl_bf) {
            case LH:
                (*root)->avl_bf = EH;
                r->avl_bf = RH;
                break;
            case EH:
                (*root)->avl_bf = EH;
                r->avl_bf = EH;
                break;
            case RH:
                (*root)->avl_bf = LH;
                r->avl_bf = EH;
                break;
            }
            l->avl_bf = EH;
            ROTATERIGHT((&r))
            (*root)->avl_right = r;
            ROTATELEFT(root)
            shorter = 1;
            break;
        case EH: /* single rotation left */
            (*root)->avl_bf = RH;
            r->avl_bf = LH;
            ROTATELEFT(root);
            shorter = 0;
            break;
        case RH: /* single rotation left */
            (*root)->avl_bf = EH;
            r->avl_bf = EH;
            ROTATELEFT(root)
            shorter = 1;
            break;
        }
        break;
    }

    return (shorter);
}

/*
 * ravl_delete() - called from avl_delete to do recursive deletion of a
 * node from an avl tree.  It finds the node recursively, deletes it,
 * and returns shorter if the tree is shorter after the deletion and
 * rebalancing.
 */

static caddr_t
ravl_delete(
    Avlnode **root,
    caddr_t data,
    IFP fcmp,
    int *shorter)
{
    int shortersubtree = 0;
    int cmp;
    caddr_t savedata;
    Avlnode *minnode, *savenode;

    if (*root == NULLAVL)
        return (0);

    cmp = (*fcmp)(data, (*root)->avl_data);

    /* found it! */
    if (cmp == 0) {
        savenode = *root;
        savedata = savenode->avl_data;

        /* simple cases: no left child */
        if ((*root)->avl_left == 0) {
            *root = (*root)->avl_right;
            *shorter = 1;
            free((char *)savenode);
            return (savedata);
            /* no right child */
        } else if ((*root)->avl_right == 0) {
            *root = (*root)->avl_left;
            *shorter = 1;
            free((char *)savenode);
            return (savedata);
        }

        /*
         * avl_getmin will return to us the smallest node greater
         * than the one we are trying to delete.  deleting this node
         * from the right subtree is guaranteed to end in one of the
         * simple cases above.
         */

        minnode = (*root)->avl_right;
        while (minnode->avl_left != NULLAVL)
            minnode = minnode->avl_left;

        /* swap the data */
        (*root)->avl_data = minnode->avl_data;
        minnode->avl_data = savedata;

        savedata = ravl_delete(&(*root)->avl_right, data, fcmp,
                               &shortersubtree);

        if (shortersubtree)
            *shorter = right_balance(root);
        else
            *shorter = 0;
        /* go left */
    } else if (cmp < 0) {
        if ((savedata = ravl_delete(&(*root)->avl_left, data, fcmp,
                                    &shortersubtree)) == 0) {
            *shorter = 0;
            return (0);
        }

        /* left subtree shorter? */
        if (shortersubtree)
            *shorter = left_balance(root);
        else
            *shorter = 0;
        /* go right */
    } else {
        if ((savedata = ravl_delete(&(*root)->avl_right, data, fcmp,
                                    &shortersubtree)) == 0) {
            *shorter = 0;
            return (0);
        }

        if (shortersubtree)
            *shorter = right_balance(root);
        else
            *shorter = 0;
    }

    return (savedata);
}

/*
 * avl_delete() - deletes the node containing data (according to fcmp) from
 * the avl tree rooted at root.
 */

caddr_t
avl_delete(Avlnode **root, void *data, IFP fcmp)
{
    int shorter;

    return ravl_delete(root, (caddr_t)data, fcmp, &shorter);
}

static int
avl_inapply(Avlnode *root, IFP fn, caddr_t arg, int stopflag)
{
    if (root == 0)
        return (AVL_NOMORE);

    if (root->avl_left != 0)
        if (avl_inapply(root->avl_left, fn, arg, stopflag) == stopflag)
            return (stopflag);

    if ((*fn)(root->avl_data, arg) == stopflag)
        return (stopflag);

    if (root->avl_right == 0)
        return (AVL_NOMORE);
    else
        return (avl_inapply(root->avl_right, fn, arg, stopflag));
}

static int
avl_postapply(Avlnode *root, IFP fn, caddr_t arg, int stopflag)
{
    if (root == 0)
        return (AVL_NOMORE);

    if (root->avl_left != 0)
        if (avl_postapply(root->avl_left, fn, arg, stopflag) == stopflag)
            return (stopflag);

    if (root->avl_right != 0)
        if (avl_postapply(root->avl_right, fn, arg, stopflag) == stopflag)
            return (stopflag);

    return ((*fn)(root->avl_data, arg));
}

static int
avl_preapply(Avlnode *root, IFP fn, caddr_t arg, int stopflag)
{
    if (root == 0)
        return (AVL_NOMORE);

    if ((*fn)(root->avl_data, arg) == stopflag)
        return (stopflag);

    if (root->avl_left != 0)
        if (avl_preapply(root->avl_left, fn, arg, stopflag) == stopflag)
            return (stopflag);

    if (root->avl_right == 0)
        return (AVL_NOMORE);
    else
        return (avl_preapply(root->avl_right, fn, arg, stopflag));
}

/*
 * avl_apply -- avl tree root is traversed, function fn is called with
 * arguments arg and the data portion of each node.  if fn returns stopflag,
 * the traversal is cut short, otherwise it continues.  Do not use -6 as
 * a stopflag, as this is what is used to indicate the traversal ran out
 * of nodes.
 */

int
avl_apply(
    Avlnode *root,
    IFP fn,
    void *arg,
    int stopflag,
    int type)
{
    switch (type) {
    case AVL_INORDER:
        return avl_inapply(root, fn, (caddr_t)arg, stopflag);
    case AVL_PREORDER:
        return avl_preapply(root, fn, (caddr_t)arg, stopflag);
    case AVL_POSTORDER:
        return avl_postapply(root, fn, (caddr_t)arg, stopflag);
    default:
        fprintf(stderr, "Invalid traversal type %d\n", type);
        return (-1);
    }

    /* NOTREACHED */
}

/*
 * avl_prefixapply - traverse avl tree root, applying function fprefix
 * to any nodes that match.  fcmp is called with data as its first arg
 * and the current node's data as its second arg.  it should return
 * 0 if they match, < 0 if data is less, and > 0 if data is greater.
 * the idea is to efficiently find all nodes that are prefixes of
 * some key...  Like avl_apply, this routine also takes a stopflag
 * and will return prematurely if fmatch returns this value.  Otherwise,
 * AVL_NOMORE is returned.
 */

int
avl_prefixapply(
    Avlnode *root,
    caddr_t data,
    IFP fmatch,
    caddr_t marg,
    IFP fcmp,
    caddr_t carg,
    int stopflag)
{
    int cmp;

    if (root == 0)
        return (AVL_NOMORE);

    cmp = (*fcmp)(data, root->avl_data, carg);
    if (cmp == 0) {
        if ((*fmatch)(root->avl_data, marg) == stopflag)
            return (stopflag);

        if (root->avl_left != 0)
            if (avl_prefixapply(root->avl_left, data, fmatch,
                                marg, fcmp, carg, stopflag) == stopflag)
                return (stopflag);

        if (root->avl_right != 0)
            return (avl_prefixapply(root->avl_right, data, fmatch,
                                    marg, fcmp, carg, stopflag));
        else
            return (AVL_NOMORE);

    } else if (cmp < 0) {
        if (root->avl_left != 0)
            return (avl_prefixapply(root->avl_left, data, fmatch,
                                    marg, fcmp, carg, stopflag));
    } else {
        if (root->avl_right != 0)
            return (avl_prefixapply(root->avl_right, data, fmatch,
                                    marg, fcmp, carg, stopflag));
    }

    return (AVL_NOMORE);
}

/*
 * avl_free -- traverse avltree root, freeing the memory it is using.
 * the dfree() is called to free the data portion of each node.  The
 * number of items actually freed is returned.
 */

int
avl_free(Avlnode *root, IFP dfree)
{
    int nleft, nright;

    if (root == 0)
        return (0);

    nleft = nright = 0;
    if (root->avl_left != 0)
        nleft = avl_free(root->avl_left, dfree);

    if (root->avl_right != 0)
        nright = avl_free(root->avl_right, dfree);

    if (dfree)
        (*dfree)(root->avl_data);

    free((char *)root);

    return (nleft + nright + 1);
}

/*
 * avl_find -- search avltree root for a node with data data.  the function
 * cmp is used to compare things.  it is called with data as its first arg
 * and the current node data as its second.  it should return 0 if they match,
 * < 0 if arg1 is less than arg2 and > 0 if arg1 is greater than arg2.
 */

caddr_t
avl_find(Avlnode *root, void *data, IFP fcmp)
{
    int cmp;

    while (root != 0 && (cmp = (*fcmp)((caddr_t)data, root->avl_data)) != 0) {
        if (cmp < 0)
            root = root->avl_left;
        else
            root = root->avl_right;
    }

    return (root ? root->avl_data : 0);
}

/*
 * avl_find_lin -- search avltree root linearly for a node with data data.
 * the function cmp is used to compare things.  it is called with data as its
 * first arg and the current node data as its second.  it should return 0 if
 * they match, non-zero otherwise.
 */

caddr_t
avl_find_lin(Avlnode *root, caddr_t data, IFP fcmp)
{
    caddr_t res;

    if (root == 0)
        return (NULL);

    if ((*fcmp)(data, root->avl_data) == 0)
        return (root->avl_data);

    if (root->avl_left != 0)
        if ((res = avl_find_lin(root->avl_left, data, fcmp)) != NULL)
            return (res);

    if (root->avl_right == 0)
        return (NULL);
    else
        return (avl_find_lin(root->avl_right, data, fcmp));
}

static caddr_t *avl_list = (caddr_t *)0;
static int avl_maxlist = 0;
static int avl_nextlist = 0;

#define AVL_GRABSIZE 100

/* ARGSUSED */
static int
avl_buildlist(caddr_t data, int arg __attribute__((unused)))
{
    static int slots = 0;

    if (avl_list == (caddr_t *)0) {
        avl_list = (caddr_t *)malloc(AVL_GRABSIZE * sizeof(caddr_t));
        slots = AVL_GRABSIZE;
        avl_maxlist = 0;
    } else if (avl_maxlist == slots) {
        slots += AVL_GRABSIZE;
        avl_list = (caddr_t *)realloc((char *)avl_list,
                                      (unsigned)slots * sizeof(caddr_t));
    }

    avl_list[avl_maxlist++] = data;

    return (0);
}

/*
 * avl_getfirst() and avl_getnext() are provided as alternate tree
 * traversal methods, to be used when a single function cannot be
 * provided to be called with every node in the tree.  avl_getfirst()
 * traverses the tree and builds a linear list of all the nodes,
 * returning the first node.  avl_getnext() returns the next thing
 * on the list built by avl_getfirst().  This means that avl_getfirst()
 * can take a while, and that the tree should not be messed with while
 * being traversed in this way, and that multiple traversals (even of
 * different trees) cannot be active at once.
 */

caddr_t
avl_getfirst(Avlnode *root)
{
    if (avl_list) {
        free((char *)avl_list);
        avl_list = (caddr_t *)0;
    }
    avl_maxlist = 0;
    avl_nextlist = 0;

    if (root == 0)
        return (0);

    (void)avl_apply(root, avl_buildlist, (caddr_t)0, -1, AVL_INORDER);
    if (avl_list && avl_list[avl_nextlist++]) {
        return avl_list[avl_nextlist];
    } else {
        return (NULL);
    }
}

caddr_t
avl_getnext(void)
{
    if (avl_list == 0)
        return (0);

    if (avl_nextlist == avl_maxlist) {
        free((caddr_t)avl_list);
        avl_list = (caddr_t *)0;
        return (0);
    }

    return (avl_list[avl_nextlist++]);
}

int
avl_dup_error(void)
{
    return (-1);
}

int
avl_dup_ok(void)
{
    return (0);
}
