// Copyright (C) 2004-2021 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include <string.h>

/* AA-tree */

struct fz_tree

{

  char *key;

  void *value;

  fz_tree *left, *right;

  int level;

};

static fz_tree tree_sentinel = { "", NULL, &tree_sentinel, &tree_sentinel, 0 };

static fz_tree *fz_tree_new_node(fz_context *ctx, const char *key, void *value)

{

  fz_tree *node = fz_malloc_struct(ctx, fz_tree);

  fz_try(ctx)

  {

    node->key = fz_strdup(ctx, key);

    node->value = value;

    node->left = node->right = &tree_sentinel;

    node->level = 1;

  }

  fz_catch(ctx)

  {

    fz_free(ctx, node);

    fz_rethrow(ctx);

  }

  return node;

}

void *fz_tree_lookup(fz_context *ctx, fz_tree *node, const char *key)

{

  if (node)

  {

    while (node != &tree_sentinel)

    {

      int c = strcmp(key, node->key);

      if (c == 0)

        return node->value;

      else if (c < 0)

        node = node->left;

      else

        node = node->right;

    }

  }

  return NULL;

}

static fz_tree *fz_tree_skew(fz_tree *node)

{

  if (node->level != 0)

  {

    if (node->left->level == node->level)

    {

      fz_tree *save = node;

      node = node->left;

      save->left = node->right;

      node->right = save;

    }

    node->right = fz_tree_skew(node->right);

  }

  return node;

}

static fz_tree *fz_tree_split(fz_tree *node)

{

  if (node->level != 0 && node->right->right->level == node->level)

  {

    fz_tree *save = node;

    node = node->right;

    save->right = node->left;

    node->left = save;

    node->level++;

    node->right = fz_tree_split(node->right);

  }

  return node;

}

fz_tree *fz_tree_insert(fz_context *ctx, fz_tree *node, const char *key, void *value)

{

  if (node && node != &tree_sentinel)

  {

    int c = strcmp(key, node->key);

    if (c < 0)

      node->left = fz_tree_insert(ctx, node->left, key, value);

    else

      node->right = fz_tree_insert(ctx, node->right, key, value);

    node = fz_tree_skew(node);

    node = fz_tree_split(node);

    return node;

  }

  else

  {

    return fz_tree_new_node(ctx, key, value);

  }

}

void fz_drop_tree(fz_context *ctx, fz_tree *node, void (*dropfunc)(fz_context *ctx, void *value))

{

  if (node)

  {

    if (node->left != &tree_sentinel)

      fz_drop_tree(ctx, node->left, dropfunc);

    if (node->right != &tree_sentinel)

      fz_drop_tree(ctx, node->right, dropfunc);

    fz_free(ctx, node->key);

    if (dropfunc)

      dropfunc(ctx, node->value);

    fz_free(ctx, node);

  }

}