/* Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program 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 General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */


#ifndef NDB_HASHMAP_HPP
#define NDB_HASHMAP_HPP

#include <ndb_global.h>
#include <my_sys.h>
#include <hash.h>


/*
  Default implementation for extracting key_ptr and
  key_length from type K. Used when the entire type
  K should be used as key.

  NOTE! Optimized inside HashMap so that it's never
  actually called
*/

inline const void* HashMap__get_key(const void* key_ptr, size_t* key_length)
{
  key_length = key_length;
  return key_ptr;
}


/*
  Hash container for storing key value pairs
*/

template<typename K, typename T,
         const void* G(const void*, size_t*) = HashMap__get_key >
class HashMap {
  class Entry {
  public:
    K m_key;
    T m_value;
    Entry(const K& k, const T& v) : m_key(k), m_value(v) {};
  };

  HASH m_hash;

  static void free_element(void * ptr) {
    Entry* entry = (Entry*)ptr;
    delete entry;
  }

  /*
    Callback function which is installed into 'my_hash'
    and thus called once for each key in the hash that need to
    be compared. Should return a pointer to where the key
    start and the key's length.
  */
  static uchar* _get_key(const uchar* ptr,
                         size_t* key_length, my_bool first) {
    const Entry * entry = reinterpret_cast<const Entry*>(ptr);
    const void* key_ptr = G(&entry->m_key, key_length);
    return (uchar*)key_ptr;
  }

  const void* get_key_ptr(const K* key, size_t *key_length) const {
    if (G == HashMap__get_key)
      return key;
    return _get_key((const uchar*)key, key_length, false);
  }

public:
  HashMap(ulong initial_size = 1024, uint grow_size = 256) {

    assert(my_init_done);

    if (my_hash_init2(&m_hash,
                      grow_size,
                      &my_charset_bin, // charset
                      initial_size,    // default_array_elements
                      0,               // key_offset
                      sizeof(K),       // key_length
                      G == HashMap__get_key ? NULL : _get_key, // get_key,
                      free_element,    // free_element
                      HASH_UNIQUE      // flags
                      ))
      abort();
  }

  ~HashMap() {
    my_hash_free(&m_hash);
  }

  bool insert(const K& k, const T& v, bool replace = false) {
    Entry* entry = new Entry(k, v);
    if (my_hash_insert(&m_hash, (const uchar*)entry) != 0) {
      // An entry already existed

      delete entry;

      T* p;
      if (replace && search(k, &p)) {
        *p = v;
        return true;
      }
      return false;
    }
    return true;
  }

  bool search(const K& k, T& v) const {
    T* p;
    if (!search(k, &p))
      return false;
    v = *p;
    return true;
  }

  bool search(const K& k, T** v) const {
    size_t key_length = sizeof(K);
    const void *key = get_key_ptr(&k, &key_length);
    Entry* entry= (Entry*)my_hash_search(&m_hash,
                                         (const uchar*)key, key_length);
    if (entry == NULL)
      return false;

    *v = &(entry->m_value);
    return true;
  }

  bool remove(const K& k) {
    size_t key_length = sizeof(K);
    const void *key = get_key_ptr(&k, &key_length);
    Entry* entry= (Entry*)my_hash_search(&m_hash,
                                         (const uchar*)key, key_length);
    if (entry == NULL)
      return false;

    if (my_hash_delete(&m_hash, (uchar*)entry))
      return false;
    return true;
  }

  bool remove(size_t i) {
    Entry* entry = (Entry*)my_hash_element(&m_hash, (ulong)i);
    if (entry == NULL)
      return false;

    if (my_hash_delete(&m_hash, (uchar*)entry))
      return false;
    return true;
  }

  size_t entries(void) const {
    return m_hash.records;
  }

  T* value(size_t i) const {
    Entry* entry = (Entry*)my_hash_element((HASH*)&m_hash, (ulong)i);
    if (entry == NULL)
      return NULL;
    return &(entry->m_value);
  }

};

#endif
