////////////////////////////////////////////////////////////////////////////////
/// @brief associative array implementation
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Martin Schoenert
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2006-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "associative.h"
#include "Basics/hashes.h"
#include "Basics/tri-strings.h"

// -----------------------------------------------------------------------------
// --SECTION--                                                   private defines
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief initial number of elements in the array
////////////////////////////////////////////////////////////////////////////////

#define INITIAL_SIZE (11)

// -----------------------------------------------------------------------------
// --SECTION--                                              ASSOCIATIVE POINTERS
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief adds a new element
////////////////////////////////////////////////////////////////////////////////

static void AddNewElementPointer (TRI_associative_pointer_t* array, void* element) {
  uint64_t hash;
  uint64_t i;

  // compute the hash
  hash = array->hashElement(array, element);

  // search the table
  i = hash % array->_nrAlloc;

  while (array->_table[i] != nullptr) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesR++;
#endif
  }

  // add a new element to the associative array
  array->_table[i] = element;
  array->_nrUsed++;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief resizes the array
////////////////////////////////////////////////////////////////////////////////

static bool ResizeAssociativePointer (TRI_associative_pointer_t* array,
                                      uint32_t targetSize) {
  void** oldTable = array->_table;
  uint32_t oldAlloc = array->_nrAlloc;

  array->_nrAlloc = targetSize;
#ifdef TRI_INTERNAL_STATS
  array->_nrResizes++;
#endif

  array->_table = static_cast<void**>(TRI_Allocate(array->_memoryZone, (size_t) (array->_nrAlloc * sizeof(void*)), true));

  if (array->_table == nullptr) {
    array->_nrAlloc = oldAlloc;
    array->_table = oldTable;

    return false;
  }

  array->_nrUsed = 0;

  if (oldTable != nullptr) {
    // table is already cleared by allocate, copy old data
    for (uint32_t j = 0; j < oldAlloc; j++) {
      if (oldTable[j] != nullptr) {
        AddNewElementPointer(array, oldTable[j]);
      }
    }

    TRI_Free(array->_memoryZone, oldTable);
  }

  return true;
}

// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief initializes an array
////////////////////////////////////////////////////////////////////////////////

int TRI_InitAssociativePointer (TRI_associative_pointer_t* array,
                                TRI_memory_zone_t* zone,
                                uint64_t (*hashKey) (TRI_associative_pointer_t*, void const*),
                                uint64_t (*hashElement) (TRI_associative_pointer_t*, void const*),
                                bool (*isEqualKeyElement) (TRI_associative_pointer_t*, void const*, void const*),
                                bool (*isEqualElementElement) (TRI_associative_pointer_t*, void const*, void const*)) {
  array->hashKey = hashKey;
  array->hashElement = hashElement;
  array->isEqualKeyElement = isEqualKeyElement;
  array->isEqualElementElement = isEqualElementElement;

  array->_memoryZone = zone;
  array->_nrAlloc = 0;
  array->_nrUsed  = 0;
  array->_table   = nullptr;

#ifdef TRI_INTERNAL_STATS
  array->_nrFinds = 0;
  array->_nrAdds = 0;
  array->_nrRems = 0;
  array->_nrResizes = 0;
  array->_nrProbesF = 0;
  array->_nrProbesA = 0;
  array->_nrProbesD = 0;
  array->_nrProbesR = 0;
#endif
  
  if (nullptr == (array->_table = static_cast<void**>(TRI_Allocate(zone, sizeof(void*) * INITIAL_SIZE, true)))) {
    return TRI_ERROR_OUT_OF_MEMORY;
  }

  array->_nrAlloc = INITIAL_SIZE;

  return TRI_ERROR_NO_ERROR;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief destroys an array, but does not free the pointer
////////////////////////////////////////////////////////////////////////////////

void TRI_DestroyAssociativePointer (TRI_associative_pointer_t* array) {
  if (array->_table != nullptr) {
    TRI_Free(array->_memoryZone, array->_table);
    array->_table = nullptr;
  }
}

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief General hash function that can be used to hash a key
////////////////////////////////////////////////////////////////////////////////

uint64_t TRI_HashStringKeyAssociativePointer (TRI_associative_pointer_t* array,
                                              void const* key) {
  return TRI_FnvHashString((char const*) key);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief General function to determine equality of two string values
////////////////////////////////////////////////////////////////////////////////

bool TRI_EqualStringKeyAssociativePointer (TRI_associative_pointer_t* array,
                                           void const* key,
                                           void const* element) {
  return TRI_EqualString((char*) key, (char*) element);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief reserves space in the array for extra elements
////////////////////////////////////////////////////////////////////////////////

bool TRI_ReserveAssociativePointer (TRI_associative_pointer_t* array,
                                    int32_t nrElements) {
  uint32_t targetSize = array->_nrUsed + nrElements;

  if (array->_nrAlloc < 2 * targetSize) {
    // we must resize
    return ResizeAssociativePointer(array, (uint32_t) (2 * targetSize) + 1);
  }

  // no seed to resize
  return true;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up an element given a key
////////////////////////////////////////////////////////////////////////////////

void* TRI_LookupByKeyAssociativePointer (TRI_associative_pointer_t* array,
                                         void const* key) {
  if (array->_nrUsed == 0) {
    return nullptr;
  }

  // compute the hash
  uint64_t hash = array->hashKey(array, key);
  uint64_t i = hash % array->_nrAlloc;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrFinds++;
#endif

  // search the table
  while (array->_table[i] != nullptr && ! array->isEqualKeyElement(array, key, array->_table[i])) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesF++;
#endif
  }

  // return whatever we found
  return array->_table[i];
}

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up an element given an element
////////////////////////////////////////////////////////////////////////////////

void* TRI_LookupByElementAssociativePointer (TRI_associative_pointer_t* array,
                                             void const* element) {
  // compute the hash
  uint64_t const hash = array->hashElement(array, element);
  uint64_t const n = array->_nrAlloc;
  uint64_t i, k;
  i = k = hash % n;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrFinds++;
#endif

  // search the table
  for (; i < n && array->_table[i] != nullptr && ! array->isEqualElementElement(array, element, array->_table[i]); ++i);

  if (i == n) {
    for (i = 0; i < k && array->_table[i] != nullptr && ! array->isEqualElementElement(array, element, array->_table[i]); ++i);
  }

  // return whatever we found
  return array->_table[i];
}

////////////////////////////////////////////////////////////////////////////////
/// @brief adds an element to the array
////////////////////////////////////////////////////////////////////////////////

void* TRI_InsertElementAssociativePointer (TRI_associative_pointer_t* array,
                                           void* element,
                                           bool overwrite) {
  uint64_t hash;
  uint64_t i;
  void* old;

  // check for out-of-memory
  if (array->_nrAlloc == array->_nrUsed) {
    TRI_set_errno(TRI_ERROR_OUT_OF_MEMORY);
    return nullptr;
  }

  // compute the hash
  hash = array->hashElement(array, element);
  i = hash % array->_nrAlloc;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrAdds++;
#endif

  // search the table
  while (array->_table[i] != nullptr && ! array->isEqualElementElement(array, element, array->_table[i])) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesA++;
#endif
  }

  old = array->_table[i];

  // if we found an element, return
  if (old != nullptr) {
    if (overwrite) {
      array->_table[i] = element;
    }

    return old;
  }

  // add a new element to the associative array
  array->_table[i] = element;
  array->_nrUsed++;

  // if we were adding and the table is more than half full, extend it
  if (array->_nrAlloc < 2 * array->_nrUsed) {
    ResizeAssociativePointer(array, (uint32_t) (2 * array->_nrAlloc) + 1);
  }

  return nullptr;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief adds an key/element to the array
////////////////////////////////////////////////////////////////////////////////

void* TRI_InsertKeyAssociativePointer (TRI_associative_pointer_t* array,
                                       void const* key,
                                       void* element,
                                       bool overwrite) {
  uint64_t hash;
  uint64_t i;
  void* old;

  // check for out-of-memory
  if (array->_nrAlloc == array->_nrUsed) {
    TRI_set_errno(TRI_ERROR_OUT_OF_MEMORY);
    return nullptr;
  }

  // compute the hash
  hash = array->hashKey(array, key);
  i = hash % array->_nrAlloc;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrAdds++;
#endif

  // search the table
  while (array->_table[i] != nullptr && ! array->isEqualKeyElement(array, key, array->_table[i])) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesA++;
#endif
  }

  old = array->_table[i];

  // if we found an element, return
  if (old != nullptr) {
    if (overwrite) {
      array->_table[i] = element;
    }

    return old;
  }

  // add a new element to the associative array
  array->_table[i] = element;
  array->_nrUsed++;

  // if we were adding and the table is more than half full, extend it
  if (array->_nrAlloc < 2 * array->_nrUsed) {
    ResizeAssociativePointer(array, (uint32_t) (2 * array->_nrAlloc) + 1);
  }

  return nullptr;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief adds an key/element to the array
/// returns a status code, and *found will contain the found element (if any)
////////////////////////////////////////////////////////////////////////////////

int TRI_InsertKeyAssociativePointer2 (TRI_associative_pointer_t* array,
                                      void const* key,
                                      void* element,
                                      void const** found) {
  uint64_t hash;
  uint64_t i;
  void* old;

  if (found != nullptr) {
    *found = nullptr;
  }

  // check for out-of-memory
  if (array->_nrAlloc == array->_nrUsed) {
    return TRI_ERROR_OUT_OF_MEMORY;
  }

  // compute the hash
  hash = array->hashKey(array, key);
  i = hash % array->_nrAlloc;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrAdds++;
#endif

  // search the table
  while (array->_table[i] != nullptr && ! array->isEqualKeyElement(array, key, array->_table[i])) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesA++;
#endif
  }

  old = array->_table[i];

  // if we found an element, return
  if (old != nullptr) {
    if (found != nullptr) {
      *found = old;
    }

    return TRI_ERROR_NO_ERROR;
  }

  // if we were adding and the table is more than half full, extend it
  if (array->_nrAlloc < 2 * array->_nrUsed) {
    if (! ResizeAssociativePointer(array, (uint32_t) (2 * array->_nrAlloc) + 1)) {
      return TRI_ERROR_OUT_OF_MEMORY;
    }

    // now we need to recalc the position
    i = hash % array->_nrAlloc;
    // search the table
    while (array->_table[i] != nullptr && ! array->isEqualKeyElement(array, key, array->_table[i])) {
      i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
      array->_nrProbesA++;
#endif
    }
  }

  // add a new element to the associative array
  array->_table[i] = element;
  array->_nrUsed++;

  return TRI_ERROR_NO_ERROR;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief removes an key/element to the array
////////////////////////////////////////////////////////////////////////////////

void* TRI_RemoveKeyAssociativePointer (TRI_associative_pointer_t* array,
                                       void const* key) {
  uint64_t hash;
  uint64_t i;
  uint64_t k;
  void* old;

  hash = array->hashKey(array, key);
  i = hash % array->_nrAlloc;

#ifdef TRI_INTERNAL_STATS
  // update statistics
  array->_nrRems++;
#endif

  // search the table
  while (array->_table[i] != nullptr && ! array->isEqualKeyElement(array, key, array->_table[i])) {
    i = TRI_IncModU64(i, array->_nrAlloc);
#ifdef TRI_INTERNAL_STATS
    array->_nrProbesD++;
#endif
  }

  // if we did not find such an item return false
  if (array->_table[i] == nullptr) {
    return nullptr;
  }

  // remove item
  old = array->_table[i];
  array->_table[i] = nullptr;
  array->_nrUsed--;

  // and now check the following places for items to move here
  k = TRI_IncModU64(i, array->_nrAlloc);

  while (array->_table[k] != nullptr) {
    uint64_t j = array->hashElement(array, array->_table[k]) % array->_nrAlloc;

    if ((i < k && !(i < j && j <= k)) || (k < i && !(i < j || j <= k))) {
      array->_table[i] = array->_table[k];
      array->_table[k] = nullptr;
      i = k;
    }

    k = TRI_IncModU64(k, array->_nrAlloc);
  }

  // return success
  return old;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief get the number of elements from the array
////////////////////////////////////////////////////////////////////////////////

size_t TRI_GetLengthAssociativePointer (const TRI_associative_pointer_t* const array) {
  return array->_nrUsed;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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