#ifndef STRINGSET_H
#define STRINGSET_H

#include <string>
#include <stdexcept>
#include <cmath>
#include <climits>
#ifdef __WXMSW__
  #include <mem.h>
#endif

template<class T>
class StringSetNode
{
  public:
    StringSetNode(T *keyParameter, size_t lenParameter)
    {
      next = NULL;
      len = lenParameter;
      key = new T[len];
      memcpy(key, keyParameter, len * sizeof(T));
    }
    ~StringSetNode()
    {
      delete[] key; 
    } 
    StringSetNode<T> *next;
    T *key;
    size_t len;
};

template<class T>
class StringSet
{
  public:
    StringSet(
      int hashSizePower = 19
    );
    ~StringSet();
    StringSet(const StringSet<T>&);
    StringSet& operator=(const StringSet<T>&);
    inline bool empty();
    inline int count();
    StringSetNode<T> *insert(std::basic_string<T> &s);
    StringSetNode<T> *insert(T *s, size_t len, uint32_t hash = UINT_MAX);
    StringSetNode<T> *find(std::basic_string<T> &s);
    StringSetNode<T> *find(T *s, size_t len, uint32_t hash = UINT_MAX);
    void clear();
  private:
    bool emptyFlag;
    uint32_t hashSize, hashMask, nodeCount;
    StringSetNode<T> **table;
    uint32_t hash(const char *s, size_t len);
    void allocateHashTable(uint32_t hashSize);
};

template<class T>
StringSet<T>::StringSet(int hashSizePower)
{
  if (hashSizePower < 1)
    throw std::runtime_error("StringSet: invalid parameter");
  hashSize = (int)pow((double)2, (double)hashSizePower);
  hashMask = hashSize - 1;
  nodeCount = 0;
  allocateHashTable(hashSize);
}

template<class T>
StringSet<T>::~StringSet()
{
  if (!empty())
    clear();
  delete[] table;
}

template<class T>
StringSet<T>::StringSet(const StringSet<T>& d)
{
  hashSize = d.hashSize;
  hashMask = hashSize - 1;
  nodeCount = 0;
  allocateHashTable(hashSize);
  StringSetNode<T> *np;
  for (uint32_t i = 0; i < d.hashSize; ++i)
    for (np = d.table[i]; np != NULL; np = np->next)
      insert(np->key, np->len, i);
}

template<class T>
StringSet<T>& StringSet<T>::operator=(const StringSet<T>& d)
{
  if (this != &d)
  {
    clear();
    StringSetNode<T> *np;
      for (uint32_t i = 0; i < d.hashSize; ++i)
        for (np = d.table[i]; np != NULL; np = np->next)
          insert(np->key, np->len, i); 
  }
  return *this;
}

// see 'one-at-a-time hash' (http://burtleburtle.net/bob/hash/doobs.html)
template<class T>
uint32_t StringSet<T>::hash(const char *key, size_t len)
{
  uint32_t hash;
  for (hash = 0; len--; ++key)
  {
    hash += *key;
    hash += (hash << 10);
    hash ^= (hash >> 6);
  }
  hash += (hash << 3);
  hash ^= (hash >> 11);
  hash += (hash << 15);
  return (hash & hashMask);
}

template<class T>
StringSetNode<T> *StringSet<T>::find(std::basic_string<T> &s)
{
  return find((T *)s.data(), s.size()); 
}

template<class T>
StringSetNode<T> *StringSet<T>::find(T *s, size_t len, uint32_t hashValue)
{
  if (hashValue == UINT_MAX)
    hashValue = hash((const char*)s, len * sizeof(T));
  StringSetNode<T> *np;
  for (np = table[hashValue]; np != NULL; np = np->next)
    if (len == np->len && (memcmp(s, np->key, len) == 0))
      return np;
  return NULL;
}

template<class T>
StringSetNode<T> *StringSet<T>::insert(std::basic_string<T> &s)
{
  return insert((T *)s.data(), s.size()); 
}

template<class T>
StringSetNode<T> *StringSet<T>::insert(T *s, size_t len, uint32_t hashValue)
{
  if (hashValue == UINT_MAX)
    hashValue = hash((const char*)s, len * sizeof(T));
  StringSetNode<T> *np;
  if ((np = find(s, len, hashValue)) == NULL)
  {
    np = new StringSetNode<T>(s, len);
    np->next = table[hashValue];
    table[hashValue] = np;
    ++nodeCount;
  }
  return np;
}

template<class T>
void StringSet<T>::clear()
{
  if (!nodeCount)
    return;
  StringSetNode<T> *np, *memory;
  for (uint32_t i = 0; i < hashSize; ++i)
  {
    for (np = table[i]; np != NULL; np = memory)
    {
      memory = np->next;
      delete np;
    }
    table[i] = NULL;
  }
  nodeCount = 0;
}

template<class T>
int StringSet<T>::count()
{
  return nodeCount;
}

template<class T>
bool StringSet<T>::empty()
{
  return (nodeCount) ? false : true;
}

template<class T>
void StringSet<T>::allocateHashTable(uint32_t hashSize)
{
  table = new StringSetNode<T> *[hashSize];
  memset(table, 0, sizeof(StringSetNode<T> *) * hashSize);
}

#endif