#ifndef DYNET_DICT_H_
#define DYNET_DICT_H_

#include <unordered_map>
#include <string>
#include <vector>
#include <iostream>
#include <stdexcept>

#include "dynet/except.h"

namespace dynet {

class Dict {
typedef std::unordered_map<std::string, int> Map;
public:
  Dict() : frozen(false), map_unk(false), unk_id(-1) {
  }

  inline unsigned size() const { return (unsigned)words_.size(); }

  inline bool contains(const std::string& words) const {
    return !(d_.find(words) == d_.end());
  }

  void freeze() { frozen = true; }
  bool is_frozen() const { return frozen; }

  inline int convert(const std::string& word) {
    auto i = d_.find(word);
    if (i == d_.end()) {
      if (frozen) {
        if (map_unk)
          return unk_id;
        else
          DYNET_RUNTIME_ERR("Unknown word encountered in frozen dictionary: " << word);
      }
      words_.push_back(word);
      return d_[word] = (int)words_.size() - 1;
    } else {
      return i->second;
    }
  }
  
  inline const std::string& convert(const int& id) const {
    DYNET_ARG_CHECK(id < (int)words_.size(), 
                            "Out-of-bounds error in Dict::convert for word ID " << id <<
                            " (dict size: " << words_.size() << ")");
    return words_[id];
  }
  
  void set_unk(const std::string& word) {
    if (!frozen)
      DYNET_RUNTIME_ERR("Please call set_unk() only after dictionary is frozen");
    if (map_unk)
      DYNET_RUNTIME_ERR("Set UNK more than one time");
  
    // temporarily unfreeze the dictionary to allow the addition of the UNK
    frozen = false;
    unk_id = convert(word);
    frozen = true;
  
    map_unk = true;
  }

  int get_unk_id() const { return unk_id; }
  const std::vector<std::string> & get_words() const { return words_; }
  
  void clear() { words_.clear(); d_.clear(); }

protected:
  bool frozen;
  bool map_unk; // if true, map unknown word to unk_id
  int unk_id; 
  std::vector<std::string> words_;
  Map d_;
};

std::vector<int> read_sentence(const std::string& line, Dict& sd);
void read_sentence_pair(const std::string& line, std::vector<int>& s, Dict& sd, std::vector<int>& t, Dict& td);

} // namespace dynet

#endif