/*
    $Id$

    Copyright (C) 2007 by The Regents of the University of California

    Redistribution of this file is permitted under the terms of the
    GNU Public License (GPL).

    Date: 01/30/2007
    Author: Rares Vernica <rvernica@ics.uci.edu>
*/

#ifndef _gram_h_
#define _gram_h_

#include <map>
#include <set>
#include <string>
#include <vector>

#include <tr1/functional>
#include <tr1/unordered_map>

using namespace std;
using namespace tr1;

// convert a string to a list of grams
void str2grams(const string &s, vector<string> &res,
               const unsigned q = 3,
               const unsigned char st = '#', unsigned char en = '$');

void str2grams(const string &s, set<string> &res, 
               const unsigned q = 3);

// convert a string to a list of hashed grams
void str2gramsHash(const string &s, vector<unsigned> &res, 
                    const unsigned q = 3,
                    const unsigned char st = '#', const unsigned char en = '$'); 

// convert a list of grams to the corresponding string
void grams2str(const vector<string> &v, string &s, const unsigned q = 3);

unsigned gram2id(const string &gram); // get ID from gram
void id2gram(unsigned id, string &res,
             const unsigned q = 3); // get ID from unsigned

extern hash<string> hashString;

class GramId                    // grams as IDs in a vector with all possible grams
{
public:
  GramId(unsigned q = 3,
         char st = '#',
         char en = '$', 
         const string &charset = charsetEn,
         bool withPerm = true);
  GramId(const string &filenamePreffix);

  void saveData(const string &filenamePreffix) const;

  unsigned getQ() const { return q; }
  unsigned getCharsetLen() const { return charsetLen; }
  unsigned getN() const { return n; }

  unsigned getId(const string &gram) const; // get ID from gram
  string getGram(unsigned id) const; // get gram from ID
  void getIds(const string &s, vector<unsigned> &ids) const;
                                // convert string to list of gram IDs
  void getGrams(const vector<unsigned> &ids, vector<string> &grams) const;
                                // convert list of gram IDs to list of grams

  bool consistData(const string &filenamePrefix, const string &filenameExt) const;

  bool operator==(const GramId& g) const;

  static const string charsetEn; // English character

private:
  unsigned q;                   // length of grams
  char st, en;                  // start and end char for grams (e.g., '#' and '$')
  string charset;               // possible characters
  unsigned charsetLen;
  unsigned n;                   // length of vector with all possible grams
  vector<unsigned> perm;        // permutation for gram IDs

  static const unsigned charsetLenMax; // max length of the charset
  static const string gramidSuffix;

  void loadData(const string &filenamePrefix);

  unsigned invPerm(unsigned id) const;
};

// convert a string to a list of words
void str2words(const string &s, vector<string> &res, const string &delims = " \t");

// Word Index
typedef set<unsigned> Ids;
typedef pair<string, Ids>  WordEntry;

// version 1
typedef unordered_map<string, Ids> WordHash;

// version 2
typedef vector<WordEntry> WordIds;
typedef unordered_map<string, unsigned> WordKey;

// version 3
typedef vector<string> WordKey3;
typedef vector<Ids> WordIds3;
typedef unordered_map<string, unsigned> WordHash3;

class WordIndex 
{
public:
  static void build(const vector<string> &data, WordHash &wordHash);
  static void build(const string &filenameDataset, WordHash &wordHash);

  static void build(const vector<string> &data,
                    WordIds &wordIds, WordKey &wordKey);
  static void build(const string &filenameDataset,
                    WordIds &wordIds, WordKey &wordKey);

  static void save(const string &filenameWords, 
                   const string &filenameIds,
                   const WordHash &wordHash);
  static void load(const string &filenameWords, 
                   const string &filenameIds, 
                   WordHash &wordHash);

  static void save(const string &filenameWids, 
                   const string &filenameWkey,
                   const WordIds &wordIds, const WordKey &wordKey);
  static void load(const string &filenameWids, 
                   const string &filenameWkey, 
                   WordIds &wordIds, WordKey &wordKey);
  static bool exist(const string &filename1, const string &filename2);
};

#endif