/*    This file is part of the Gudhi Library. The Gudhi library 
 *    (Geometric Understanding in Higher Dimensions) is a generic C++ 
 *    library for computational topology.
 *
 *    Author(s):       Clement Maria, Pawel Dlotko
 *
 *    Copyright (C) 2014  INRIA
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    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 for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef READER_UTILS_H_
#define READER_UTILS_H_

#include <gudhi/graph_simplicial_complex.h>

#include <boost/graph/adjacency_list.hpp>

#include <iostream>
#include <fstream>
#include <map>
#include <limits>  // for numeric_limits
#include <string>
#include <vector>
#include <utility>  // for pair

// Keep this file tag for Doxygen to parse the code, otherwise, functions are not documented.
// It is required for global functions and variables.

/** @file
 * @brief This file includes common file reader for GUDHI
 */

/**
 * @brief Read a set of points to turn it into a vector< vector<double> > by filling points.
 *
 * File format: 1 point per line<br>
 * X11 X12 ... X1d<br>
 * X21 X22 ... X2d<br>
 * etc<br>
 */
inline void read_points(std::string file_name, std::vector< std::vector< double > > & points) {
  std::ifstream in_file(file_name.c_str(), std::ios::in);
  if (!in_file.is_open()) {
    std::cerr << "Unable to open file " << file_name << std::endl;
    return;
  }

  std::string line;
  double x;
  while (getline(in_file, line)) {
    std::vector< double > point;
    std::istringstream iss(line);
    while (iss >> x) {
      point.push_back(x);
    }
    // Check for empty lines
    if (!point.empty())
      points.push_back(point);
  }
  in_file.close();
}

/**
 * @brief Read a graph from a file.
 *
 * \tparam Graph_t Type for the return graph. Must be constructible from iterators on pairs of Vertex_handle
 * \tparam Filtration_value Type for the value of the read filtration
 * \tparam Vertex_handle Type for the value of the read vertices
 *
 * File format: 1 simplex per line<br>
 * Dim1 X11 X12 ... X1d Fil1<br>
 * Dim2 X21 X22 ... X2d Fil2<br>
 * etc<br>
 *
 * The vertices must be labeled from 0 to n-1.
 * Every simplex must appear exactly once.
 * Simplices of dimension more than 1 are ignored.
 */
template< typename Graph_t, typename Filtration_value, typename Vertex_handle >
Graph_t read_graph(std::string file_name) {
  std::ifstream in_(file_name.c_str(), std::ios::in);
  if (!in_.is_open()) {
    std::cerr << "Unable to open file " << file_name << std::endl;
  }

  typedef std::pair< Vertex_handle, Vertex_handle > Edge_t;
  std::vector< Edge_t > edges;
  std::vector< Filtration_value > edges_fil;
  std::map< Vertex_handle, Filtration_value > vertices;

  std::string line;
  int dim;
  Vertex_handle u, v, max_h = -1;
  Filtration_value fil;
  while (getline(in_, line)) {
    std::istringstream iss(line);
    while (iss >> dim) {
      switch (dim) {
        case 0:
        {
          iss >> u;
          iss >> fil;
          vertices[u] = fil;
          if (max_h < u) {
            max_h = u;
          }
          break;
        }
        case 1:
        {
          iss >> u;
          iss >> v;
          iss >> fil;
          edges.push_back(Edge_t(u, v));
          edges_fil.push_back(fil);
          break;
        }
        default:
        {
          break;
        }
      }
    }
  }
  in_.close();

  if ((size_t) (max_h + 1) != vertices.size()) {
    std::cerr << "Error: vertices must be labeled from 0 to n-1 \n";
  }

  Graph_t skel_graph(edges.begin(), edges.end(), edges_fil.begin(), vertices.size());
  auto vertex_prop = boost::get(vertex_filtration_t(), skel_graph);

  typename boost::graph_traits<Graph_t>::vertex_iterator vi, vi_end;
  auto v_it = vertices.begin();
  for (std::tie(vi, vi_end) = boost::vertices(skel_graph); vi != vi_end; ++vi, ++v_it) {
    boost::put(vertex_prop, *vi, v_it->second);
  }

  return skel_graph;
}

/**
 * @brief Read a face from a file.
 *
 * File format: 1 simplex per line<br>
 * Dim1 X11 X12 ... X1d Fil1<br>
 * Dim2 X21 X22 ... X2d Fil2<br>
 * etc<br>
 *
 * The vertices must be labeled from 0 to n-1.
 * Every simplex must appear exactly once.
 * Simplices of dimension more than 1 are ignored.
 */
template< typename Vertex_handle, typename Filtration_value >
bool read_simplex(std::istream & in_, std::vector< Vertex_handle > & simplex, Filtration_value & fil) {
  int dim = 0;
  if (!(in_ >> dim)) return false;
  Vertex_handle v;
  for (int i = 0; i < dim + 1; ++i) {
    in_ >> v;
    simplex.push_back(v);
  }
  in_ >> fil;
  in_.ignore((std::numeric_limits<std::streamsize>::max)(), '\n');  // ignore until the carriage return
  return true;
}

/**
 * @brief Read a hasse simplex from a file.
 *
 * File format: 1 simplex per line<br>
 * Dim1 k11 k12 ... k1Dim1 Fil1<br>
 * Dim2 k21 k22 ... k2Dim2 Fil2<br>
 * etc<br>
 *
 * The key of a simplex is its position in the filtration order and also the number of its row in the file.
 * Dimi ki1 ki2 ... kiDimi Fili means that the ith simplex in the filtration has dimension Dimi, filtration value
 * fil1 and simplices with key ki1 ... kiDimi in its boundary.*/
template< typename Simplex_key, typename Filtration_value >
bool read_hasse_simplex(std::istream & in_, std::vector< Simplex_key > & boundary, Filtration_value & fil) {
  int dim;
  if (!(in_ >> dim)) return false;
  if (dim == 0) {
    in_ >> fil;
    return true;
  }
  Simplex_key key;
  for (int i = 0; i < dim + 1; ++i) {
    in_ >> key;
    boundary.push_back(key);
  }
  in_ >> fil;
  return true;
}

/**
 * @brief Read a lower triangular distance matrix from a csv file. We assume that the .csv store the whole
 * (square) matrix.
 * 
 * @author Pawel Dlotko
 *
 * Square matrix file format:<br>
 * 0;D12;...;D1j<br>
 * D21;0;...;D2j<br>
 * ...<br>
 * Dj1;Dj2;...;0<br>
 *
 * lower matrix file format:<br>
 * 0<br>
 * D21;<br>
 * D31;D32;<br>
 * ...<br>
 * Dj1;Dj2;...;Dj(j-1);<br>
 *
 **/
template< typename Filtration_value >
std::vector< std::vector< Filtration_value > > read_lower_triangular_matrix_from_csv_file(const std::string& filename,
                                                                                          const char separator = ';') {
#ifdef DEBUG_TRACES
  std::cout << "Using procedure read_lower_triangular_matrix_from_csv_file \n";
#endif  // DEBUG_TRACES
  std::vector< std::vector< Filtration_value > > result;
  std::ifstream in;
  in.open(filename.c_str());
  if (!in.is_open()) {
    return result;
  }

  std::string line;

  // the first line is emtpy, so we ignore it:
  std::getline(in, line);
  std::vector< Filtration_value > values_in_this_line;
  result.push_back(values_in_this_line);

  int number_of_line = 0;

  // first, read the file line by line to a string:
  while (std::getline(in, line)) {
    // if line is empty, break
    if (line.size() == 0)
      break;

    // if the last element of a string is comma:
    if (line[ line.size() - 1 ] == separator) {
      // then shrink the string by one
      line.pop_back();
    }

    // replace all commas with spaces
    std::replace(line.begin(), line.end(), separator, ' ');

    // put the new line to a stream
    std::istringstream iss(line);
    // and now read the doubles.

    int number_of_entry = 0;
    std::vector< Filtration_value > values_in_this_line;
    while (iss.good()) {
      double entry;
      iss >> entry;
      if (number_of_entry <= number_of_line) {
        values_in_this_line.push_back(entry);
      }
      ++number_of_entry;
    }
    if (!values_in_this_line.empty())result.push_back(values_in_this_line);
    ++number_of_line;
  }
  in.close();

#ifdef DEBUG_TRACES
  std::cerr << "Here is the matrix we read : \n";
  for (size_t i = 0; i != result.size(); ++i) {
    for (size_t j = 0; j != result[i].size(); ++j) {
      std::cerr << result[i][j] << " ";
    }
    std::cerr << std::endl;
  }
#endif  // DEBUG_TRACES

  return result;
}  // read_lower_triangular_matrix_from_csv_file

#endif  // READER_UTILS_H_