/*    This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
 *    See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
 *    Author(s):       Siddharth Pritam, Vincent Rouvreau
 *
 *    Copyright (C) 2020 Inria
 *
 *    Modification(s):
 *      - YYYY/MM Author: Description of the modification
 */

#include <gudhi/Flag_complex_edge_collapser.h>
#include <gudhi/Simplex_tree.h>
#include <gudhi/Persistent_cohomology.h>
#include <gudhi/reader_utils.h>
#include <gudhi/graph_simplicial_complex.h>

#include <boost/program_options.hpp>
#include <boost/range/adaptor/transformed.hpp>

using Simplex_tree = Gudhi::Simplex_tree<Gudhi::Simplex_tree_options_fast_persistence>;
using Filtration_value = Simplex_tree::Filtration_value;
using Vertex_handle = Simplex_tree::Vertex_handle;

using Filtered_edge = std::tuple<Vertex_handle, Vertex_handle, Filtration_value>;
using Proximity_graph = Gudhi::Proximity_graph<Simplex_tree>;

using Field_Zp = Gudhi::persistent_cohomology::Field_Zp;
using Persistent_cohomology = Gudhi::persistent_cohomology::Persistent_cohomology<Simplex_tree, Field_Zp>;
using Distance_matrix = std::vector<std::vector<Filtration_value>>;

void program_options(int argc, char* argv[], std::string& csv_matrix_file, std::string& filediag,
                     Filtration_value& threshold, int& dim_max, int& p, int& edge_collapse_iter_nb,
                     Filtration_value& min_persistence);

int main(int argc, char* argv[]) {
  std::string csv_matrix_file;
  std::string filediag;
  Filtration_value threshold;
  int dim_max = 2;
  int p;
  int edge_collapse_iter_nb;
  Filtration_value min_persistence;

  program_options(argc, argv, csv_matrix_file, filediag, threshold, dim_max, p, edge_collapse_iter_nb,
                  min_persistence);

  Distance_matrix distances = Gudhi::read_lower_triangular_matrix_from_csv_file<Filtration_value>(csv_matrix_file);
  std::cout << "Read the distance matrix successfully, of size: " << distances.size() << std::endl;

  Proximity_graph proximity_graph = Gudhi::compute_proximity_graph<Simplex_tree>(boost::irange((size_t)0,
                                                                                               distances.size()),
                                                                                 threshold,
                                                                                 [&distances](size_t i, size_t j) {
                                                                                   return distances[j][i];
                                                                                 });

  auto edges_from_graph = boost::adaptors::transform(edges(proximity_graph), [&](auto&&edge){
        return std::make_tuple(source(edge, proximity_graph),
                               target(edge, proximity_graph),
                               get(Gudhi::edge_filtration_t(), proximity_graph, edge));
      });
  std::vector<Filtered_edge> edges_list(edges_from_graph.begin(), edges_from_graph.end());
  std::vector<Filtered_edge> remaining_edges;
  for (int iter = 0; iter < edge_collapse_iter_nb; iter++) {
    auto remaining_edges = Gudhi::collapse::flag_complex_collapse_edges(edges_list);
    edges_list = std::move(remaining_edges);
    remaining_edges.clear();
  }

  Simplex_tree stree;
  for (Vertex_handle vertex = 0; static_cast<std::size_t>(vertex) < distances.size(); vertex++) {
    // insert the vertex with a 0. filtration value just like a Rips
    stree.insert_simplex({vertex}, 0.);
  }
  for (auto filtered_edge : edges_list) {
    stree.insert_simplex({std::get<0>(filtered_edge), std::get<1>(filtered_edge)}, std::get<2>(filtered_edge));
  }

  stree.expansion(dim_max);

  std::cout << "The complex contains " << stree.num_simplices() << " simplices  after collapse. \n";
  std::cout << "   and has dimension " << stree.dimension() << " \n";

  // Sort the simplices in the order of the filtration
  stree.initialize_filtration();
  // Compute the persistence diagram of the complex
  Persistent_cohomology pcoh(stree);
  // initializes the coefficient field for homology
  pcoh.init_coefficients(3);

  pcoh.compute_persistent_cohomology(min_persistence);
  if (filediag.empty()) {
    pcoh.output_diagram();
  } else {
    std::ofstream out(filediag);
    pcoh.output_diagram(out);
    out.close();
  }
  return 0;
}

void program_options(int argc, char* argv[], std::string& csv_matrix_file, std::string& filediag,
                     Filtration_value& threshold, int& dim_max, int& p, int& edge_collapse_iter_nb,
                     Filtration_value& min_persistence) {
  namespace po = boost::program_options;
  po::options_description hidden("Hidden options");
  hidden.add_options()(
      "input-file", po::value<std::string>(&csv_matrix_file),
      "Name of file containing a distance matrix. Can be square or lower triangular matrix. Separator is ';'.");

  po::options_description visible("Allowed options", 100);
  visible.add_options()("help,h", "produce help message")(
      "output-file,o", po::value<std::string>(&filediag)->default_value(std::string()),
      "Name of file in which the persistence diagram is written. Default print in standard output")(
      "max-edge-length,r",
      po::value<Filtration_value>(&threshold)->default_value(std::numeric_limits<Filtration_value>::infinity()),
      "Maximal length of an edge for the Rips complex construction.")(
      "cpx-dimension,d", po::value<int>(&dim_max)->default_value(1),
      "Maximal dimension of the Rips complex we want to compute.")(
      "field-charac,p", po::value<int>(&p)->default_value(11),
      "Characteristic p of the coefficient field Z/pZ for computing homology.")(
      "edge-collapse-iterations,i", po::value<int>(&edge_collapse_iter_nb)->default_value(1),
      "Number of iterations edge collapse is performed.")(
      "min-persistence,m", po::value<Filtration_value>(&min_persistence),
      "Minimal lifetime of homology feature to be recorded. Default is 0. Enter a negative value to see zero length "
      "intervals");

  po::positional_options_description pos;
  pos.add("input-file", 1);

  po::options_description all;
  all.add(visible).add(hidden);

  po::variables_map vm;
  po::store(po::command_line_parser(argc, argv).options(all).positional(pos).run(), vm);
  po::notify(vm);

  if (vm.count("help") || !vm.count("input-file")) {
    std::cout << std::endl;
    std::cout << "Compute the persistent homology with coefficient field Z/pZ \n";
    std::cout << "of a Rips complex after edge collapse defined on a set of distance matrix.\n \n";
    std::cout << "The output diagram contains one bar per line, written with the convention: \n";
    std::cout << "   p   dim b d \n";
    std::cout << "where dim is the dimension of the homological feature,\n";
    std::cout << "b and d are respectively the birth and death of the feature and \n";
    std::cout << "p is the characteristic of the field Z/pZ used for homology coefficients." << std::endl << std::endl;

    std::cout << "Usage: " << argv[0] << " [options] input-file" << std::endl << std::endl;
    std::cout << visible << std::endl;
    exit(-1);
  }
}
