#include <string>
#include <iostream>

#include "options.hpp"

void print_usage(const std::string & invocation)
{
  std::cerr << "Usage:" << std::endl;
  std::cerr << invocation << " " << usage_args << std::endl;
}

void print_help(const std::string & invocation)
{
  print_usage(invocation);
  std::cerr << "FIXME: Write help." << std::endl;
}

int parse_opts(int argc, char ** argv, Options & opts)
{
  std::string invocation(argv[0]);
  
  for (int i = 1; i < argc; ++i)
  {
    std::string arg(argv[i]);

    if (arg == std::string("-h") || arg == std::string("--help"))
    {
      print_help(invocation);
      return 2;
    }

    else if (arg == std::string("-l") || arg == std::string("--laplacian"))
    {
      if (i+1 < argc && argv[i+1][0] != '-')
        opts.infile = std::string(argv[++i]);
      else
      {
        std::cerr << "Missing argument to --laplacian." << std::endl;
        print_usage(invocation);
        return 1;
      }
    }

    else if (arg == std::string("--vals"))
    {
       if (i+1 < argc && argv[i+1][0] != '-')
        opts.outfile_vals = std::string(argv[++i]);
      else
      {
        std::cerr << "Missing argument to --vals." << std::endl;
        print_usage(invocation);
        return 1;
      }
    }

    else if (arg == std::string("--vecs"))
    {
       if (i+1 < argc && argv[i+1][0] != '-')
        opts.outfile_vecs = std::string(argv[++i]);
      else
      {
        std::cerr << "Missing argument to --vecs." << std::endl;
        print_usage(invocation);
        return 1;
      }
    }

    else
    {
      std::cout << "The argument \"" << arg << "\" will be dealt with by PETSc/SLEPc if they understand it. Otherwise it will be silently ignored." << std::endl;
    }
  }

  // Begin options validation. 
  if (opts.infile.empty())
  {
    std::cerr << "Missing Laplacian file." << std::endl;
    print_usage(invocation);
    return 1;
  }
   
  if (opts.outfile_vecs.empty())
  {
    std::cerr << "Missing output eigenvectors file." << std::endl;
    print_usage(invocation);
    return 1;
  }
  if (opts.outfile_vals.empty())
  {
    std::cerr << "Missing output eigenvalues file." << std::endl;
    print_usage(invocation);
    return 1;
  }
  // End validation.
  
  return 0;
}