/*
* (C) 2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include "cli.h"
#include "../tests/test_rng.h" // FIXME

#include <botan/entropy_src.h>

#if defined(BOTAN_HAS_COMPRESSION)
#include <botan/compression.h>
#endif

namespace Botan_CLI {

class Entropy final : public Command
   {
   public:
      Entropy() : Command("entropy --truncate-at=128 source") {}

      std::string group() const override
         {
         return "misc";
         }

      std::string description() const override
         {
         return "Sample a raw entropy source";
         }

      void go() override
         {
         const std::string req_source = get_arg("source");
         const size_t truncate_sample = get_arg_sz("truncate-at");

         auto& entropy_sources = Botan::Entropy_Sources::global_sources();

         std::vector<std::string> sources;
         if(req_source == "all")
            sources = entropy_sources.enabled_sources();
         else
            sources.push_back(req_source);

         for(const std::string& source : sources)
            {
            Botan_Tests::SeedCapturing_RNG rng;
            const size_t entropy_estimate = entropy_sources.poll_just(rng, source);

            if(rng.samples() == 0)
               {
               output() << "Source " << source << " is unavailable\n";
               continue;
               }

            const auto& sample = rng.seed_material();

            output() << "Polling " << source << " gathered " << sample.size()
                     << " bytes in " << rng.samples() << " outputs with estimated entropy "
                     << entropy_estimate << "\n";

#if defined(BOTAN_HAS_COMPRESSION)
            if(!sample.empty())
               {
               auto comp = Botan::Compression_Algorithm::create("zlib");
               if(comp)
                  {
                  try
                     {
                     Botan::secure_vector<uint8_t> compressed;
                     compressed.assign(sample.begin(), sample.end());
                     comp->start(9);
                     comp->finish(compressed);

                     if(compressed.size() < sample.size())
                        {
                        output() << "Sample from " << source << " was zlib compressed from " << sample.size()
                                 << " bytes to " << compressed.size() << " bytes\n";
                        }
                     }
                  catch(std::exception& e)
                     {
                     error_output() << "Error while attempting to compress: " << e.what() << "\n";
                     }
                  }
               }
#endif

            if(sample.size() <= truncate_sample)
               {
               output() << Botan::hex_encode(sample) << "\n";
               }
            else if(truncate_sample > 0)
               {
               output() << Botan::hex_encode(&sample[0], truncate_sample) << "...\n";
               }
            }
         }
   };

BOTAN_REGISTER_COMMAND("entropy", Entropy);

}