/*
* (C) 2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include "tests.h"
#include <botan/entropy_src.h>

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

namespace Botan_Tests {

namespace {

class Entropy_Source_Tests : public Test
   {
   public:
      std::vector<Test::Result> run() override
         {
         static const size_t MAX_ENTROPY = 512;
         static const size_t MAX_SAMPLES = 256;
         static const size_t MAX_ENTROPY_BYTES = 256*1024;

         Botan::Entropy_Sources& srcs = Botan::Entropy_Sources::global_sources();

         std::vector<std::string> src_names = srcs.enabled_sources();

         std::vector<Test::Result> results;

         for(auto&& src_name : src_names)
            {
            Test::Result result("Entropy source " + src_name);

            result.start_timer();

            try
               {
               std::vector<uint8_t> entropy;
               size_t samples = 0;
               size_t entropy_estimate = 0;

               Botan::Entropy_Accumulator accum(
                  [&](const uint8_t buf[], size_t buf_len, size_t buf_entropy) -> bool {
                     entropy.insert(entropy.end(), buf, buf + buf_len);
                     entropy_estimate += buf_entropy;
                     ++samples;

                     result.test_note("sample " + std::to_string(samples) + " " +
                                      Botan::hex_encode(buf, buf_len) + " " + std::to_string(buf_entropy));

                     result.test_gte("impossible entropy", buf_len * 8, buf_entropy);

                     return (entropy_estimate > MAX_ENTROPY ||
                             samples > MAX_SAMPLES ||
                             entropy.size() > MAX_ENTROPY_BYTES);
                  });

               result.confirm("polled source", srcs.poll_just(accum, src_name));

               result.test_note("saw " + std::to_string(samples) +
                                " samples with total estimated entropy " +
                                std::to_string(entropy_estimate));
               result.test_note("poll result", entropy);

#if defined(BOTAN_HAS_COMPRESSION)
               if(!entropy.empty())
                  {
                  for(const std::string comp_algo : { "zlib", "bzip2", "lzma" })
                     {
                     std::unique_ptr<Botan::Compressor_Transform> comp(Botan::make_compressor(comp_algo, 9));

                     if(comp)
                        {
                        size_t comp1_size = 0;

                        try
                           {
                           Botan::secure_vector<byte> compressed;
                           compressed.assign(entropy.begin(), entropy.end());
                           comp->start();
                           comp->finish(compressed);

                           comp1_size = compressed.size();

                           result.test_gte(comp_algo + " compressed entropy better than advertised",
                                           compressed.size() * 8, entropy_estimate);
                           }
                        catch(std::exception& e)
                           {
                           result.test_failure(comp_algo + " exception while compressing", e.what());
                           }

                        std::vector<uint8_t> entropy2;
                        size_t entropy_estimate2 = 0;
                        Botan::Entropy_Accumulator accum2(
                           [&](const uint8_t buf[], size_t buf_len, size_t buf_entropy) -> bool {
                           entropy2.insert(entropy2.end(), buf, buf + buf_len);
                           entropy_estimate2 += buf_entropy;
                           return entropy2.size() >= entropy.size();
                           });

                        result.confirm("polled source", srcs.poll_just(accum2, src_name));
                        result.test_note("poll 2 result", entropy2);

                        try
                           {
                           Botan::secure_vector<byte> compressed;
                           compressed.insert(compressed.end(), entropy.begin(), entropy.end());
                           compressed.insert(compressed.end(), entropy2.begin(), entropy2.end());

                           comp->start();
                           comp->finish(compressed);

                           size_t comp2_size = compressed.size();

                           result.test_lt("Two blocks of entropy are larger than one",
                                          comp1_size, comp2_size);

                           size_t comp_diff = comp2_size - comp1_size;

                           result.test_gte(comp_algo + " diff compressed entropy better than advertised",
                                           comp_diff*8, entropy_estimate2);
                           }
                        catch(std::exception& e)
                           {
                           result.test_failure(comp_algo + " exception while compressing", e.what());
                           }
                        }
                     }
                  }
#endif
               }
            catch(std::exception& e)
               {
               result.test_failure("during entropy collection test", e.what());
               }

            result.end_timer();
            results.push_back(result);
            }

         return results;
         }
   };

BOTAN_REGISTER_TEST("entropy", Entropy_Source_Tests);

}

}