// Copyright 2023 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#include <pw_random/xor_shift.h>
#include <pw_string/format.h>

#include <cstdlib>

#include "pw_bluetooth_sapphire/internal/host/common/assert.h"
#include "pw_bluetooth_sapphire/internal/host/common/log.h"
#include "pw_bluetooth_sapphire/internal/host/common/random.h"
#include "pw_bluetooth_sapphire/internal/host/testing/parse_args.h"
#include "pw_unit_test/framework.h"

#ifdef PW_LOG_DECLARE_FAKE_DRIVER
PW_LOG_DECLARE_FAKE_DRIVER();
#endif

using bt::LogSeverity;
using bt::testing::GetArgValue;

namespace {

constexpr LogSeverity LogSeverityFromString(std::string_view str) {
  if (str == "DEBUG") {
    return LogSeverity::DEBUG;
  } else if (str == "INFO") {
    return LogSeverity::INFO;
  } else if (str == "WARN") {
    return LogSeverity::WARN;
  } else if (str == "ERROR") {
    return LogSeverity::ERROR;
  }
  return LogSeverity::ERROR;
}

// A valid random seed must be in [1, kMaxRandomSeed].
constexpr uint32_t kMaxRandomSeed = 99999;

// Normalizes the seed to range [1, kMaxRandomSeed].
int32_t NormalizeRandomSeed(uint32_t seed) {
  return static_cast<int32_t>((seed - 1U) % kMaxRandomSeed) + 1;
}

int32_t GenerateRandomSeed() {
  // TODO(fxbug.dev/42069982): Get time using pw::chrono for portability.
  const int64_t time_ms = std::chrono::duration_cast<std::chrono::milliseconds>(
                              std::chrono::system_clock::now() -
                              std::chrono::system_clock::from_time_t(0))
                              .count();
  return NormalizeRandomSeed(static_cast<uint32_t>(time_ms));
}

}  // namespace

int main(int argc, char** argv) {
  LogSeverity log_severity = LogSeverity::ERROR;

  std::optional<std::string_view> severity_arg_value =
      GetArgValue("severity", argc, argv);
  if (severity_arg_value) {
    log_severity = LogSeverityFromString(*severity_arg_value);
  }

  // Set all library log messages to use printf.
  bt::UsePrintf(log_severity);

  // If --gtest_random_seed is not specified, then GoogleTest calculates a seed
  // based on time. To avoid using different seeds, we need to tell GoogleTest
  // what seed we are using.
  std::vector<char*> new_argv(argv, argv + argc);
  char new_argv_seed_option[sizeof("--gtest_random_seed=-2147483648")] = {};

  // GoogleTest doesn't initialize the random seed (UnitTest::random_seed())
  // until RUN_ALL_TESTS, so we need to parse it now to avoid configuring the
  // random generator in every test suite.
  int32_t random_seed = 0;
  std::optional<std::string_view> seed_arg_value =
      GetArgValue("gtest_random_seed", argc, argv);
  if (seed_arg_value) {
    std::from_chars_result result =
        std::from_chars(seed_arg_value->data(),
                        seed_arg_value->data() + seed_arg_value->size(),
                        random_seed);
    if (result.ec != std::errc()) {
      fprintf(stderr, "\nERROR: Invalid gtest_random_seed value\n");
      return 1;
    }
    random_seed = NormalizeRandomSeed(random_seed);
  } else {
    random_seed = GenerateRandomSeed();
    bool format_ok =
        pw::string::Format(
            new_argv_seed_option, "--gtest_random_seed=%d", random_seed)
            .ok();
    BT_ASSERT(format_ok);
    new_argv.push_back(new_argv_seed_option);
  }

  // Print the random seed so that it is easy to reproduce a test run.
  printf("\nGTEST_RANDOM_SEED=%d\n", random_seed);

  pw::random::XorShiftStarRng64 rng(random_seed);
  bt::set_random_generator(&rng);

  int new_argc = static_cast<int>(new_argv.size());
  // argv[argc] must be nullptr according to the C++ standard.
  new_argv.push_back(nullptr);

  testing::InitGoogleTest(&new_argc, new_argv.data());

  return RUN_ALL_TESTS();
}