#include <cmath>
#include <functional>
#include <mutex>
#include <thread>
#include <unordered_map>
#include "benchmark/benchmark.h"
#include "glog/logging.h"
#include "logger.hh"

//! AI generated
static double taylor_approximation(
    double x,                                             // Point to evaluate
    double a,                                             // Expansion point
    int n,                                                // Number of terms
    const std::function<double(double)>& func,            // f(a)
    const std::function<double(int, double)>& derivative  // f^(k)(a)
) {
  double result = 0.0;
  double power = 1.0;      // (x - a)^0
  double factorial = 1.0;  // 0!

  // Zeroth derivative term (k=0)
  result += func(a) * power / factorial;

  // Subsequent terms (k=1 to n-1)
  for (int k = 1; k < n; k++) {
    factorial *= k;    // k!
    power *= (x - a);  // (x - a)^k

    double deriv = derivative(k, a);
    result += deriv * power / factorial;
  }

  return result;
}

static double calc_exp_taylor() {
  auto exp_deriv = [](int k, double a) -> double {
    return std::exp(a);  // k-th derivative of e^x is e^x
  };
  double x = 1.0;
  double a_exp = 0.0;
  int terms = 10;
  return taylor_approximation(
      x, a_exp, terms, [](double a) { return std::exp(a); },  // f(a)
      exp_deriv);
}

vptyp::Logger& getLogger() {
  static vptyp::Logger l(std::cout);
  if (!l.isConfigured()) {
    l.configure({"size", "apprx", "garbage", "garbage2"});
  }

  return l;
}

void initGlog() {
  if (!google::IsGoogleLoggingInitialized()) {
    google::InitGoogleLogging("loggerBench");
  }
}

static void BM_taylor_logger(benchmark::State& state) {
  auto& l = getLogger();
  for (auto _ : state) {
    double res = calc_exp_taylor();
    l.add("apprx", res);
  }
}

static void BM_wo_logger(benchmark::State& state) {
  for (auto _ : state)
    double res = calc_exp_taylor();
}

static void BM_taylor_glog(benchmark::State& state) {
  initGlog();
  for (auto _ : state) {
    double res = calc_exp_taylor();
    LOG(INFO) << "apprx=" << res;
  }
}

std::atomic<double>& getValue() {
  static std::atomic<double> d;
  return d;
}

static void BM_taylor_atomic_upd(benchmark::State& state) {
  for (auto _ : state) {
    double res = calc_exp_taylor();
    getValue().store(res);
  }
}

void updMapValue(double res, const std::string& key) {
  static std::unordered_map<std::string, double> d = {{"key", 10.0},
                                                      {"assembly", 11.0},
                                                      {"draw", 123.3},
                                                      {"d2", 0.0},
                                                      {"d55", 0.23}};
  d[key] = res;
}

static void BM_taylor_map_upd(benchmark::State& state) {
  for (auto _ : state) {
    double res = calc_exp_taylor();
    updMapValue(res, "assembly");
  }
}

void updValue(double res) {
  static double d;
  static std::mutex mtx;
  {
    std::lock_guard lock(mtx);
    d = res;
  }
}

static void BM_taylor_mutex_upd(benchmark::State& state) {
  for (auto _ : state) {
    double res = calc_exp_taylor();
    updValue(res);
  }
}

BENCHMARK(BM_wo_logger);
BENCHMARK(BM_taylor_logger);
BENCHMARK(BM_taylor_glog);
BENCHMARK(BM_taylor_atomic_upd);
BENCHMARK(BM_taylor_mutex_upd);
BENCHMARK(BM_taylor_map_upd);

std::string caesar_encoder(const std::string& input) {
  static constexpr int small = 'a';
  static constexpr int big = 'A';
  std::string encoded;
  encoded.reserve(input.size());
  for (auto& c : input) {
    assert((c - small < 25 && c - small >= 0) ||
           (c - big < 25 && c - big >= 0));
    int id, begin;
    if (c - small < 0) {
      id = c - big;
      begin = big;
    } else {
      id = c - small;
      begin = small;
    }
    encoded += begin + (id + 3) % 25;
  }
  return encoded;
}

int caesar_base(int size = 1000) {
  std::string a(size, 'a');
  auto res = caesar_encoder(a);
  return size;
}

static void BM_caesar_wo_logger(benchmark::State& state) {
  for (auto _ : state) {
    int res = caesar_base();
  }
}

static void BM_caesar_logger(benchmark::State& state) {
  auto& l = getLogger();

  for (auto _ : state) {
    int res = caesar_base();
    l.add("size", res);
  }
}

BENCHMARK(BM_caesar_logger);
BENCHMARK(BM_caesar_wo_logger);

static void DoNothing(benchmark::State& state) {
  while (state.KeepRunning())
    ;
}
BENCHMARK(DoNothing);

BENCHMARK_MAIN();