#ifndef FORTUNA_GENERATOR_H
#define FORTUNA_GENERATOR_H

#include <cryptopp/cryptlib.h>
#include <cryptopp/modes.h>
#include <cryptopp/secblock.h>
#include <cryptopp/serpent.h>

#include <array>
#include <chrono>
#include <cstdint>
#include <mutex>
#include <string>

namespace fortuna {
namespace generator {

class Generator {
public:
	std::chrono::milliseconds reseed_interval{100};
	mutable std::recursive_mutex mtx;
	std::mutex crypt_mtx;
	std::mutex reseed_mtx;

	Generator(); // ad noexcept: perhaps _do_ throw*
	Generator(const Generator& Gen) = delete; // no
	Generator& operator=(const Generator& Gen) = delete; // copies
	~Generator() noexcept;

	/* n is the number of random bytes to generate */
	auto generate_random_data(const uint64_t& n) -> std::string;

	auto reseed(const std::string& s) -> void;

	[[optimize_for_synchronized]] auto time_to_reseed(
		const uint64_t& pool0_len,
		const unsigned int& min_p_size,
		const std::chrono::duration<int64_t, std::ratio<1, 1000>>& time_elapsed,
		const std::chrono::milliseconds& reseed_interval) const -> bool;

	auto is_seeded() const -> bool {
		std::lock_guard<std::recursive_mutex> lg(mtx);
		return !(this->G.ctr == this->null_blk);
	}


private:
	static constexpr const std::size_t ctr_len{16};
	static constexpr const std::array<std::byte, ctr_len> null_blk{
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
		std::byte{0x00},
	}; // used for comparison with G.ctr in is_seeded() and generate_blocks()
	CryptoPP::CTR_Mode<CryptoPP::Serpent>::Encryption enc;

	struct G_state {
		static constexpr const std::size_t k_length{32};

		CryptoPP::FixedSizeSecBlock<CryptoPP::byte, k_length> k;
		std::array<std::byte, ctr_len> ctr;
	};
	G_state G;

	void initialize_generator();

	auto do_crypto() -> std::string;

	auto generate_blocks(unsigned int k_blocks) -> std::string;

	auto ctr_inc() -> void;

protected:
	auto get_state() const -> Generator::G_state;

}; // class generator

} // namespace generator
} // namespace fortuna
#endif // FORTUNA_GENERATOR_H