text: /*
   * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #pragma once
  
  #include <AK/ByteBuffer.h>
  #include <AK/LogStream.h>
  #include <AK/String.h>
  #include <AK/Types.h>
  #include <AK/Vector.h>
  
  namespace Crypto {
  
  struct UnsignedDivisionResult;
  constexpr size_t STARTING_WORD_SIZE = 512;
  
  class UnsignedBigInteger {
  public:
      UnsignedBigInteger(u32 x) { m_words.append(x); }
  
      explicit UnsignedBigInteger(AK::Vector<u32, STARTING_WORD_SIZE>&& words)
          : m_words(move(words))
      {
      }
  
      UnsignedBigInteger() { }
  
      static UnsignedBigInteger create_invalid();
  
      static UnsignedBigInteger import_data(const AK::StringView& data) { return import_data((const u8*)data.characters_without_null_termination(), data.length()); }
      static UnsignedBigInteger import_data(const u8* ptr, size_t length);
  
      size_t export_data(AK::ByteBuffer& data) const;
      size_t export_data(const u8* ptr, size_t length) const
      {
          auto buffer = ByteBuffer::wrap(ptr, length);
          return export_data(buffer);
      }
  
      static UnsignedBigInteger from_base10(const String& str);
      String to_base10() const;
  
      const AK::Vector<u32, STARTING_WORD_SIZE>& words() const { return m_words; }
  
      void set_to_0();
      void set_to(u32 other);
      void set_to(const UnsignedBigInteger& other);
  
      void invalidate()
      {
          m_is_invalid = true;
          m_cached_trimmed_length = {};
      }
  
      bool is_invalid() const { return m_is_invalid; }
  
      size_t length() const { return m_words.size(); }
      // The "trimmed length" is the number of words after trimming leading zeroed words
      size_t trimmed_length() const;
  
      UnsignedBigInteger plus(const UnsignedBigInteger& other) const;
      UnsignedBigInteger minus(const UnsignedBigInteger& other) const;
      UnsignedBigInteger shift_left(size_t num_bits) const;
      UnsignedBigInteger multiplied_by(const UnsignedBigInteger& other) const;
      UnsignedDivisionResult divided_by(const UnsignedBigInteger& divisor) const;
  
      void set_bit_inplace(size_t bit_index);
  
      static void add_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
      static void subtract_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
      static void shift_left_without_allocation(const UnsignedBigInteger& number, size_t bits_to_shift_by, UnsignedBigInteger& temp_result, UnsignedBigInteger& temp_plus, UnsignedBigInteger& output);
      static void multiply_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& temp_shift_result, UnsignedBigInteger& temp_shift_plus, UnsignedBigInteger& temp_shift, UnsignedBigInteger& temp_plus, UnsignedBigInteger& output);
      static void divide_without_allocation(const UnsignedBigInteger& numerator, const UnsignedBigInteger& denominator, UnsignedBigInteger& temp_shift_result, UnsignedBigInteger& temp_shift_plus, UnsignedBigInteger& temp_shift, UnsignedBigInteger& temp_minus, UnsignedBigInteger& quotient, UnsignedBigInteger& remainder);
      static void divide_u16_without_allocation(const UnsignedBigInteger& numerator, u32 denominator, UnsignedBigInteger& quotient, UnsignedBigInteger& remainder);
  
      bool operator==(const UnsignedBigInteger& other) const;
      bool operator!=(const UnsignedBigInteger& other) const;
      bool operator<(const UnsignedBigInteger& other) const;
  
  private:
      ALWAYS_INLINE static void shift_left_by_n_words(const UnsignedBigInteger& number, size_t number_of_words, UnsignedBigInteger& output);
      ALWAYS_INLINE static u32 shift_left_get_one_word(const UnsignedBigInteger& number, size_t num_bits, size_t result_word_index);
  
      static constexpr size_t BITS_IN_WORD = 32;
      AK::Vector<u32, STARTING_WORD_SIZE> m_words;
  
      // Used to indicate a negative result, or a result of an invalid operation
      bool m_is_invalid { false };
  
      mutable Optional<size_t> m_cached_trimmed_length;
  };
  
  struct UnsignedDivisionResult {
      Crypto::UnsignedBigInteger quotient;
      Crypto::UnsignedBigInteger remainder;
  };
  
  }
  
  inline const LogStream&
  operator<<(const LogStream& stream, const Crypto::UnsignedBigInteger value)
  {
      if (value.is_invalid()) {
          stream << "Invalid BigInt";
          return stream;
      }
      for (int i = value.length() - 1; i >= 0; --i) {
          stream << value.words()[i] << "|";
      }
      return stream;
  }
  
  inline Crypto::UnsignedBigInteger
  operator""_bigint(const char* string, size_t length)
  {
      return Crypto::UnsignedBigInteger::from_base10({ string, length });
  }
  