using Org.BouncyCastle.Crypto.Parameters;

namespace Org.BouncyCastle.Crypto.Modes
{
	/// <summary>
	/// A block cipher mode that includes authenticated encryption with a streaming mode
	/// and optional associated data.</summary>
	/// <see cref="AeadParameters"/>
	public interface IAeadBlockCipher
	{
		/// <summary>The name of the algorithm this cipher implements.</summary>
		string AlgorithmName { get; }

		/// <summary>The block cipher underlying this algorithm.</summary>
		IBlockCipher GetUnderlyingCipher();

		/// <summary>Initialise the cipher.</summary>
		/// <remarks>Parameter can either be an AeadParameters or a ParametersWithIV object.</remarks>
		/// <param name="forEncryption">Initialise for encryption if true, for decryption if false.</param>
		/// <param name="parameters">The key or other data required by the cipher.</param>
		void Init(bool forEncryption, ICipherParameters parameters);

		/// <returns>The block size for this cipher, in bytes.</returns>
		int GetBlockSize();

        /// <summary>Add a single byte to the associated data check.</summary>
		/// <remarks>If the implementation supports it, this will be an online operation and will not retain the associated data.</remarks>
        /// <param name="input">The byte to be processed.</param>
        void ProcessAadByte(byte input);

        /// <summary>Add a sequence of bytes to the associated data check.</summary>
		/// <remarks>If the implementation supports it, this will be an online operation and will not retain the associated data.</remarks>
        /// <param name="inBytes">The input byte array.</param>
        /// <param name="inOff">The offset into the input array where the data to be processed starts.</param>
        /// <param name="len">The number of bytes to be processed.</param>
        void ProcessAadBytes(byte[] inBytes, int inOff, int len);

        /**
		* Encrypt/decrypt a single byte.
		*
		* @param input the byte to be processed.
		* @param outBytes the output buffer the processed byte goes into.
		* @param outOff the offset into the output byte array the processed data starts at.
		* @return the number of bytes written to out.
		* @exception DataLengthException if the output buffer is too small.
		*/
		int ProcessByte(byte input, byte[] outBytes, int outOff);

		/**
		* Process a block of bytes from in putting the result into out.
		*
		* @param inBytes the input byte array.
		* @param inOff the offset into the in array where the data to be processed starts.
		* @param len the number of bytes to be processed.
		* @param outBytes the output buffer the processed bytes go into.
		* @param outOff the offset into the output byte array the processed data starts at.
		* @return the number of bytes written to out.
		* @exception DataLengthException if the output buffer is too small.
		*/
		int ProcessBytes(byte[] inBytes, int inOff, int len, byte[] outBytes, int outOff);

		/**
		* Finish the operation either appending or verifying the MAC at the end of the data.
		*
		* @param outBytes space for any resulting output data.
		* @param outOff offset into out to start copying the data at.
		* @return number of bytes written into out.
		* @throws InvalidOperationException if the cipher is in an inappropriate state.
		* @throws InvalidCipherTextException if the MAC fails to match.
		*/
		int DoFinal(byte[] outBytes, int outOff);

		/**
		* Return the value of the MAC associated with the last stream processed.
		*
		* @return MAC for plaintext data.
		*/
		byte[] GetMac();

		/**
		* Return the size of the output buffer required for a ProcessBytes
		* an input of len bytes.
		*
		* @param len the length of the input.
		* @return the space required to accommodate a call to ProcessBytes
		* with len bytes of input.
		*/
		int GetUpdateOutputSize(int len);

		/**
		* Return the size of the output buffer required for a ProcessBytes plus a
		* DoFinal with an input of len bytes.
		*
		* @param len the length of the input.
		* @return the space required to accommodate a call to ProcessBytes and DoFinal
		* with len bytes of input.
		*/
		int GetOutputSize(int len);

		/// <summary>
		/// Reset the cipher to the same state as it was after the last init (if there was one).
		/// </summary>
		void Reset();
	}
}
