#ifndef SIGNATURE_H__
#define SIGNATURE_H__

#include <inttypes.h>
#include <cryptopp/dsa.h>
#include <cryptopp/rsa.h>
#include <cryptopp/asn.h>
#include <cryptopp/oids.h>
#include <cryptopp/osrng.h>
#include <cryptopp/eccrypto.h>
#include "CryptoConst.h"

namespace i2p
{
namespace crypto
{
	class Verifier
	{
		public:
			
			virtual ~Verifier () {};
			virtual bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const = 0;
			virtual size_t GetPublicKeyLen () const = 0;
			virtual size_t GetSignatureLen () const = 0;
			virtual size_t GetPrivateKeyLen () const { return GetSignatureLen ()/2; };
	};

	class Signer
	{
		public:

			virtual ~Signer () {};		
			virtual void Sign (CryptoPP::RandomNumberGenerator& rnd, const uint8_t * buf, int len, uint8_t * signature) const = 0; 
	};

	const size_t DSA_PUBLIC_KEY_LENGTH = 128;
	const size_t DSA_SIGNATURE_LENGTH = 40;	
	const size_t DSA_PRIVATE_KEY_LENGTH = DSA_SIGNATURE_LENGTH/2;
	class DSAVerifier: public Verifier
	{
		public:

			DSAVerifier (const uint8_t * signingKey)
			{
				m_PublicKey.Initialize (dsap, dsaq, dsag, CryptoPP::Integer (signingKey, DSA_PUBLIC_KEY_LENGTH));
			}
	
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const
			{
				CryptoPP::DSA::Verifier verifier (m_PublicKey);
				return verifier.VerifyMessage (buf, len, signature, DSA_SIGNATURE_LENGTH);
			}	

			size_t GetPublicKeyLen () const { return DSA_PUBLIC_KEY_LENGTH; };
			size_t GetSignatureLen () const { return DSA_SIGNATURE_LENGTH; };
			
		private:

			CryptoPP::DSA::PublicKey m_PublicKey;
	};

	class DSASigner: public Signer
	{
		public:

			DSASigner (const uint8_t * signingPrivateKey)
			{
				m_PrivateKey.Initialize (dsap, dsaq, dsag, CryptoPP::Integer (signingPrivateKey, DSA_PRIVATE_KEY_LENGTH));
			}

			void Sign (CryptoPP::RandomNumberGenerator& rnd, const uint8_t * buf, int len, uint8_t * signature) const
			{
				CryptoPP::DSA::Signer signer (m_PrivateKey);
				signer.SignMessage (rnd, buf, len, signature);
			}

		private:

			CryptoPP::DSA::PrivateKey m_PrivateKey;
	};

	inline void CreateDSARandomKeys (CryptoPP::RandomNumberGenerator& rnd, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CryptoPP::DSA::PrivateKey privateKey;
		CryptoPP::DSA::PublicKey publicKey;
		privateKey.Initialize (rnd, dsap, dsaq, dsag);
		privateKey.MakePublicKey (publicKey);
		privateKey.GetPrivateExponent ().Encode (signingPrivateKey, DSA_PRIVATE_KEY_LENGTH);	
		publicKey.GetPublicElement ().Encode (signingPublicKey, DSA_PUBLIC_KEY_LENGTH);
	}	

	template<typename Hash, size_t keyLen>
	class ECDSAVerifier: public Verifier
	{		
		public:

			template<typename Curve>
			ECDSAVerifier (Curve curve, const uint8_t * signingKey)
			{
				m_PublicKey.Initialize (curve, 
					CryptoPP::ECP::Point (CryptoPP::Integer (signingKey, keyLen/2), 
					CryptoPP::Integer (signingKey + keyLen/2, keyLen/2)));
			}

			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const
			{
				typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::Verifier verifier (m_PublicKey);
				return verifier.VerifyMessage (buf, len, signature, keyLen); // signature length
			}	

			size_t GetPublicKeyLen () const { return keyLen; };
			size_t GetSignatureLen () const { return keyLen; }; // signature length = key length
			
		private:

			typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::PublicKey m_PublicKey;
	};

	template<typename Hash>
	class ECDSASigner: public Signer
	{
		public:

			template<typename Curve>
			ECDSASigner (Curve curve, const uint8_t * signingPrivateKey, size_t keyLen)
			{
				m_PrivateKey.Initialize (curve, CryptoPP::Integer (signingPrivateKey, keyLen/2)); // private key length
			}

			void Sign (CryptoPP::RandomNumberGenerator& rnd, const uint8_t * buf, int len, uint8_t * signature) const
			{
				typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::Signer signer (m_PrivateKey);
				signer.SignMessage (rnd, buf, len, signature);
			}

		private:

			typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::PrivateKey m_PrivateKey;
	};

	template<typename Hash, typename Curve>
	inline void CreateECDSARandomKeys (CryptoPP::RandomNumberGenerator& rnd, Curve curve, 
		size_t keyLen, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::PrivateKey privateKey;
		typename CryptoPP::ECDSA<CryptoPP::ECP, Hash>::PublicKey publicKey;
		privateKey.Initialize (rnd, curve);
		privateKey.MakePublicKey (publicKey);
		privateKey.GetPrivateExponent ().Encode (signingPrivateKey, keyLen/2);	
		auto q = publicKey.GetPublicElement ();
		q.x.Encode (signingPublicKey, keyLen/2);
		q.y.Encode (signingPublicKey + keyLen/2, keyLen/2);
	}	

// ECDSA_SHA256_P256
	const size_t ECDSAP256_KEY_LENGTH = 64;	
	class ECDSAP256Verifier: public ECDSAVerifier<CryptoPP::SHA256, ECDSAP256_KEY_LENGTH>
	{
		public:

			ECDSAP256Verifier (const uint8_t * signingKey): 
				ECDSAVerifier (CryptoPP::ASN1::secp256r1(), signingKey)
			{
			}			
	};	

	class ECDSAP256Signer: public ECDSASigner<CryptoPP::SHA256>
	{
		public:

			ECDSAP256Signer (const uint8_t * signingPrivateKey):
				ECDSASigner (CryptoPP::ASN1::secp256r1(), signingPrivateKey, ECDSAP256_KEY_LENGTH)
			{
			}
	};

	inline void CreateECDSAP256RandomKeys (CryptoPP::RandomNumberGenerator& rnd, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys<CryptoPP::SHA256> (rnd, CryptoPP::ASN1::secp256r1(), ECDSAP256_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}	

// ECDSA_SHA384_P384
	const size_t ECDSAP384_KEY_LENGTH = 96;
	class ECDSAP384Verifier: public ECDSAVerifier<CryptoPP::SHA384, ECDSAP384_KEY_LENGTH>
	{
		public:

			ECDSAP384Verifier (const uint8_t * signingKey): 
				ECDSAVerifier (CryptoPP::ASN1::secp384r1(), signingKey)
			{
			}			
	};	

	class ECDSAP384Signer: public ECDSASigner<CryptoPP::SHA384>
	{
		public:

			ECDSAP384Signer (const uint8_t * signingPrivateKey):
				ECDSASigner (CryptoPP::ASN1::secp384r1(), signingPrivateKey, ECDSAP384_KEY_LENGTH)
			{
			}
	};

	inline void CreateECDSAP384RandomKeys (CryptoPP::RandomNumberGenerator& rnd, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys<CryptoPP::SHA384> (rnd, CryptoPP::ASN1::secp384r1(), ECDSAP384_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}	

// ECDSA_SHA512_P521
	const size_t ECDSAP521_KEY_LENGTH = 132;
	class ECDSAP521Verifier: public ECDSAVerifier<CryptoPP::SHA512, ECDSAP521_KEY_LENGTH>
	{
		public:

			ECDSAP521Verifier (const uint8_t * signingKey): 
				ECDSAVerifier (CryptoPP::ASN1::secp521r1(), signingKey)
			{
			}			
	};	

	class ECDSAP521Signer: public ECDSASigner<CryptoPP::SHA512>
	{
		public:

			ECDSAP521Signer (const uint8_t * signingPrivateKey):
				ECDSASigner (CryptoPP::ASN1::secp521r1(), signingPrivateKey, ECDSAP521_KEY_LENGTH)
			{
			}
	};

	inline void CreateECDSAP521RandomKeys (CryptoPP::RandomNumberGenerator& rnd, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys<CryptoPP::SHA512> (rnd, CryptoPP::ASN1::secp521r1(), ECDSAP521_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}

// RSA
	template<typename Hash, size_t keyLen>	
	class RSAVerifier: public Verifier
	{
		public:

			RSAVerifier (const uint8_t * signingKey)
			{
				m_PublicKey.Initialize (CryptoPP::Integer (signingKey, keyLen), CryptoPP::Integer (rsae));
			}

			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const 
			{
				typename CryptoPP::RSASS<CryptoPP::PKCS1v15, Hash>::Verifier verifier (m_PublicKey);
				return verifier.VerifyMessage (buf, len, signature, keyLen); // signature length
			}
			size_t GetPublicKeyLen () const { return keyLen; }
			size_t GetSignatureLen () const { return keyLen; }	
			size_t GetPrivateKeyLen () const { return GetSignatureLen ()*2; };

		private:
			
			CryptoPP::RSA::PublicKey m_PublicKey;			
	};	

	
	template<typename Hash>
	class RSASigner: public Signer
	{
		public:

			RSASigner (const uint8_t * signingPrivateKey, size_t keyLen)
			{
				m_PrivateKey.Initialize (CryptoPP::Integer (signingPrivateKey, keyLen/2),
				    rsae,                 			
					CryptoPP::Integer (signingPrivateKey + keyLen/2, keyLen/2));
			}

			void Sign (CryptoPP::RandomNumberGenerator& rnd, const uint8_t * buf, int len, uint8_t * signature) const
			{
				typename CryptoPP::RSASS<CryptoPP::PKCS1v15, Hash>::Signer signer (m_PrivateKey);
				signer.SignMessage (rnd, buf, len, signature);
			}
			
		private:

			CryptoPP::RSA::PrivateKey m_PrivateKey;
	};		

	inline void CreateRSARandomKeys (CryptoPP::RandomNumberGenerator& rnd, 
		size_t publicKeyLen, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CryptoPP::RSA::PrivateKey privateKey;
		privateKey.Initialize (rnd, publicKeyLen*8, rsae);
		privateKey.GetModulus ().Encode (signingPrivateKey, publicKeyLen);	
		privateKey.GetPrivateExponent ().Encode (signingPrivateKey + publicKeyLen, publicKeyLen);	
		privateKey.GetModulus ().Encode (signingPublicKey, publicKeyLen);
	}	

	
//  RSA_SHA256_2048
	const size_t RSASHA2562048_KEY_LENGTH = 256;
	class RSASHA2562048Verifier: public RSAVerifier<CryptoPP::SHA256, RSASHA2562048_KEY_LENGTH> 
	{
		public:

			RSASHA2562048Verifier (const uint8_t * signingKey): RSAVerifier (signingKey) 
			{
			}
	};

	class RSASHA2562048Signer: public RSASigner<CryptoPP::SHA256> 
	{
		public:

			RSASHA2562048Signer (const uint8_t * signingPrivateKey): 
				RSASigner (signingPrivateKey, RSASHA2562048_KEY_LENGTH*2) 
			{
			}
	};

//  RSA_SHA384_3072
	const size_t RSASHA3843072_KEY_LENGTH = 384;
	class RSASHA3843072Verifier: public RSAVerifier<CryptoPP::SHA384, RSASHA3843072_KEY_LENGTH> 
	{
		public:

			RSASHA3843072Verifier (const uint8_t * signingKey): RSAVerifier (signingKey) 
			{
			}
	};

	class RSASHA3843072Signer: public RSASigner<CryptoPP::SHA384> 
	{
		public:

			RSASHA3843072Signer (const uint8_t * signingPrivateKey): 
				RSASigner (signingPrivateKey, RSASHA3843072_KEY_LENGTH*2) 
			{
			}
	};

//  RSA_SHA512_4096
	const size_t RSASHA5124096_KEY_LENGTH = 512;
	class RSASHA5124096Verifier: public RSAVerifier<CryptoPP::SHA512, RSASHA5124096_KEY_LENGTH> 
	{
		public:

			RSASHA5124096Verifier (const uint8_t * signingKey): RSAVerifier (signingKey) 
			{
			}
	};

	class RSASHA5124096Signer: public RSASigner<CryptoPP::SHA512> 
	{
		public:

			RSASHA5124096Signer (const uint8_t * signingPrivateKey): 
				RSASigner (signingPrivateKey, RSASHA5124096_KEY_LENGTH*2) 
			{
			}
	};

// Raw verifiers	
	class RawVerifier
	{
		public:
			
			virtual ~RawVerifier () {};
			virtual void Update (const uint8_t * buf, size_t len) = 0;
			virtual bool Verify (const uint8_t * signature) = 0;
	};		

	template<typename Hash, size_t keyLen>
	class RSARawVerifier: public RawVerifier
	{
		public:

			RSARawVerifier (const uint8_t * signingKey):
				n (signingKey, keyLen)
			{
			}

			void Update (const uint8_t * buf, size_t len)
			{
				m_Hash.Update (buf, len);
			}
			
			bool Verify (const uint8_t * signature)
			{
				// RSA encryption first
				CryptoPP::Integer enSig (a_exp_b_mod_c (CryptoPP::Integer (signature, keyLen), 
					CryptoPP::Integer (i2p::crypto::rsae), n)); // s^e mod n 
				uint8_t enSigBuf[keyLen];
				enSig.Encode (enSigBuf, keyLen);

				uint8_t digest[Hash::DIGESTSIZE];
				m_Hash.Final (digest);
				if ((int)keyLen < Hash::DIGESTSIZE) return false; // can't verify digest longer than key
				// we assume digest is right aligned, at least for PKCS#1 v1.5 padding 
				return !memcmp (enSigBuf + (keyLen - Hash::DIGESTSIZE), digest, Hash::DIGESTSIZE); 				
			}

		private:

			CryptoPP::Integer n; // RSA modulus	
			Hash m_Hash;
	};	

	class RSASHA5124096RawVerifier: public RSARawVerifier<CryptoPP::SHA512, RSASHA5124096_KEY_LENGTH> 
	{
		public:

			RSASHA5124096RawVerifier (const uint8_t * signingKey): RSARawVerifier (signingKey) 
			{
			}
	};

	// EdDSA
	const size_t EDDSA25519_PUBLIC_KEY_LENGTH = 32;
	const size_t EDDSA25519_SIGNATURE_LENGTH = 64;
	const size_t EDDSA25519_PRIVATE_KEY_LENGTH = 32;		
	class EDDSA25519Verifier: public Verifier
	{
		public:

			EDDSA25519Verifier (const uint8_t * signingKey)
			{
			}
	
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const;

			size_t GetPublicKeyLen () const { return EDDSA25519_PUBLIC_KEY_LENGTH; };
			size_t GetSignatureLen () const { return EDDSA25519_SIGNATURE_LENGTH; };	
	};
}
}

#endif