#ifndef SIGNATURE_H__
#define SIGNATURE_H__

#include <inttypes.h>
#include <string.h>
#include <openssl/dsa.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#include "Crypto.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 (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 = CreateDSA ();
				DSA_set0_key (m_PublicKey, BN_bin2bn (signingKey, DSA_PUBLIC_KEY_LENGTH, NULL), NULL);
			}

			~DSAVerifier ()
			{
				DSA_free (m_PublicKey);
			}
			
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const
			{
				// calculate SHA1 digest
				uint8_t digest[20];
				SHA1 (buf, len, digest);
				// signature
				DSA_SIG * sig = DSA_SIG_new();
				DSA_SIG_set0 (sig, BN_bin2bn (signature, DSA_SIGNATURE_LENGTH/2, NULL), BN_bin2bn (signature + DSA_SIGNATURE_LENGTH/2, DSA_SIGNATURE_LENGTH/2, NULL));
				// DSA verification
				int ret = DSA_do_verify (digest, 20, sig, m_PublicKey);
				DSA_SIG_free(sig);
				return ret;
			}	

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

			DSA * m_PublicKey;
	};

	class DSASigner: public Signer
	{
		public:

			DSASigner (const uint8_t * signingPrivateKey, const uint8_t * signingPublicKey)
			// openssl 1.1 always requires DSA public key even for signing
			{
				m_PrivateKey = CreateDSA ();
				DSA_set0_key (m_PrivateKey, BN_bin2bn (signingPublicKey, DSA_PUBLIC_KEY_LENGTH, NULL), BN_bin2bn (signingPrivateKey, DSA_PRIVATE_KEY_LENGTH, NULL));
			}

			~DSASigner ()
			{
				DSA_free (m_PrivateKey);
			}
			
			void Sign (const uint8_t * buf, int len, uint8_t * signature) const
			{
				uint8_t digest[20];
				SHA1 (buf, len, digest);
				DSA_SIG * sig = DSA_do_sign (digest, 20, m_PrivateKey);
				const BIGNUM * r, * s;
				DSA_SIG_get0 (sig, &r, &s);
				bn2buf (r, signature, DSA_SIGNATURE_LENGTH/2);
				bn2buf (s, signature + DSA_SIGNATURE_LENGTH/2, DSA_SIGNATURE_LENGTH/2);
				DSA_SIG_free(sig);
			}

		private:

			DSA * m_PrivateKey;
	};

	inline void CreateDSARandomKeys (uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		DSA * dsa = CreateDSA ();
		DSA_generate_key (dsa);
		const BIGNUM * pub_key, * priv_key;
		DSA_get0_key(dsa, &pub_key, &priv_key);
		bn2buf (priv_key, signingPrivateKey, DSA_PRIVATE_KEY_LENGTH);
		bn2buf (pub_key, signingPublicKey, DSA_PUBLIC_KEY_LENGTH);
		DSA_free (dsa);	
	}	

	struct SHA256Hash
	{	
		static void CalculateHash (const uint8_t * buf, size_t len, uint8_t * digest)
		{
			SHA256 (buf, len, digest);
		}

		enum { hashLen = 32 };
	};	

	struct SHA384Hash
	{	
		static void CalculateHash (const uint8_t * buf, size_t len, uint8_t * digest)
		{
			SHA384 (buf, len, digest);
		}

		enum { hashLen = 48 };
	};

	struct SHA512Hash
	{	
		static void CalculateHash (const uint8_t * buf, size_t len, uint8_t * digest)
		{
			SHA512 (buf, len, digest);
		}

		enum { hashLen = 64 };
	};
	
	template<typename Hash, int curve, size_t keyLen>
	class ECDSAVerifier: public Verifier
	{		
		public:

			ECDSAVerifier (const uint8_t * signingKey)
			{
				m_PublicKey = EC_KEY_new_by_curve_name (curve);
				BIGNUM * x = BN_bin2bn (signingKey, keyLen/2, NULL);
				BIGNUM * y = BN_bin2bn (signingKey + keyLen/2, keyLen/2, NULL);
				EC_KEY_set_public_key_affine_coordinates (m_PublicKey, x, y);
				BN_free (x); BN_free (y);
			}

			~ECDSAVerifier ()
			{
				EC_KEY_free (m_PublicKey);
			}
			
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const
			{
				uint8_t digest[Hash::hashLen];
				Hash::CalculateHash (buf, len, digest);
				ECDSA_SIG * sig = ECDSA_SIG_new();
				auto r = BN_bin2bn (signature, GetSignatureLen ()/2, NULL);
				auto s = BN_bin2bn (signature + GetSignatureLen ()/2, GetSignatureLen ()/2, NULL);
				ECDSA_SIG_set0(sig, r, s);
				// ECDSA verification
				int ret = ECDSA_do_verify (digest, Hash::hashLen, sig, m_PublicKey);
				ECDSA_SIG_free(sig);
				return ret;
			}	
			
			size_t GetPublicKeyLen () const { return keyLen; };
			size_t GetSignatureLen () const { return keyLen; }; // signature length = key length

			
		private:

			EC_KEY * m_PublicKey;
	};

	template<typename Hash, int curve, size_t keyLen>
	class ECDSASigner: public Signer
	{
		public:

			ECDSASigner (const uint8_t * signingPrivateKey)
			{
				m_PrivateKey = EC_KEY_new_by_curve_name (curve);
				EC_KEY_set_private_key (m_PrivateKey, BN_bin2bn (signingPrivateKey, keyLen/2, NULL));			
			}

			~ECDSASigner ()
			{
				EC_KEY_free (m_PrivateKey);
			}
			
			void Sign (const uint8_t * buf, int len, uint8_t * signature) const
			{
				uint8_t digest[Hash::hashLen];
				Hash::CalculateHash (buf, len, digest);
				ECDSA_SIG * sig = ECDSA_do_sign (digest, Hash::hashLen, m_PrivateKey);
				const BIGNUM * r, * s;
				ECDSA_SIG_get0 (sig, &r, &s);
				// signatureLen = keyLen
				bn2buf (r, signature, keyLen/2);
				bn2buf (s, signature + keyLen/2, keyLen/2);
				ECDSA_SIG_free(sig);
			}

		private:

			EC_KEY * m_PrivateKey;
	};

	inline void CreateECDSARandomKeys (int curve, size_t keyLen, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		EC_KEY * signingKey = EC_KEY_new_by_curve_name (curve);
		EC_KEY_generate_key (signingKey);
		bn2buf (EC_KEY_get0_private_key (signingKey), signingPrivateKey, keyLen/2);
		BIGNUM * x = BN_new(), * y = BN_new();
		EC_POINT_get_affine_coordinates_GFp (EC_KEY_get0_group(signingKey),
			EC_KEY_get0_public_key (signingKey), x, y, NULL);
		bn2buf (x, signingPublicKey, keyLen/2);
		bn2buf (y, signingPublicKey + keyLen/2, keyLen/2);
		BN_free (x); BN_free (y);
		EC_KEY_free (signingKey);		
	}

// ECDSA_SHA256_P256
	const size_t ECDSAP256_KEY_LENGTH = 64;	
	typedef ECDSAVerifier<SHA256Hash, NID_X9_62_prime256v1, ECDSAP256_KEY_LENGTH> ECDSAP256Verifier;
	typedef ECDSASigner<SHA256Hash, NID_X9_62_prime256v1, ECDSAP256_KEY_LENGTH> ECDSAP256Signer;

	inline void CreateECDSAP256RandomKeys (uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys (NID_X9_62_prime256v1, ECDSAP256_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}	

// ECDSA_SHA384_P384
	const size_t ECDSAP384_KEY_LENGTH = 96;
	typedef ECDSAVerifier<SHA384Hash, NID_secp384r1, ECDSAP384_KEY_LENGTH> ECDSAP384Verifier;
	typedef ECDSASigner<SHA384Hash, NID_secp384r1, ECDSAP384_KEY_LENGTH> ECDSAP384Signer;

	inline void CreateECDSAP384RandomKeys (uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys (NID_secp384r1, ECDSAP384_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}	

// ECDSA_SHA512_P521
	const size_t ECDSAP521_KEY_LENGTH = 132;
	typedef ECDSAVerifier<SHA512Hash, NID_secp521r1, ECDSAP521_KEY_LENGTH> ECDSAP521Verifier;
	typedef ECDSASigner<SHA512Hash, NID_secp521r1, ECDSAP521_KEY_LENGTH> ECDSAP521Signer;

	inline void CreateECDSAP521RandomKeys (uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		CreateECDSARandomKeys (NID_secp521r1, ECDSAP521_KEY_LENGTH, signingPrivateKey, signingPublicKey);
	}

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

			RSAVerifier (const uint8_t * signingKey)
			{
				m_PublicKey = RSA_new ();
				RSA_set0_key (m_PublicKey, BN_bin2bn (signingKey, keyLen, NULL) /* n */ , BN_dup (GetRSAE ()) /* d */, NULL);
			}

			~RSAVerifier ()
			{
				RSA_free (m_PublicKey);
			}
			
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const 
			{
				uint8_t digest[Hash::hashLen];
				Hash::CalculateHash (buf, len, digest);
				return RSA_verify (type, digest, Hash::hashLen, signature, GetSignatureLen (), m_PublicKey);
			}
			size_t GetPublicKeyLen () const { return keyLen; }
			size_t GetSignatureLen () const { return keyLen; }	
			size_t GetPrivateKeyLen () const { return GetSignatureLen ()*2; };

		private:
			
			RSA * m_PublicKey;			
	};	

	
	template<typename Hash, int type, size_t keyLen>
	class RSASigner: public Signer
	{
		public:

			RSASigner (const uint8_t * signingPrivateKey)
			{
				m_PrivateKey = RSA_new ();
				RSA_set0_key (m_PrivateKey, BN_bin2bn (signingPrivateKey, keyLen, NULL), /* n */
					BN_dup (GetRSAE ()) /* e */, BN_bin2bn (signingPrivateKey + keyLen, keyLen, NULL) /* d */);
			}

			~RSASigner ()
			{
				RSA_free (m_PrivateKey);
			}
			
			void Sign (const uint8_t * buf, int len, uint8_t * signature) const
			{
				uint8_t digest[Hash::hashLen];
				Hash::CalculateHash (buf, len, digest);
				unsigned int signatureLen = keyLen;
				RSA_sign (type, digest, Hash::hashLen, signature, &signatureLen, m_PrivateKey);
			}
			
		private:

			RSA * m_PrivateKey;
	};		

	inline void CreateRSARandomKeys (size_t publicKeyLen, uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		RSA * rsa = RSA_new ();
		BIGNUM * e = BN_dup (GetRSAE ()); // make it non-const
		RSA_generate_key_ex (rsa, publicKeyLen*8, e, NULL);
		const BIGNUM * n, * d, * e1;
		RSA_get0_key (rsa, &n, &e1, &d);	
		bn2buf (n, signingPrivateKey, publicKeyLen);
		bn2buf (d, signingPrivateKey + publicKeyLen, publicKeyLen);
		bn2buf (n, signingPublicKey, publicKeyLen);
		BN_free (e); // this e is not assigned to rsa->e
		RSA_free (rsa);
	}	
	
//  RSA_SHA256_2048
	const size_t RSASHA2562048_KEY_LENGTH = 256;
	typedef RSAVerifier<SHA256Hash, NID_sha256, RSASHA2562048_KEY_LENGTH> RSASHA2562048Verifier;
	typedef RSASigner<SHA256Hash, NID_sha256, RSASHA2562048_KEY_LENGTH> RSASHA2562048Signer;

//  RSA_SHA384_3072
	const size_t RSASHA3843072_KEY_LENGTH = 384;
	typedef RSAVerifier<SHA384Hash, NID_sha384, RSASHA3843072_KEY_LENGTH> RSASHA3843072Verifier;
	typedef RSASigner<SHA384Hash, NID_sha384, RSASHA3843072_KEY_LENGTH> RSASHA3843072Signer;	

//  RSA_SHA512_4096
	const size_t RSASHA5124096_KEY_LENGTH = 512;
	typedef RSAVerifier<SHA512Hash, NID_sha512, RSASHA5124096_KEY_LENGTH> RSASHA5124096Verifier;
	typedef RSASigner<SHA512Hash, NID_sha512, RSASHA5124096_KEY_LENGTH> RSASHA5124096Signer;

	// EdDSA
	struct EDDSAPoint
	{
		BIGNUM * x, * y;
		BIGNUM * z, * t; // projective coordinates
		EDDSAPoint (): x(nullptr), y(nullptr), z(nullptr), t(nullptr) {};
		EDDSAPoint (const EDDSAPoint& other): x(nullptr), y(nullptr), z(nullptr), t(nullptr) 
		{ *this = other; };	
		EDDSAPoint (EDDSAPoint&& other): x(nullptr), y(nullptr), z(nullptr), t(nullptr)  
		{ *this = std::move (other); };	
		EDDSAPoint (BIGNUM * x1, BIGNUM * y1, BIGNUM * z1 = nullptr, BIGNUM * t1 = nullptr): x(x1), y(y1), z(z1), t(t1) {};	
		~EDDSAPoint () { BN_free (x); BN_free (y); BN_free(z); BN_free(t); };

		EDDSAPoint& operator=(EDDSAPoint&& other) 
		{
			if (x) BN_free (x); x = other.x; other.x = nullptr;
			if (y) BN_free (y); y = other.y; other.y = nullptr;
			if (z) BN_free (z); z = other.z; other.z = nullptr;
			if (t) BN_free (t); t = other.t; other.t = nullptr;
			return *this;
		} 	

		EDDSAPoint& operator=(const EDDSAPoint& other) 
		{
			if (x) BN_free (x); x = other.x ? BN_dup (other.x) : nullptr;
			if (y) BN_free (y); y = other.y ? BN_dup (other.y) : nullptr;
			if (z) BN_free (z); z = other.z ? BN_dup (other.z) : nullptr;
			if (t) BN_free (t); t = other.t ? BN_dup (other.t) : nullptr;
			return *this;
		}

		EDDSAPoint operator-() const
		{
			BIGNUM * x1 = NULL, * y1 = NULL, * z1 = NULL, * t1 = NULL;
			if (x) { x1 = BN_dup (x); BN_set_negative (x1, !BN_is_negative (x)); };
			if (y) y1 = BN_dup (y);
			if (z) z1 = BN_dup (z);
			if (t) { t1 = BN_dup (t); BN_set_negative (t1, !BN_is_negative (t)); };
			return EDDSAPoint {x1, y1, z1, t1};
		}
	};	

	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; };

		private:

			EDDSAPoint m_PublicKey;	
			uint8_t m_PublicKeyEncoded[EDDSA25519_PUBLIC_KEY_LENGTH];
	};

	class EDDSA25519Signer: public Signer
	{
		public:

			EDDSA25519Signer (const uint8_t * signingPrivateKey, const uint8_t * signingPublicKey = nullptr); 
			// we pass signingPublicKey to check if it matches private key 
			void Sign (const uint8_t * buf, int len, uint8_t * signature) const; 
			const uint8_t * GetPublicKey () const { return m_PublicKeyEncoded; };
			
		private:

			uint8_t m_ExpandedPrivateKey[64]; 
			uint8_t m_PublicKeyEncoded[EDDSA25519_PUBLIC_KEY_LENGTH];
	};

	inline void CreateEDDSA25519RandomKeys (uint8_t * signingPrivateKey, uint8_t * signingPublicKey)
	{
		RAND_bytes (signingPrivateKey, EDDSA25519_PRIVATE_KEY_LENGTH);
		EDDSA25519Signer signer (signingPrivateKey);
		memcpy (signingPublicKey, signer.GetPublicKey (), EDDSA25519_PUBLIC_KEY_LENGTH);
	}

	// ГОСТ Р 34.10-2001

	enum GOSTR3410ParamSet
	{
		eGOSTR3410CryptoProA = 0,   // 1.2.643.2.2.35.1
		eGOSTR3410CryptoProB,	    // 1.2.643.2.2.35.2
		eGOSTR3410CryptoProC,	    // 1.2.643.2.2.35.3
		//eGOSTR3410CryptoProXchA,    // 1.2.643.2.2.36.0
		//eGOSTR3410CryptoProXchB,	// 1.2.643.2.2.36.1
		// XchA = A, XchB = C
		eGOSTR3410NumParamSets
	};	
	
	const size_t GOSTR3410_PUBLIC_KEY_LENGTH = 64;
	const size_t GOSTR3410_SIGNATURE_LENGTH = 64;

	class GOSTR3410Verifier: public Verifier
	{
		public:

			GOSTR3410Verifier (const uint8_t * signingKey) 
			{ 
				m_PublicKey = EVP_PKEY_new (); 
				EC_KEY * ecKey = EC_KEY_new ();
				EVP_PKEY_assign (m_PublicKey, NID_id_GostR3410_2001, ecKey);
				EVP_PKEY_copy_parameters (m_PublicKey, GetGostPKEY ());		
				BIGNUM * x = BN_bin2bn (signingKey, GOSTR3410_PUBLIC_KEY_LENGTH/2, NULL);
				BIGNUM * y = BN_bin2bn (signingKey + GOSTR3410_PUBLIC_KEY_LENGTH/2, GOSTR3410_PUBLIC_KEY_LENGTH/2, NULL);
				EC_KEY_set_public_key_affine_coordinates (ecKey, x, y);
				BN_free (x); BN_free (y);
			} 
			~GOSTR3410Verifier () { EVP_PKEY_free (m_PublicKey); }
			
			bool Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const
			{
				uint8_t digest[32];
				GOSTR3411 (buf, len, digest);
				EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new (m_PublicKey, nullptr);
				EVP_PKEY_verify_init (ctx);
				int ret = EVP_PKEY_verify (ctx, signature, GOSTR3410_SIGNATURE_LENGTH, digest, 32);
				EVP_PKEY_CTX_free (ctx);
				return ret == 1;
			}
			
			size_t GetPublicKeyLen () const { return GOSTR3410_PUBLIC_KEY_LENGTH; }
			size_t GetSignatureLen () const { return GOSTR3410_SIGNATURE_LENGTH; }

		private:

			EVP_PKEY * m_PublicKey;
	};	

	class GOSTR3410Signer: public Signer
	{
		public:

			GOSTR3410Signer (GOSTR3410ParamSet paramSet, const uint8_t * signingPrivateKey):
				m_ParamSet (paramSet)
			{ 
				m_PrivateKey = BN_bin2bn (signingPrivateKey, GOSTR3410_PUBLIC_KEY_LENGTH/2, nullptr); 
			}
			~GOSTR3410Signer () { BN_free (m_PrivateKey); }

			void Sign (const uint8_t * buf, int len, uint8_t * signature) const;
			
		private:

			GOSTR3410ParamSet m_ParamSet;
			BIGNUM * m_PrivateKey;
	};	

	void CreateGOSTR3410RandomKeys (GOSTR3410ParamSet paramSet, uint8_t * signingPrivateKey, uint8_t * signingPublicKey);
}
}

#endif