/*
* Copyright (c) 2013-2021, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/

#ifndef IDENTITY_H__
#define IDENTITY_H__

#include <inttypes.h>
#include <string.h>
#include <string>
#include <memory>
#include <atomic>
#include <vector>
#include <mutex>
#include "Base.h"
#include "Signature.h"
#include "CryptoKey.h"

namespace i2p {
    namespace data {
        typedef Tag<32> IdentHash;

        inline std::string GetIdentHashAbbreviation(const IdentHash &ident) {
            return ident.ToBase64().substr(0, 4);
        }

        struct Keys {
            uint8_t privateKey[256];
            uint8_t signingPrivateKey[20];
            uint8_t publicKey[256];
            uint8_t signingKey[128];
        };

        const uint8_t CERTIFICATE_TYPE_NULL = 0;
        const uint8_t CERTIFICATE_TYPE_HASHCASH = 1;
        const uint8_t CERTIFICATE_TYPE_HIDDEN = 2;
        const uint8_t CERTIFICATE_TYPE_SIGNED = 3;
        const uint8_t CERTIFICATE_TYPE_MULTIPLE = 4;
        const uint8_t CERTIFICATE_TYPE_KEY = 5;

        struct Identity {
            uint8_t publicKey[256];
            uint8_t signingKey[128];
            uint8_t certificate[3];    // byte 1 - type, bytes 2-3 - length

            Identity() = default;

            Identity(const Keys &keys) { *this = keys; };

            Identity &operator=(const Keys &keys);

            size_t FromBuffer(const uint8_t *buf, size_t len);

            IdentHash Hash() const;
        };

        Keys CreateRandomKeys();

        const size_t DEFAULT_IDENTITY_SIZE = sizeof(Identity); // 387 bytes

        const uint16_t CRYPTO_KEY_TYPE_ELGAMAL = 0;
        const uint16_t CRYPTO_KEY_TYPE_ECIES_P256_SHA256_AES256CBC = 1;
        const uint16_t CRYPTO_KEY_TYPE_ECIES_X25519_AEAD = 4;
        const uint16_t CRYPTO_KEY_TYPE_ECIES_P256_SHA256_AES256CBC_TEST = 65280; // TODO: remove later
        const uint16_t CRYPTO_KEY_TYPE_ECIES_GOSTR3410_CRYPTO_PRO_A_SHA256_AES256CBC = 65281; // TODO: use GOST R 34.11 instead SHA256 and GOST 28147-89 instead AES

        const uint16_t SIGNING_KEY_TYPE_DSA_SHA1 = 0;
        const uint16_t SIGNING_KEY_TYPE_ECDSA_SHA256_P256 = 1;
        const uint16_t SIGNING_KEY_TYPE_ECDSA_SHA384_P384 = 2;
        const uint16_t SIGNING_KEY_TYPE_ECDSA_SHA512_P521 = 3;
        const uint16_t SIGNING_KEY_TYPE_RSA_SHA256_2048 = 4;
        const uint16_t SIGNING_KEY_TYPE_RSA_SHA384_3072 = 5;
        const uint16_t SIGNING_KEY_TYPE_RSA_SHA512_4096 = 6;
        const uint16_t SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519 = 7;
        const uint16_t SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519ph = 8; // not implemented
        const uint16_t SIGNING_KEY_TYPE_GOSTR3410_CRYPTO_PRO_A_GOSTR3411_256 = 9;
        const uint16_t SIGNING_KEY_TYPE_GOSTR3410_TC26_A_512_GOSTR3411_512 = 10; // approved by FSB
        const uint16_t SIGNING_KEY_TYPE_REDDSA_SHA512_ED25519 = 11; // for LeaseSet2 only

        typedef uint16_t SigningKeyType;
        typedef uint16_t CryptoKeyType;

        const size_t MAX_EXTENDED_BUFFER_SIZE = 8; // cryptoKeyType + signingKeyType + 4 extra bytes of P521
        class IdentityEx {
        public:

            IdentityEx();

            IdentityEx(const uint8_t *publicKey, const uint8_t *signingKey,
                       SigningKeyType type = SIGNING_KEY_TYPE_DSA_SHA1,
                       CryptoKeyType cryptoType = CRYPTO_KEY_TYPE_ELGAMAL);

            IdentityEx(const uint8_t *buf, size_t len);

            IdentityEx(const IdentityEx &other);

            IdentityEx(const Identity &standard);

            ~IdentityEx();

            IdentityEx &operator=(const IdentityEx &other);

            IdentityEx &operator=(const Identity &standard);

            size_t FromBuffer(const uint8_t *buf, size_t len);

            size_t ToBuffer(uint8_t *buf, size_t len) const;

            size_t FromBase64(const std::string &s);

            std::string ToBase64() const;

            const Identity &GetStandardIdentity() const { return m_StandardIdentity; };

            const IdentHash &GetIdentHash() const { return m_IdentHash; };

            const uint8_t *GetEncryptionPublicKey() const { return m_StandardIdentity.publicKey; };

            uint8_t *GetEncryptionPublicKeyBuffer() { return m_StandardIdentity.publicKey; };

            std::shared_ptr<i2p::crypto::CryptoKeyEncryptor> CreateEncryptor(const uint8_t *key) const;

            size_t GetFullLen() const { return m_ExtendedLen + DEFAULT_IDENTITY_SIZE; };

            size_t GetSigningPublicKeyLen() const;

            const uint8_t *GetSigningPublicKeyBuffer() const; // returns NULL for P521
            size_t GetSigningPrivateKeyLen() const;

            size_t GetSignatureLen() const;

            bool Verify(const uint8_t *buf, size_t len, const uint8_t *signature) const;

            SigningKeyType GetSigningKeyType() const;

            bool IsRSA() const; // signing key type
            CryptoKeyType GetCryptoKeyType() const;

            void DropVerifier() const; // to save memory

            bool operator==(const IdentityEx &other) const { return GetIdentHash() == other.GetIdentHash(); }

            void RecalculateIdentHash(uint8_t *buff = nullptr);

            static i2p::crypto::Verifier *CreateVerifier(SigningKeyType keyType);

            static std::shared_ptr<i2p::crypto::CryptoKeyEncryptor>
            CreateEncryptor(CryptoKeyType keyType, const uint8_t *key);

        private:

            void CreateVerifier() const;

            void UpdateVerifier(i2p::crypto::Verifier *verifier) const;

        private:

            Identity m_StandardIdentity;
            IdentHash m_IdentHash;
            mutable i2p::crypto::Verifier *m_Verifier = nullptr;
            mutable std::mutex m_VerifierMutex;
            size_t m_ExtendedLen;
            uint8_t m_ExtendedBuffer[MAX_EXTENDED_BUFFER_SIZE];
        };

        class PrivateKeys // for eepsites
        {
        public:

            PrivateKeys() = default;

            PrivateKeys(const PrivateKeys &other) { *this = other; };

            PrivateKeys(const Keys &keys) { *this = keys; };

            PrivateKeys &operator=(const Keys &keys);

            PrivateKeys &operator=(const PrivateKeys &other);

            ~PrivateKeys() = default;

            std::shared_ptr<const IdentityEx> GetPublic() const { return m_Public; };

            const uint8_t *GetPrivateKey() const { return m_PrivateKey; };

            const uint8_t *GetSigningPrivateKey() const { return m_SigningPrivateKey; };

            size_t GetSignatureLen() const; // might not match identity
            bool IsOfflineSignature() const { return m_TransientSignatureLen > 0; };

            uint8_t *GetPadding();

            void RecalculateIdentHash(uint8_t *buf = nullptr) { m_Public->RecalculateIdentHash(buf); }

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

            size_t GetFullLen() const;

            size_t FromBuffer(const uint8_t *buf, size_t len);

            size_t ToBuffer(uint8_t *buf, size_t len) const;

            size_t FromBase64(const std::string &s);

            std::string ToBase64() const;

            std::shared_ptr<i2p::crypto::CryptoKeyDecryptor> CreateDecryptor(const uint8_t *key) const;

            static std::shared_ptr<i2p::crypto::CryptoKeyDecryptor>
            CreateDecryptor(CryptoKeyType cryptoType, const uint8_t *key);

            static PrivateKeys CreateRandomKeys(SigningKeyType type = SIGNING_KEY_TYPE_DSA_SHA1,
                                                CryptoKeyType cryptoType = CRYPTO_KEY_TYPE_ELGAMAL);

            static void GenerateSigningKeyPair(SigningKeyType type, uint8_t *priv, uint8_t *pub);

            static void
            GenerateCryptoKeyPair(CryptoKeyType type, uint8_t *priv, uint8_t *pub); // priv and pub are 256 bytes long
            static i2p::crypto::Signer *CreateSigner(SigningKeyType keyType, const uint8_t *priv);

            // offline keys
            PrivateKeys CreateOfflineKeys(SigningKeyType type, uint32_t expires) const;

            const std::vector<uint8_t> &GetOfflineSignature() const { return m_OfflineSignature; };

        private:

            void CreateSigner() const;

            void CreateSigner(SigningKeyType keyType) const;

            size_t GetPrivateKeyLen() const;

        private:

            std::shared_ptr<IdentityEx> m_Public;
            uint8_t m_PrivateKey[256];
            uint8_t m_SigningPrivateKey[128]; // assume private key doesn't exceed 128 bytes
            mutable std::unique_ptr<i2p::crypto::Signer> m_Signer;
            std::vector<uint8_t> m_OfflineSignature; // non zero length, if applicable
            size_t m_TransientSignatureLen = 0;
            size_t m_TransientSigningPrivateKeyLen = 0;
        };

        // kademlia
        struct XORMetric {
            union {
                uint8_t metric[32];
                uint64_t metric_ll[4];
            };

            void SetMin() { memset(metric, 0, 32); };

            void SetMax() { memset(metric, 0xFF, 32); };

            bool operator<(const XORMetric &other) const { return memcmp(metric, other.metric, 32) < 0; };
        };

        IdentHash CreateRoutingKey(const IdentHash &ident);

        XORMetric operator^(const IdentHash &key1, const IdentHash &key2);

        // destination for delivery instructions
        class RoutingDestination {
        public:

            RoutingDestination() {};

            virtual ~RoutingDestination() {};

            virtual std::shared_ptr<const IdentityEx> GetIdentity() const = 0;

            virtual void Encrypt(const uint8_t *data, uint8_t *encrypted) const = 0; // encrypt data for
            virtual bool IsDestination() const = 0; // for garlic

            const IdentHash &GetIdentHash() const { return GetIdentity()->GetIdentHash(); };

            virtual CryptoKeyType
            GetEncryptionType() const { return GetIdentity()->GetCryptoKeyType(); }; // override in LeaseSet2
        };

        class LocalDestination {
        public:

            virtual ~LocalDestination() {};

            virtual bool Decrypt(const uint8_t *encrypted, uint8_t *data,
                                 CryptoKeyType preferredCrypto = CRYPTO_KEY_TYPE_ELGAMAL) const = 0;

            virtual std::shared_ptr<const IdentityEx> GetIdentity() const = 0;

            const IdentHash &GetIdentHash() const { return GetIdentity()->GetIdentHash(); };

            virtual bool SupportsEncryptionType(CryptoKeyType keyType) const {
                return GetIdentity()->GetCryptoKeyType() == keyType;
            }; // override for LeaseSet
            virtual const uint8_t *GetEncryptionPublicKey(
                    CryptoKeyType keyType) const { return GetIdentity()->GetEncryptionPublicKey(); }; // override for LeaseSet
        };
    }
}

#endif