#include "../include/odhtdb/Signature.hpp"
#include "../include/odhtdb/Hash.hpp"
#include "../include/odhtdb/bin2hex.hpp"
#include <sodium/crypto_sign_ed25519.h>
#include <cstring>

using namespace std;

namespace odhtdb
{
    namespace Signature
    {
        const PublicKey PublicKey::ZERO("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", PUBLIC_KEY_NUM_BYTES);
        
        PublicKey::PublicKey()
        {
            memset(data, 0, PUBLIC_KEY_NUM_BYTES);
        }
        
        PublicKey::PublicKey(const char *_data, size_t size)
        {
            if(size != PUBLIC_KEY_NUM_BYTES)
            {
                string errMsg = "Expected public key size to be ";
                errMsg += to_string(PUBLIC_KEY_NUM_BYTES);
                errMsg += " bytes, was: ";
                errMsg += to_string(size);
                throw InvalidSignatureKeySize(errMsg);
            }
            memmove(data, _data, PUBLIC_KEY_NUM_BYTES);
        }
        
        PublicKey::PublicKey(const PublicKey &other)
        {
            memmove(data, other.data, PUBLIC_KEY_NUM_BYTES);
        }
        
        PublicKey& PublicKey::operator=(const PublicKey &other)
        {
            memmove(data, other.data, PUBLIC_KEY_NUM_BYTES);
            return *this;
        }
        
        string PublicKey::unsign(const DataView &signedMessage) const
        {
            if(signedMessage.size < SIGNED_HASH_SIZE)
                throw UnsignInvalidSizeException("Signed message is too small (corrupt or malicious signed message)");
            
            string result;
            result.resize(signedMessage.size - SIGNED_HASH_SIZE);
            if(crypto_sign_ed25519_open((unsigned char*)&result[0], nullptr, (const unsigned char*)signedMessage.data, signedMessage.size, (unsigned char*)data) < 0)
                throw UnsignWrongKeyException("Message was not signed with matching private key");
            
            return result;
        }
        
        size_t PublicKey::operator()() const
        {
            return fnvHash((const unsigned char*)data, PUBLIC_KEY_NUM_BYTES);
        }
        
        bool PublicKey::operator==(const PublicKey &other) const
        {
            return memcmp(data, other.data, PUBLIC_KEY_NUM_BYTES) == 0;
        }
        
        bool PublicKey::operator!=(const PublicKey &other) const
        {
            return !operator==(other);
        }
        
        string PublicKey::toString() const
        {
            return bin2hex(data, PUBLIC_KEY_NUM_BYTES);
        }
        
        const PrivateKey PrivateKey::ZERO("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", PRIVATE_KEY_NUM_BYTES);
        
        PrivateKey::PrivateKey()
        {
            memset(data, 0, PRIVATE_KEY_NUM_BYTES);
        }
        
        PrivateKey::PrivateKey(const char *_data, size_t size)
        {
            if(size != PRIVATE_KEY_NUM_BYTES)
            {
                string errMsg = "Expected private key size to be ";
                errMsg += to_string(PRIVATE_KEY_NUM_BYTES);
                errMsg += " bytes, was: ";
                errMsg += to_string(size);
                throw InvalidSignatureKeySize(errMsg);
            }
            memmove(data, _data, PRIVATE_KEY_NUM_BYTES);
        }
        
        PrivateKey::PrivateKey(const PrivateKey &other)
        {
            memmove(data, other.data, PRIVATE_KEY_NUM_BYTES);
        }
        
        PrivateKey& PrivateKey::operator=(const PrivateKey &other)
        {
            memmove(data, other.data, PRIVATE_KEY_NUM_BYTES);
            return *this;
        }
        
        bool PrivateKey::operator==(const PrivateKey &other) const
        {
            return memcmp(data, other.data, PRIVATE_KEY_NUM_BYTES) == 0;
        }
        
        bool PrivateKey::operator!=(const PrivateKey &other) const
        {
            return !operator==(other);
        }
        
        string PrivateKey::sign(const DataView &dataToSign) const
        {
            string result;
            result.resize(crypto_sign_ed25519_BYTES + dataToSign.size);
            unsigned long long resultSize;
            
            if(crypto_sign_ed25519((unsigned char*)&result[0], &resultSize, (unsigned char*)dataToSign.data, dataToSign.size, (unsigned char*)data) < 0)
                throw DataSignException("Failed to sign data. Is private key invalid?");
            
            if(resultSize != result.size())
                throw DataSignException("Failed to sign data. The signed data is not of expected size (bug)");
            
            return result;
        }
        
        string PrivateKey::toString() const
        {
            return bin2hex(data, PRIVATE_KEY_NUM_BYTES);
        }
        
        KeyPair::KeyPair()
        {
            if(crypto_sign_ed25519_keypair((unsigned char*)publicKey.data, (unsigned char*)privateKey.data) < 0)
                throw SignatureGenerationException("Failed to generate signature keypair");
        }
        
        KeyPair::KeyPair(const PublicKey &_publicKey, const PrivateKey &_privateKey) : 
            publicKey(_publicKey),
            privateKey(_privateKey)
        {
            
        }
        
        KeyPair::KeyPair(const KeyPair &other)
        {
            memmove(publicKey.data, other.publicKey.data, PUBLIC_KEY_NUM_BYTES);
            memmove(privateKey.data, other.privateKey.data, PRIVATE_KEY_NUM_BYTES);
        }
    }
}