// This file is part of the Eccoin project
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2015-2017 The Bitcoin Unlimited developers
// Copyright (c) 2014-2018 The Eccoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_KEY_H
#define BITCOIN_KEY_H

#include "pubkey.h"
#include "serialize.h"
#include "support/allocators/secure.h"
#include "uint256.h"

#include <stdexcept>
#include <vector>


/**
 * secure_allocator is defined in allocators.h
 * CPrivKey is a serialized private key, with all parameters included (279 bytes)
 */
typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;

/** An encapsulated private key. */
class CKey
{
private:
    //! Whether this private key is valid. We check for correctness when modifying the key
    //! data, so fValid should always correspond to the actual state.
    bool fValid;

    //! Whether the public key corresponding to this private key is (to be) compressed.
    bool fCompressed;

    //! The actual byte data
    unsigned char vch[32];

    //! Check whether the 32-byte array pointed to be vch is valid keydata.
    bool static Check(const unsigned char *vch);

public:
    //! Construct an invalid private key.
    CKey() : fValid(false), fCompressed(false) { LockObject(vch); }
    //! Copy constructor. This is necessary because of memlocking.
    CKey(const CKey &secret) : fValid(secret.fValid), fCompressed(secret.fCompressed)
    {
        LockObject(vch);
        memcpy(vch, secret.vch, sizeof(vch));
    }

    //! Destructor (again necessary because of memlocking).
    ~CKey() { UnlockObject(vch); }
    friend bool operator==(const CKey &a, const CKey &b)
    {
        return a.fCompressed == b.fCompressed && a.size() == b.size() && memcmp(&a.vch[0], &b.vch[0], a.size()) == 0;
    }

    //! Initialize using begin and end iterators to byte data.
    template <typename T>
    void Set(const T pbegin, const T pend, bool fCompressedIn)
    {
        if (pend - pbegin != 32)
        {
            fValid = false;
            return;
        }
        if (Check(&pbegin[0]))
        {
            memcpy(vch, (unsigned char *)&pbegin[0], 32);
            fValid = true;
            fCompressed = fCompressedIn;
        }
        else
        {
            fValid = false;
        }
    }

    //! Simple read-only vector-like interface.
    unsigned int size() const { return (fValid ? 32 : 0); }
    const unsigned char *begin() const { return vch; }
    const unsigned char *end() const { return vch + size(); }
    //! Check whether this private key is valid.
    bool IsValid() const { return fValid; }
    //! Check whether the public key corresponding to this private key is (to be) compressed.
    bool IsCompressed() const { return fCompressed; }
    //! Initialize from a CPrivKey (serialized OpenSSL private key data).
    bool SetPrivKey(const CPrivKey &vchPrivKey, bool fCompressed);

    //! Generate a new private key using a cryptographic PRNG.
    void MakeNewKey(bool fCompressed);

    /**
     * Convert the private key to a CPrivKey (serialized OpenSSL private key data).
     * This is expensive.
     */
    CPrivKey GetPrivKey() const;

    /**
     * Compute the public key from a private key.
     * This is expensive.
     */
    CPubKey GetPubKey() const;

    /**
     * Create a DER-serialized signature.
     * The test_case parameter tweaks the deterministic nonce.
     */
    bool Sign(const uint256 &hash, std::vector<unsigned char> &vchSig, uint32_t test_case = 0) const;

    /**
     * Create a compact signature (65 bytes), which allows reconstructing the used public key.
     * The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
     * The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
     *                  0x1D = second key with even y, 0x1E = second key with odd y,
     *                  add 0x04 for compressed keys.
     */
    bool SignCompact(const uint256 &hash, std::vector<unsigned char> &vchSig) const;

    //! Derive BIP32 child key.
    bool Derive(CKey &keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const;

    /**
     * Verify thoroughly whether a private key and a public key match.
     * This is done using a different mechanism than just regenerating it.
     */
    bool VerifyPubKey(const CPubKey &vchPubKey) const;

    //! Load private key and check that public key matches.
    bool Load(CPrivKey &privkey, CPubKey &vchPubKey, bool fSkipCheck = false);
};

struct CExtKey
{
    unsigned char nDepth;
    unsigned char vchFingerprint[4];
    unsigned int nChild;
    unsigned char vchChainCode[32];
    CKey key;

    friend bool operator==(const CExtKey &a, const CExtKey &b)
    {
        return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 &&
               a.nChild == b.nChild && memcmp(&a.vchChainCode[0], &b.vchChainCode[0], 32) == 0 && a.key == b.key;
    }

    void Encode(unsigned char code[74]) const;
    void Decode(const unsigned char code[74]);
    bool Derive(CExtKey &out, unsigned int nChild) const;
    CExtPubKey Neuter() const;
    void SetMaster(const unsigned char *seed, unsigned int nSeedLen);
};

/** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
void ECC_Start(void);

/** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
void ECC_Stop(void);

/** Check that required EC support is available at runtime. */
bool ECC_InitSanityCheck(void);

#endif // BITCOIN_KEY_H
