// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2017 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_SCRIPT_SIGN_H
#define BITCOIN_SCRIPT_SIGN_H

#include <script/interpreter.h>

class CKey;
class CKeyID;
class CScript;
class CScriptID;
class CTransaction;

struct CMutableTransaction;

/** An interface to be implemented by keystores that support signing. */
class SigningProvider
{
public:
    virtual ~SigningProvider() {}
    virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
    virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
    virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
};

extern const SigningProvider& DUMMY_SIGNING_PROVIDER;

/** Interface for signature creators. */
class BaseSignatureCreator {
public:
    virtual ~BaseSignatureCreator() {}
    virtual const BaseSignatureChecker& Checker() const =0;

    /** Create a singular (non-script) signature. */
    virtual bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const =0;
};

/** A signature creator for transactions. */
class MutableTransactionSignatureCreator : public BaseSignatureCreator {
    const CMutableTransaction* txTo;
    unsigned int nIn;
    int nHashType;
    CAmount amount;
    const MutableTransactionSignatureChecker checker;

public:
    MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn = SIGHASH_ALL);
    const BaseSignatureChecker& Checker() const override { return checker; }
    bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
};

/** A signature creator that just produces 72-byte empty signatures. */
extern const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR;

typedef std::pair<CPubKey, std::vector<unsigned char>> SigPair;

// This struct contains information from a transaction input and also contains signatures for that input.
// The information contained here can be used to create a signature and is also filled by ProduceSignature
// in order to construct final scriptSigs and scriptWitnesses.
struct SignatureData {
    bool complete = false; ///< Stores whether the scriptSig and scriptWitness are complete
    CScript scriptSig; ///< The scriptSig of an input. Contains complete signatures or the traditional partial signatures format
    CScript redeem_script; ///< The redeemScript (if any) for the input
    CScript witness_script; ///< The witnessScript (if any) for the input. witnessScripts are used in P2WSH outputs.
    CScriptWitness scriptWitness; ///< The scriptWitness of an input. Contains complete signatures or the traditional partial signatures format. scriptWitness is part of a transaction input per BIP 144.
    std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig or scriptWitness.

    SignatureData() {}
    explicit SignatureData(const CScript& script) : scriptSig(script) {}
    void MergeSignatureData(SignatureData sigdata);
};

/** Produce a script signature using a generic signature creator. */
bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);

/** Produce a script signature for a transaction. */
bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);
bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);

/** Extract signature data from a transaction input, and insert it. */
SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
void UpdateInput(CTxIn& input, const SignatureData& data);

/* Check whether we know how to sign for an output like this, assuming we
 * have all private keys. While this function does not need private keys, the passed
 * provider is used to look up public keys and redeemscripts by hash.
 * Solvability is unrelated to whether we consider this output to be ours. */
bool IsSolvable(const SigningProvider& provider, const CScript& script);

#endif // BITCOIN_SCRIPT_SIGN_H
