// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2026 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#pragma once

#include "crypto/common.h"
#include "prevector.h"
#include "serialize.h"

#include <cassert>
#include <cstdint>
#include <cstring>
#include <iterator>
#include <limits>
#include <optional>
#include <span>
#include <stdexcept>
#include <string>
#include <vector>

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-parameter"
#pragma clang diagnostic ignored "-Wweak-vtables"
#pragma clang diagnostic ignored "-Wsign-conversion"
#pragma clang diagnostic ignored "-Wconversion"
#pragma clang diagnostic ignored "-Wtautological-unsigned-enum-zero-compare"
#pragma clang diagnostic ignored "-Wtautological-type-limit-compare"
#pragma clang diagnostic ignored "-Wold-style-cast"
#endif
namespace bitcoin {

// Maximum number of bytes pushable to the stack
inline constexpr unsigned int MAX_SCRIPT_ELEMENT_SIZE = 520;

// Maximum number of non-push operations per script
inline constexpr int MAX_OPS_PER_SCRIPT = 201;

// Maximum number of public keys per multisig
inline constexpr int MAX_PUBKEYS_PER_MULTISIG = 20;

// Maximum script length in bytes
inline constexpr int MAX_SCRIPT_SIZE = 10000;

// Threshold for nLockTime: below this value it is interpreted as block number,
// otherwise as UNIX timestamp. Thresold is Tue Nov 5 00:53:20 1985 UTC
inline constexpr unsigned int LOCKTIME_THRESHOLD = 500000000;

/** Script opcodes */
enum opcodetype {
    // push value
    OP_0 = 0x00,
    OP_FALSE = OP_0,
    OP_PUSHDATA1 = 0x4c,
    OP_PUSHDATA2 = 0x4d,
    OP_PUSHDATA4 = 0x4e,
    OP_1NEGATE = 0x4f,
    OP_RESERVED = 0x50,
    OP_1 = 0x51,
    OP_TRUE = OP_1,
    OP_2 = 0x52,
    OP_3 = 0x53,
    OP_4 = 0x54,
    OP_5 = 0x55,
    OP_6 = 0x56,
    OP_7 = 0x57,
    OP_8 = 0x58,
    OP_9 = 0x59,
    OP_10 = 0x5a,
    OP_11 = 0x5b,
    OP_12 = 0x5c,
    OP_13 = 0x5d,
    OP_14 = 0x5e,
    OP_15 = 0x5f,
    OP_16 = 0x60,

    // control
    OP_NOP = 0x61,
    OP_VER = 0x62,
    OP_IF = 0x63,
    OP_NOTIF = 0x64,
    OP_VERIF = 0x65,
    OP_VERNOTIF = 0x66,
    OP_ELSE = 0x67,
    OP_ENDIF = 0x68,
    OP_VERIFY = 0x69,
    OP_RETURN = 0x6a,

    // stack ops
    OP_TOALTSTACK = 0x6b,
    OP_FROMALTSTACK = 0x6c,
    OP_2DROP = 0x6d,
    OP_2DUP = 0x6e,
    OP_3DUP = 0x6f,
    OP_2OVER = 0x70,
    OP_2ROT = 0x71,
    OP_2SWAP = 0x72,
    OP_IFDUP = 0x73,
    OP_DEPTH = 0x74,
    OP_DROP = 0x75,
    OP_DUP = 0x76,
    OP_NIP = 0x77,
    OP_OVER = 0x78,
    OP_PICK = 0x79,
    OP_ROLL = 0x7a,
    OP_ROT = 0x7b,
    OP_SWAP = 0x7c,
    OP_TUCK = 0x7d,

    // splice ops
    OP_CAT = 0x7e,
    OP_SPLIT = 0x7f,   // after monolith upgrade (May 2018)
    OP_NUM2BIN = 0x80, // after monolith upgrade (May 2018)
    OP_BIN2NUM = 0x81, // after monolith upgrade (May 2018)
    OP_SIZE = 0x82,

    // bit logic
    OP_INVERT = 0x83,
    OP_AND = 0x84,
    OP_OR = 0x85,
    OP_XOR = 0x86,
    OP_EQUAL = 0x87,
    OP_EQUALVERIFY = 0x88,
    OP_RESERVED1 = 0x89,
    OP_RESERVED2 = 0x8a,

    // numeric
    OP_1ADD = 0x8b,
    OP_1SUB = 0x8c,
    OP_2MUL = 0x8d,
    OP_2DIV = 0x8e,
    OP_NEGATE = 0x8f,
    OP_ABS = 0x90,
    OP_NOT = 0x91,
    OP_0NOTEQUAL = 0x92,

    OP_ADD = 0x93,
    OP_SUB = 0x94,
    OP_MUL = 0x95,
    OP_DIV = 0x96,
    OP_MOD = 0x97,
    OP_LSHIFT = 0x98,
    OP_RSHIFT = 0x99,

    OP_BOOLAND = 0x9a,
    OP_BOOLOR = 0x9b,
    OP_NUMEQUAL = 0x9c,
    OP_NUMEQUALVERIFY = 0x9d,
    OP_NUMNOTEQUAL = 0x9e,
    OP_LESSTHAN = 0x9f,
    OP_GREATERTHAN = 0xa0,
    OP_LESSTHANOREQUAL = 0xa1,
    OP_GREATERTHANOREQUAL = 0xa2,
    OP_MIN = 0xa3,
    OP_MAX = 0xa4,

    OP_WITHIN = 0xa5,

    // crypto
    OP_RIPEMD160 = 0xa6,
    OP_SHA1 = 0xa7,
    OP_SHA256 = 0xa8,
    OP_HASH160 = 0xa9,
    OP_HASH256 = 0xaa,
    OP_CODESEPARATOR = 0xab,
    OP_CHECKSIG = 0xac,
    OP_CHECKSIGVERIFY = 0xad,
    OP_CHECKMULTISIG = 0xae,
    OP_CHECKMULTISIGVERIFY = 0xaf,

    // expansion
    OP_NOP1 = 0xb0,
    OP_CHECKLOCKTIMEVERIFY = 0xb1,
    OP_NOP2 = OP_CHECKLOCKTIMEVERIFY,
    OP_CHECKSEQUENCEVERIFY = 0xb2,
    OP_NOP3 = OP_CHECKSEQUENCEVERIFY,
    OP_NOP4 = 0xb3,
    OP_NOP5 = 0xb4,
    OP_NOP6 = 0xb5,
    OP_NOP7 = 0xb6,
    OP_NOP8 = 0xb7,
    OP_NOP9 = 0xb8,
    OP_NOP10 = 0xb9,

    // More crypto
    OP_CHECKDATASIG = 0xba,
    OP_CHECKDATASIGVERIFY = 0xbb,

    // additional byte string operations
    OP_REVERSEBYTES = 0xbc,

    // Available codepoints
    // 0xbd,
    // 0xbe,
    // 0xbf,

    // Native Introspection opcodes
    OP_INPUTINDEX = 0xc0,
    OP_ACTIVEBYTECODE = 0xc1,
    OP_TXVERSION = 0xc2,
    OP_TXINPUTCOUNT = 0xc3,
    OP_TXOUTPUTCOUNT = 0xc4,
    OP_TXLOCKTIME = 0xc5,
    OP_UTXOVALUE = 0xc6,
    OP_UTXOBYTECODE = 0xc7,
    OP_OUTPOINTTXHASH = 0xc8,
    OP_OUTPOINTINDEX = 0xc9,
    OP_INPUTBYTECODE = 0xca,
    OP_INPUTSEQUENCENUMBER = 0xcb,
    OP_OUTPUTVALUE = 0xcc,
    OP_OUTPUTBYTECODE = 0xcd,

    // Native Introspection of tokens (SCRIPT_ENABLE_TOKENS must be set)
    OP_UTXOTOKENCATEGORY = 0xce,
    OP_UTXOTOKENCOMMITMENT = 0xcf,
    OP_UTXOTOKENAMOUNT = 0xd0,
    OP_OUTPUTTOKENCATEGORY = 0xd1,
    OP_OUTPUTTOKENCOMMITMENT = 0xd2,
    OP_OUTPUTTOKENAMOUNT = 0xd3,

    OP_RESERVED3 = 0xd4,
    OP_RESERVED4 = 0xd5,

    // The first op_code value after all defined opcodes
    FIRST_UNDEFINED_OP_VALUE,

    // Invalid opcode if executed, but used for special token prefix if at
    // position 0 in scriptPubKey. See: primitives/token.h
    SPECIAL_TOKEN_PREFIX = 0xef,

    // multi-byte opcodes
    OP_PREFIX_BEGIN = 0xf0,
    OP_PREFIX_END = 0xf7,

    // template matching params
    OP_SMALLINTEGER = 0xfa,
    OP_PUBKEYS = 0xfb,
    OP_PUBKEYHASH = 0xfd,
    OP_PUBKEY = 0xfe,

    OP_INVALIDOPCODE = 0xff,
};

const char *GetOpName(opcodetype opcode);

class scriptnum_error : public std::runtime_error {
public:
    explicit scriptnum_error(const std::string &str)
        : std::runtime_error(str) {}
};

/**
 * NOTE: This was copied from BCHN for CashToken support (token::SafeAmount)
 * but is not used for CScruptNum.  Original comment from BCHN follows:
 *
 * Base template class for CScriptNum and ScriptInt. This class implements
 * some of the functionality common to both subclasses, and also captures
 * some enforcement of the consensus rules related to:
 *
 *  - valid 64 bit range (INT64_MIN is forbidden)
 *  - trapping for arithmetic operations that overflow or that produce a
 *    result equal to INT64_MIN
 */
template <typename Derived>
struct ScriptIntBase {
    /**
     * Factory method to safely construct an instance from a raw int64_t.
     *
     * Note the unusual enforcement of the rules regarding valid 64-bit
     * ranges. We enforce a strict range of [INT64_MIN+1, INT64_MAX].
     */
    static constexpr
    std::optional<Derived> fromInt(int64_t x) noexcept {
        if ( ! valid64BitRange(x)) {
            return std::nullopt;
        }
        return Derived(x);
    }

    /// Performance/convenience optimization: Construct an instance from a raw
    /// int64_t where the caller already knows that the supplied value is in range.
    static constexpr
    Derived fromIntUnchecked(int64_t x) noexcept {
        return Derived(x);
    }

    friend constexpr auto operator<=>(const ScriptIntBase &a, const ScriptIntBase &b) noexcept = default;
    friend bool operator==(const ScriptIntBase &a, const ScriptIntBase &b) noexcept = default;

    constexpr auto operator<=>(int64_t x) const noexcept { return value_ <=> x; }
    constexpr bool operator==(int64_t x) noexcept { return this->operator<=>(x) == 0; }

    // Arithmetic operations
    std::optional<Derived> safeAdd(int64_t x) const noexcept {
        bool const res = __builtin_add_overflow(value_, x, &x);
        if (res) {
            return std::nullopt;
        }
        if ( ! valid64BitRange(x)) {
            return std::nullopt;
        }
        return Derived(x);
    }

    std::optional<Derived> safeAdd(Derived const& x) const noexcept {
        return safeAdd(x.value_);
    }

    std::optional<Derived> safeSub(int64_t x) const noexcept {
        bool const res = __builtin_sub_overflow(value_, x, &x);
        if (res) {
            return std::nullopt;
        }
        if ( ! valid64BitRange(x)) {
            return std::nullopt;
        }
        return Derived(x);
    }

    std::optional<Derived> safeSub(Derived const& x) const noexcept {
        return safeSub(x.value_);
    }

    std::optional<Derived> safeMul(int64_t x) const noexcept {
        bool const res = __builtin_mul_overflow(value_, x, &x);
        if (res) {
            return std::nullopt;
        }
        if ( ! valid64BitRange(x)) {
            return std::nullopt;
        }
        return Derived(x);
    }

    std::optional<Derived> safeMul(Derived const& x) const noexcept {
        return safeMul(x.value_);
    }

    constexpr
    Derived operator/(int64_t x) const noexcept {
        if (x == -1 && ! valid64BitRange(value_)) {
            // Guard against overflow, which can't normally happen unless class is misused
            // by the fromIntUnchecked() factory method (may happen in tests).
            // This will return INT64_MIN which is what ARM & x86 does anyway for INT64_MIN / -1.
            return Derived(value_);
        }
        return Derived(value_ / x);
    }

    constexpr
    Derived operator/(Derived const& x) const noexcept {
        return operator/(x.value_);
    }

    constexpr
    Derived operator%(int64_t x) const noexcept {
        if (x == -1 && ! valid64BitRange(value_)) {
            // INT64_MIN % -1 is UB in C++, but mathematically it would yield 0
            return Derived(0);
        }
        return Derived(value_ % x);
    }

    constexpr
    Derived operator%(Derived const& x) const noexcept {
        return operator%(x.value_);
    }

    // Bitwise operations
    std::optional<Derived> safeBitwiseAnd(int64_t x) const noexcept {
        x = value_ & x;
        if ( ! valid64BitRange(x)) {
            return std::nullopt;
        }
        return Derived(x);
    }

    std::optional<Derived> safeBitwiseAnd(Derived const& x) const noexcept {
        return safeBitwiseAnd(x.value_);
    }

    constexpr
    Derived operator-() const noexcept {
        // Defensive programming: -INT64_MIN is UB
        return Derived(valid64BitRange(value_) ? -value_ : value_);
    }

    constexpr
    int64_t getint64() const noexcept {
        return value_;
    }

protected:
    static constexpr
    bool valid64BitRange(int64_t x) {
        return x != std::numeric_limits<int64_t>::min();
    }

    explicit constexpr
    ScriptIntBase(int64_t x)
        : value_(x)
    {}

    int64_t value_;
};

class CScriptNum {
    /**
     * Numeric opcodes (OP_1ADD, etc) are restricted to operating on 4-byte
     * integers. The semantics are subtle, though: operands must be in the range
     * [-2^31 +1...2^31 -1], but results may overflow (and are valid as long as
     * they are not used in a subsequent numeric operation). CScriptNum enforces
     * those semantics by storing results as an int64 and allowing out-of-range
     * values to be returned as a vector of bytes but throwing an exception if
     * arithmetic is done or the result is interpreted as an integer.
     */
public:
    static constexpr size_t MAXIMUM_ELEMENT_SIZE = 4;

    explicit CScriptNum(const int64_t &n) { m_value = n; }

    explicit CScriptNum(const std::vector<uint8_t> &vch, bool fRequireMinimal,
                        const size_t nMaxNumSize = MAXIMUM_ELEMENT_SIZE) {
        if (vch.size() > nMaxNumSize) {
            throw scriptnum_error("script number overflow");
        }
        if (fRequireMinimal && !IsMinimallyEncoded(vch, nMaxNumSize)) {
            throw scriptnum_error("non-minimally encoded script number");
        }
        m_value = set_vch(vch);
    }

    static bool IsMinimallyEncoded(
        const std::vector<uint8_t> &vch,
        const size_t nMaxNumSize = CScriptNum::MAXIMUM_ELEMENT_SIZE);

    static bool MinimallyEncode(std::vector<uint8_t> &data);

    inline bool operator==(const int64_t &rhs) const { return m_value == rhs; }
    inline bool operator!=(const int64_t &rhs) const { return m_value != rhs; }
    inline bool operator<=(const int64_t &rhs) const { return m_value <= rhs; }
    inline bool operator<(const int64_t &rhs) const { return m_value < rhs; }
    inline bool operator>=(const int64_t &rhs) const { return m_value >= rhs; }
    inline bool operator>(const int64_t &rhs) const { return m_value > rhs; }

    inline bool operator==(const CScriptNum &rhs) const {
        return operator==(rhs.m_value);
    }
    inline bool operator!=(const CScriptNum &rhs) const {
        return operator!=(rhs.m_value);
    }
    inline bool operator<=(const CScriptNum &rhs) const {
        return operator<=(rhs.m_value);
    }
    inline bool operator<(const CScriptNum &rhs) const {
        return operator<(rhs.m_value);
    }
    inline bool operator>=(const CScriptNum &rhs) const {
        return operator>=(rhs.m_value);
    }
    inline bool operator>(const CScriptNum &rhs) const {
        return operator>(rhs.m_value);
    }

    inline CScriptNum operator+(const int64_t &rhs) const {
        return CScriptNum(m_value + rhs);
    }
    inline CScriptNum operator-(const int64_t &rhs) const {
        return CScriptNum(m_value - rhs);
    }
    inline CScriptNum operator+(const CScriptNum &rhs) const {
        return operator+(rhs.m_value);
    }
    inline CScriptNum operator-(const CScriptNum &rhs) const {
        return operator-(rhs.m_value);
    }

    inline CScriptNum operator/(const int64_t &rhs) const {
        return CScriptNum(m_value / rhs);
    }
    inline CScriptNum operator/(const CScriptNum &rhs) const {
        return operator/(rhs.m_value);
    }

    inline CScriptNum operator%(const int64_t &rhs) const {
        return CScriptNum(m_value % rhs);
    }
    inline CScriptNum operator%(const CScriptNum &rhs) const {
        return operator%(rhs.m_value);
    }

    inline CScriptNum &operator+=(const CScriptNum &rhs) {
        return operator+=(rhs.m_value);
    }
    inline CScriptNum &operator-=(const CScriptNum &rhs) {
        return operator-=(rhs.m_value);
    }

    inline CScriptNum operator&(const int64_t &rhs) const {
        return CScriptNum(m_value & rhs);
    }
    inline CScriptNum operator&(const CScriptNum &rhs) const {
        return operator&(rhs.m_value);
    }

    inline CScriptNum &operator&=(const CScriptNum &rhs) {
        return operator&=(rhs.m_value);
    }

    inline CScriptNum operator-() const {
        assert(m_value != std::numeric_limits<int64_t>::min());
        return CScriptNum(-m_value);
    }

    inline CScriptNum &operator=(const int64_t &rhs) {
        m_value = rhs;
        return *this;
    }

    inline CScriptNum &operator+=(const int64_t &rhs) {
        assert(
            rhs == 0 ||
            (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) ||
            (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs));
        m_value += rhs;
        return *this;
    }

    inline CScriptNum &operator-=(const int64_t &rhs) {
        assert(
            rhs == 0 ||
            (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) ||
            (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs));
        m_value -= rhs;
        return *this;
    }

    inline CScriptNum &operator&=(const int64_t &rhs) {
        m_value &= rhs;
        return *this;
    }

    int getint() const {
        if (m_value > std::numeric_limits<int>::max())
            return std::numeric_limits<int>::max();
        else if (m_value < std::numeric_limits<int>::min())
            return std::numeric_limits<int>::min();
        return m_value;
    }

    std::vector<uint8_t> getvch() const { return serialize(m_value); }

    static std::vector<uint8_t> serialize(const int64_t &value) {
        if (value == 0) {
            return {};
        }

        std::vector<uint8_t> result;
        const bool neg = value < 0;
        uint64_t absvalue = neg ? -value : value;

        while (absvalue) {
            result.push_back(absvalue & 0xff);
            absvalue >>= 8;
        }

        // - If the most significant byte is >= 0x80 and the value is positive,
        // push a new zero-byte to make the significant byte < 0x80 again.
        // - If the most significant byte is >= 0x80 and the value is negative,
        // push a new 0x80 byte that will be popped off when converting to an
        // integral.
        // - If the most significant byte is < 0x80 and the value is negative,
        // add 0x80 to it, since it will be subtracted and interpreted as a
        // negative when converting to an integral.
        if (result.back() & 0x80) {
            result.push_back(neg ? 0x80 : 0);
        } else if (neg) {
            result.back() |= 0x80;
        }

        return result;
    }

private:
    static int64_t set_vch(const std::vector<uint8_t> &vch) {
        if (vch.empty()) {
            return 0;
        }

        int64_t result = 0;
        for (size_t i = 0; i != vch.size(); ++i) {
            result |= int64_t(vch[i]) << 8 * i;
        }

        // If the input vector's most significant byte is 0x80, remove it from
        // the result's msb and return a negative.
        if (vch.back() & 0x80) {
            return -int64_t(result & ~(0x80ULL << (8 * (vch.size() - 1))));
        }

        return result;
    }

    int64_t m_value;
};

using CScriptBase = prevector<28, uint8_t>;

/** Serialized script, used inside transaction inputs and outputs */
class CScript : public CScriptBase {
protected:
    CScript &push_int64(int64_t n) {
        if (n == -1 || (n >= 1 && n <= 16)) {
            push_back(n + (OP_1 - 1));
        } else if (n == 0) {
            push_back(OP_0);
        } else {
            *this << CScriptNum::serialize(n);
        }
        return *this;
    }

public:
    constexpr CScript() noexcept = default;

    template <std::random_access_iterator It>
    CScript(It pbegin, It pend)
        : CScriptBase(pbegin, pend) {}

    SERIALIZE_METHODS(CScript, obj) { READWRITEAS(CScriptBase, obj); }

    CScript &operator+=(const CScript &b) {
        insert(end(), b.begin(), b.end());
        return *this;
    }

    friend CScript operator+(const CScript &a, const CScript &b) {
        CScript ret = a;
        ret += b;
        return ret;
    }

    CScript(int64_t b) { operator<<(b); }

    explicit CScript(opcodetype b) { operator<<(b); }
    explicit CScript(const CScriptNum &b) { operator<<(b); }
    explicit CScript(const std::vector<uint8_t> &b) { operator<<(b); }

    CScript &operator<<(int64_t b) { return push_int64(b); }

    CScript &operator<<(opcodetype opcode) {
        if (opcode < 0 || opcode > 0xff) {
            throw std::runtime_error("CScript::operator<<(): invalid opcode");
        }
        insert(end(), uint8_t(opcode));
        return *this;
    }

    CScript &operator<<(const CScriptNum &b) {
        *this << b.getvch();
        return *this;
    }

    /// Append a byte blob to the script, including the pushdata opcode, if any, and the length byte(s) prepended.
    ///
    /// Note that unlike the streams classes in streams.h, pushing a vector vs pushing a span (ByteView) will yield
    /// identical results, with the length byte(s) *always* present; e.g. the following are identical:
    ///     `script << someVector`
    ///     `script << std::span{someVector}`
    CScript &operator<<(const std::span<const uint8_t> &b) {
        if (!b.empty() && b.data() >= begin() && b.data() < end()) [[unlikely]] {
            // Detect class mis-use which may result in UB: an attempt to push a (sub)script onto itself, and compensate
            // by allocating a temporary vector to hold the bytes to be pushed.
            return this->operator<<(std::span<const uint8_t>{std::vector<uint8_t>(b.begin(), b.end())});
        }
        if (b.size() < OP_PUSHDATA1) {
            insert(end(), uint8_t(b.size()));
        } else if (b.size() <= 0xff) {
            insert(end(), OP_PUSHDATA1);
            insert(end(), uint8_t(b.size()));
        } else if (b.size() <= 0xffff) {
            insert(end(), OP_PUSHDATA2);
            uint8_t _data[2];
            WriteLE16(_data, b.size());
            insert(end(), _data, _data + sizeof(_data));
        } else {
            insert(end(), OP_PUSHDATA4);
            uint8_t _data[4];
            WriteLE32(_data, b.size());
            insert(end(), _data, _data + sizeof(_data));
        }
        insert(end(), b.begin(), b.end());
        return *this;
    }

    CScript &operator<<(const std::span<const std::byte> &b) {
        const uint8_t *const p = reinterpret_cast<const uint8_t *>(b.data());
        return this->operator<<(std::span<const uint8_t>{p, b.size()});
    }

    /// Intentionally unimplemented; it's not clear if this should push the script or concatenate scripts. If there's
    /// ever a need for pushing one script onto another script, one may cast the argument to a span, e.g.:
    ///     `script << std::span<const uint8_t>{otherScript}`
    CScript &operator<<(const CScript &b) = delete;

    bool GetOp(iterator &pc, opcodetype &opcodeRet,
               std::vector<uint8_t> &vchRet) {
        // Wrapper so it can be called with either iterator or const_iterator.
        const_iterator pc2 = pc;
        bool fRet = GetOp2(pc2, opcodeRet, &vchRet);
        pc = begin() + (pc2 - begin());
        return fRet;
    }

    bool GetOp(iterator &pc, opcodetype &opcodeRet) {
        const_iterator pc2 = pc;
        bool fRet = GetOp2(pc2, opcodeRet, nullptr);
        pc = begin() + (pc2 - begin());
        return fRet;
    }

    bool GetOp(const_iterator &pc, opcodetype &opcodeRet,
               std::vector<uint8_t> &vchRet) const {
        return GetOp2(pc, opcodeRet, &vchRet);
    }

    bool GetOp(const_iterator &pc, opcodetype &opcodeRet) const {
        return GetOp2(pc, opcodeRet, nullptr);
    }

    bool GetOp2(const_iterator &pc, opcodetype &opcodeRet,
                std::vector<uint8_t> *pvchRet) const {
        opcodeRet = OP_INVALIDOPCODE;
        if (pvchRet) pvchRet->clear();
        if (pc >= end()) return false;

        // Read instruction
        if (end() - pc < 1) return false;

        uint32_t opcode = *pc++;

        // Immediate operand
        if (opcode <= OP_PUSHDATA4) {
            uint32_t nSize = 0;
            if (opcode < OP_PUSHDATA1) {
                nSize = opcode;
            } else if (opcode == OP_PUSHDATA1) {
                if (end() - pc < 1) return false;
                nSize = *pc++;
            } else if (opcode == OP_PUSHDATA2) {
                if (end() - pc < 2) return false;
                nSize = ReadLE16(&pc[0]);
                pc += 2;
            } else if (opcode == OP_PUSHDATA4) {
                if (end() - pc < 4) return false;
                nSize = ReadLE32(&pc[0]);
                pc += 4;
            }
            if (end() - pc < 0 || uint32_t(end() - pc) < nSize) {
                return false;
            }
            if (pvchRet) pvchRet->assign(pc, pc + nSize);
            pc += nSize;
        }

        opcodeRet = static_cast<opcodetype>(opcode);
        return true;
    }

    /** Encode/decode small integers: */
    static int DecodeOP_N(opcodetype opcode) {
        if (opcode == OP_0) {
            return 0;
        }

        assert(opcode >= OP_1 && opcode <= OP_16);
        return int(opcode) - int(OP_1 - 1);
    }
    static opcodetype EncodeOP_N(int n) {
        assert(n >= 0 && n <= 16);
        if (n == 0) {
            return OP_0;
        }

        return (opcodetype)(OP_1 + n - 1);
    }

    int FindAndDelete(const CScript &b) {
        int nFound = 0;
        if (b.empty()) {
            return nFound;
        }

        CScript result;
        iterator pc = begin(), pc2 = begin();
        opcodetype opcode;
        do {
            result.insert(result.end(), pc2, pc);
            while (size_t(end() - pc) >= b.size() &&
                   std::equal(b.begin(), b.end(), pc)) {
                pc = pc + b.size();
                ++nFound;
            }
            pc2 = pc;
        } while (GetOp(pc, opcode));

        if (nFound > 0) {
            result.insert(result.end(), pc2, end());
            *this = result;
        }

        return nFound;
    }
    int Find(opcodetype op) const {
        int nFound = 0;
        opcodetype opcode;
        for (const_iterator pc = begin(); pc != end() && GetOp(pc, opcode);) {
            if (opcode == op) {
                ++nFound;
            }
        }
        return nFound;
    }

    /**
     * Pre-version-0.6, Bitcoin always counted CHECKMULTISIGs as 20 sigops. With
     * pay-to-script-hash, that changed: CHECKMULTISIGs serialized in scriptSigs
     * are counted more accurately, assuming they are of the form
     *  ... OP_N CHECKMULTISIG ...
     */
    uint32_t GetSigOpCount(uint32_t flags, bool fAccurate) const;

    /**
     * Accurately count sigOps, including sigOps in pay-to-script-hash
     * transactions:
     */
    uint32_t GetSigOpCount(uint32_t flags, const CScript &scriptSig) const;

    bool IsPayToScriptHash() const;
    bool IsCommitment(const std::vector<uint8_t> &data) const;

    // A witness program is any valid CScript that consists of a 1-byte push opcode
    // followed by a data push between 2 and 40 bytes.
    static bool IsWitnessProgram(const std::span<const uint8_t> &blob, int *pversion = nullptr,
                                 std::vector<uint8_t> *pprogram = nullptr);
    bool IsWitnessProgram(int *pversion = nullptr, std::vector<uint8_t> *pprogram = nullptr) const {
        return IsWitnessProgram(*this, pversion, pprogram);
    }
    bool IsWitnessProgram(int &version, std::vector<uint8_t> &program) const {
        return IsWitnessProgram(&version, &program);
    }

    /**
     * Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it
     * consensus-critical).
     */
    bool IsPushOnly(const_iterator pc, std::vector<uint8_t> *lastPush = nullptr, bool disallowOpReserved = false,
                    size_t *pnPushes = nullptr) const;
    bool IsPushOnly(std::vector<uint8_t> *lastPush = nullptr, bool disallowOpReserved = false, size_t *pnPushes = nullptr) const;

    /**
     * Returns whether the script is guaranteed to fail at execution, regardless
     * of the initial stack. This allows outputs to be pruned instantly when
     * entering the UTXO set.
     */
    bool IsUnspendable() const {
        return (size() > 0 && *begin() == OP_RETURN) ||
               (size() > MAX_SCRIPT_SIZE);
    }

    void clear() {
        // The default prevector::clear() does not release memory
        CScriptBase::clear();
        shrink_to_fit();
    }
};

class CReserveScript {
public:
    CScript reserveScript;
    virtual void KeepScript() {}
    CReserveScript() {}
    virtual ~CReserveScript() {}
};

/// Added by Calin to support deserializing BTC Core blocks via RPC
/// If you update this file from fresh BCHN sources, be sure to keep
/// this struct around
struct CScriptWitness
{
    // Note that this encodes the data elements being pushed, rather than
    // encoding them as a CScript that pushes them.
    std::vector<std::vector<unsigned char> > stack;

    // Some compilers complain without a default constructor
    constexpr CScriptWitness() noexcept = default;

    constexpr bool IsNull() const noexcept { return stack.empty(); }

    void SetNull() { stack.clear(); stack.shrink_to_fit(); }

    std::string ToString() const;

    bool operator==(const CScriptWitness &) const noexcept = default;
};

} // end namespace bitcoin

#ifdef __clang__
#pragma clang diagnostic pop
#endif
