rust-bitcoin-unsafe-fast/bitcoin/src/blockdata/transaction.rs

// Written in 2014 by Andrew Poelstra <apoelstra@wpsoftware.net>
// SPDX-License-Identifier: CC0-1.0

//! Bitcoin transactions.
//!
//! A transaction describes a transfer of money. It consumes previously-unspent
//! transaction outputs and produces new ones, satisfying the condition to spend
//! the old outputs (typically a digital signature with a specific key must be
//! provided) and defining the condition to spend the new ones. The use of digital
//! signatures ensures that coins cannot be spent by unauthorized parties.
//!
//! This module provides the structures and functions needed to support transactions.
//!

use core::convert::TryFrom;
use core::default::Default;
use core::{cmp, fmt, str};

use bitcoin_internals::write_err;

use super::Weight;
use crate::blockdata::constants::WITNESS_SCALE_FACTOR;
use crate::blockdata::locktime::absolute::{self, Height, Time};
use crate::blockdata::locktime::relative;
#[cfg(feature = "bitcoinconsensus")]
use crate::blockdata::script;
use crate::blockdata::script::{Script, ScriptBuf};
use crate::blockdata::witness::Witness;
use crate::consensus::{encode, Decodable, Encodable};
use crate::crypto::sighash::LegacySighash;
use crate::hash_types::{Txid, Wtxid};
use crate::hashes::{self, sha256d, Hash};
use crate::internal_macros::impl_consensus_encoding;
use crate::parse::impl_parse_str_from_int_infallible;
use crate::prelude::*;
#[cfg(doc)]
use crate::sighash::{EcdsaSighashType, TapSighashType};
use crate::string::FromHexStr;
use crate::{io, VarInt};

/// A reference to a transaction output.
///
/// ### Bitcoin Core References
///
/// * [COutPoint definition](https://github.com/bitcoin/bitcoin/blob/345457b542b6a980ccfbc868af0970a6f91d1b82/src/primitives/transaction.h#L26)
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
pub struct OutPoint {
    /// The referenced transaction's txid.
    pub txid: Txid,
    /// The index of the referenced output in its transaction's vout.
    pub vout: u32,
}
#[cfg(feature = "serde")]
crate::serde_utils::serde_struct_human_string_impl!(OutPoint, "an OutPoint", txid, vout);

impl OutPoint {
    /// Creates a new [`OutPoint`].
    #[inline]
    pub fn new(txid: Txid, vout: u32) -> OutPoint { OutPoint { txid, vout } }

    /// Creates a "null" `OutPoint`.
    ///
    /// This value is used for coinbase transactions because they don't have any previous outputs.
    #[inline]
    pub fn null() -> OutPoint { OutPoint { txid: Hash::all_zeros(), vout: u32::max_value() } }

    /// Checks if an `OutPoint` is "null".
    ///
    /// # Examples
    ///
    /// ```rust
    /// use bitcoin::constants::genesis_block;
    /// use bitcoin::network::constants::Network;
    ///
    /// let block = genesis_block(Network::Bitcoin);
    /// let tx = &block.txdata[0];
    ///
    /// // Coinbase transactions don't have any previous output.
    /// assert!(tx.input[0].previous_output.is_null());
    /// ```
    #[inline]
    pub fn is_null(&self) -> bool { *self == OutPoint::null() }
}

impl Default for OutPoint {
    fn default() -> Self { OutPoint::null() }
}

impl fmt::Display for OutPoint {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}:{}", self.txid, self.vout)
    }
}

/// An error in parsing an OutPoint.
#[derive(Clone, PartialEq, Eq, Debug)]
#[non_exhaustive]
pub enum ParseOutPointError {
    /// Error in TXID part.
    Txid(hashes::hex::Error),
    /// Error in vout part.
    Vout(crate::error::ParseIntError),
    /// Error in general format.
    Format,
    /// Size exceeds max.
    TooLong,
    /// Vout part is not strictly numeric without leading zeroes.
    VoutNotCanonical,
}

impl fmt::Display for ParseOutPointError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            ParseOutPointError::Txid(ref e) => write_err!(f, "error parsing TXID"; e),
            ParseOutPointError::Vout(ref e) => write_err!(f, "error parsing vout"; e),
            ParseOutPointError::Format => write!(f, "OutPoint not in <txid>:<vout> format"),
            ParseOutPointError::TooLong => write!(f, "vout should be at most 10 digits"),
            ParseOutPointError::VoutNotCanonical =>
                write!(f, "no leading zeroes or + allowed in vout part"),
        }
    }
}

#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
impl std::error::Error for ParseOutPointError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        use self::ParseOutPointError::*;

        match self {
            Txid(e) => Some(e),
            Vout(e) => Some(e),
            Format | TooLong | VoutNotCanonical => None,
        }
    }
}

/// Parses a string-encoded transaction index (vout).
///
/// Does not permit leading zeroes or non-digit characters.
fn parse_vout(s: &str) -> Result<u32, ParseOutPointError> {
    if s.len() > 1 {
        let first = s.chars().next().unwrap();
        if first == '0' || first == '+' {
            return Err(ParseOutPointError::VoutNotCanonical);
        }
    }
    crate::parse::int(s).map_err(ParseOutPointError::Vout)
}

impl core::str::FromStr for OutPoint {
    type Err = ParseOutPointError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if s.len() > 75 {
            // 64 + 1 + 10
            return Err(ParseOutPointError::TooLong);
        }
        let find = s.find(':');
        if find.is_none() || find != s.rfind(':') {
            return Err(ParseOutPointError::Format);
        }
        let colon = find.unwrap();
        if colon == 0 || colon == s.len() - 1 {
            return Err(ParseOutPointError::Format);
        }
        Ok(OutPoint {
            txid: s[..colon].parse().map_err(ParseOutPointError::Txid)?,
            vout: parse_vout(&s[colon + 1..])?,
        })
    }
}

/// Bitcoin transaction input.
///
/// It contains the location of the previous transaction's output,
/// that it spends and set of scripts that satisfy its spending
/// conditions.
///
/// ### Bitcoin Core References
///
/// * [CTxIn definition](https://github.com/bitcoin/bitcoin/blob/345457b542b6a980ccfbc868af0970a6f91d1b82/src/primitives/transaction.h#L65)
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct TxIn {
    /// The reference to the previous output that is being used an an input.
    pub previous_output: OutPoint,
    /// The script which pushes values on the stack which will cause
    /// the referenced output's script to be accepted.
    pub script_sig: ScriptBuf,
    /// The sequence number, which suggests to miners which of two
    /// conflicting transactions should be preferred, or 0xFFFFFFFF
    /// to ignore this feature. This is generally never used since
    /// the miner behaviour cannot be enforced.
    pub sequence: Sequence,
    /// Witness data: an array of byte-arrays.
    /// Note that this field is *not* (de)serialized with the rest of the TxIn in
    /// Encodable/Decodable, as it is (de)serialized at the end of the full
    /// Transaction. It *is* (de)serialized with the rest of the TxIn in other
    /// (de)serialization routines.
    pub witness: Witness,
}

impl TxIn {
    /// Returns true if this input enables the [`absolute::LockTime`] (aka `nLockTime`) of its
    /// [`Transaction`].
    ///
    /// `nLockTime` is enabled if *any* input enables it. See [`Transaction::is_lock_time_enabled`]
    ///  to check the overall state. If none of the inputs enables it, the lock time value is simply
    ///  ignored. If this returns false and OP_CHECKLOCKTIMEVERIFY is used in the redeem script with
    ///  this input then the script execution will fail [BIP-0065].
    ///
    /// [BIP-65](https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki)
    pub fn enables_lock_time(&self) -> bool { self.sequence != Sequence::MAX }

    /// The weight of the TxIn when it's included in a legacy transaction (i.e., a transaction
    /// having only legacy inputs).
    ///
    /// The witness weight is ignored here even when the witness is non-empty.
    /// If you want the witness to be taken into account, use `TxIn::segwit_weight` instead.
    ///
    /// Keep in mind that when adding a TxIn to a transaction, the total weight of the transaction
    /// might increase more than `TxIn::legacy_weight`. This happens when the new input added causes
    /// the input length `VarInt` to increase its encoding length.
    pub fn legacy_weight(&self) -> usize {
        let script_sig_size = self.script_sig.len();
        // Size in vbytes:
        // previous_output (36) + script_sig varint len + script_sig push + sequence (4)
        // We then multiply by 4 to convert to WU
        (36 + VarInt(script_sig_size as u64).len() + script_sig_size + 4) * 4
    }

    /// The weight of the TxIn when it's included in a segwit transaction (i.e., a transcation
    /// having at least one segwit input).
    ///
    /// This always takes into account the witness, even when empty, in which
    /// case 1WU for the witness length varint (`00`) is included.
    ///
    /// Keep in mind that when adding a TxIn to a transaction, the total weight of the transaction
    /// might increase more than `TxIn::segwit_weight`. This happens when:
    /// - the new input added causes the input length `VarInt` to increase its encoding length
    /// - the new input is the first segwit input added - this will add an additional 2WU to the
    ///   transaction weight to take into account the segwit marker
    pub fn segwit_weight(&self) -> usize { self.legacy_weight() + self.witness.serialized_len() }
}

impl Default for TxIn {
    fn default() -> TxIn {
        TxIn {
            previous_output: OutPoint::default(),
            script_sig: ScriptBuf::new(),
            sequence: Sequence::MAX,
            witness: Witness::default(),
        }
    }
}

/// Bitcoin transaction input sequence number.
///
/// The sequence field is used for:
/// - Indicating whether absolute lock-time (specified in `lock_time` field of [`Transaction`])
///   is enabled.
/// - Indicating and encoding [BIP-68] relative lock-times.
/// - Indicating whether a transcation opts-in to [BIP-125] replace-by-fee.
///
/// Note that transactions spending an output with `OP_CHECKLOCKTIMEVERIFY`MUST NOT use
/// `Sequence::MAX` for the corresponding input. [BIP-65]
///
/// [BIP-65]: <https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki>
/// [BIP-68]: <https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki>
/// [BIP-125]: <https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki>
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct Sequence(pub u32);

impl Sequence {
    /// The maximum allowable sequence number.
    ///
    /// This sequence number disables absolute lock time and replace-by-fee.
    pub const MAX: Self = Sequence(0xFFFFFFFF);
    /// Zero value sequence.
    ///
    /// This sequence number enables replace-by-fee and absolute lock time.
    pub const ZERO: Self = Sequence(0);
    /// The sequence number that enables absolute lock time but disables replace-by-fee
    /// and relative lock time.
    pub const ENABLE_LOCKTIME_NO_RBF: Self = Sequence::MIN_NO_RBF;
    /// The sequence number that enables replace-by-fee and absolute lock time but
    /// disables relative lock time.
    pub const ENABLE_RBF_NO_LOCKTIME: Self = Sequence(0xFFFFFFFD);

    /// The lowest sequence number that does not opt-in for replace-by-fee.
    ///
    /// A transaction is considered to have opted in to replacement of itself
    /// if any of it's inputs have a `Sequence` number less than this value
    /// (Explicit Signalling [BIP-125]).
    ///
    /// [BIP-125]: <https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki]>
    const MIN_NO_RBF: Self = Sequence(0xFFFFFFFE);
    /// BIP-68 relative lock time disable flag mask.
    const LOCK_TIME_DISABLE_FLAG_MASK: u32 = 0x80000000;
    /// BIP-68 relative lock time type flag mask.
    const LOCK_TYPE_MASK: u32 = 0x00400000;

    /// The maximum allowable sequence number.
    ///
    /// This is provided for consistency with Rust 1.41.1, newer code should use [`Sequence::MAX`].
    pub const fn max_value() -> Self { Self::MAX }

    /// Returns `true` if the sequence number enables absolute lock-time ([`Transaction::lock_time`]).
    #[inline]
    pub fn enables_absolute_lock_time(&self) -> bool { *self != Sequence::MAX }

    /// Returns `true` if the sequence number indicates that the transaction is finalized.
    ///
    /// Instead of this method please consider using `!enables_absolute_lock_time` because it
    /// is equivalent and improves readability for those not steeped in Bitcoin folklore.
    ///
    /// ## Historical note
    ///
    /// The term 'final' is an archaic Bitcoin term, it may have come about because the sequence
    /// number in the original Bitcoin code was intended to be incremented in order to replace a
    /// transaction, so once the sequence number got to `u64::MAX` it could no longer be increased,
    /// hence it was 'final'.
    ///
    ///
    /// Some other references to the term:
    /// - `CTxIn::SEQUENCE_FINAL` in the Bitcoin Core code.
    /// - [BIP-112]: "BIP 68 prevents a non-final transaction from being selected for inclusion in a
    ///   block until the corresponding input has reached the specified age"
    ///
    /// [BIP-112]: <https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki>
    #[inline]
    pub fn is_final(&self) -> bool { !self.enables_absolute_lock_time() }

    /// Returns true if the transaction opted-in to BIP125 replace-by-fee.
    ///
    /// Replace by fee is signaled by the sequence being less than 0xfffffffe which is checked by
    /// this method. Note, this is the highest "non-final" value (see [`Sequence::is_final`]).
    #[inline]
    pub fn is_rbf(&self) -> bool { *self < Sequence::MIN_NO_RBF }

    /// Returns `true` if the sequence has a relative lock-time.
    #[inline]
    pub fn is_relative_lock_time(&self) -> bool {
        self.0 & Sequence::LOCK_TIME_DISABLE_FLAG_MASK == 0
    }

    /// Returns `true` if the sequence number encodes a block based relative lock-time.
    #[inline]
    pub fn is_height_locked(&self) -> bool {
        self.is_relative_lock_time() & (self.0 & Sequence::LOCK_TYPE_MASK == 0)
    }

    /// Returns `true` if the sequene number encodes a time interval based relative lock-time.
    #[inline]
    pub fn is_time_locked(&self) -> bool {
        self.is_relative_lock_time() & (self.0 & Sequence::LOCK_TYPE_MASK > 0)
    }

    /// Creates a relative lock-time using block height.
    #[inline]
    pub fn from_height(height: u16) -> Self { Sequence(u32::from(height)) }

    /// Creates a relative lock-time using time intervals where each interval is equivalent
    /// to 512 seconds.
    ///
    /// Encoding finer granularity of time for relative lock-times is not supported in Bitcoin
    #[inline]
    pub fn from_512_second_intervals(intervals: u16) -> Self {
        Sequence(u32::from(intervals) | Sequence::LOCK_TYPE_MASK)
    }

    /// Creates a relative lock-time from seconds, converting the seconds into 512 second
    /// interval with floor division.
    ///
    /// Will return an error if the input cannot be encoded in 16 bits.
    #[inline]
    pub fn from_seconds_floor(seconds: u32) -> Result<Self, relative::Error> {
        if let Ok(interval) = u16::try_from(seconds / 512) {
            Ok(Sequence::from_512_second_intervals(interval))
        } else {
            Err(relative::Error::IntegerOverflow(seconds))
        }
    }

    /// Creates a relative lock-time from seconds, converting the seconds into 512 second
    /// interval with ceiling division.
    ///
    /// Will return an error if the input cannot be encoded in 16 bits.
    #[inline]
    pub fn from_seconds_ceil(seconds: u32) -> Result<Self, relative::Error> {
        if let Ok(interval) = u16::try_from((seconds + 511) / 512) {
            Ok(Sequence::from_512_second_intervals(interval))
        } else {
            Err(relative::Error::IntegerOverflow(seconds))
        }
    }

    /// Creates a sequence from a u32 value.
    #[inline]
    pub fn from_consensus(n: u32) -> Self { Sequence(n) }

    /// Returns the inner 32bit integer value of Sequence.
    #[inline]
    pub fn to_consensus_u32(self) -> u32 { self.0 }

    /// Creates a [`relative::LockTime`] from this [`Sequence`] number.
    #[inline]
    pub fn to_relative_lock_time(&self) -> Option<relative::LockTime> {
        use crate::locktime::relative::{Height, LockTime, Time};

        if !self.is_relative_lock_time() {
            return None;
        }

        let lock_value = self.low_u16();

        if self.is_time_locked() {
            Some(LockTime::from(Time::from_512_second_intervals(lock_value)))
        } else {
            Some(LockTime::from(Height::from(lock_value)))
        }
    }

    /// Returns the low 16 bits from sequence number.
    ///
    /// BIP-68 only uses the low 16 bits for relative lock value.
    fn low_u16(&self) -> u16 { self.0 as u16 }
}

impl FromHexStr for Sequence {
    type Error = crate::parse::ParseIntError;

    fn from_hex_str_no_prefix<S: AsRef<str> + Into<String>>(s: S) -> Result<Self, Self::Error> {
        let sequence = crate::parse::hex_u32(s)?;
        Ok(Self::from_consensus(sequence))
    }
}

impl Default for Sequence {
    /// The default value of sequence is 0xffffffff.
    fn default() -> Self { Sequence::MAX }
}

impl From<Sequence> for u32 {
    fn from(sequence: Sequence) -> u32 { sequence.0 }
}

impl fmt::Display for Sequence {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
}

impl fmt::LowerHex for Sequence {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
}

impl fmt::UpperHex for Sequence {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::UpperHex::fmt(&self.0, f) }
}

impl_parse_str_from_int_infallible!(Sequence, u32, from_consensus);

/// Bitcoin transaction output.
///
/// Defines new coins to be created as a result of the transaction,
/// along with spending conditions ("script", aka "output script"),
/// which an input spending it must satisfy.
///
/// An output that is not yet spent by an input is called Unspent Transaction Output ("UTXO").
///
/// ### Bitcoin Core References
///
/// * [CTxOut definition](https://github.com/bitcoin/bitcoin/blob/345457b542b6a980ccfbc868af0970a6f91d1b82/src/primitives/transaction.h#L148)
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct TxOut {
    /// The value of the output, in satoshis.
    pub value: u64,
    /// The script which must be satisfied for the output to be spent.
    pub script_pubkey: ScriptBuf,
}

impl TxOut {
    /// The weight of the txout in witness units
    ///
    /// Keep in mind that when adding a TxOut to a transaction, the total weight of the transaction
    /// might increase more than `TxOut::weight`. This happens when the new output added causes
    /// the output length `VarInt` to increase its encoding length.
    pub fn weight(&self) -> usize {
        let script_len = self.script_pubkey.len();
        // In vbytes:
        // value (8) + script varint len + script push
        // Then we multiply by 4 to convert to WU
        (8 + VarInt(script_len as u64).len() + script_len) * 4
    }

    /// Creates a `TxOut` with given script and the smallest possible `value` that is **not** dust
    /// per current Core policy.
    ///
    /// The current dust fee rate is 3 sat/vB.
    pub fn minimal_non_dust(script_pubkey: ScriptBuf) -> Self {
        let len = script_pubkey.len() + VarInt(script_pubkey.len() as u64).len() + 8;
        let len = len
            + if script_pubkey.is_witness_program() {
                32 + 4 + 1 + (107 / 4) + 4
            } else {
                32 + 4 + 1 + 107 + 4
            };
        let dust_amount = (len as u64) * 3;

        TxOut {
            value: dust_amount + 1, // minimal non-dust amount is one higher than dust amount
            script_pubkey,
        }
    }
}

// This is used as a "null txout" in consensus signing code.
impl Default for TxOut {
    fn default() -> TxOut { TxOut { value: 0xffffffffffffffff, script_pubkey: ScriptBuf::new() } }
}

/// Result of [`Transaction::encode_signing_data_to`].
///
/// This type forces the caller to handle SIGHASH_SINGLE bug case.
///
/// This corner case can't be expressed using standard `Result`,
/// in a way that is both convenient and not-prone to accidental
/// mistakes (like calling `.expect("writer never fails")`).
#[must_use]
pub enum EncodeSigningDataResult<E> {
    /// Input data is an instance of `SIGHASH_SINGLE` bug
    SighashSingleBug,
    /// Operation performed normally.
    WriteResult(Result<(), E>),
}

impl<E> EncodeSigningDataResult<E> {
    /// Checks for SIGHASH_SINGLE bug returning error if the writer failed.
    ///
    /// This method is provided for easy and correct handling of the result because
    /// SIGHASH_SINGLE bug is a special case that must not be ignored nor cause panicking.
    /// Since the data is usually written directly into a hasher which never fails,
    /// the recommended pattern to handle this is:
    ///
    /// ```rust
    /// # use bitcoin::consensus::deserialize;
    /// # use bitcoin::sighash::{LegacySighash, SighashCache};
    /// # use bitcoin::Transaction;
    /// # use bitcoin_hashes::{Hash, hex::FromHex};
    /// # let mut writer = LegacySighash::engine();
    /// # let input_index = 0;
    /// # let script_pubkey = bitcoin::ScriptBuf::new();
    /// # let sighash_u32 = 0u32;
    /// # const SOME_TX: &'static str = "0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000";
    /// # let raw_tx = Vec::from_hex(SOME_TX).unwrap();
    /// # let tx: Transaction = deserialize(&raw_tx).unwrap();
    /// let cache = SighashCache::new(&tx);
    /// if cache.legacy_encode_signing_data_to(&mut writer, input_index, &script_pubkey, sighash_u32)
    ///         .is_sighash_single_bug()
    ///         .expect("writer can't fail") {
    ///     // use a hash value of "1", instead of computing the actual hash due to SIGHASH_SINGLE bug
    /// }
    /// ```
    #[allow(clippy::wrong_self_convention)] // E is not Copy so we consume self.
    pub fn is_sighash_single_bug(self) -> Result<bool, E> {
        match self {
            EncodeSigningDataResult::SighashSingleBug => Ok(true),
            EncodeSigningDataResult::WriteResult(Ok(())) => Ok(false),
            EncodeSigningDataResult::WriteResult(Err(e)) => Err(e),
        }
    }

    /// Maps a `Result<T, E>` to `Result<T, F>` by applying a function to a
    /// contained [`Err`] value, leaving an [`Ok`] value untouched.
    ///
    /// Like [`Result::map_err`].
    pub fn map_err<E2, F>(self, f: F) -> EncodeSigningDataResult<E2>
    where
        F: FnOnce(E) -> E2,
    {
        match self {
            EncodeSigningDataResult::SighashSingleBug => EncodeSigningDataResult::SighashSingleBug,
            EncodeSigningDataResult::WriteResult(Err(e)) =>
                EncodeSigningDataResult::WriteResult(Err(f(e))),
            EncodeSigningDataResult::WriteResult(Ok(o)) =>
                EncodeSigningDataResult::WriteResult(Ok(o)),
        }
    }
}

/// Bitcoin transaction.
///
/// An authenticated movement of coins.
///
/// See [Bitcoin Wiki: Transaction][wiki-transaction] for more information.
///
/// [wiki-transaction]: https://en.bitcoin.it/wiki/Transaction
///
/// ### Bitcoin Core References
///
/// * [CTtransaction definition](https://github.com/bitcoin/bitcoin/blob/345457b542b6a980ccfbc868af0970a6f91d1b82/src/primitives/transaction.h#L279)
///
/// ### Serialization notes
///
/// If any inputs have nonempty witnesses, the entire transaction is serialized
/// in the post-BIP141 Segwit format which includes a list of witnesses. If all
/// inputs have empty witnesses, the transaction is serialized in the pre-BIP141
/// format.
///
/// There is one major exception to this: to avoid deserialization ambiguity,
/// if the transaction has no inputs, it is serialized in the BIP141 style. Be
/// aware that this differs from the transaction format in PSBT, which _never_
/// uses BIP141. (Ordinarily there is no conflict, since in PSBT transactions
/// are always unsigned and therefore their inputs have empty witnesses.)
///
/// The specific ambiguity is that Segwit uses the flag bytes `0001` where an old
/// serializer would read the number of transaction inputs. The old serializer
/// would interpret this as "no inputs, one output", which means the transaction
/// is invalid, and simply reject it. Segwit further specifies that this encoding
/// should *only* be used when some input has a nonempty witness; that is,
/// witness-less transactions should be encoded in the traditional format.
///
/// However, in protocols where transactions may legitimately have 0 inputs, e.g.
/// when parties are cooperatively funding a transaction, the "00 means Segwit"
/// heuristic does not work. Since Segwit requires such a transaction be encoded
/// in the original transaction format (since it has no inputs and therefore
/// no input witnesses), a traditionally encoded transaction may have the `0001`
/// Segwit flag in it, which confuses most Segwit parsers including the one in
/// Bitcoin Core.
///
/// We therefore deviate from the spec by always using the Segwit witness encoding
/// for 0-input transactions, which results in unambiguously parseable transactions.
///
/// ### A note on ordering
///
/// This type implements `Ord`, even though it contains a locktime, which is not
/// itself `Ord`. This was done to simplify applications that may need to hold
/// transactions inside a sorted container. We have ordered the locktimes based
/// on their representation as a `u32`, which is not a semantically meaningful
/// order, and therefore the ordering on `Transaction` itself is not semantically
/// meaningful either.
///
/// The ordering is, however, consistent with the ordering present in this library
/// before this change, so users should not notice any breakage (here) when
/// transitioning from 0.29 to 0.30.
#[derive(Clone, PartialEq, Eq, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct Transaction {
    /// The protocol version, is currently expected to be 1 or 2 (BIP 68).
    pub version: i32,
    /// Block height or timestamp. Transaction cannot be included in a block until this height/time.
    ///
    /// ### Relevant BIPs
    ///
    /// * [BIP-65 OP_CHECKLOCKTIMEVERIFY](https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki)
    /// * [BIP-113 Median time-past as endpoint for lock-time calculations](https://github.com/bitcoin/bips/blob/master/bip-0113.mediawiki)
    pub lock_time: absolute::LockTime,
    /// List of transaction inputs.
    pub input: Vec<TxIn>,
    /// List of transaction outputs.
    pub output: Vec<TxOut>,
}

impl cmp::PartialOrd for Transaction {
    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { Some(self.cmp(other)) }
}
impl cmp::Ord for Transaction {
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        self.version
            .cmp(&other.version)
            .then(self.lock_time.to_consensus_u32().cmp(&other.lock_time.to_consensus_u32()))
            .then(self.input.cmp(&other.input))
            .then(self.output.cmp(&other.output))
    }
}

impl Transaction {
    /// Computes a "normalized TXID" which does not include any signatures.
    ///
    /// This gives a way to identify a transaction that is "the same" as
    /// another in the sense of having same inputs and outputs.
    pub fn ntxid(&self) -> sha256d::Hash {
        let cloned_tx = Transaction {
            version: self.version,
            lock_time: self.lock_time,
            input: self
                .input
                .iter()
                .map(|txin| TxIn {
                    script_sig: ScriptBuf::new(),
                    witness: Witness::default(),
                    ..*txin
                })
                .collect(),
            output: self.output.clone(),
        };
        cloned_tx.txid().into()
    }

    /// Computes the [`Txid`].
    ///
    /// Hashes the transaction **excluding** the segwit data (i.e. the marker, flag bytes, and the
    /// witness fields themselves). For non-segwit transactions which do not have any segwit data,
    /// this will be equal to [`Transaction::wtxid()`].
    pub fn txid(&self) -> Txid {
        let mut enc = Txid::engine();
        self.version.consensus_encode(&mut enc).expect("engines don't error");
        self.input.consensus_encode(&mut enc).expect("engines don't error");
        self.output.consensus_encode(&mut enc).expect("engines don't error");
        self.lock_time.consensus_encode(&mut enc).expect("engines don't error");
        Txid::from_engine(enc)
    }

    /// Computes the segwit version of the transaction id.
    ///
    /// Hashes the transaction **including** all segwit data (i.e. the marker, flag bytes, and the
    /// witness fields themselves). For non-segwit transactions which do not have any segwit data,
    /// this will be equal to [`Transaction::txid()`].
    pub fn wtxid(&self) -> Wtxid {
        let mut enc = Wtxid::engine();
        self.consensus_encode(&mut enc).expect("engines don't error");
        Wtxid::from_engine(enc)
    }

    /// Encodes the signing data from which a signature hash for a given input index with a given
    /// sighash flag can be computed.
    ///
    /// To actually produce a scriptSig, this hash needs to be run through an ECDSA signer, the
    /// [`EcdsaSighashType`] appended to the resulting sig, and a script written around this, but
    /// this is the general (and hard) part.
    ///
    /// The `sighash_type` supports an arbitrary `u32` value, instead of just [`EcdsaSighashType`],
    /// because internally 4 bytes are being hashed, even though only the lowest byte is appended to
    /// signature in a transaction.
    ///
    /// # Warning
    ///
    /// - Does NOT attempt to support OP_CODESEPARATOR. In general this would require evaluating
    /// `script_pubkey` to determine which separators get evaluated and which don't, which we don't
    /// have the information to determine.
    /// - Does NOT handle the sighash single bug (see "Returns" section)
    ///
    /// # Returns
    ///
    /// This function can't handle the SIGHASH_SINGLE bug internally, so it returns [`EncodeSigningDataResult`]
    /// that must be handled by the caller (see [`EncodeSigningDataResult::is_sighash_single_bug`]).
    ///
    /// # Panics
    ///
    /// If `input_index` is out of bounds (greater than or equal to `self.input.len()`).
    #[deprecated(
        since = "0.30.0",
        note = "Use SighashCache::legacy_encode_signing_data_to instead"
    )]
    pub fn encode_signing_data_to<Write: io::Write, U: Into<u32>>(
        &self,
        writer: Write,
        input_index: usize,
        script_pubkey: &Script,
        sighash_type: U,
    ) -> EncodeSigningDataResult<io::Error> {
        use EncodeSigningDataResult::*;

        use crate::sighash::{self, SighashCache};

        assert!(input_index < self.input.len()); // Panic on OOB

        let cache = SighashCache::new(self);
        match cache.legacy_encode_signing_data_to(writer, input_index, script_pubkey, sighash_type)
        {
            SighashSingleBug => SighashSingleBug,
            WriteResult(res) => match res {
                Ok(()) => WriteResult(Ok(())),
                Err(e) => match e {
                    sighash::Error::Io(e) => WriteResult(Err(e.into())),
                    _ => unreachable!("we check input_index above"),
                },
            },
        }
    }

    /// Computes a signature hash for a given input index with a given sighash flag.
    ///
    /// To actually produce a scriptSig, this hash needs to be run through an ECDSA signer, the
    /// [`EcdsaSighashType`] appended to the resulting sig, and a script written around this, but
    /// this is the general (and hard) part.
    ///
    /// The `sighash_type` supports an arbitrary `u32` value, instead of just [`EcdsaSighashType`],
    /// because internally 4 bytes are being hashed, even though only the lowest byte is appended to
    /// signature in a transaction.
    ///
    /// This function correctly handles the sighash single bug by returning the 'one array'. The
    /// sighash single bug becomes exploitable when one tries to sign a transaction with
    /// `SIGHASH_SINGLE` and there is not a corresponding output with the same index as the input.
    ///
    /// # Warning
    ///
    /// Does NOT attempt to support OP_CODESEPARATOR. In general this would require evaluating
    /// `script_pubkey` to determine which separators get evaluated and which don't, which we don't
    /// have the information to determine.
    ///
    /// # Panics
    ///
    /// If `input_index` is out of bounds (greater than or equal to `self.input.len()`).
    #[deprecated(since = "0.30.0", note = "Use SighashCache::legacy_signature_hash instead")]
    pub fn signature_hash(
        &self,
        input_index: usize,
        script_pubkey: &Script,
        sighash_u32: u32,
    ) -> LegacySighash {
        assert!(input_index < self.input.len()); // Panic on OOB, enables expect below.

        let cache = crate::sighash::SighashCache::new(self);
        cache
            .legacy_signature_hash(input_index, script_pubkey, sighash_u32)
            .expect("cache method doesn't error")
    }

    /// Returns the "weight" of this transaction, as defined by BIP141.
    ///
    /// For transactions with an empty witness, this is simply the consensus-serialized size times
    /// four. For transactions with a witness, this is the non-witness consensus-serialized size
    /// multiplied by three plus the with-witness consensus-serialized size.
    ///
    /// For transactions with no inputs, this function will return a value 2 less than the actual
    /// weight of the serialized transaction. The reason is that zero-input transactions, post-segwit,
    /// cannot be unambiguously serialized; we make a choice that adds two extra bytes. For more
    /// details see [BIP 141](https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki)
    /// which uses a "input count" of `0x00` as a `marker` for a Segwit-encoded transaction.
    ///
    /// If you need to use 0-input transactions, we strongly recommend you do so using the PSBT
    /// API. The unsigned transaction encoded within PSBT is always a non-segwit transaction
    /// and can therefore avoid this ambiguity.
    #[inline]
    pub fn weight(&self) -> Weight {
        Weight::from_wu(self.scaled_size(WITNESS_SCALE_FACTOR) as u64)
    }

    /// Returns the regular byte-wise consensus-serialized size of this transaction.
    #[inline]
    pub fn size(&self) -> usize { self.scaled_size(1) }

    /// Computes the weight and checks that it matches the output of `predict_weight`.
    #[cfg(test)]
    fn check_weight(&self) -> Weight {
        let weight1 = self.weight();
        let inputs = self.input.iter().map(|txin| {
            InputWeightPrediction::new(
                txin.script_sig.len(),
                txin.witness.iter().map(|elem| elem.len()),
            )
        });
        let outputs = self.output.iter().map(|txout| txout.script_pubkey.len());
        let weight2 = predict_weight(inputs, outputs);
        assert_eq!(weight1, weight2);
        weight1
    }

    /// Returns the "virtual size" (vsize) of this transaction.
    ///
    /// Will be `ceil(weight / 4.0)`. Note this implements the virtual size as per [`BIP141`], which
    /// is different to what is implemented in Bitcoin Core. The computation should be the same for
    /// any remotely sane transaction, and a standardness-rule-correct version is available in the
    /// [`policy`] module.
    ///
    /// [`BIP141`]: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki
    /// [`policy`]: ../policy/mod.rs.html
    #[inline]
    pub fn vsize(&self) -> usize {
        // No overflow because it's computed from data in memory
        self.weight().to_vbytes_ceil() as usize
    }

    /// Returns the size of this transaction excluding the witness data.
    pub fn strippedsize(&self) -> usize {
        let mut input_size = 0;
        for input in &self.input {
            input_size += 32 + 4 + 4 + // outpoint (32+4) + nSequence
                VarInt(input.script_sig.len() as u64).len() +
                input.script_sig.len();
        }
        let mut output_size = 0;
        for output in &self.output {
            output_size += 8 + // value
                VarInt(output.script_pubkey.len() as u64).len() +
                output.script_pubkey.len();
        }
        let non_input_size =
        // version:
        4 +
        // count varints:
        VarInt(self.input.len() as u64).len() +
        VarInt(self.output.len() as u64).len() +
        output_size +
        // lock_time
        4;
        non_input_size + input_size
    }

    /// Internal utility function for size/weight functions.
    fn scaled_size(&self, scale_factor: usize) -> usize {
        let mut input_weight = 0;
        let mut inputs_with_witnesses = 0;
        for input in &self.input {
            input_weight += scale_factor
                * (32 + 4 + 4 + // outpoint (32+4) + nSequence
                VarInt(input.script_sig.len() as u64).len() +
                input.script_sig.len());
            if !input.witness.is_empty() {
                inputs_with_witnesses += 1;
                input_weight += input.witness.serialized_len();
            }
        }
        let mut output_size = 0;
        for output in &self.output {
            output_size += 8 + // value
                VarInt(output.script_pubkey.len() as u64).len() +
                output.script_pubkey.len();
        }
        let non_input_size =
        // version:
        4 +
        // count varints:
        VarInt(self.input.len() as u64).len() +
        VarInt(self.output.len() as u64).len() +
        output_size +
        // lock_time
        4;
        if inputs_with_witnesses == 0 {
            non_input_size * scale_factor + input_weight
        } else {
            non_input_size * scale_factor + input_weight + self.input.len() - inputs_with_witnesses
                + 2
        }
    }

    /// Shorthand for [`Self::verify_with_flags`] with flag [`bitcoinconsensus::VERIFY_ALL`].
    #[cfg(feature = "bitcoinconsensus")]
    #[cfg_attr(docsrs, doc(cfg(feature = "bitcoinconsensus")))]
    pub fn verify<S>(&self, spent: S) -> Result<(), script::Error>
    where
        S: FnMut(&OutPoint) -> Option<TxOut>,
    {
        self.verify_with_flags(spent, bitcoinconsensus::VERIFY_ALL)
    }

    /// Verify that this transaction is able to spend its inputs.
    ///
    /// The `spent` closure should not return the same [`TxOut`] twice!
    #[cfg(feature = "bitcoinconsensus")]
    #[cfg_attr(docsrs, doc(cfg(feature = "bitcoinconsensus")))]
    pub fn verify_with_flags<S, F>(&self, mut spent: S, flags: F) -> Result<(), script::Error>
    where
        S: FnMut(&OutPoint) -> Option<TxOut>,
        F: Into<u32>,
    {
        let tx = encode::serialize(self);
        let flags: u32 = flags.into();
        for (idx, input) in self.input.iter().enumerate() {
            if let Some(output) = spent(&input.previous_output) {
                output.script_pubkey.verify_with_flags(
                    idx,
                    crate::Amount::from_sat(output.value),
                    tx.as_slice(),
                    flags,
                )?;
            } else {
                return Err(script::Error::UnknownSpentOutput(input.previous_output));
            }
        }
        Ok(())
    }

    /// Checks if this is a coinbase transaction.
    ///
    /// The first transaction in the block distributes the mining reward and is called the coinbase
    /// transaction. It is impossible to check if the transaction is first in the block, so this
    /// function checks the structure of the transaction instead - the previous output must be
    /// all-zeros (creates satoshis "out of thin air").
    pub fn is_coin_base(&self) -> bool {
        self.input.len() == 1 && self.input[0].previous_output.is_null()
    }

    /// Returns `true` if the transaction itself opted in to be BIP-125-replaceable (RBF).
    ///
    /// # Warning
    ///
    /// **Incorrectly relying on RBF may lead to monetary loss!**
    ///
    /// This **does not** cover the case where a transaction becomes replaceable due to ancestors
    /// being RBF. Please note that transactions **may be replaced** even if they **do not** include
    /// the RBF signal: <https://bitcoinops.org/en/newsletters/2022/10/19/#transaction-replacement-option>.
    pub fn is_explicitly_rbf(&self) -> bool {
        self.input.iter().any(|input| input.sequence.is_rbf())
    }

    /// Returns true if this [`Transaction`]'s absolute timelock is satisfied at `height`/`time`.
    ///
    /// # Returns
    ///
    /// By definition if the lock time is not enabled the transaction's absolute timelock is
    /// considered to be satisfied i.e., there are no timelock constraints restricting this
    /// transaction from being mined immediately.
    pub fn is_absolute_timelock_satisfied(&self, height: Height, time: Time) -> bool {
        if !self.is_lock_time_enabled() {
            return true;
        }
        self.lock_time.is_satisfied_by(height, time)
    }

    /// Returns `true` if this transactions nLockTime is enabled ([BIP-65]).
    ///
    /// [BIP-65]: https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki
    pub fn is_lock_time_enabled(&self) -> bool { self.input.iter().any(|i| i.enables_lock_time()) }

    /// Returns an iterator over lengths of `script_pubkey`s in the outputs.
    ///
    /// This is useful in combination with [`predict_weight`] if you have the transaction already
    /// constructed with a dummy value in the fee output which you'll adjust after calculating the
    /// weight.
    pub fn script_pubkey_lens(&self) -> impl Iterator<Item = usize> + '_ {
        self.output.iter().map(|txout| txout.script_pubkey.len())
    }
}

impl_consensus_encoding!(TxOut, value, script_pubkey);

impl Encodable for OutPoint {
    fn consensus_encode<W: io::Write + ?Sized>(&self, w: &mut W) -> Result<usize, io::Error> {
        let len = self.txid.consensus_encode(w)?;
        Ok(len + self.vout.consensus_encode(w)?)
    }
}
impl Decodable for OutPoint {
    fn consensus_decode<R: io::Read + ?Sized>(r: &mut R) -> Result<Self, encode::Error> {
        Ok(OutPoint {
            txid: Decodable::consensus_decode(r)?,
            vout: Decodable::consensus_decode(r)?,
        })
    }
}

impl Encodable for TxIn {
    fn consensus_encode<W: io::Write + ?Sized>(&self, w: &mut W) -> Result<usize, io::Error> {
        let mut len = 0;
        len += self.previous_output.consensus_encode(w)?;
        len += self.script_sig.consensus_encode(w)?;
        len += self.sequence.consensus_encode(w)?;
        Ok(len)
    }
}
impl Decodable for TxIn {
    #[inline]
    fn consensus_decode_from_finite_reader<R: io::Read + ?Sized>(
        r: &mut R,
    ) -> Result<Self, encode::Error> {
        Ok(TxIn {
            previous_output: Decodable::consensus_decode_from_finite_reader(r)?,
            script_sig: Decodable::consensus_decode_from_finite_reader(r)?,
            sequence: Decodable::consensus_decode_from_finite_reader(r)?,
            witness: Witness::default(),
        })
    }
}

impl Encodable for Sequence {
    fn consensus_encode<W: io::Write + ?Sized>(&self, w: &mut W) -> Result<usize, io::Error> {
        self.0.consensus_encode(w)
    }
}

impl Decodable for Sequence {
    fn consensus_decode<R: io::Read + ?Sized>(r: &mut R) -> Result<Self, encode::Error> {
        Decodable::consensus_decode(r).map(Sequence)
    }
}

impl Encodable for Transaction {
    fn consensus_encode<W: io::Write + ?Sized>(&self, w: &mut W) -> Result<usize, io::Error> {
        let mut len = 0;
        len += self.version.consensus_encode(w)?;
        // To avoid serialization ambiguity, no inputs means we use BIP141 serialization (see
        // `Transaction` docs for full explanation).
        let mut have_witness = self.input.is_empty();
        for input in &self.input {
            if !input.witness.is_empty() {
                have_witness = true;
                break;
            }
        }
        if !have_witness {
            len += self.input.consensus_encode(w)?;
            len += self.output.consensus_encode(w)?;
        } else {
            len += 0u8.consensus_encode(w)?;
            len += 1u8.consensus_encode(w)?;
            len += self.input.consensus_encode(w)?;
            len += self.output.consensus_encode(w)?;
            for input in &self.input {
                len += input.witness.consensus_encode(w)?;
            }
        }
        len += self.lock_time.consensus_encode(w)?;
        Ok(len)
    }
}

impl Decodable for Transaction {
    fn consensus_decode_from_finite_reader<R: io::Read + ?Sized>(
        r: &mut R,
    ) -> Result<Self, encode::Error> {
        let version = i32::consensus_decode_from_finite_reader(r)?;
        let input = Vec::<TxIn>::consensus_decode_from_finite_reader(r)?;
        // segwit
        if input.is_empty() {
            let segwit_flag = u8::consensus_decode_from_finite_reader(r)?;
            match segwit_flag {
                // BIP144 input witnesses
                1 => {
                    let mut input = Vec::<TxIn>::consensus_decode_from_finite_reader(r)?;
                    let output = Vec::<TxOut>::consensus_decode_from_finite_reader(r)?;
                    for txin in input.iter_mut() {
                        txin.witness = Decodable::consensus_decode_from_finite_reader(r)?;
                    }
                    if !input.is_empty() && input.iter().all(|input| input.witness.is_empty()) {
                        Err(encode::Error::ParseFailed("witness flag set but no witnesses present"))
                    } else {
                        Ok(Transaction {
                            version,
                            input,
                            output,
                            lock_time: Decodable::consensus_decode_from_finite_reader(r)?,
                        })
                    }
                }
                // We don't support anything else
                x => Err(encode::Error::UnsupportedSegwitFlag(x)),
            }
        // non-segwit
        } else {
            Ok(Transaction {
                version,
                input,
                output: Decodable::consensus_decode_from_finite_reader(r)?,
                lock_time: Decodable::consensus_decode_from_finite_reader(r)?,
            })
        }
    }
}

impl From<Transaction> for Txid {
    fn from(tx: Transaction) -> Txid { tx.txid() }
}

impl From<&Transaction> for Txid {
    fn from(tx: &Transaction) -> Txid { tx.txid() }
}

impl From<Transaction> for Wtxid {
    fn from(tx: Transaction) -> Wtxid { tx.wtxid() }
}

impl From<&Transaction> for Wtxid {
    fn from(tx: &Transaction) -> Wtxid { tx.wtxid() }
}

/// Predicts the weight of a to-be-constructed transaction.
///
/// This function computes the weight of a transaction which is not fully known. All that is needed
/// is the lengths of scripts and witness elements.
///
/// # Arguments
///
/// * `inputs` - an iterator which returns `InputWeightPrediction` for each input of the
///   to-be-constructed transaction.
/// * `output_script_lens` - an iterator which returns the length of `script_pubkey` of each output
///   of the to-be-constructed transaction.
///
/// Note that lengths of the scripts and witness elements must be non-serialized, IOW *without* the
/// preceding compact size. The lenght of preceding compact size is computed and added inside the
/// function for convenience.
///
/// If you  have the transaction already constructed (except for signatures) with a dummy value for
/// fee output you can use the return value of [`Transaction::script_pubkey_lens`] method directly
/// as the second argument.
///
/// # Usage
///
/// When signing a transaction one doesn't know the signature before knowing the transaction fee and
/// the transaction fee is not known before knowing the transaction size which is not known before
/// knowing the signature. This apparent dependency cycle can be broken by knowing the length of the
/// signature without knowing the contents of the signature e.g., we know all Schnorr signatures
/// are 64 bytes long.
///
/// Additionally, some protocols may require calculating the amounts before knowing various parts
/// of the transaction (assuming their length is known).
///
/// # Notes on integer overflow
///
/// Overflows are intentionally not checked because one of the following holds:
///
/// * The transaction is valid (obeys the block size limit) and the code feeds correct values to
///   this function - no overflow can happen.
/// * The transaction will be so large it doesn't fit in the memory - overflow will happen but
///   then the transaction will fail to construct and even if one serialized it on disk directly
///   it'd be invalid anyway so overflow doesn't matter.
/// * The values fed into this function are inconsistent with the actual lengths the transaction
///   will have - the code is already broken and checking overflows doesn't help. Unfortunately
///   this probably cannot be avoided.
pub fn predict_weight<I, O>(inputs: I, output_script_lens: O) -> Weight
where
    I: IntoIterator<Item = InputWeightPrediction>,
    O: IntoIterator<Item = usize>,
{
    let (input_count, partial_input_weight, inputs_with_witnesses) = inputs.into_iter().fold(
        (0, 0, 0),
        |(count, partial_input_weight, inputs_with_witnesses), prediction| {
            (
                count + 1,
                partial_input_weight + prediction.script_size * 4 + prediction.witness_size,
                inputs_with_witnesses + (prediction.witness_size > 0) as usize,
            )
        },
    );
    let (output_count, output_scripts_size) = output_script_lens.into_iter().fold(
        (0, 0),
        |(output_count, total_scripts_size), script_len| {
            let script_size = script_len + VarInt(script_len as u64).len();
            (output_count + 1, total_scripts_size + script_size)
        },
    );
    predict_weight_internal(
        input_count,
        partial_input_weight,
        inputs_with_witnesses,
        output_count,
        output_scripts_size,
    )
}

crate::internal_macros::maybe_const_fn! {
    fn predict_weight_internal(input_count: usize, partial_input_weight: usize, inputs_with_witnesses: usize, output_count: usize, output_scripts_size: usize) -> Weight {
        let input_weight = partial_input_weight + input_count * 4 * (32 + 4 + 4);
        let output_size = 8 * output_count + output_scripts_size;
        let non_input_size =
            // version:
            4 +
            // count varints:
            VarInt(input_count as u64).len() +
            VarInt(output_count as u64).len() +
            output_size +
            // lock_time
            4;
        let weight = if inputs_with_witnesses == 0 {
            non_input_size * 4 + input_weight
        } else {
            non_input_size * 4 + input_weight + input_count - inputs_with_witnesses + 2
        };
        Weight::from_wu(weight as u64)
    }
}

/// Predicts the weight of a to-be-constructed transaction in const context.
///
/// *Important: only available in Rust 1.46+*
///
/// This is a `const` version of [`predict_weight`] which only allows slices due to current Rust
/// limitations around `const fn`. Because of these limitations it may be less efficient than
/// `predict_weight` and thus is intended to be only used in `const` context.
///
/// Please see the documentation of `predict_weight` to learn more about this function.
#[cfg(rust_v_1_46)]
pub const fn predict_weight_from_slices(
    inputs: &[InputWeightPrediction],
    output_script_lens: &[usize],
) -> Weight {
    let mut partial_input_weight = 0;
    let mut inputs_with_witnesses = 0;

    // for loops not supported in const fn
    let mut i = 0;
    while i < inputs.len() {
        let prediction = inputs[i];
        partial_input_weight += prediction.script_size * 4 + prediction.witness_size;
        inputs_with_witnesses += (prediction.witness_size > 0) as usize;
        i += 1;
    }

    let mut output_scripts_size = 0;

    i = 0;
    while i < output_script_lens.len() {
        let script_len = output_script_lens[i];
        output_scripts_size += script_len + VarInt(script_len as u64).len();
        i += 1;
    }

    predict_weight_internal(
        inputs.len(),
        partial_input_weight,
        inputs_with_witnesses,
        output_script_lens.len(),
        output_scripts_size,
    )
}

/// Weight prediction of an individual input.
///
/// This helper type collects information about an input to be used in [`predict_weight`] function.
/// It can only be created using the [`new`](InputWeightPrediction::new) function.
#[derive(Copy, Clone, Debug)]
pub struct InputWeightPrediction {
    script_size: usize,
    witness_size: usize,
}

impl InputWeightPrediction {
    /// Input weight prediction corresponding to spending of P2WPKH output with the largest possible
    /// DER-encoded signature.
    ///
    /// If the input in your transaction uses P2WPKH you can use this instead of
    /// [`InputWeightPrediction::new`].
    ///
    /// This is useful when you **do not** use [signature grinding] and want to ensure you are not
    /// under-paying. See [`ground_p2wpkh`](Self::ground_p2wpkh) if you do use signature grinding.
    ///
    /// [signature grinding]: https://bitcoin.stackexchange.com/questions/111660/what-is-signature-grinding
    pub const P2WPKH_MAX: Self =
        InputWeightPrediction { script_size: 0, witness_size: 1 + 1 + 73 + 1 + 33 };

    /// Input weight prediction corresponding to spending of taproot output using the key and
    /// default sighash.
    ///
    /// If the input in your transaction uses Taproot key spend you can use this instead of
    /// [`InputWeightPrediction::new`].
    pub const P2TR_KEY_DEFAULT_SIGHASH: Self =
        InputWeightPrediction { script_size: 0, witness_size: 1 + 1 + 64 };

    /// Input weight prediction corresponding to spending of taproot output using the key and
    /// **non**-default sighash.
    ///
    /// If the input in your transaction uses Taproot key spend you can use this instead of
    /// [`InputWeightPrediction::new`].
    pub const P2TR_KEY_NON_DEFAULT_SIGHASH: Self =
        InputWeightPrediction { script_size: 0, witness_size: 1 + 1 + 65 };

    /// Input weight prediction corresponding to spending of P2WPKH output using [signature
    /// grinding].
    ///
    /// If the input in your transaction uses P2WPKH and you use signature grinding you can use this
    /// instead of [`InputWeightPrediction::new`]. See [`P2WPKH_MAX`](Self::P2WPKH_MAX) if you don't
    /// use signature grinding.
    ///
    /// Note: `bytes_to_grind` is usually `1` because of exponential cost of higher values.
    ///
    /// # Panics
    ///
    /// The funcion panics in const context and debug builds if `bytes_to_grind` is higher than 62.
    ///
    /// [signature grinding]: https://bitcoin.stackexchange.com/questions/111660/what-is-signature-grinding
    pub const fn ground_p2wpkh(bytes_to_grind: usize) -> Self {
        // Written to trigger const/debug panic for unreasonably high values.
        let der_signature_size = 10 + (62 - bytes_to_grind);
        let witness_size = 1 // length of element count varint
            + 1 // length of element size varint (max signature length is 73B)
            + der_signature_size
            + 1 // sighash flag
            + 1 // length of element size varint
            + 33; // length of (always-compressed) public key
        InputWeightPrediction { script_size: 0, witness_size }
    }

    /// Computes the prediction for a single input.
    pub fn new<T>(input_script_len: usize, witness_element_lengths: T) -> Self
    where
        T: IntoIterator,
        T::Item: Borrow<usize>,
    {
        let (count, total_size) =
            witness_element_lengths.into_iter().fold((0, 0), |(count, total_size), elem_len| {
                let elem_len = *elem_len.borrow();
                let elem_size = elem_len + VarInt(elem_len as u64).len();
                (count + 1, total_size + elem_size)
            });
        let witness_size = if count > 0 { total_size + VarInt(count as u64).len() } else { 0 };
        let script_size = input_script_len + VarInt(input_script_len as u64).len();

        InputWeightPrediction { script_size, witness_size }
    }

    /// Computes the prediction for a single input in `const` context.
    ///
    /// *Important: only available in Rust 1.46+*
    ///
    /// This is a `const` version of [`new`](Self::new) which only allows slices due to current Rust
    /// limitations around `const fn`. Because of these limitations it may be less efficient than
    /// `new` and thus is intended to be only used in `const` context.
    #[cfg(rust_v_1_46)]
    pub const fn from_slice(input_script_len: usize, witness_element_lengths: &[usize]) -> Self {
        let mut i = 0;
        let mut total_size = 0;
        // for loops not supported in const fn
        while i < witness_element_lengths.len() {
            let elem_len = witness_element_lengths[i];
            let elem_size = elem_len + VarInt(elem_len as u64).len();
            total_size += elem_size;
            i += 1;
        }
        let witness_size = if !witness_element_lengths.is_empty() {
            total_size + VarInt(witness_element_lengths.len() as u64).len()
        } else {
            0
        };
        let script_size = input_script_len + VarInt(input_script_len as u64).len();

        InputWeightPrediction { script_size, witness_size }
    }
}

#[cfg(test)]
mod tests {
    use core::str::FromStr;

    use super::*;
    use crate::blockdata::constants::WITNESS_SCALE_FACTOR;
    use crate::blockdata::locktime::absolute;
    use crate::blockdata::script::ScriptBuf;
    use crate::consensus::encode::{deserialize, serialize};
    use crate::hashes::hex::FromHex;
    use crate::internal_macros::hex;
    use crate::sighash::EcdsaSighashType;

    const SOME_TX: &str = "0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000";

    #[test]
    fn encode_to_unsized_writer() {
        let mut buf = [0u8; 1024];
        let raw_tx = hex!(SOME_TX);
        let tx: Transaction = Decodable::consensus_decode(&mut raw_tx.as_slice()).unwrap();

        let size = tx.consensus_encode(&mut &mut buf[..]).unwrap();
        assert_eq!(size, SOME_TX.len() / 2);
        assert_eq!(raw_tx, &buf[..size]);
    }

    #[test]
    fn test_outpoint() {
        assert_eq!(OutPoint::from_str("i don't care"), Err(ParseOutPointError::Format));
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:1:1"
            ),
            Err(ParseOutPointError::Format)
        );
        assert_eq!(
            OutPoint::from_str("5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:"),
            Err(ParseOutPointError::Format)
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:11111111111"
            ),
            Err(ParseOutPointError::TooLong)
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:01"
            ),
            Err(ParseOutPointError::VoutNotCanonical)
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:+42"
            ),
            Err(ParseOutPointError::VoutNotCanonical)
        );
        assert_eq!(
            OutPoint::from_str("i don't care:1"),
            Err(ParseOutPointError::Txid("i don't care".parse::<Txid>().unwrap_err()))
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c945X:1"
            ),
            Err(ParseOutPointError::Txid(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c945X"
                    .parse::<Txid>()
                    .unwrap_err()
            ))
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:lol"
            ),
            Err(ParseOutPointError::Vout(crate::parse::int::<u32, _>("lol").unwrap_err()))
        );

        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:42"
            ),
            Ok(OutPoint {
                txid: "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456"
                    .parse()
                    .unwrap(),
                vout: 42,
            })
        );
        assert_eq!(
            OutPoint::from_str(
                "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:0"
            ),
            Ok(OutPoint {
                txid: "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456"
                    .parse()
                    .unwrap(),
                vout: 0,
            })
        );
    }

    #[test]
    fn test_txin() {
        let txin: Result<TxIn, _> = deserialize(&hex!("a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff"));
        assert!(txin.is_ok());
    }

    #[test]
    fn test_txin_default() {
        let txin = TxIn::default();
        assert_eq!(txin.previous_output, OutPoint::default());
        assert_eq!(txin.script_sig, ScriptBuf::new());
        assert_eq!(txin.sequence, Sequence::from_consensus(0xFFFFFFFF));
        assert_eq!(txin.previous_output, OutPoint::default());
        assert_eq!(txin.witness.len(), 0);
    }

    #[test]
    fn test_is_coinbase() {
        use crate::blockdata::constants;
        use crate::network::constants::Network;

        let genesis = constants::genesis_block(Network::Bitcoin);
        assert!(genesis.txdata[0].is_coin_base());
        let tx_bytes = hex!("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000");
        let tx: Transaction = deserialize(&tx_bytes).unwrap();
        assert!(!tx.is_coin_base());
    }

    #[test]
    fn test_nonsegwit_transaction() {
        let tx_bytes = hex!("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000");
        let tx: Result<Transaction, _> = deserialize(&tx_bytes);
        assert!(tx.is_ok());
        let realtx = tx.unwrap();
        // All these tests aren't really needed because if they fail, the hash check at the end
        // will also fail. But these will show you where the failure is so I'll leave them in.
        assert_eq!(realtx.version, 1);
        assert_eq!(realtx.input.len(), 1);
        // In particular this one is easy to get backward -- in bitcoin hashes are encoded
        // as little-endian 256-bit numbers rather than as data strings.
        assert_eq!(
            format!("{:x}", realtx.input[0].previous_output.txid),
            "ce9ea9f6f5e422c6a9dbcddb3b9a14d1c78fab9ab520cb281aa2a74a09575da1".to_string()
        );
        assert_eq!(realtx.input[0].previous_output.vout, 1);
        assert_eq!(realtx.output.len(), 1);
        assert_eq!(realtx.lock_time, absolute::LockTime::ZERO);

        assert_eq!(
            format!("{:x}", realtx.txid()),
            "a6eab3c14ab5272a58a5ba91505ba1a4b6d7a3a9fcbd187b6cd99a7b6d548cb7".to_string()
        );
        assert_eq!(
            format!("{:x}", realtx.wtxid()),
            "a6eab3c14ab5272a58a5ba91505ba1a4b6d7a3a9fcbd187b6cd99a7b6d548cb7".to_string()
        );
        assert_eq!(realtx.check_weight().to_wu() as usize, tx_bytes.len() * WITNESS_SCALE_FACTOR);
        assert_eq!(realtx.size(), tx_bytes.len());
        assert_eq!(realtx.vsize(), tx_bytes.len());
        assert_eq!(realtx.strippedsize(), tx_bytes.len());
    }

    #[test]
    fn test_segwit_transaction() {
        let tx_bytes = hex!(
            "02000000000101595895ea20179de87052b4046dfe6fd515860505d6511a9004cf12a1f93cac7c01000000\
            00ffffffff01deb807000000000017a9140f3444e271620c736808aa7b33e370bd87cb5a078702483045022\
            100fb60dad8df4af2841adc0346638c16d0b8035f5e3f3753b88db122e70c79f9370220756e6633b17fd271\
            0e626347d28d60b0a2d6cbb41de51740644b9fb3ba7751040121028fa937ca8cba2197a37c007176ed89410\
            55d3bcb8627d085e94553e62f057dcc00000000"
        );
        let tx: Result<Transaction, _> = deserialize(&tx_bytes);
        assert!(tx.is_ok());
        let realtx = tx.unwrap();
        // All these tests aren't really needed because if they fail, the hash check at the end
        // will also fail. But these will show you where the failure is so I'll leave them in.
        assert_eq!(realtx.version, 2);
        assert_eq!(realtx.input.len(), 1);
        // In particular this one is easy to get backward -- in bitcoin hashes are encoded
        // as little-endian 256-bit numbers rather than as data strings.
        assert_eq!(
            format!("{:x}", realtx.input[0].previous_output.txid),
            "7cac3cf9a112cf04901a51d605058615d56ffe6d04b45270e89d1720ea955859".to_string()
        );
        assert_eq!(realtx.input[0].previous_output.vout, 1);
        assert_eq!(realtx.output.len(), 1);
        assert_eq!(realtx.lock_time, absolute::LockTime::ZERO);

        assert_eq!(
            format!("{:x}", realtx.txid()),
            "f5864806e3565c34d1b41e716f72609d00b55ea5eac5b924c9719a842ef42206".to_string()
        );
        assert_eq!(
            format!("{:x}", realtx.wtxid()),
            "80b7d8a82d5d5bf92905b06f2014dd699e03837ca172e3a59d51426ebbe3e7f5".to_string()
        );
        const EXPECTED_WEIGHT: Weight = Weight::from_wu(442);
        assert_eq!(realtx.check_weight(), EXPECTED_WEIGHT);
        assert_eq!(realtx.size(), tx_bytes.len());
        assert_eq!(realtx.vsize(), 111);
        // Since
        //     size   =                        stripped_size + witness_size
        //     weight = WITNESS_SCALE_FACTOR * stripped_size + witness_size
        // then,
        //     stripped_size = (weight - size) / (WITNESS_SCALE_FACTOR - 1)
        let expected_strippedsize =
            (EXPECTED_WEIGHT.to_wu() as usize - tx_bytes.len()) / (WITNESS_SCALE_FACTOR - 1);
        assert_eq!(realtx.strippedsize(), expected_strippedsize);
        // Construct a transaction without the witness data.
        let mut tx_without_witness = realtx;
        tx_without_witness.input.iter_mut().for_each(|input| input.witness.clear());
        assert_eq!(
            tx_without_witness.check_weight().to_wu() as usize,
            expected_strippedsize * WITNESS_SCALE_FACTOR
        );
        assert_eq!(tx_without_witness.size(), expected_strippedsize);
        assert_eq!(tx_without_witness.vsize(), expected_strippedsize);
        assert_eq!(tx_without_witness.strippedsize(), expected_strippedsize);
    }

    // We temporarily abuse `Transaction` for testing consensus serde adapter.
    #[cfg(feature = "serde")]
    #[test]
    fn test_consensus_serde() {
        use crate::consensus::serde as con_serde;
        let json = "\"010000000001010000000000000000000000000000000000000000000000000000000000000000ffffffff3603da1b0e00045503bd5704c7dd8a0d0ced13bb5785010800000000000a636b706f6f6c122f4e696e6a61506f6f6c2f5345475749542fffffffff02b4e5a212000000001976a914876fbb82ec05caa6af7a3b5e5a983aae6c6cc6d688ac0000000000000000266a24aa21a9edf91c46b49eb8a29089980f02ee6b57e7d63d33b18b4fddac2bcd7db2a39837040120000000000000000000000000000000000000000000000000000000000000000000000000\"";
        let mut deserializer = serde_json::Deserializer::from_str(json);
        let tx =
            con_serde::With::<con_serde::Hex>::deserialize::<'_, Transaction, _>(&mut deserializer)
                .unwrap();
        let tx_bytes = Vec::from_hex(&json[1..(json.len() - 1)]).unwrap();
        let expected = deserialize::<Transaction>(&tx_bytes).unwrap();
        assert_eq!(tx, expected);
        let mut bytes = Vec::new();
        let mut serializer = serde_json::Serializer::new(&mut bytes);
        con_serde::With::<con_serde::Hex>::serialize(&tx, &mut serializer).unwrap();
        assert_eq!(bytes, json.as_bytes())
    }

    #[test]
    fn test_transaction_version() {
        let tx_bytes = hex!("ffffff7f0100000000000000000000000000000000000000000000000000000000000000000000000000ffffffff0100f2052a01000000434104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac00000000");
        let tx: Result<Transaction, _> = deserialize(&tx_bytes);
        assert!(tx.is_ok());
        let realtx = tx.unwrap();
        assert_eq!(realtx.version, 2147483647);

        let tx2_bytes = hex!("000000800100000000000000000000000000000000000000000000000000000000000000000000000000ffffffff0100f2052a01000000434104678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5fac00000000");
        let tx2: Result<Transaction, _> = deserialize(&tx2_bytes);
        assert!(tx2.is_ok());
        let realtx2 = tx2.unwrap();
        assert_eq!(realtx2.version, -2147483648);
    }

    #[test]
    fn tx_no_input_deserialization() {
        let tx_bytes = hex!(
            "010000000001000100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000"
        );
        let tx: Transaction = deserialize(&tx_bytes).expect("deserialize tx");

        assert_eq!(tx.input.len(), 0);
        assert_eq!(tx.output.len(), 1);

        let reser = serialize(&tx);
        assert_eq!(tx_bytes, reser);
    }

    #[test]
    fn test_ntxid() {
        let tx_bytes = hex!("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000");
        let mut tx: Transaction = deserialize(&tx_bytes).unwrap();

        let old_ntxid = tx.ntxid();
        assert_eq!(
            format!("{:x}", old_ntxid),
            "c3573dbea28ce24425c59a189391937e00d255150fa973d59d61caf3a06b601d"
        );
        // changing sigs does not affect it
        tx.input[0].script_sig = ScriptBuf::new();
        assert_eq!(old_ntxid, tx.ntxid());
        // changing pks does
        tx.output[0].script_pubkey = ScriptBuf::new();
        assert!(old_ntxid != tx.ntxid());
    }

    #[test]
    fn test_txid() {
        // segwit tx from Liquid integration tests, txid/hash from Core decoderawtransaction
        let tx_bytes = hex!(
            "01000000000102ff34f95a672bb6a4f6ff4a7e90fa8c7b3be7e70ffc39bc99be3bda67942e836c00000000\
             23220020cde476664d3fa347b8d54ef3aee33dcb686a65ced2b5207cbf4ec5eda6b9b46e4f414d4c934ad8\
             1d330314e888888e3bd22c7dde8aac2ca9227b30d7c40093248af7812201000000232200200af6f6a071a6\
             9d5417e592ed99d256ddfd8b3b2238ac73f5da1b06fc0b2e79d54f414d4c0ba0c8f505000000001976a914\
             dcb5898d9036afad9209e6ff0086772795b1441088ac033c0f000000000017a914889f8c10ff2bd4bb9dab\
             b68c5c0d700a46925e6c87033c0f000000000017a914889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c87\
             033c0f000000000017a914889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c87033c0f000000000017a914\
             889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c87033c0f000000000017a914889f8c10ff2bd4bb9dabb6\
             8c5c0d700a46925e6c87033c0f000000000017a914889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c8703\
             3c0f000000000017a914889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c87033c0f000000000017a91488\
             9f8c10ff2bd4bb9dabb68c5c0d700a46925e6c87033c0f000000000017a914889f8c10ff2bd4bb9dabb68c\
             5c0d700a46925e6c87033c0f000000000017a914889f8c10ff2bd4bb9dabb68c5c0d700a46925e6c870500\
             47304402200380b8663e727d7e8d773530ef85d5f82c0b067c97ae927800a0876a1f01d8e2022021ee611e\
             f6507dfd217add2cd60a8aea3cbcfec034da0bebf3312d19577b8c290147304402207bd9943ce1c2c5547b\
             120683fd05d78d23d73be1a5b5a2074ff586b9c853ed4202202881dcf435088d663c9af7b23efb3c03b9db\
             c0c899b247aa94a74d9b4b3c84f501483045022100ba12bba745af3f18f6e56be70f8382ca8e107d1ed5ce\
             aa3e8c360d5ecf78886f022069b38ebaac8fe6a6b97b497cbbb115f3176f7213540bef08f9292e5a72de52\
             de01695321023c9cd9c6950ffee24772be948a45dc5ef1986271e46b686cb52007bac214395a2102756e27\
             cb004af05a6e9faed81fd68ff69959e3c64ac8c9f6cd0e08fd0ad0e75d2103fa40da236bd82202a985a910\
             4e851080b5940812685769202a3b43e4a8b13e6a53ae050048304502210098b9687b81d725a7970d1eee91\
             ff6b89bc9832c2e0e3fb0d10eec143930b006f02206f77ce19dc58ecbfef9221f81daad90bb4f468df3912\
             12abc4f084fe2cc9bdef01483045022100e5479f81a3ad564103da5e2ec8e12f61f3ac8d312ab68763c1dd\
             d7bae94c20610220789b81b7220b27b681b1b2e87198897376ba9d033bc387f084c8b8310c8539c2014830\
             45022100aa1cc48a2d256c0e556616444cc08ae4959d464e5ffff2ae09e3550bdab6ce9f02207192d5e332\
             9a56ba7b1ead724634d104f1c3f8749fe6081e6233aee3e855817a016953210260de9cc68658c61af984e3\
             ab0281d17cfca1cc035966d335f474932d5e6c5422210355fbb768ce3ce39360277345dbb5f376e706459e\
             5a2b5e0e09a535e61690647021023222ceec58b94bd25925dd9743dae6b928737491bd940fc5dd7c6f5d5f\
             2adc1e53ae00000000"
        );
        let tx: Transaction = deserialize(&tx_bytes).unwrap();

        assert_eq!(
            format!("{:x}", tx.wtxid()),
            "d6ac4a5e61657c4c604dcde855a1db74ec6b3e54f32695d72c5e11c7761ea1b4"
        );
        assert_eq!(
            format!("{:x}", tx.txid()),
            "9652aa62b0e748caeec40c4cb7bc17c6792435cc3dfe447dd1ca24f912a1c6ec"
        );
        assert_eq!(tx.check_weight(), Weight::from_wu(2718));

        // non-segwit tx from my mempool
        let tx_bytes = hex!(
            "01000000010c7196428403d8b0c88fcb3ee8d64f56f55c8973c9ab7dd106bb4f3527f5888d000000006a47\
             30440220503a696f55f2c00eee2ac5e65b17767cd88ed04866b5637d3c1d5d996a70656d02202c9aff698f\
             343abb6d176704beda63fcdec503133ea4f6a5216b7f925fa9910c0121024d89b5a13d6521388969209df2\
             7a8469bd565aff10e8d42cef931fad5121bfb8ffffffff02b825b404000000001976a914ef79e7ee9fff98\
             bcfd08473d2b76b02a48f8c69088ac0000000000000000296a273236303039343836393731373233313237\
             3633313032313332353630353838373931323132373000000000"
        );
        let tx: Transaction = deserialize(&tx_bytes).unwrap();

        assert_eq!(
            format!("{:x}", tx.wtxid()),
            "971ed48a62c143bbd9c87f4bafa2ef213cfa106c6e140f111931d0be307468dd"
        );
        assert_eq!(
            format!("{:x}", tx.txid()),
            "971ed48a62c143bbd9c87f4bafa2ef213cfa106c6e140f111931d0be307468dd"
        );
    }

    #[test]
    #[cfg(feature = "serde")]
    fn test_txn_encode_decode() {
        let tx_bytes = hex!("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000");
        let tx: Transaction = deserialize(&tx_bytes).unwrap();
        serde_round_trip!(tx);
    }

    // Test decoding transaction `4be105f158ea44aec57bf12c5817d073a712ab131df6f37786872cfc70734188`
    // from testnet, which is the first BIP144-encoded transaction I encountered.
    #[test]
    #[cfg(feature = "serde")]
    fn test_segwit_tx_decode() {
        let tx_bytes = hex!("010000000001010000000000000000000000000000000000000000000000000000000000000000ffffffff3603da1b0e00045503bd5704c7dd8a0d0ced13bb5785010800000000000a636b706f6f6c122f4e696e6a61506f6f6c2f5345475749542fffffffff02b4e5a212000000001976a914876fbb82ec05caa6af7a3b5e5a983aae6c6cc6d688ac0000000000000000266a24aa21a9edf91c46b49eb8a29089980f02ee6b57e7d63d33b18b4fddac2bcd7db2a39837040120000000000000000000000000000000000000000000000000000000000000000000000000");
        let tx: Transaction = deserialize(&tx_bytes).unwrap();
        assert_eq!(tx.check_weight(), Weight::from_wu(780));
        serde_round_trip!(tx);

        let consensus_encoded = serialize(&tx);
        assert_eq!(consensus_encoded, tx_bytes);
    }

    #[test]
    fn test_sighashtype_fromstr_display() {
        let sighashtypes = vec![
            ("SIGHASH_ALL", EcdsaSighashType::All),
            ("SIGHASH_NONE", EcdsaSighashType::None),
            ("SIGHASH_SINGLE", EcdsaSighashType::Single),
            ("SIGHASH_ALL|SIGHASH_ANYONECANPAY", EcdsaSighashType::AllPlusAnyoneCanPay),
            ("SIGHASH_NONE|SIGHASH_ANYONECANPAY", EcdsaSighashType::NonePlusAnyoneCanPay),
            ("SIGHASH_SINGLE|SIGHASH_ANYONECANPAY", EcdsaSighashType::SinglePlusAnyoneCanPay),
        ];
        for (s, sht) in sighashtypes {
            assert_eq!(sht.to_string(), s);
            assert_eq!(EcdsaSighashType::from_str(s).unwrap(), sht);
        }
        let sht_mistakes = vec![
            "SIGHASH_ALL | SIGHASH_ANYONECANPAY",
            "SIGHASH_NONE |SIGHASH_ANYONECANPAY",
            "SIGHASH_SINGLE| SIGHASH_ANYONECANPAY",
            "SIGHASH_ALL SIGHASH_ANYONECANPAY",
            "SIGHASH_NONE |",
            "SIGHASH_SIGNLE",
            "sighash_none",
            "Sighash_none",
            "SigHash_None",
            "SigHash_NONE",
        ];
        for s in sht_mistakes {
            assert_eq!(
                EcdsaSighashType::from_str(s).unwrap_err().to_string(),
                format!("Unrecognized SIGHASH string '{}'", s)
            );
        }
    }

    #[test]
    fn test_huge_witness() {
        deserialize::<Transaction>(&hex!(include_str!("../../tests/data/huge_witness.hex").trim()))
            .unwrap();
    }

    #[test]
    #[cfg(feature = "bitcoinconsensus")]
    fn test_transaction_verify() {
        use std::collections::HashMap;

        use crate::blockdata::script;
        use crate::blockdata::witness::Witness;

        // a random recent segwit transaction from blockchain using both old and segwit inputs
        let mut spending: Transaction = deserialize(hex!("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")
            .as_slice()).unwrap();
        let spent1: Transaction = deserialize(hex!("020000000001040aacd2c49f5f3c0968cfa8caf9d5761436d95385252e3abb4de8f5dcf8a582f20000000017160014bcadb2baea98af0d9a902e53a7e9adff43b191e9feffffff96cd3c93cac3db114aafe753122bd7d1afa5aa4155ae04b3256344ecca69d72001000000171600141d9984579ceb5c67ebfbfb47124f056662fe7adbfeffffffc878dd74d3a44072eae6178bb94b9253177db1a5aaa6d068eb0e4db7631762e20000000017160014df2a48cdc53dae1aba7aa71cb1f9de089d75aac3feffffffe49f99275bc8363f5f593f4eec371c51f62c34ff11cc6d8d778787d340d6896c0100000017160014229b3b297a0587e03375ab4174ef56eeb0968735feffffff03360d0f00000000001976a9149f44b06f6ee92ddbc4686f71afe528c09727a5c788ac24281b00000000001976a9140277b4f68ff20307a2a9f9b4487a38b501eb955888ac227c0000000000001976a9148020cd422f55eef8747a9d418f5441030f7c9c7788ac0247304402204aa3bd9682f9a8e101505f6358aacd1749ecf53a62b8370b97d59243b3d6984f02200384ad449870b0e6e89c92505880411285ecd41cf11e7439b973f13bad97e53901210205b392ffcb83124b1c7ce6dd594688198ef600d34500a7f3552d67947bbe392802473044022033dfd8d190a4ae36b9f60999b217c775b96eb10dee3a1ff50fb6a75325719106022005872e4e36d194e49ced2ebcf8bb9d843d842e7b7e0eb042f4028396088d292f012103c9d7cbf369410b090480de2aa15c6c73d91b9ffa7d88b90724614b70be41e98e0247304402207d952de9e59e4684efed069797e3e2d993e9f98ec8a9ccd599de43005fe3f713022076d190cc93d9513fc061b1ba565afac574e02027c9efbfa1d7b71ab8dbb21e0501210313ad44bc030cc6cb111798c2bf3d2139418d751c1e79ec4e837ce360cc03b97a024730440220029e75edb5e9413eb98d684d62a077b17fa5b7cc19349c1e8cc6c4733b7b7452022048d4b9cae594f03741029ff841e35996ef233701c1ea9aa55c301362ea2e2f68012103590657108a72feb8dc1dec022cf6a230bb23dc7aaa52f4032384853b9f8388baf9d20700")
            .as_slice()).unwrap();
        let spent2: Transaction = deserialize(hex!("0200000000010166c3d39490dc827a2594c7b17b7d37445e1f4b372179649cd2ce4475e3641bbb0100000017160014e69aa750e9bff1aca1e32e57328b641b611fc817fdffffff01e87c5d010000000017a914f3890da1b99e44cd3d52f7bcea6a1351658ea7be87024830450221009eb97597953dc288de30060ba02d4e91b2bde1af2ecf679c7f5ab5989549aa8002202a98f8c3bd1a5a31c0d72950dd6e2e3870c6c5819a6c3db740e91ebbbc5ef4800121023f3d3b8e74b807e32217dea2c75c8d0bd46b8665b3a2d9b3cb310959de52a09bc9d20700")
            .as_slice()).unwrap();
        let spent3: Transaction = deserialize(hex!("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")
            .as_slice()).unwrap();

        let mut spent = HashMap::new();
        spent.insert(spent1.txid(), spent1);
        spent.insert(spent2.txid(), spent2);
        spent.insert(spent3.txid(), spent3);
        let mut spent2 = spent.clone();
        let mut spent3 = spent.clone();

        spending
            .verify(|point: &OutPoint| {
                if let Some(tx) = spent.remove(&point.txid) {
                    return tx.output.get(point.vout as usize).cloned();
                }
                None
            })
            .unwrap();

        // test that we fail with repeated use of same input
        let mut double_spending = spending.clone();
        let re_use = double_spending.input[0].clone();
        double_spending.input.push(re_use);

        assert!(double_spending
            .verify(|point: &OutPoint| {
                if let Some(tx) = spent2.remove(&point.txid) {
                    return tx.output.get(point.vout as usize).cloned();
                }
                None
            })
            .is_err());

        // test that we get a failure if we corrupt a signature
        let mut witness: Vec<_> = spending.input[1].witness.to_vec();
        witness[0][10] = 42;
        spending.input[1].witness = Witness::from_slice(&witness);
        match spending
            .verify(|point: &OutPoint| {
                if let Some(tx) = spent3.remove(&point.txid) {
                    return tx.output.get(point.vout as usize).cloned();
                }
                None
            })
            .err()
            .unwrap()
        {
            script::Error::BitcoinConsensus(_) => {}
            _ => panic!("Wrong error type"),
        }
    }

    #[test]
    fn sequence_number_tests() {
        let seq_final = Sequence::from_consensus(0xFFFFFFFF);
        let seq_non_rbf = Sequence::from_consensus(0xFFFFFFFE);
        let block_time_lock = Sequence::from_consensus(0xFFFF);
        let unit_time_lock = Sequence::from_consensus(0x40FFFF);
        let lock_time_disabled = Sequence::from_consensus(0x80000000);

        assert!(seq_final.is_final());
        assert!(!seq_final.is_rbf());
        assert!(!seq_final.is_relative_lock_time());
        assert!(!seq_non_rbf.is_rbf());
        assert!(block_time_lock.is_relative_lock_time());
        assert!(block_time_lock.is_height_locked());
        assert!(block_time_lock.is_rbf());
        assert!(unit_time_lock.is_relative_lock_time());
        assert!(unit_time_lock.is_time_locked());
        assert!(unit_time_lock.is_rbf());
        assert!(!lock_time_disabled.is_relative_lock_time());
    }

    #[test]
    fn sequence_from_str_hex_happy_path() {
        let sequence = Sequence::from_hex_str("0xFFFFFFFF").unwrap();
        assert_eq!(sequence, Sequence::MAX);
    }

    #[test]
    fn sequence_from_str_hex_no_prefix_happy_path() {
        let sequence = Sequence::from_hex_str_no_prefix("FFFFFFFF").unwrap();
        assert_eq!(sequence, Sequence::MAX);
    }

    #[test]
    fn sequence_from_str_hex_invalid_hex_should_err() {
        let hex = "0xzb93";
        let result = Sequence::from_hex_str(hex);
        assert!(result.is_err());
    }

    #[test]
    fn txin_txout_weight_tests() {
        // [(is_segwit, tx_hex)]
        let txs = [
                // one segwit input (P2WPKH)
                (true, "020000000001018a763b78d3e17acea0625bf9e52b0dc1beb2241b2502185348ba8ff4a253176e0100000000ffffffff0280d725000000000017a914c07ed639bd46bf7087f2ae1dfde63b815a5f8b488767fda20300000000160014869ec8520fa2801c8a01bfdd2e82b19833cd0daf02473044022016243edad96b18c78b545325aaff80131689f681079fb107a67018cb7fb7830e02205520dae761d89728f73f1a7182157f6b5aecf653525855adb7ccb998c8e6143b012103b9489bde92afbcfa85129a82ffa512897105d1a27ad9806bded27e0532fc84e700000000"),
                // one segwit input (P2WSH)
                (true, "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"),
                // one segwit input (P2WPKH) and two legacy inputs (P2PKH)
                (true, "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"),
                // three legacy inputs (P2PKH)
                (false, "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"),
                // one segwit input (P2TR)
                (true, "01000000000101b5cee87f1a60915c38bb0bc26aaf2b67be2b890bbc54bb4be1e40272e0d2fe0b0000000000ffffffff025529000000000000225120106daad8a5cb2e6fc74783714273bad554a148ca2d054e7a19250e9935366f3033760000000000002200205e6d83c44f57484fd2ef2a62b6d36cdcd6b3e06b661e33fd65588a28ad0dbe060141df9d1bfce71f90d68bf9e9461910b3716466bfe035c7dbabaa7791383af6c7ef405a3a1f481488a91d33cd90b098d13cb904323a3e215523aceaa04e1bb35cdb0100000000"),
                // one legacy input (P2PKH)
                (false, "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"),
            ];

        let empty_transaction_weight = Transaction {
            version: 0,
            lock_time: absolute::LockTime::ZERO,
            input: vec![],
            output: vec![],
        }
        .check_weight();

        for (is_segwit, tx) in &txs {
            let txin_weight = if *is_segwit { TxIn::segwit_weight } else { TxIn::legacy_weight };
            let tx: Transaction = deserialize(Vec::from_hex(tx).unwrap().as_slice()).unwrap();
            // The empty tx size doesn't include the segwit marker (`0001`), so, in case of segwit txs,
            // we have to manually add it ourselves
            let segwit_marker_weight = if *is_segwit { 2 } else { 0 };
            let calculated_size = empty_transaction_weight.to_wu() as usize
                + segwit_marker_weight
                + tx.input.iter().fold(0, |sum, i| sum + txin_weight(i))
                + tx.output.iter().fold(0, |sum, o| sum + o.weight());
            assert_eq!(calculated_size, tx.check_weight().to_wu() as usize);
        }
    }
}

#[cfg(bench)]
mod benches {
    use test::{black_box, Bencher};

    use super::Transaction;
    use crate::consensus::{deserialize, Encodable};
    use crate::internal_macros::hex;
    use crate::EmptyWrite;

    const SOME_TX: &str = "0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000";

    #[bench]
    pub fn bench_transaction_size(bh: &mut Bencher) {
        let raw_tx = hex!(SOME_TX);

        let mut tx: Transaction = deserialize(&raw_tx).unwrap();

        bh.iter(|| {
            black_box(black_box(&mut tx).size());
        });
    }

    #[bench]
    pub fn bench_transaction_serialize(bh: &mut Bencher) {
        let raw_tx = hex!(SOME_TX);
        let tx: Transaction = deserialize(&raw_tx).unwrap();

        let mut data = Vec::with_capacity(raw_tx.len());

        bh.iter(|| {
            let result = tx.consensus_encode(&mut data);
            black_box(&result);
            data.clear();
        });
    }

    #[bench]
    pub fn bench_transaction_serialize_logic(bh: &mut Bencher) {
        let raw_tx = hex!(SOME_TX);
        let tx: Transaction = deserialize(&raw_tx).unwrap();

        bh.iter(|| {
            let size = tx.consensus_encode(&mut EmptyWrite);
            black_box(&size);
        });
    }

    #[bench]
    pub fn bench_transaction_deserialize(bh: &mut Bencher) {
        let raw_tx = hex!(SOME_TX);

        bh.iter(|| {
            let tx: Transaction = deserialize(&raw_tx).unwrap();
            black_box(&tx);
        });
    }
}