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

//! Utility functions.
//!
//! Functions needed by all parts of the Bitcoin library.
//!

pub mod key;
pub mod ecdsa;
pub mod schnorr;
pub mod address;
pub mod amount;
pub mod base58;
pub mod bip32;
pub mod bip143;
pub mod bip152;
pub mod hash;
pub mod merkleblock;
pub mod misc;
pub mod psbt;
pub mod taproot;
pub mod uint;
pub mod bip158;
pub mod sighash;

pub(crate) mod endian;

use crate::prelude::*;
use crate::io;
use core::fmt;

use crate::consensus::encode;
use crate::internal_macros::write_err;

/// A trait which allows numbers to act as fixed-size bit arrays
pub trait BitArray {
    /// Is bit set?
    fn bit(&self, idx: usize) -> bool;

    /// Returns an array which is just the bits from start to end
    fn bit_slice(&self, start: usize, end: usize) -> Self;

    /// Bitwise and with `n` ones
    fn mask(&self, n: usize) -> Self;

    /// Trailing zeros
    fn trailing_zeros(&self) -> usize;

    /// Create all-zeros value
    fn zero() -> Self;

    /// Create value representing one
    fn one() -> Self;
}

/// A general error code, other errors should implement conversions to/from this
/// if appropriate.
#[derive(Debug)]
#[non_exhaustive]
pub enum Error {
    /// Encoding error
    Encode(encode::Error),
    /// The header hash is not below the target
    BlockBadProofOfWork,
    /// The `target` field of a block header did not match the expected difficulty
    BlockBadTarget,
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Error::Encode(ref e) => write_err!(f, "encoding error"; e),
            Error::BlockBadProofOfWork => f.write_str("block target correct but not attained"),
            Error::BlockBadTarget => f.write_str("block target incorrect"),
        }
    }
}

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

        match self {
            Encode(e) => Some(e),
            BlockBadProofOfWork | BlockBadTarget => None
        }
    }
}

#[doc(hidden)]
impl From<encode::Error> for Error {
    fn from(e: encode::Error) -> Error {
        Error::Encode(e)
    }
}

// core2 doesn't have read_to_end
pub(crate) fn read_to_end<D: io::Read>(mut d: D) -> Result<Vec<u8>, io::Error> {
    let mut result = vec![];
    let mut buf = [0u8; 64];
    loop {
        match d.read(&mut buf) {
            Ok(0) => break,
            Ok(n) => result.extend_from_slice(&buf[0..n]),
            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {},
            Err(e) => return Err(e),
        };
    }
    Ok(result)
}