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//! This file is derived from Rust's library/std/src/io/buffered at revision
//! f7801d6c7cc19ab22bdebcc8efa894a564c53469.
//!
//! Buffering wrappers for I/O traits.
//!
//! This differs from [`bufreaderwriter`] in not requiring or implementing
//! `Seek`. This crate is meant for interactive streams, and not files.
//!
//! [`bufreaderwriter`]: https://crates.io/crates/bufreaderwriter

mod buf_duplexer;
mod buf_reader_line_writer;
mod buf_reader_line_writer_shim;

use std::io::Error;
use std::{error, fmt};

pub use buf_duplexer::BufDuplexer;
pub use buf_reader_line_writer::BufReaderLineWriter;
use buf_reader_line_writer_shim::BufReaderLineWriterShim;

/// The value from `library/std/src/sys_common/io.rs`.
pub(super) const DEFAULT_BUF_SIZE: usize = 8 * 1024;

/// An error returned by [`BufWriter::into_inner`] which combines an error that
/// happened while writing out the buffer, and the buffered writer object
/// which may be used to recover from the condition.
///
/// # Examples
///
/// ```no_run
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // do stuff with the stream
///
/// // we want to get our `TcpStream` back, so let's try:
///
/// let stream = match stream.into_inner() {
///     Ok(s) => s,
///     Err(e) => {
///         // Here, e is an `IntoInnerError`
///         panic!("An error occurred");
///     }
/// };
/// ```
///
/// [`BufWriter::into_inner`]: https://doc.rust-lang.org/std/io/struct.BufWriter.html#method.into_inner
#[derive(Debug)]
pub struct IntoInnerError<W>(W, Error);

impl<W> IntoInnerError<W> {
    /// Construct a new `IntoInnerError`
    fn new(writer: W, error: Error) -> Self {
        Self(writer, error)
    }

    /// Helper to construct a new `IntoInnerError`; intended to help with`
    /// adapters that wrap other adapters
    fn new_wrapped<W2>(self, f: impl FnOnce(W) -> W2) -> IntoInnerError<W2> {
        let Self(writer, error) = self;
        IntoInnerError::new(f(writer), error)
    }

    /// Returns the error which caused the call to [`BufWriter::into_inner()`]
    /// to fail.
    ///
    /// This error was returned when attempting to write the internal buffer.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io::BufWriter;
    /// use std::net::TcpStream;
    ///
    /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
    ///
    /// // do stuff with the stream
    ///
    /// // we want to get our `TcpStream` back, so let's try:
    ///
    /// let stream = match stream.into_inner() {
    ///     Ok(s) => s,
    ///     Err(e) => {
    ///         // Here, e is an `IntoInnerError`, let's log the inner error.
    ///         //
    ///         // We'll just 'log' to stdout for this example.
    ///         println!("{}", e.error());
    ///
    ///         panic!("An unexpected error occurred.");
    ///     }
    /// };
    /// ```
    ///
    /// [`BufWriter::into_inner()`]: std::io::BufWriter::into_inner
    pub fn error(&self) -> &Error {
        &self.1
    }

    /// Returns the buffered writer instance which generated the error.
    ///
    /// The returned object can be used for error recovery, such as
    /// re-inspecting the buffer.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io::BufWriter;
    /// use std::net::TcpStream;
    ///
    /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
    ///
    /// // do stuff with the stream
    ///
    /// // we want to get our `TcpStream` back, so let's try:
    ///
    /// let stream = match stream.into_inner() {
    ///     Ok(s) => s,
    ///     Err(e) => {
    ///         // Here, e is an `IntoInnerError`, let's re-examine the buffer:
    ///         let buffer = e.into_inner();
    ///
    ///         // do stuff to try to recover
    ///
    ///         // afterwards, let's just return the stream
    ///         buffer.into_inner().unwrap()
    ///     }
    /// };
    /// ```
    pub fn into_inner(self) -> W {
        self.0
    }
}

impl<W> From<IntoInnerError<W>> for Error {
    fn from(iie: IntoInnerError<W>) -> Self {
        iie.1
    }
}

impl<W: Send + fmt::Debug> error::Error for IntoInnerError<W> {
    #[allow(deprecated, deprecated_in_future)]
    fn description(&self) -> &str {
        error::Error::description(self.error())
    }
}

impl<W> fmt::Display for IntoInnerError<W> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.error().fmt(f)
    }
}