use core::fmt::{Debug, Formatter, Result};

use super::BytesRef;

use crate::{Bytes, BytesMut};

/// Alternative implementation of `std::fmt::Debug` for byte slice.

///

/// Standard `Debug` implementation for `[u8]` is comma separated

/// list of numbers. Since large amount of byte strings are in fact

/// ASCII strings or contain a lot of ASCII strings (e. g. HTTP),

/// it is convenient to print strings as ASCII when possible.

impl Debug for BytesRef<'_> {

    fn fmt(&self, f: &mut Formatter<'_>) -> Result {

        write!(f, "b\"")?;

        for &b in self.0 {

            // https://doc.rust-lang.org/reference/tokens.html#byte-escapes

            if b == b'\n' {

                write!(f, "\\n")?;

            } else if b == b'\r' {

                write!(f, "\\r")?;

            } else if b == b'\t' {

                write!(f, "\\t")?;

            } else if b == b'\\' || b == b'"' {

                write!(f, "\\{}", b as char)?;

            } else if b == b'\0' {

                write!(f, "\\0")?;

            // ASCII printable

            } else if (0x20..0x7f).contains(&b) {

                write!(f, "{}", b as char)?;

            } else {

                write!(f, "\\x{:02x}", b)?;

            }

        }

        write!(f, "\"")?;

        Ok(())

    }

}

fmt_impl!(Debug, Bytes);

fmt_impl!(Debug, BytesMut);