use bytes;

use std::borrow::Borrow;
use std::fmt::{Display, Write};
use std::io;

pub fn comma_delimited<T: Display + ?Sized, B: Borrow<T>, I: IntoIterator<Item = B>>(
    iter: I,
) -> String {
    let mut iter = iter.into_iter();
    let mut ret = String::new();
    if let Some(b) = iter.next() {
        write!(ret, "{}", b.borrow()).unwrap();
        for b in iter {
            write!(ret, ",{}", b.borrow()).unwrap();
        }
    }
    ret
}

//const DEFAULT_CAPACITY: usize = 4096;
const SMOL_CAPCITY: usize = 64;

pub(crate) struct BytesWriter {
    buf: bytes::BytesMut,
}

impl BytesWriter {
    pub fn with_smol_capacity() -> Self {
        Self::with_capacity(SMOL_CAPCITY)
    }

    pub fn with_capacity(capacity: usize) -> Self {
        Self {
            buf: bytes::BytesMut::with_capacity(capacity),
        }
    }

    pub fn into_inner(self) -> bytes::BytesMut {
        self.buf
    }
}

impl io::Write for BytesWriter {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.buf.extend_from_slice(buf);
        Ok(buf.len())
    }

    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.buf.extend_from_slice(buf);
        Ok(())
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}