use std::{
    io::{self, Read, Write,},
};

pub struct MulticastStream<T>
where T: Write
{
    outputs: Vec<T>,
    continue_on_fail: bool,
}

impl<T> MulticastStream<T>
where T: Write
{
    pub fn new() -> Self {
	Self {
	    outputs: Vec::new(),
	    continue_on_fail: false,
	}
    }
    pub fn continue_on_fail(self, set: bool) -> Self {
	Self {
	    continue_on_fail: set,
	    ..self
	}
    }
    pub fn cast(&mut self, output: T) {
	self.outputs.push(output);
    }
}

impl<T> Write for MulticastStream<T>
where T: Write
{
    fn write(&mut self, buf: &[u8]) -> io::Result<usize>
    {
	let mut sz =0;
	let mut one_ok = self.outputs.len() < 1;
	for res in self.outputs.iter_mut().map(|output| output.write(&buf)) {
	    match res {
		Ok(res) if res > sz => sz = res,
		Err(err) if !self.continue_on_fail => return Err(err),
		Err(_) => continue,
		_ => (),
	    };
	    one_ok = true;
	}

	if !one_ok {
	    Err(io::Error::new(io::ErrorKind::UnexpectedEof, "All write streams failed"))
	} else {
	    Ok(sz)
	}
    }

    fn flush(&mut self) -> io::Result<()>
    {
	let mut errors = 0;
	for res in self.outputs.iter_mut().map(|output| output.flush()) {
	    if let Err(err) = res {
		if !self.continue_on_fail {
		    return Err(err);
		}
		errors += 1;
	    }
	}

	if errors > 0 && errors == self.outputs.len() {
	    Err(io::Error::new(io::ErrorKind::UnexpectedEof, "All write streams failed"))
	} else {
	    Ok(())
	}
    }
}