use std::io::stderr;
use std::io::Write;

pub trait Logger {
  fn write(&mut self, &str);
  fn debug(&mut self, &str);
}

pub struct StdErrLogger;

impl Logger for StdErrLogger {
  fn debug(&mut self, str: &str) {
    writeln!(&mut stderr(), "{}", str).unwrap();
  }
  fn write(&mut self, str: &str) {
    writeln!(&mut stderr(), "{}", str).unwrap();
  }
}

pub struct FilteringLogger<'a> {
  logger: &'a mut dyn Logger,
}

impl<'a> FilteringLogger<'a> {
  pub fn new(logger: &'a mut dyn Logger) -> Self {
    FilteringLogger { logger }
  }
}

impl<'a> Logger for FilteringLogger<'a> {
  fn debug(&mut self, _str: &str) {}
  fn write(&mut self, str: &str) {
    self.logger.write(str)
  }
}

#[cfg(test)]
mod test {}