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use std::cell::UnsafeCell;
use std::rc::Rc;
use std::os::raw::c_void;

use crate::Sender;
use crate::priv_traits::*;

pub struct Take<'a, T>{
    take: usize,
    taken: usize,
    sender: Sender<'a,T>,
    then: Option<T>,
}

impl<'a, T> Take<'a,T>{
    pub fn new(take: usize) -> Take<'a,T>{
        Take{
            take: take,
            taken: 0,
            sender: Sender::new(),
            then: None,
        }
    }

    pub fn new_with_then(take: usize, then: T) -> Take<'a,T>{
        Take{
            take: take,
            taken: 0,
            sender: Sender::new(),
            then: Some(then),
        }
    }
}

impl<'a, 'p, T> StreamInner<'a,T> for Take<'a,T>{
    #[inline]
    fn push(&mut self, st: Rc<UnsafeCell<dyn SinkInner<'a,T>+'a>>){
        self.sender.push(st)
    }

    #[inline]
    fn send(&mut self, t: T){
        self.sender.send(t)
    }
}

impl<'a, T> Remove for Take<'a, T>{
    fn remove_raw(&mut self, st: *const c_void){
        self.sender.remove_raw(st)
    }
}

impl<'a,T> SinkInner<'a,T> for Take<'a,T>{
    #[inline]
    fn call(&mut self, t: T) -> Result<(),()>{
        if self.taken < self.take {
            self.sender.send(t);
            self.taken += 1;
            Ok(())
        }else{
            match self.then.take() {
                Some(then) => self.sender.send(then),
                _ => (),
            }
            Err(())
        }
    }

    #[inline]
    fn is_alive(&self) -> bool {
        self.taken < self.take
    }
}