use std::{
    time::Duration,
    sync::{Arc, atomic::{AtomicBool, Ordering::*}},
    thread::{Builder, JoinHandle, sleep},
};
#[cfg(feature = "term")] use ::crossterm::event::poll;
use crate::time::PerfModel;

#[derive(Debug)] pub struct Task {
    /// Exit flag.
    pub exit: Arc<AtomicBool>,
    /// Performance counter.
    pub perf: Arc<PerfModel>,
    /// Use this to wait for the thread to finish.
    pub join: JoinHandle<()>,
}

impl Task {
    /// Spawn a TUI thread that runs `callt least one, then repeats until `exit`.
    pub fn new <F> (exit: Arc<AtomicBool>, mut call: F) -> Result<Self, std::io::Error>
        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
    {
        let perf = Arc::new(PerfModel::default());
        Ok(Self {
            exit: exit.clone(),
            perf: perf.clone(),
            join: Builder::new().name("tengri tui output".into()).spawn(move || {
                while !exit.fetch_and(true, Relaxed) {
                    let _ = perf.cycle(&mut call);
                }
            })?.into()
        })
    }

    /// Spawn a thread that runs `call` least one, then repeats
    /// until `exit`, sleeping for `time` msec after every iteration.
    pub fn new_sleep <F> (
        exit: Arc<AtomicBool>, time: Duration, mut call: F
    ) -> Result<Self, std::io::Error>
        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
    {
        Self::new(exit, move |perf| {
            let _ = call(perf);
            sleep(time);
        })
    }

    /// Spawn a thread that uses [crossterm::event::poll]
    /// to run `call` every `time` msec.
    #[cfg(feature = "term")] pub fn new_poll <F> (
        exit: Arc<AtomicBool>, time: Duration, mut call: F
    ) -> Result<Self, std::io::Error>
        where F: FnMut(&PerfModel)->() + Send + Sync + 'static
    {
        Self::new(exit, move |perf| {
            if poll(time).is_ok() {
                let _ = call(perf);
            }
        })
    }

    pub fn join (self) -> Result<(), Box<dyn std::any::Any + Send>> {
        self.join.join()
    }
}