use crate::{*, tui::*};
use ratatui::prelude::Size;
use std::time::Duration;
use std::thread::{spawn, JoinHandle};

pub trait TuiRun<R: Render<Tui> + Handle<Tui> + Sized + 'static> {
    /// Run an app in the main loop.
    fn run (&self, state: &Arc<RwLock<R>>) -> Usually<()>;
    /// Spawn the input thread.
    fn run_input (&self, state: &Arc<RwLock<R>>, poll: Duration) -> JoinHandle<()>;
    /// Spawn the output thread.
    fn run_output (&self, state: &Arc<RwLock<R>>, sleep: Duration) -> JoinHandle<()>;
}

impl<T: Render<Tui> + Handle<Tui> + Sized + 'static> TuiRun<T> for Arc<RwLock<Tui>> {
    fn run (&self, state: &Arc<RwLock<T>>) -> Usually<()> {
        let _input_thread = self.run_input(state, Duration::from_millis(100));
        self.write().unwrap().setup()?;
        let render_thread = self.run_output(state, Duration::from_millis(10));
        render_thread.join().expect("main thread failed");
        self.write().unwrap().teardown()?;
        Ok(())
    }
    fn run_input (&self, state: &Arc<RwLock<T>>, poll: Duration) -> JoinHandle<()> {
        let exited = self.read().unwrap().exited.clone();
        let state  = state.clone();
        spawn(move || loop {
            if exited.fetch_and(true, Relaxed) {
                break
            }
            if ::crossterm::event::poll(poll).is_ok() {
                let event = ::crossterm::event::read().unwrap();
                match event {
                    kpat!(Ctrl-KeyCode::Char('c')) => {
                        exited.store(true, Relaxed);
                    },
                    _ => {
                        let exited = exited.clone();
                        if let Err(e) = state.write().unwrap().handle(&TuiIn(exited, event)) {
                            panic!("{e}")
                        }
                    }
                }
            }
        })
    }
    fn run_output (&self, state: &Arc<RwLock<T>>, sleep: Duration) -> JoinHandle<()> {
        let exited = self.read().unwrap().exited.clone();
        let engine = self.clone();
        let state  = state.clone();
        let Size { width, height } = engine.read().unwrap().backend.size().expect("get size failed");
        let mut buffer = Buffer::empty(Rect { x: 0, y: 0, width, height });
        spawn(move || loop {
            if exited.fetch_and(true, Relaxed) {
                break
            }
            let Size { width, height } = engine.read().unwrap().backend.size()
                .expect("get size failed");
            if let Ok(state) = state.try_read() {
                let size = Rect { x: 0, y: 0, width, height };
                if buffer.area != size {
                    engine.write().unwrap().backend.clear_region(ClearType::All)
                        .expect("clear failed");
                    buffer.resize(size);
                    buffer.reset();
                }
                let mut output = TuiOut { buffer, area: [0, 0, width, height] };
                state.render(&mut output);
                buffer = engine.write().unwrap().flip(output.buffer, size);
            }
            std::thread::sleep(sleep);
        })
    }
}