use std::sync::{
    Arc,
    atomic::{AtomicU8, Ordering},
};
use std::thread::{self, JoinHandle};

/// 使用 rdev 监听系统级键盘事件。
/// bit0 = Up, bit1 = Left, bit2 = Right
pub fn spawn_listener() -> (JoinHandle<()>, Arc<AtomicU8>) {
    let state = Arc::new(AtomicU8::new(0));
    let state_cloned = Arc::clone(&state);

    let handle = thread::spawn(move || {
        if let Err(err) = rdev::listen(move |event| {
            match event.event_type {
                rdev::EventType::KeyPress(key) => {
                    let bit = match key {
                        rdev::Key::UpArrow => Some(0x1),
                        rdev::Key::LeftArrow => Some(0x2),
                        rdev::Key::RightArrow => Some(0x4),
                        _ => None,
                    };

                    if let Some(mask) = bit {
                        state_cloned.fetch_or(mask, Ordering::SeqCst);
                        let s = state_cloned.load(Ordering::SeqCst);
                        println!("[CMD] {:?} (state=0b{:03b})", state_to_vector(s), s);
                    }
                }
                rdev::EventType::KeyRelease(key) => {
                    let bit = match key {
                        rdev::Key::UpArrow => Some(0x1),
                        rdev::Key::LeftArrow => Some(0x2),
                        rdev::Key::RightArrow => Some(0x4),
                        _ => None,
                    };

                    if let Some(mask) = bit {
                        state_cloned.fetch_and(!mask, Ordering::SeqCst);
                        let s = state_cloned.load(Ordering::SeqCst);
                        println!("[CMD] {:?} (state=0b{:03b})", state_to_vector(s), s);
                    }
                }
                _ => {}
            }
        }) {
            eprintln!("rdev listen failed: {:?}", err);
        }
    });

    (handle, state)
}

pub fn state_from_arc(state: &Arc<AtomicU8>) -> [f32; 3] {
    state_to_vector(state.load(Ordering::SeqCst))
}

/// 状态位转成控制向量。
pub fn state_to_vector(state: u8) -> [f32; 3] {
    if state & 0x1 != 0 {
        if state & 0x2 != 0 {
            [0.2, 0.0, -0.5]
        } else if state & 0x4 != 0 {
            [0.2, 0.0, 0.5]
        } else {
            [0.2, 0.0, 0.0]
        }
    } else {
        [0.0, 0.0, 0.0]
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_no_key() {
        assert_eq!(state_to_vector(0), [0.0, 0.0, 0.0]);
    }

    #[test]
    fn test_up_only() {
        assert_eq!(state_to_vector(0x1), [0.2, 0.0, 0.0]);
    }

    #[test]
    fn test_up_left() {
        assert_eq!(state_to_vector(0x1 | 0x2), [0.2, 0.0, -0.5]);
    }

    #[test]
    fn test_up_right() {
        assert_eq!(state_to_vector(0x1 | 0x4), [0.2, 0.0, 0.5]);
    }
}