use log::{debug, warn};
use std::thread;
use std::time::{Duration, Instant};

/// Converts helios Geometry to Helios
#[derive(Debug, Clone, Copy)]
pub struct Framerate {
    start: Instant,
    prev_trace_time: Instant,
    framerate: u8,
}

impl Framerate {
    pub fn new(framerate: u8) -> Result<Self, Box<dyn std::error::Error>> {
        Ok(Framerate {
            start: Instant::now(),
            prev_trace_time: Instant::now(),
            framerate,
        })
    }
    pub fn handle_time(&mut self) -> Result<(f64), Box<dyn std::error::Error>> {
        let frame_time = 1000000000 / self.framerate as u128;
        let now = Instant::now();
        // How long since last loop ?
        let nanotime_spent = self.prev_trace_time.elapsed().as_nanos();
        // Diw it go too fast? If so : sleep a bit
        if frame_time > nanotime_spent {
            let nanotime_towait = frame_time - nanotime_spent;
            let dur = Duration::new(0, (nanotime_towait as f32 * 0.9) as u32);
            //debug!( "{:?} - {:?} : {:?}", nanotime_towait, self.prev_trace_time, now);
            thread::sleep(dur);
            //debug!("Framerate OK");
        } else {
            //warn!(
            //    "Frame slower than expected {:?} > {:?}",
            //    nanotime_spent, frame_time,
            //);
        }

        let time_from_begin = self.start.elapsed().as_nanos() as f64 / 1000000000.;
        self.prev_trace_time = now;
        Ok(time_from_begin)
    }
}