use std::error::Error;

use nannou::prelude::*;
use once_cell::sync::Lazy;

const FPS: f64 = 60.0;
static RECORDING: Lazy<bool> = Lazy::new(|| std::env::args().any(|s| s == "--record"));

pub fn dump_frame(app: &App, frame: &Frame) -> Result<(), Box<dyn Error>> {
    if !*RECORDING {
        return Ok(());
    }

    let path = app
        .project_path()?
        .join("frames")
        .join(format!("{:05}", frame.nth()))
        .with_extension("png");

    println!("-> {:05} {:.3}", frame.nth(), absolute_t(app));

    app.main_window().capture_frame(path);

    Ok(())
}

pub fn delta_t(app: &App) -> f64 {
    if *RECORDING {
        1.0 / FPS
    } else {
        app.duration.since_prev_update.as_secs_f64()
    }
}

pub fn absolute_t(app: &App) -> f64 {
    if *RECORDING {
        (app.elapsed_frames() as f64) / FPS
    } else {
        app.duration.since_start.as_secs_f64()
    }
}