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use aimc_hal::clock::Clock;
use core::time::Duration;

/// A [`Clock`] which uses the browser's native `performance.now()` function
/// to keep track of time.
#[derive(Debug, Clone, Default)]
pub struct PerformanceClock;

impl Clock for PerformanceClock {
    fn elapsed(&self) -> Duration {
        let perf = web_sys::window()
            .expect("The window always exists")
            .performance()
            .expect("The window should always have a performance timer");

        let now_ms = perf.now();
        let secs = (now_ms / 1000.0).floor();
        let secs = secs as u64;

        let nanos = ((now_ms / 1000.0).fract() * 1e9).floor();
        let nanos = nanos as u32;

        Duration::new(secs as u64, nanos as u32)
    }
}