pub fn format_time(seconds: f64) -> String {
    if !seconds.is_finite() || seconds < 0.0 {
        return "00:00".to_string();
    }
    let total_secs = seconds as u64;
    let hours = total_secs / 3600;
    let minutes = (total_secs % 3600) / 60;
    let secs = total_secs % 60;
    if hours > 0 {
        format!("{hours:02}:{minutes:02}:{secs:02}")
    } else {
        format!("{minutes:02}:{secs:02}")
    }
}

pub fn format_duration_ns(ns: u64) -> String {
    format_time((ns / 1_000_000_000) as f64)
}

pub fn format_duration_human(ns: u64) -> String {
    let total_mins = ns / 60_000_000_000;
    let hours = total_mins / 60;
    let mins = total_mins % 60;
    match (hours, mins) {
        (0, 0) => "< 1 min".to_string(),
        (0, m) => format!("{m} min"),
        (h, 0) => format!("{h} hr"),
        (h, m) => format!("{h} hr {m} min"),
    }
}

#[cfg(any(test, all(target_family = "wasm", target_os = "unknown")))]
pub fn seek_position_from_click(click_x: f64, rect_left: f64, rect_width: f64, duration: f64) -> f64 {
    if rect_width <= 0.0 || !duration.is_finite() || duration <= 0.0 {
        return 0.0;
    }
    let ratio = ((click_x - rect_left) / rect_width).clamp(0.0, 1.0);
    ratio * duration
}

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

    #[test]
    fn zero_seconds() {
        assert_eq!(format_time(0.0), "00:00");
    }

    #[test]
    fn sub_minute() {
        assert_eq!(format_time(45.0), "00:45");
    }

    #[test]
    fn minutes_and_seconds() {
        assert_eq!(format_time(125.0), "02:05");
    }

    #[test]
    fn hours() {
        assert_eq!(format_time(3661.0), "01:01:01");
    }

    #[test]
    fn negative_returns_zero() {
        assert_eq!(format_time(-5.0), "00:00");
    }

    #[test]
    fn nan_returns_zero() {
        assert_eq!(format_time(f64::NAN), "00:00");
    }

    #[test]
    fn infinity_returns_zero() {
        assert_eq!(format_time(f64::INFINITY), "00:00");
    }

    #[test]
    fn duration_ns_one_minute() {
        assert_eq!(format_duration_ns(60_000_000_000), "01:00");
    }

    #[test]
    fn duration_ns_ninety_minutes() {
        assert_eq!(format_duration_ns(5_400_000_000_000), "01:30:00");
    }

    #[test]
    fn human_sub_minute() {
        assert_eq!(format_duration_human(30_000_000_000), "< 1 min");
    }

    #[test]
    fn human_minutes_only() {
        assert_eq!(format_duration_human(1_451_000_000_000), "24 min");
    }

    #[test]
    fn human_hours_and_minutes() {
        assert_eq!(format_duration_human(5_580_000_000_000), "1 hr 33 min");
    }

    #[test]
    fn human_exact_hours() {
        assert_eq!(format_duration_human(7_200_000_000_000), "2 hr");
    }

    #[test]
    fn seek_midpoint() {
        let t = seek_position_from_click(150.0, 100.0, 200.0, 60.0);
        assert!((t - 15.0).abs() < 0.001);
    }

    #[test]
    fn seek_clamps_left() {
        let t = seek_position_from_click(50.0, 100.0, 200.0, 60.0);
        assert_eq!(t, 0.0);
    }

    #[test]
    fn seek_clamps_right() {
        let t = seek_position_from_click(350.0, 100.0, 200.0, 60.0);
        assert_eq!(t, 60.0);
    }

    #[test]
    fn seek_zero_width() {
        assert_eq!(seek_position_from_click(100.0, 100.0, 0.0, 60.0), 0.0);
    }

    #[test]
    fn seek_nan_duration() {
        assert_eq!(seek_position_from_click(150.0, 100.0, 200.0, f64::NAN), 0.0);
    }
}