#[derive(Clone)]
pub struct Enemy {
    pub x: f32,
    pub y: f32,
    pub width: f32,
    pub height: f32,
    pub alive: bool,
}

impl Enemy {
    pub fn new(x: f32, y: f32, width: f32, height: f32) -> Self {
        Self { x, y, width, height, alive: true }
    }

    pub fn scroll(&mut self, speed: f32, dt: f32) {
        self.x -= speed * dt;
    }

    pub fn is_off_screen(&self) -> bool {
        self.x + self.width < 0.0
    }

    pub fn top(&self) -> f32 {
        self.y
    }

    pub fn bottom(&self) -> f32 {
        self.y + self.height
    }

    pub fn right(&self) -> f32 {
        self.x + self.width
    }
}

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

    #[test]
    fn scroll_moves_enemy_left() {
        let mut e = Enemy::new(200.0, 400.0, 40.0, 40.0);
        e.scroll(200.0, 0.5);
        assert!((e.x - 100.0).abs() < 1e-4);
    }

    #[test]
    fn off_screen_when_right_edge_is_negative() {
        let e = Enemy::new(-50.0, 400.0, 40.0, 40.0);
        assert!(e.is_off_screen());
    }

    #[test]
    fn not_off_screen_when_partially_visible() {
        let e = Enemy::new(-20.0, 400.0, 40.0, 40.0);
        assert!(!e.is_off_screen());
    }
}