mod lamp {
    enum Direction {
        to_right,
        to_left
    }
    pub struct Lamp {
        direction: Direction,
        lamp_no: u32
    }
    
    impl Lamp {
        pub fn duration(&self) -> f32 {
            match self.lamp_no {
                1..=4 => 1.5,
                5..=7 => 2.5,
                _ => unreachable!()
            }
        }
    
        pub fn next(&mut self) {
            use Direction::{to_left, to_right};
            match (&self.direction, &mut self.lamp_no) {
                (to_right, 6) => *self = Self {direction: to_left, lamp_no: 7},
                (to_left, 2) => *self = Self {direction: to_right, lamp_no: 1},
                (to_right, n) => *n += 1,
                (to_left, n) => *n -= 1
            }
        }
    }
    
    impl Default for Lamp {
        fn default() -> Self {
            Self { direction: Direction::to_right, lamp_no: 1 }
        }
    }
    
    impl ToString for Lamp {
        fn to_string(&self) -> String {
            match self.lamp_no {
                1 => "K".into(),
                2 => "L".into(),
                3 => "M".into(),
                4 => "N".into(),
                5 => "P".into(),
                6 => "R".into(), 
                7 => "S".into(),
                _ => unreachable!()
            }
        }
    }
}

fn main() {
    let mut my_lamp = lamp::Lamp::default();

    let mut start_time = 0.0;
    let mut end_time = start_time + my_lamp.duration();

    while end_time < 150.0 {
        my_lamp.next();
        start_time = end_time;
        end_time = start_time + my_lamp.duration();
    }

    println!("Lambanın yanmaya başlama süresi: {}, Lambanın sönme süresi: {}, Lambanın harfi: {}", start_time, end_time, my_lamp.to_string())
}