typestate 0.5.3

// use maintenance::*;
use traffic_light::*;
use typestate::typestate;

const N_CYCLES_MAINTENANCE: u64 = 1000;

fn main() {
    let red_light = TrafficLight::<Red>::turn_on();
    let mut green_light = red_light.to_green();
    if green_light.requires_maintenance() {
        green_light.reset_cycles()
    }
    let yellow_light = green_light.to_yellow();
    let red_light = yellow_light.to_red();
    red_light.turn_off();
}

// #[typestate]
// mod test {
//     #[automata]
//     pub struct Automata {}
// }

// #[typestate]
// mod maintenance {
//     use super::traffic_light::*;
//     #[automata]
//     pub struct Maintenance {
//         pub tl: TrafficLight<Red>,
//     }

//     #[state]
//     pub struct In;
//     #[state]
//     pub struct Out;

//     pub trait In {
//         fn new() -> In;
//         fn perform(self) -> Out;
//     }

//     pub trait Out {
//         fn test(self) -> Out;
//         fn end(self);
//     }
// }

// impl InState for Maintenance<In> {
//     fn new() -> Maintenance<In> {
//         Maintenance::<In> {
//             tl: TrafficLight::<Red>::turn_on(),
//             state: In,
//         }
//     }
//     fn perform(self) -> Maintenance<Out> {
//         Maintenance::<Out> {
//             tl: self.tl,
//             state: Out,
//         }
//     }
// }

// impl OutState for Maintenance<Out> {
//     fn test(mut self) -> Maintenance<Out> {
//         let green = self.tl.to_green();
//         let yellow = green.to_yellow();
//         let red = yellow.to_red();
//         self.tl = red;
//         self
//     }
//     fn end(self) {}
// }

#[typestate(enumerate, state_constructors)]
mod traffic_light {
    #[derive(Debug)]
    #[automata]
    pub struct TrafficLight {
        pub cycles: u64,
    }
    #[state]
    pub struct Green;
    #[state]
    pub struct Yellow;
    #[state]
    pub struct Red;

    // #[transition]
    pub trait Green {
        fn to_yellow(self) -> Yellow;
    }
    pub trait Yellow {
        fn to_red(self) -> Red;
    }
    pub trait Red {
        fn to_green(self) -> Green;
        fn turn_on() -> Red;
        fn turn_off(self);
        fn to_either(self) -> Either;
    }

    pub enum Either {
        Yellow,
        Red,
    }
}

impl GreenState for TrafficLight<Green> {
    fn to_yellow(self) -> TrafficLight<Yellow> {
        println!("Green -> Yellow");
        TrafficLight::<Yellow> {
            cycles: self.cycles,
            state: Yellow,
        }
    }
}

impl YellowState for TrafficLight<Yellow> {
    fn to_red(self) -> TrafficLight<Red> {
        println!("Yellow -> Red");
        TrafficLight::<Red> {
            // increment the cycle
            cycles: self.cycles + 1,
            state: Red,
        }
    }
}

impl RedState for TrafficLight<Red> {
    fn to_either(self) -> Either {
        Either::Yellow(TrafficLight::<Yellow> {
            cycles: self.cycles,
            state: Yellow,
        })
    }

    fn to_green(self) -> TrafficLight<Green> {
        println!("Red -> Green");
        TrafficLight::<Green> {
            cycles: self.cycles,
            state: Green,
        }
    }

    fn turn_on() -> TrafficLight<Red> {
        println!("Turning on...");
        TrafficLight::<Red> {
            cycles: 0,
            state: Red,
        }
    }

    fn turn_off(self) {
        println!("Turning off...");
        // ... consume
    }
}

impl<State> TrafficLight<State>
where
    State: TrafficLightState,
{
    fn requires_maintenance(&self) -> bool {
        self.cycles > N_CYCLES_MAINTENANCE
    }

    fn reset_cycles(&mut self) {
        self.cycles = 0;
    }
}