ns nr::train

use object::{assign, Props, props!}

pub int Train
    name: String
    primaryColor: Color

    fld destination: String
    fld volume: Int

    fn blowHorn() -> IO
end

pub enum Color
    White,
    Blue,
    Red
end

pub type Printer = fn (message: String) -> IO

pub fn create(props: obj Props<Train> + { printer: Printer }) -> Train =
    SimpleTrain(props).with {
        volume = 80
    }

class SimpleTrain : Train
    props!::<Train>()
    printer: Printer

    ctor(props: obj Props<Train> + { printer: Printer })
        assign(self, props)
    end

    impl fn blowHorn() -> IO
        printer("Train ${name} is blowing its horn at volume ${volume}!")
    end
end

pub fn createViaObj(props: obj Props<Train>, printer: Printer) -> obj Train
    obj {
        ...props,
        printer,
        blowHorn: fn () -> IO
            printer("Dynamic object Train ${train} is blowing its horn at volume ${self.volume}!")
        end
    }
end

// props lib file
ns std::core::object

pub fn assign(target: obj, source: obj)
    for [key, value] source.props() do
        target[key] = value
    end
end

pub type Props<T> = obj {
    [K in keyof T]: T[K]
}

pub macro fn <T> props!(_: TokenStream) -> TokenStream
    let result = TokenStream()
    for [key, type] in std::intrinsics::propsAndTypes::<T>() do
        result << quote! {
            #key: #type
        }
    end
    result
end

// io lib file
ns std::core

pub enum IO<S : Stream = Stream, E = Error> : fn () -> IO<S, E>
    Success(stream: S)
        impl ()
            try
                doCall(stream)
            catch (e: E)
                Failure(e)
            end
        end
    end,
    Failure(_)
        impl ()
            self
        end
    end;

    int
        fn <Z : Stream = S> doCall(stream: S) -> IO<Z, E>
    end
end

// main example file
ns nr::example

use nr::train::{create, createViaObj, Train, Color}

fn main()
    let train = create(obj {
        name: 'Test Train',
        primaryColor: Color::Blue,
        destination: 'Nonavosa Central',
        printer: println
    })
    train.blowHorn()
    train.volume = 100
    train.blowHorn()

    let objTrain: obj Train = createViaObj(obj {
        name: 'Obj Train',
        primaryColor: Color::Red,
        destination: 'Durandana',
        printer: println
    })
    // Since it's an obj, we can dynamically add properties and override methods, similar to JS
    objTrain.secondaryColor = Color::White
    let originalBlowHorn = objTrain.blowHorn
    objTrain.blowHorn = fn ()
        originalBlowHorn()
        println "Hello again! The train's colors are ${self.primaryColor} and ${self.secondaryColor}!"
    end
    objTrain.blowHorn()
end