//This module defines the domain specific language.

use std::{borrow::Cow, rc::Rc};

use super::data::{Location, Mood, Speaker};
use higher::Functor;
use higher_free_macro::free;
use std::convert::identity;

#[derive(Clone)]
pub enum SausageRoll<'a, 's, A> {
    SayDialogueLine {
        speaker: Speaker,
        text: Cow<'s, str>, //In a real project I would just make this a String. Here it's a reference to show off lifetime support.
        mood: Mood,
        next: A,
    },
    GivePlayerOptions {
        options: Vec<&'s str>,
        next: Rc<dyn Fn(usize) -> A + 'a>, //let's just assume that the interpreter validates input.
    },
    PresentLocation {
        location: Location,
        next: A,
    },
    Exposition {
        text: &'s str,
        next: A,
    },
}

impl<'a, 's, A: 'a> Functor<'a, A> for SausageRoll<'a, 's, A> {
    type Target<T> = SausageRoll<'a, 's, T>;

    fn fmap<B, F>(self, f: F) -> Self::Target<B>
    where
        F: Fn(A) -> B + 'a,
    {
        match self {
            SausageRoll::SayDialogueLine {
                speaker,
                text,
                mood,
                next,
            } => SausageRoll::SayDialogueLine {
                speaker,
                text,
                mood,
                next: f(next),
            },
            SausageRoll::GivePlayerOptions { options, next } => SausageRoll::GivePlayerOptions {
                options,
                next: Rc::new(move |x| f(next(x))),
            },
            SausageRoll::PresentLocation { location, next } => SausageRoll::PresentLocation {
                location,
                next: f(next),
            },
            SausageRoll::Exposition { text, next } => SausageRoll::Exposition {
                text,
                next: f(next),
            },
        }
    }
}

free!(<'a>, pub FreeSausageRoll<'a,'s,A>, SausageRoll<'a, 's, FreeSausageRoll<'a,'s,A>>);

pub fn say_dialogue_line<'a, 's: 'a>(
    speaker: Speaker,
    text: Cow<'s, str>,
    mood: Mood,
) -> FreeSausageRoll<'a, 's, ()> {
    FreeSausageRoll::lift_f(SausageRoll::SayDialogueLine {
        speaker,
        text,
        mood,
        next: (),
    })
}

pub fn give_player_options<'a, 's: 'a>(options: Vec<&'s str>) -> FreeSausageRoll<'a, 's, usize> {
    FreeSausageRoll::lift_f(SausageRoll::GivePlayerOptions {
        options,
        next: Rc::new(identity),
    })
}

pub fn present_location<'a, 's: 'a>(location: Location) -> FreeSausageRoll<'a, 's, ()> {
    FreeSausageRoll::lift_f(SausageRoll::PresentLocation { location, next: () })
}

pub fn exposition<'a, 's: 'a>(text: &'s str) -> FreeSausageRoll<'a, 's, ()> {
    FreeSausageRoll::lift_f(SausageRoll::Exposition { text, next: () })
}