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use crate::reactor::*;

macro_rules! impl_reactor_for_tuple {
    ( $($args:ident,)+ ) => {
        /// Notifies all [`Reactor`]s in the tuple in order.
        ///
        /// <small>Currently implemented for tuples of up to 12 elements.</small>
        ///
        /// # Example
        ///
        /// ```rust
        /// use reducer::*;
        /// use std::error::Error;
        ///
        /// #[derive(Debug)]
        /// struct State { /* ... */ }
        /// struct Action { /* ... */ }
        ///
        /// impl Reducer<Action> for State {
        ///     fn reduce(&mut self, action: Action) {
        ///         // ...
        ///     }
        /// }
        ///
        /// struct GUI { /* ... */ }
        /// struct DebugLogger { /* ... */ }
        ///
        /// impl Reactor<State> for GUI {
        ///     type Error = Box<dyn Error>;
        ///     fn react(&mut self, state: &State) -> Result<(), Self::Error> {
        ///         // ...
        ///         Ok(())
        ///     }
        /// }
        ///
        /// impl Reactor<State> for DebugLogger {
        ///     type Error = Box<dyn Error>;
        ///     fn react(&mut self, state: &State) -> Result<(), Self::Error> {
        ///         println!("[DEBUG] {:#?}", state);
        ///         Ok(())
        ///     }
        /// }
        ///
        /// let gui = GUI { /* ... */ };
        /// let logger = DebugLogger { /* ... */ };
        ///
        /// let mut store = Store::new(State { /* ... */ }, (gui, logger));
        ///
        /// // Both `gui` and `logger` get notified of state changes.
        /// store.dispatch(Action { /* ... */ });
        /// ```
        impl<S, X, $($args,)+> Reactor<S> for ($($args,)+)
        where
            $($args: Reactor<S, Error = X>,)+
        {
            type Error = X;

            fn react(&mut self, state: &S) -> Result<(), Self::Error> {
                #[allow(non_snake_case)]
                let ($($args,)+) = self;
                $($args.react(state)?;)+
                Ok(())
            }
        }
    };
}

macro_rules! impl_reactor_for_tuples {
    () => {};

    ( $head:ident $(, $tail:ident)* $(,)? ) => {
        impl_reactor_for_tuples!($($tail,)*);
        reverse!(impl_reactor_for_tuple!($head $(, $tail)*));
    };
}

impl_reactor_for_tuples!(L, K, J, I, H, G, F, E, D, C, B, A);

#[cfg(test)]
mod tests {
    use crate::mock::*;
    use proptest::prelude::*;

    mod ok {
        use super::*;

        macro_rules! test_reactor_for_tuples {
            () => {};

            ( $head:ident $(, $tail:ident)* $(,)? ) => {
                type $head<T> = TaggedMock<[(); count!($($tail,)*)], T>;

                proptest! {
                    #[test]
                    fn $head(states: Vec<u8>) {
                        let mut reactors = ($head::default(), $($tail::default(),)*);

                        for (i, state) in states.iter().enumerate() {
                            assert_eq!(react(&mut reactors, state), Ok(()));

                            let ($head, $($tail,)*) = &reactors;

                            assert_eq!($head.calls(), &states[0..=i]);
                            $(assert_eq!($tail.calls(), &states[0..=i]);)*
                        }
                    }
                }

                test_reactor_for_tuples!($($tail,)*);
            };
        }

        test_reactor_for_tuples!(_12, _11, _10, _09, _08, _07, _06, _05, _04, _03, _02, _01);
    }

    mod err {
        use super::*;

        macro_rules! test_reactor_for_tuples {
            () => {};

            ( $head:ident $(, $tail:ident)* $(,)? ) => {
                proptest! {
                    #[test]
                    fn $head(state: u8, error: String, at in 0usize..=count!($($tail,)*)) {
                        let mut mocks: [Mock<_, _>; count!($($tail,)*) + 1] = Default::default();
                        mocks[at].fail_if(state, &error[..]);

                        {
                            let [$head, $($tail,)*] = &mut mocks;
                            let mut reactors = ($head, $($tail,)*);

                            assert_eq!(react(&mut reactors, &state), Err(&error[..]));
                        }

                        for mock in mocks.iter().take(at + 1) {
                            assert_eq!(mock.calls(), &[state])
                        }

                        for mock in mocks.iter().skip(at + 1) {
                            assert_eq!(mock.calls(), &[])
                        }
                    }
                }

                test_reactor_for_tuples!($($tail,)*);
            };
        }

        test_reactor_for_tuples!(_12, _11, _10, _09, _08, _07, _06, _05, _04, _03, _02, _01);
    }
}