use crate::*;
use std::sync::{Mutex, Arc, RwLock};

/// Implement the [Handle] trait.
#[macro_export] macro_rules! handle {
    (|$self:ident:$Struct:ty,$input:ident|$handler:expr) => {
        impl<E: Engine> Handle<E> for $Struct {
            fn handle (&mut $self, $input: &E) -> Perhaps<E::Handled> {
                $handler
            }
        }
    };
    ($E:ty: |$self:ident:$Struct:ty,$input:ident|$handler:expr) => {
        impl Handle<$E> for $Struct {
            fn handle (&mut $self, $input: &$E) -> Perhaps<<$E as Input>::Handled> {
                $handler
            }
        }
    }
}

/// Handle input
pub trait Handle<E: Input>: Send + Sync {
    fn handle (&mut self, _input: &E) -> Perhaps<E::Handled> {
        Ok(None)
    }
}
impl<E: Input, H: Handle<E>> Handle<E> for &mut H {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        (*self).handle(context)
    }
}
impl<E: Input, H: Handle<E>> Handle<E> for Option<H> {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        if let Some(ref mut handle) = self {
            handle.handle(context)
        } else {
            Ok(None)
        }
    }
}
impl<H, E: Input> Handle<E> for Mutex<H> where H: Handle<E> {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        self.get_mut().unwrap().handle(context)
    }
}
impl<H, E: Input> Handle<E> for Arc<Mutex<H>> where H: Handle<E> {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        self.lock().unwrap().handle(context)
    }
}
impl<H, E: Input> Handle<E> for RwLock<H> where H: Handle<E> {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        self.write().unwrap().handle(context)
    }
}
impl<H, E: Input> Handle<E> for Arc<RwLock<H>> where H: Handle<E> {
    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
        self.write().unwrap().handle(context)
    }
}