use crate::core::*;

/// Trait for things that handle input events.
pub trait Handle {
    /// Handle an input event.
    /// Returns Ok(true) if the device handled the event.
    /// This is the mechanism which allows nesting of components;.
    fn handle (&mut self, _e: &AppEvent) -> Usually<bool> {
        Ok(false)
    }
}

/// Implement the `Handle` trait.
#[macro_export] macro_rules! handle {
    ($T:ty) => {
        impl Handle for $T {}
    };
    ($T:ty |$self:ident, $e:ident|$block:tt) => {
        impl Handle for $T {
            fn handle (&mut $self, $e: &AppEvent) -> Usually<bool> {
                $block
            }
        }
    };
    ($T:ty = $handle:path) => {
        impl Handle for $T {
            fn handle (&mut self, e: &AppEvent) -> Usually<bool> {
                $handle(self, e)
            }
        }
    }
}

#[derive(Debug)]
pub enum AppEvent {
    /// Terminal input
    Input(::crossterm::event::Event),
    /// Update values but not the whole form.
    Update,
    /// Update the whole form.
    Redraw,
    /// Device gains focus
    Focus,
    /// Device loses focus
    Blur,
    /// JACK notification
    Jack(JackEvent)
}

pub type KeyHandler<T> = &'static dyn Fn(&mut T)->Usually<bool>;

pub type KeyBinding<T> = (
    KeyCode, KeyModifiers, &'static str, &'static str, KeyHandler<T>
);

pub type KeyMap<T> = [KeyBinding<T>];

pub fn handle_keymap <T> (
    state: &mut T, event: &AppEvent, keymap: &KeyMap<T>,
) -> Usually<bool> {
    match event {
        AppEvent::Input(Event::Key(event)) => {
            for (code, modifiers, _, _, command) in keymap.iter() {
                if *code == event.code && modifiers.bits() == event.modifiers.bits() {
                    return command(state)
                }
            }
        },
        _ => {}
    };
    Ok(false)
}

/// Define a key binding.
#[macro_export] macro_rules! key {
    ($k:ident $(($char:literal))?, $m:ident, $n: literal, $d: literal, $f: expr) => {
        (KeyCode::$k $(($char))?, KeyModifiers::$m, $n, $d, &$f)
    };
}

/// Define a keymap.
#[macro_export] macro_rules! keymap {
    ($T:ty { $([$k:ident $(($char:literal))?, $m:ident, $n: literal, $d: literal, $f: expr]),* $(,)? }) => {
        &[
            $((KeyCode::$k $(($char))?, KeyModifiers::$m, $n, $d, &$f as KeyHandler<$T>)),*
        ] as &'static [KeyBinding<$T>]
    }
}