use crate::*;

pub trait Command<S>: Sized {
    fn run (&self, state: &mut S) -> Perhaps<Self>;
}
pub trait MatchInput<E: Engine, S>: Sized {
    fn match_input (state: &S, input: &E::Input) -> Option<Self>;
}
pub struct MenuBar<E: Engine, S, C: Command<S>> {
    pub menus: Vec<Menu<E, S, C>>,
    pub index: usize,
}
impl<E: Engine, S, C: Command<S>> MenuBar<E, S, C> {
    pub fn new () -> Self { Self { menus: vec![], index: 0 } }
    pub fn add (mut self, menu: Menu<E, S, C>) -> Self {
        self.menus.push(menu);
        self
    }
}
pub struct Menu<E: Engine, S, C: Command<S>> {
    pub title: String,
    pub items: Vec<MenuItem<E, S, C>>,
    pub index: usize,
}
impl<E: Engine, S, C: Command<S>> Menu<E, S, C> {
    pub fn new (title: impl AsRef<str>) -> Self {
        Self {
            title: title.as_ref().to_string(),
            items: vec![],
            index: 0
        }
    }
    pub fn add (mut self, item: MenuItem<E, S, C>) -> Self {
        self.items.push(item);
        self
    }
    pub fn sep (mut self) -> Self {
        self.items.push(MenuItem::sep());
        self
    }
    pub fn cmd (mut self, hotkey: &'static str, text: &'static str, command: C) -> Self {
        self.items.push(MenuItem::cmd(hotkey, text, command));
        self
    }
    pub fn off (mut self, hotkey: &'static str, text: &'static str) -> Self {
        self.items.push(MenuItem::off(hotkey, text));
        self
    }
}
pub enum MenuItem<E: Engine, S, C: Command<S>> {
    /// Unused.
    __(PhantomData<E>, PhantomData<S>),
    /// A separator. Skip it.
    Separator,
    /// A menu item with command, description and hotkey.
    Command(&'static str, &'static str, C),
    /// A menu item that can't be activated but has description and hotkey
    Disabled(&'static str, &'static str)
}
impl<E: Engine, S, C: Command<S>> MenuItem<E, S, C> {
    pub fn sep () -> Self {
        Self::Separator
    }
    pub fn cmd (hotkey: &'static str, text: &'static str, command: C) -> Self {
        Self::Command(hotkey, text, command)
    }
    pub fn off (hotkey: &'static str, text: &'static str) -> Self {
        Self::Disabled(hotkey, text)
    }
}