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//! Like onions

extern crate sdl2;

use sdl2::render::Canvas;
use sdl2::video::Window;

use drawable::{DrawSettings, Drawable, Position, State};

/// I'm not sure why this is needed, but when just storing the dyn Drawable, the compiler complains about
/// Layered::content_mut
///
/// Please ignore this
#[allow(missing_docs)]
pub trait Layerable: Drawable {
    fn as_drawable(&self) -> &dyn Drawable;
    fn as_drawable_mut(&mut self) -> &mut dyn Drawable;
}

impl<T: Drawable> Layerable for T {
    fn as_drawable(&self) -> &dyn Drawable {
        self
    }
    fn as_drawable_mut(&mut self) -> &mut dyn Drawable {
        self
    }
}

/// A list of object on top of each other
pub struct Layered {
    /// Should the items be stepped in order, i.e. sequentially, or should they be
    /// stepped all at the same time?
    update_seq: bool,
    /// The object to be layered
    content: Vec<Box<dyn Layerable>>,
}

impl Layered {
    /// Create a new Layered
    pub fn new(update_seq: bool, content: Vec<Box<dyn Layerable>>) -> Layered {
        Layered {
            content,
            update_seq,
        }
    }
}

impl Drawable for Layered {
    fn content(&self) -> Vec<&dyn Drawable> {
        self.content.iter().map(|x| x.as_drawable()).collect()
    }

    fn content_mut(&mut self) -> Vec<&mut dyn Drawable> {
        self.content
            .iter_mut()
            .map(|x| x.as_drawable_mut())
            .collect()
    }

    fn draw(&self, canvas: &mut Canvas<Window>, pos: &Position, settings: DrawSettings) {
        for obj in &self.content {
            obj.draw(canvas, pos, settings);
        }
    }

    fn step(&mut self) {
        let mut any_stepped = false;
        for item in &mut self.content {
            if item.state() == State::Working {
                item.step();
                any_stepped = true;
                if self.update_seq {
                    return;
                }
            }
        }

        if !any_stepped {
            for item in &mut self.content {
                if item.state() == State::Final {
                    item.step();
                }
            }
        }
    }

    fn state(&self) -> State {
        self.content
            .iter()
            .map(|x| x.state())
            .min()
            .unwrap_or(State::Hidden)
    }
}