use serde::{Deserialize, Serialize};
use specs::{SystemData, Component, DerefFlaggedStorage};
use specs_idvs::IdvStorage;
use std::{
    ops::Deref,
    sync::Arc,
};

pub trait Link: Sized + Send + Sync + 'static {
    type CreateData<'a>: SystemData<'a>;
    fn create(this: &LinkHandle<Self>, data: Self::CreateData<'_>) -> Result<(), ()>;

    type PersistData<'a>: SystemData<'a>;
    fn persist(this: &LinkHandle<Self>, data: Self::PersistData<'_>) -> bool;

    type DeleteData<'a>: SystemData<'a>;
    fn delete(this: &LinkHandle<Self>, data: Self::DeleteData<'_>);
}

pub trait Role {
    type Link: Link;
}

#[derive(Serialize, Deserialize, Debug)]
pub struct Is<R: Role> {
    #[serde(bound(serialize = "R::Link: Serialize"))]
    #[serde(bound(deserialize = "R::Link: Deserialize<'de>"))]
    link: LinkHandle<R::Link>,
}

impl<R: Role> Is<R> {
    pub fn delete(&self, data: <R::Link as Link>::DeleteData<'_>) {
        R::Link::delete(&self.link, data)
    }
}

impl<R: Role> Clone for Is<R> {
    fn clone(&self) -> Self { Self { link: self.link.clone() } }
}

impl<R: Role> Deref for Is<R> {
    type Target = R::Link;
    fn deref(&self) -> &Self::Target { &self.link }
}

impl<R: Role + 'static> Component for Is<R>
    where R::Link: Send + Sync + 'static
{
    type Storage = DerefFlaggedStorage<Self, IdvStorage<Self>>;
}

#[derive(Serialize, Deserialize, Debug)]
pub struct LinkHandle<L: Link> {
    link: Arc<L>,
}

impl<L: Link> Clone for LinkHandle<L> {
    fn clone(&self) -> Self {
        Self { link: self.link.clone() }
    }
}

impl<L: Link> LinkHandle<L> {
    pub fn from_link(link: L) -> Self {
        Self { link: Arc::new(link) }
    }

    pub fn make_role<R: Role<Link = L>>(&self) -> Is<R> {
        Is { link: self.clone() }
    }
}

impl<L: Link> Deref for LinkHandle<L> {
    type Target = L;
    fn deref(&self) -> &Self::Target { &self.link }
}