use objects::{ObjectPayload, ObjectRef, ObjectStore, TypeConstructor, Value, VmError};

#[derive(Debug)]
struct Proxy(ObjectRef);
impl ObjectPayload for Proxy {
    fn as_any(&self) -> &dyn std::any::Any {
        self
    }
    fn kind_name(&self) -> &'static str {
        "proxy"
    }
    fn trace(&self, visit: &mut dyn FnMut(ObjectRef)) {
        visit(self.0);
    }
    fn attribute_target(&self, _: &ObjectStore) -> Result<Option<ObjectRef>, VmError> {
        Ok(Some(self.0))
    }
}

#[test]
fn storage_retargeting_preserves_type_identity_and_releases_old_state() {
    let mut store = ObjectStore::new().unwrap();
    let roots = store.bootstrap_types().unwrap();
    let class = store
        .new_type("Proxy", roots.object, TypeConstructor::Record)
        .unwrap();
    let storage = store.new_object().unwrap();
    let old_value = store.new_object().unwrap();
    let weak_value = store.downgrade(old_value).unwrap();
    store
        .set_attr(storage, "value", Value::Object(old_value))
        .unwrap();
    store.release(old_value).unwrap();
    let proxy = store.allocate(Proxy(storage)).unwrap();
    store.attach_type(proxy, class).unwrap();
    store.release(storage).unwrap();
    assert_eq!(store.attribute_path(proxy).unwrap(), vec![proxy, storage]);
    assert_eq!(store.get_attr(proxy, "type").unwrap(), Value::Object(class));
    assert_eq!(
        store.get_attr(proxy, "value").unwrap(),
        Value::Object(old_value)
    );
    let next = store.new_object().unwrap();
    store.replace_payload(proxy, Proxy(next)).unwrap();
    store.release(next).unwrap();
    assert!(store.upgrade(weak_value).unwrap().is_none());
    store
        .set_attr(proxy, "value", Value::Number(9_i64.into()))
        .unwrap();
    assert_eq!(
        store.get_attr(next, "value").unwrap(),
        Value::Number(9_i64.into())
    );
    store.del_attr(proxy, "value").unwrap();
    assert!(store.get_attr(next, "value").is_err());
    for object in [proxy, class, roots.object, roots.type_type] {
        store.release(object).unwrap();
    }
    store.collect_cycles();
    assert_eq!(store.object_count(), 0);
}

#[test]
fn cyclic_and_foreign_attribute_storage_fail_without_mutating_fields() {
    let mut store = ObjectStore::new().unwrap();
    let storage = store.new_object().unwrap();
    let proxy = store.allocate(Proxy(storage)).unwrap();
    store.replace_payload(proxy, Proxy(proxy)).unwrap();
    let version = store.change_version(proxy).unwrap();
    assert!(store.get_attr(proxy, "field").is_err());
    assert!(store.set_attr(proxy, "field", Value::Nil).is_err());
    assert_eq!(store.change_version(proxy).unwrap(), version);
    let other = ObjectStore::new().unwrap();
    assert_eq!(other.attribute_path(proxy), Err(VmError::ForeignHandle));
    store.release(storage).unwrap();
    store.release(proxy).unwrap();
    assert_eq!(store.collect_cycles(), 1);
}