/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

//! Trait representing the concept of [serializable objects]
//! (<https://html.spec.whatwg.org/multipage/#serializable-objects>).

use std::collections::HashMap;

use base::id::{Index, NamespaceIndex, PipelineNamespaceId};

use crate::dom::bindings::reflector::DomObject;
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::structuredclone::StructuredData;
use crate::dom::globalscope::GlobalScope;
use crate::script_runtime::CanGc;

/// The key corresponding to the storage location
/// of a serialized platform object stored in a StructuredDataHolder.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub(crate) struct StorageKey {
    pub(crate) index: u32,
    pub(crate) name_space: u32,
}

impl StorageKey {
    pub(crate) fn new<T>(index: NamespaceIndex<T>) -> StorageKey {
        let name_space = index.namespace_id.0.to_ne_bytes();
        let index = index.index.0.get().to_ne_bytes();
        StorageKey {
            index: u32::from_ne_bytes(index),
            name_space: u32::from_ne_bytes(name_space),
        }
    }
}

impl<T> From<StorageKey> for NamespaceIndex<T> {
    fn from(key: StorageKey) -> NamespaceIndex<T> {
        NamespaceIndex {
            namespace_id: PipelineNamespaceId(key.name_space),
            index: Index::new(key.index).expect("Index must not be zero"),
        }
    }
}

/// Interface for serializable platform objects.
/// <https://html.spec.whatwg.org/multipage/#serializable>
pub(crate) trait Serializable: DomObject
where
    Self: Sized,
{
    type Index: Copy + Eq + std::hash::Hash;
    type Data;

    /// <https://html.spec.whatwg.org/multipage/#serialization-steps>
    fn serialize(&self) -> Result<(NamespaceIndex<Self::Index>, Self::Data), ()>;
    /// <https://html.spec.whatwg.org/multipage/#deserialization-steps>
    fn deserialize(
        owner: &GlobalScope,
        serialized: Self::Data,
        can_gc: CanGc,
    ) -> Result<DomRoot<Self>, ()>
    where
        Self: Sized;

    /// Returns the field of [StructuredDataReader]/[StructuredDataWriter] that
    /// should be used to read/store serialized instances of this type.
    fn serialized_storage<'a>(
        data: StructuredData<'a, '_>,
    ) -> &'a mut Option<HashMap<NamespaceIndex<Self::Index>, Self::Data>>;
}