naia-shared 0.25.0

use crate::world::local::local_entity::RemoteEntity;
use crate::world::local::local_world_manager::LocalWorldManager;
use crate::{
    messages::channels::receivers::indexed_message_reader::IndexedMessageReader,
    world::host::host_world_manager::SubCommandId, BitReader, ComponentKind, ComponentKinds,
    EntityAuthStatus, EntityMessage, EntityMessageType, HostEntity, MessageIndex, OwnedLocalEntity,
    Serde, SerdeErr, Tick,
};

/// Stateless helper that deserializes entity update and message payloads from a bit stream into a [`LocalWorldManager`].
pub struct WorldReader;

impl WorldReader {
    // Reading

    fn read_message_index(
        reader: &mut BitReader,
        last_index_opt: &mut Option<MessageIndex>,
    ) -> Result<MessageIndex, SerdeErr> {
        // read index
        let current_index = IndexedMessageReader::read_message_index(reader, last_index_opt)?;

        *last_index_opt = Some(current_index);

        Ok(current_index)
    }

    /// Deserializes both component updates and entity messages from `reader` into `world_manager`.
    pub fn read_world_events(
        world_manager: &mut LocalWorldManager,
        component_kinds: &ComponentKinds,
        tick: &Tick,
        reader: &mut BitReader,
    ) -> Result<(), SerdeErr> {
        // read entity updates
        Self::read_updates(world_manager, component_kinds, tick, reader)?;

        // read entity messages
        Self::read_messages(world_manager, component_kinds, reader)?;

        Ok(())
    }

    /// Read incoming Entity messages.
    fn read_messages(
        world_manager: &mut LocalWorldManager,
        component_kinds: &ComponentKinds,
        reader: &mut BitReader,
    ) -> Result<(), SerdeErr> {
        let mut last_read_id: Option<MessageIndex> = None;

        loop {
            // read message continue bit
            let message_continue = bool::de(reader)?;
            if !message_continue {
                break;
            }

            Self::read_message(world_manager, component_kinds, reader, &mut last_read_id)?;
        }

        Ok(())
    }

    /// Read the bits corresponding to the EntityMessage and adds the [`EntityMessage`]
    /// to an internal buffer.
    ///
    /// We can use a UnorderedReliableReceiver buffer because the messages have already been
    /// ordered by the client's jitter buffer
    fn read_message(
        world_manager: &mut LocalWorldManager,
        component_kinds: &ComponentKinds,
        reader: &mut BitReader,
        last_read_id: &mut Option<MessageIndex>,
    ) -> Result<(), SerdeErr> {
        let message_id = Self::read_message_index(reader, last_read_id)?;

        let message_type = EntityMessageType::de(reader)?;

        match message_type {
            EntityMessageType::Spawn => {
                // Count when Spawn message KIND is recognized on wire (before routing)
                #[cfg(feature = "e2e_debug")]
                {
                    extern "Rust" {
                        fn client_saw_spawn_increment();
                    }
                    // Safety: client_saw_spawn_increment is defined by the naia-tests harness
                    // when compiled with feature = "e2e_debug". It atomically increments a
                    // counter and has no preconditions. The e2e_debug feature is never enabled
                    // in production builds.
                    unsafe {
                        client_saw_spawn_increment();
                    }
                }

                // read remote entity
                let remote_entity = RemoteEntity::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::Spawn(remote_entity.copy_to_owned()),
                );
            }
            EntityMessageType::SpawnWithComponents => {
                // read entity as full OwnedLocalEntity (carries is_static) then reverse to Remote
                let local_entity = OwnedLocalEntity::de(reader)?.to_reversed();

                // read component count
                let count = u8::de(reader)?;

                let mut kinds = Vec::with_capacity(count as usize);
                for _ in 0..count {
                    let converter = world_manager.entity_converter();
                    let new_component = component_kinds.read(reader, converter)?;
                    let new_component_kind = new_component.kind();
                    world_manager.insert_received_component(
                        &local_entity,
                        &new_component_kind,
                        new_component,
                    );
                    kinds.push(new_component_kind);
                }

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::SpawnWithComponents(local_entity, kinds),
                );
            }
            EntityMessageType::Despawn => {
                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                world_manager
                    .receiver_buffer_message(message_id, EntityMessage::Despawn(local_entity));
            }
            EntityMessageType::InsertComponent => {
                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                // read component
                let converter = world_manager.entity_converter();
                let new_component = component_kinds.read(reader, converter)?;
                let new_component_kind = new_component.kind();

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::InsertComponent(local_entity, new_component_kind),
                );
                world_manager.insert_received_component(
                    &local_entity,
                    &new_component_kind,
                    new_component,
                );
            }
            EntityMessageType::RemoveComponent => {
                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                // read component kind
                let component_kind = ComponentKind::de(component_kinds, reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::RemoveComponent(local_entity, component_kind),
                );
            }
            EntityMessageType::Publish => {
                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::Publish(sub_command_id, local_entity),
                );
            }
            EntityMessageType::Unpublish => {
                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::Unpublish(sub_command_id, local_entity),
                );
            }
            EntityMessageType::EnableDelegation => {
                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::EnableDelegation(sub_command_id, local_entity),
                );
            }
            EntityMessageType::DisableDelegation => {
                // this command is only ever received by clients, regarding server-owned entities

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read remote entity
                let remote_entity = RemoteEntity::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::DisableDelegation(sub_command_id, remote_entity.copy_to_owned()),
                );
            }
            EntityMessageType::SetAuthority => {
                // this command is only ever received by clients, regarding server-owned entities

                // Count when SetAuthority message KIND is recognized on wire (before entity mapping)
                #[cfg(feature = "e2e_debug")]
                {
                    extern "Rust" {
                        fn client_saw_set_auth_wire_increment();
                    }
                    // Safety: same as client_saw_spawn_increment above — atomic counter defined
                    // by the test harness; no preconditions; e2e_debug is never active in prod.
                    unsafe {
                        client_saw_set_auth_wire_increment();
                    }
                }

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read remote entity
                let remote_entity = RemoteEntity::de(reader)?;

                // read auth status
                let auth_status = EntityAuthStatus::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::SetAuthority(
                        sub_command_id,
                        remote_entity.copy_to_owned(),
                        auth_status,
                    ),
                );
            }

            // below are response-type messages
            EntityMessageType::RequestAuthority => {
                // this command is only read by the server, regarding server-owned entities

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read host entity
                let host_entity = HostEntity::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::RequestAuthority(sub_command_id, host_entity.copy_to_owned()),
                );
            }
            EntityMessageType::ReleaseAuthority => {
                // this command is only read by the server, regarding server-owned entities

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read local entity
                let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
                // apply redirect if entity was migrated
                local_entity = world_manager.apply_entity_redirect(local_entity);

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::ReleaseAuthority(sub_command_id, local_entity),
                );
            }
            EntityMessageType::EnableDelegationResponse => {
                // this command is only read by the server, regarding server-owned entities

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read host entity
                let host_entity = HostEntity::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::EnableDelegationResponse(
                        sub_command_id,
                        host_entity.copy_to_owned(),
                    ),
                );
            }
            EntityMessageType::MigrateResponse => {
                // this command is only ever received by clients, regarding newly delegated server-owned entities

                // read subcommand id
                let sub_command_id = SubCommandId::de(reader)?;

                // read client's HostEntity (so client can look it up in entity_map!)
                let client_host_entity = HostEntity::de(reader)?;

                // read new RemoteEntity (what the client will create)
                let new_remote_entity = RemoteEntity::de(reader)?;

                world_manager.receiver_buffer_message(
                    message_id,
                    EntityMessage::MigrateResponse(
                        sub_command_id,
                        client_host_entity.copy_to_owned(),
                        new_remote_entity,
                    ),
                );
            }
            EntityMessageType::Noop => {
                world_manager.receiver_buffer_message(message_id, EntityMessage::Noop);
            }
        }

        Ok(())
    }

    /// Read component updates from raw bits
    fn read_updates(
        world_manager: &mut LocalWorldManager,
        component_kinds: &ComponentKinds,
        tick: &Tick,
        reader: &mut BitReader,
    ) -> Result<(), SerdeErr> {
        let mut _update_count = 0;
        loop {
            // read update continue bit
            let update_continue = bool::de(reader)?;
            if !update_continue {
                break;
            }
            _update_count += 1;

            let mut local_entity = OwnedLocalEntity::de(reader)?.to_reversed();
            // apply redirect if entity was migrated
            local_entity = world_manager.apply_entity_redirect(local_entity);

            Self::read_update(world_manager, component_kinds, tick, reader, &local_entity)?;
        }

        Ok(())
    }

    /// Read component updates from raw bits for a given entity
    fn read_update(
        world_manager: &mut LocalWorldManager,
        component_kinds: &ComponentKinds,
        tick: &Tick,
        reader: &mut BitReader,
        local_entity: &OwnedLocalEntity,
    ) -> Result<(), SerdeErr> {
        loop {
            // read update continue bit
            let component_continue = bool::de(reader)?;
            if !component_continue {
                break;
            }

            let component_update = component_kinds.read_create_update(reader)?;

            // At this point, the WorldChannel/EntityReceiver should guarantee the Entity is in scope, correct?
            if world_manager.has_local_entity(local_entity) {
                world_manager.insert_received_update(*tick, local_entity, component_update);
            }
        }

        Ok(())
    }
}