// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use {
    crate::client::Client,
    crate::object::{NewObjectExt, ObjectRef, RequestReceiver},
    crate::registry::Registry,
    anyhow::{format_err, Error},
    fidl::endpoints::ClientEnd,
    fidl_fuchsia_element::{GraphicalPresenterMarker, GraphicalPresenterProxy},
    fidl_fuchsia_ui_app::ViewProviderMarker,
    fidl_fuchsia_ui_gfx::DisplayInfo,
    fidl_fuchsia_ui_scenic::{ScenicMarker, ScenicProxy},
    fuchsia_async as fasync,
    fuchsia_component::client::connect_to_protocol,
    fuchsia_sync::Mutex,
    fuchsia_zircon as zx,
    futures::channel::mpsc,
    std::sync::{
        atomic::{AtomicUsize, Ordering},
        Arc,
    },
    wayland_server_protocol::*,
};

/// When the connection is created it is initialized with a 'wl_display' object
/// that the client can immediately interact with.
pub const DISPLAY_SINGLETON_OBJECT_ID: u32 = 1;

pub trait LocalViewProducerClient: Send + Sync {
    /// Notifes the view producer client that a new view has been created.
    ///
    /// # Parameters
    /// - `view_provider`: The view provider associated with the new view.
    /// - `view_id`: The identifier for the view that was created.
    fn new_view(&mut self, view_provider: ClientEnd<ViewProviderMarker>, view_id: u32);

    /// Notifies the ViewProducer client that the view with `view_id` is being shut down.
    fn shutdown_view(&mut self, view_id: u32);
}

#[derive(Clone)]
enum ViewProducerClient {
    Local(Arc<Mutex<Box<dyn LocalViewProducerClient>>>),
    Invalid,
}

/// |Display| is the global object used to manage a wayland server.
///
/// The |Display| has a |Registry| that will hold the set of global
/// interfaces that will be advertised to clients.
#[derive(Clone)]
pub struct Display {
    registry: Arc<Mutex<Registry>>,
    /// A connection to the 'Scenic' service.
    scenic: Arc<ScenicProxy>,
    /// A connection to the 'GraphicalPresenter' service.
    graphical_presenter: Arc<GraphicalPresenterProxy>,
    /// A binding to a public `ViewProducer` service. This is used to publish
    /// new views to the consumer.
    ///
    /// This must be bound before any views are created.
    view_producer_client: ViewProducerClient,
    /// Number of view providers requested.
    view_provider_requests: Arc<AtomicUsize>,
    /// The current display info.
    display_info: DisplayInfo,
}

impl Display {
    pub fn new(registry: Registry) -> Result<Self, Error> {
        let scenic =
            connect_to_protocol::<ScenicMarker>().expect("failed to connect to Scenic service");
        let graphical_presenter = connect_to_protocol::<GraphicalPresenterMarker>()
            .expect("failed to connect to GraphicalPresenter service");
        Ok(Display {
            registry: Arc::new(Mutex::new(registry)),
            scenic: Arc::new(scenic),
            graphical_presenter: Arc::new(graphical_presenter),
            view_producer_client: ViewProducerClient::Invalid,
            view_provider_requests: Arc::new(AtomicUsize::new(0)),
            display_info: DisplayInfo { width_in_px: 0, height_in_px: 0 },
        })
    }

    pub fn new_local(
        registry: Registry,
        client: Arc<Mutex<Box<dyn LocalViewProducerClient>>>,
    ) -> Result<Self, Error> {
        let scenic =
            connect_to_protocol::<ScenicMarker>().expect("failed to connect to Scenic service");
        let graphical_presenter = connect_to_protocol::<GraphicalPresenterMarker>()
            .expect("failed to connect to GraphicalPresenter service");
        Ok(Display {
            registry: Arc::new(Mutex::new(registry)),
            scenic: Arc::new(scenic),
            graphical_presenter: Arc::new(graphical_presenter),
            view_producer_client: ViewProducerClient::Local(client),
            // Set this to 0 when new_local clients have been updated to request views.
            view_provider_requests: Arc::new(AtomicUsize::new(1)),
            // TODO(https://fxbug.dev/42172104): Remove these default values.
            display_info: DisplayInfo { width_in_px: 1920, height_in_px: 1080 },
        })
    }

    /// Creates a `Display` without a valid scenic connection. This is intended
    /// for unit testing purposes only.
    #[cfg(test)]
    pub fn new_no_scenic(registry: Registry) -> Result<Self, Error> {
        let (c1, _c2) = zx::Channel::create();
        let scenic = ScenicProxy::new(fasync::Channel::from_channel(c1));
        let (c1, _c2) = zx::Channel::create();
        let graphical_presenter = GraphicalPresenterProxy::new(fasync::Channel::from_channel(c1));
        Ok(Display {
            registry: Arc::new(Mutex::new(registry)),
            scenic: Arc::new(scenic),
            graphical_presenter: Arc::new(graphical_presenter),
            view_producer_client: ViewProducerClient::Invalid,
            view_provider_requests: Arc::new(AtomicUsize::new(0)),
            display_info: DisplayInfo { width_in_px: 0, height_in_px: 0 },
        })
    }

    /// Provides access to the Scenic connection for this display.
    pub fn scenic(&self) -> &Arc<ScenicProxy> {
        &self.scenic
    }

    /// Provides access to the GraphicalPresenter connection for this display.
    pub fn graphical_presenter(&self) -> &Arc<GraphicalPresenterProxy> {
        &self.graphical_presenter
    }

    /// Provides access to the global registry for this display.
    pub fn registry(&self) -> Arc<Mutex<Registry>> {
        self.registry.clone()
    }

    /// Take one view provider request off the top. Returns false if no
    /// request exists.
    pub fn take_view_provider_requests(&mut self) -> bool {
        if self.view_provider_requests.load(Ordering::Relaxed) > 0 {
            self.view_provider_requests.fetch_sub(1, Ordering::SeqCst);
            true
        } else {
            false
        }
    }

    /// Publish a new view back to the client for presentation.
    pub fn new_view_provider(&self, view_provider: ClientEnd<ViewProviderMarker>, view_id: u32) {
        match &self.view_producer_client {
            ViewProducerClient::Local(view_producer_client) => {
                view_producer_client.lock().new_view(view_provider, view_id);
            }
            ViewProducerClient::Invalid => {
                panic!("new_view_provider called without a valid view producer");
            }
        }
    }

    /// Notify client that presentation of view should stop.
    pub fn delete_view_provider(&self, view_id: u32) {
        match &self.view_producer_client {
            ViewProducerClient::Local(view_producer_client) => {
                view_producer_client.lock().shutdown_view(view_id);
            }
            ViewProducerClient::Invalid => {
                panic!("delete_view_provider called without a valid view producer");
            }
        }
    }

    /// Create a new client and begin polling `chan` for requests.
    pub fn spawn_new_client(self, chan: fasync::Channel, protocol_logging: bool) {
        Display::spawn_client(Client::new(chan, self), protocol_logging);
    }

    pub fn spawn_new_local_client(
        self,
        sender: mpsc::UnboundedSender<zx::MessageBuf>,
        receiver: mpsc::UnboundedReceiver<zx::MessageBuf>,
        protocol_logging: bool,
    ) {
        Display::spawn_client(Client::new_local(sender, receiver, self), protocol_logging);
    }

    fn spawn_client(mut client: Client, protocol_logging: bool) {
        client.set_protocol_logging(protocol_logging);

        // Add the global wl_display object. We unwrap here since the object map
        // is empty so failure should not be possible.
        client.add_object(DISPLAY_SINGLETON_OBJECT_ID, DisplayReceiver).unwrap();

        // Start polling the channel for messages.
        client.start();
    }

    /// The current display info.
    pub fn display_info(&self) -> DisplayInfo {
        self.display_info
    }

    /// Set the current display info.
    pub fn set_display_info(&mut self, display_info: &DisplayInfo) {
        self.display_info = *display_info;
    }
}

/// An implementation of wl_display.
struct DisplayReceiver;

impl RequestReceiver<WlDisplay> for DisplayReceiver {
    fn receive(
        this: ObjectRef<Self>,
        request: WlDisplayRequest,
        client: &mut Client,
    ) -> Result<(), Error> {
        match request {
            WlDisplayRequest::GetRegistry { registry } => {
                let registry = registry.implement(client, RegistryReceiver)?;
                RegistryReceiver::report_globals(registry, client)?;
                Ok(())
            }
            WlDisplayRequest::Sync { callback } => {
                // Since we callback immediately we'll skip actually adding this
                // object, but we need to send the wl_display::delete_id event
                // explicitly, which is otherwise done for us in
                // Client:delete_id.
                client
                    .event_queue()
                    .post(callback.id(), WlCallbackEvent::Done { callback_data: 0 })?;
                client
                    .event_queue()
                    .post(this.id(), WlDisplayEvent::DeleteId { id: callback.id() })?;
                Ok(())
            }
        }
    }
}

/// An implementation of wl_registry.
struct RegistryReceiver;

impl RegistryReceiver {
    /// Sends a wl_registry::global event for each entry in the |Registry|.
    pub fn report_globals(this: ObjectRef<Self>, client: &Client) -> Result<(), Error> {
        let registry = client.display().registry();
        for (name, global) in registry.lock().globals().iter().enumerate() {
            client.event_queue().post(
                this.id(),
                WlRegistryEvent::Global {
                    name: name as u32,
                    interface: global.interface().into(),
                    version: global.version(),
                },
            )?;
        }
        Ok(())
    }
}

impl RequestReceiver<WlRegistry> for RegistryReceiver {
    fn receive(
        _this: ObjectRef<Self>,
        request: WlRegistryRequest,
        client: &mut Client,
    ) -> Result<(), Error> {
        let WlRegistryRequest::Bind { name, id, id_interface_version: version, .. } = request;
        let registry = client.display().registry();
        let (spec, receiver) = {
            let mut lock = registry.lock();
            if let Some(global) = lock.globals().get_mut(name as usize) {
                (global.request_spec(), global.bind(id, version, client)?)
            } else {
                return Err(format_err!("Invalid global name {}", name));
            }
        };
        client.add_object_raw(id, receiver, spec)?;
        Ok(())
    }
}

/// An implementation of wl_callback.
pub struct Callback;

impl Callback {
    /// Posts the `done` event for this callback.
    pub fn done(
        this: ObjectRef<Self>,
        client: &mut Client,
        callback_data: u32,
    ) -> Result<(), Error> {
        client.event_queue().post(this.id(), WlCallbackEvent::Done { callback_data })
    }
}

impl RequestReceiver<WlCallback> for Callback {
    fn receive(
        _this: ObjectRef<Self>,
        request: WlCallbackRequest,
        _client: &mut Client,
    ) -> Result<(), Error> {
        match request {}
    }
}