// 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.
library fuchsia.bluetooth.host;

using fuchsia.bluetooth as bt;
using fuchsia.bluetooth.sys as sys;

using fuchsia.bluetooth.bredr;
using fuchsia.bluetooth.gatt;
using fuchsia.bluetooth.gatt2;
using fuchsia.bluetooth.le;

/// Receives a bt-host by protocol for use in the Bluetooth Host Subsystem
@discoverable
open protocol Receiver {
    /// Adds a new bt-host. If `request` cannot be handled, it should be closed.
    flexible AddHost(resource struct {
        request client_end:Host;
    });
};

/// Interface for interacting with a Bluetooth host device (bt-host)
closed protocol Host {
    /// The following methods fulfill a given interface request. bt-host device
    /// will start processing FIDL messages. If the request cannot be fulfilled,
    /// the bt-host device will close its end of the given channel.
    strict RequestLowEnergyCentral(resource struct {
        central server_end:fuchsia.bluetooth.le.Central;
    });
    strict RequestLowEnergyPeripheral(resource struct {
        peripheral server_end:fuchsia.bluetooth.le.Peripheral;
    });
    strict RequestGattServer(resource struct {
        server server_end:fuchsia.bluetooth.gatt.Server;
    });
    strict RequestGatt2Server(resource struct {
        server server_end:fuchsia.bluetooth.gatt2.Server;
    });
    strict RequestProfile(resource struct {
        profile server_end:fuchsia.bluetooth.bredr.Profile;
    });

    /// Shuts down the host, ending all active Bluetooth procedures:
    ///
    /// * All FIDL interface handles associated with this host are closed and all
    ///   connections initiated via FIDL clients are severed.
    /// * All scan, discovery, and advertising procedures are stopped.
    /// * Bonded devices are cleared and removed from the auto-connect lists.
    /// * Auto-connected peripherals are disconnected.
    ///
    /// This effectively resets the host to its initial state and the host remains
    /// available for future requests.
    ///
    /// The Host will continue to send OnDeviceUpdated events as procedures get
    /// terminated.
    strict Close();

    /// Returns information about the Bluetooth host subsystem and controller managed by this Host
    /// instance. If there has been no change to the state since the last call to this method, the
    /// response will be deferred until there is a change.
    ///
    /// The returned `info` structure will be populated with the current state of the bt-host
    /// device. However the `active` parameter will never be populated. This field is managed
    /// by a higher layer.
    strict WatchState() -> (struct {
        info sys.HostInfo;
    });

    /// Assigns local data to this host.
    strict SetLocalData(struct {
        host_data sys.HostData;
    });

    /// Monitors updates for connectable peers known to the system. Replies only when
    /// peers have been added, modified, or removed since the most recent call to WatchPeers().
    ///
    /// Peers are added and updated as new information is obtained during discovery, connection
    /// establishment, and bonding procedures.
    ///
    /// Peers are removed either:
    ///   a. explicitly via [`fuchsia.bluetooth.host.Host/Forget`], or
    ///   b. no transmission has been received from the peer for an internally determined duration
    ///      of time and the peer is neither connected nor bonded.
    ///
    /// - response `updated` Peers that were added or updated since the last call to WatchPeers().
    /// - response `removed` Ids of peers that were removed since the last call to WatchPeers().
    strict WatchPeers() -> (struct {
        updated vector<sys.Peer>:MAX;
        removed vector<bt.PeerId>:MAX;
    });

    /// Sets the local name for this host device.
    strict SetLocalName(struct {
        local_name bt.DeviceName;
    }) -> () error sys.Error;

    /// Sets the device class for this host device.
    strict SetDeviceClass(struct {
        device_class bt.DeviceClass;
    }) -> () error sys.Error;

    /// Initiates a general discovery procedure for BR/EDR and LE devices. On success, discovered
    /// peers can be monitored using the [`fuchsia.bluetooth.host/Host.WatchPeers`] method.
    ///
    /// On the LE transport, only general-discoverable and connectable peripherals will be reported.
    ///
    /// Discovery will continue until it is terminated via StopDiscovery() or if the Host protocol
    /// channel gets closed. If the device does not support BR/EDR, only LE discovery will be
    /// performed.
    strict StartDiscovery() -> () error sys.Error;

    /// Terminates discovery if one was started via StartDiscovery().
    ///
    /// NOTE: If another client is performing discovery (e.g. via its own le.Central interface
    /// handle), then the system will continue performing device discovery even if this method
    /// results in success.
    strict StopDiscovery();

    /// Sets whether this host should be connectable.
    strict SetConnectable(struct {
        enabled bool;
    }) -> () error sys.Error;

    /// Sets whether this host should be discoverable.
    strict SetDiscoverable(struct {
        enabled bool;
    }) -> () error sys.Error;

    /// Establish a BR/EDR and/or LE connection to the peer with identifier `id`:
    ///
    ///   - If the peer is known to support the BR/EDR transport then a logical link over that
    ///     transport will be established to the device. If the connection attempt is successful,
    ///     local services registered using "RequestProfile()" will be available to the peer.
    ///     Traditional services discovered on the peer will be notified to local services
    ///     asynchronously.
    ///
    ///   - If the peer is known to support the LE transport then a logical link over that
    ///     transport will be established to the device. If the connection attempt is successful,
    ///     GATT services in the local database (populated via RequestGattServer()) will become
    ///     available to the peer. Similarly, remote GATT services that are discovered on the
    ///     peer will become available to holders of a gatt.Client capability and to device drivers
    ///     that can bind to the bt-gatt-svc class of devices.
    ///
    /// The result of the procedure will be communicated via `status`. If the remote device
    /// supports both BR/EDR and LE transports and a link cannot be established over both, then an
    /// error Status will be returned and neither transport will be connected.
    strict Connect(struct {
        id bt.PeerId;
    }) -> () error sys.Error;

    /// Terminate all connections (BR/EDR or LE) to the remote peer with identifier `id`.
    ///
    /// + request `id` The identifier of the peer to disconnect.
    /// - response `status` Contains an error if either LE or BR/EDR transport fails to disconnect.
    ///                     Contains success when both transports are successfully disconnected or
    ///                     if the peer is already disconnected.
    strict Disconnect(struct {
        id bt.PeerId;
    }) -> () error sys.Error;

    /// Initiates pairing to the peer with the supplied `id` and `options`. Returns an error if no
    /// connected peer with `id` is found or the pairing procedure fails.
    ///
    /// If `options` specifies a higher security level than the current pairing, this method
    /// attempts to raise the security level. Otherwise this method has no effect and returns
    /// success.
    ///
    /// NOTE: This is intended to satisfy test scenarios that require pairing procedures to be
    /// initiated without relying on service access. In normal operation, Bluetooth security is
    /// enforced during service access.
    strict Pair(struct {
        id bt.PeerId;
        options sys.PairingOptions;
    }) -> () error sys.Error;

    /// Deletes a peer from the Bluetooth host. If the peer is connected, it will be disconnected.
    /// `device_id` will no longer refer to any peer, even if a device with the same address is
    /// discovered again.
    ///
    /// Returns success after no peer exists that's identified by `device_id` (even if it didn't
    /// exist before Forget), failure if the peer specified by `device_id` could not be
    /// disconnected or deleted and still exists.
    strict Forget(struct {
        id bt.PeerId;
    }) -> () error sys.Error;

    /// Enable or disable a passive LE background scan. When enabled, the bt-host
    /// device will continuously perform a passive LE scan in the background when
    /// no device discovery sessions are active and accept connection requests from
    /// bonded peripherals.
    strict EnableBackgroundScan(struct {
        enabled bool;
    });

    /// Enable or disable the LE privacy feature. When enabled, the bt-host device will use a
    /// private device address in all LE procedures. When disabled, the public identity address will
    /// be used instead (which is the default).
    strict EnablePrivacy(struct {
        enabled bool;
    });

    /// Set the GAP BR/EDR Security Mode of the host. bt-host only supports encrypted,
    /// connection-based security modes, i.e. Mode 4 and Secure Connections Only mode. If the
    /// security mode is set to Secure Connections Only, any existing encrypted connections which
    /// do not meet the security requirements of Secure Connections Only mode will be disconnected.
    strict SetBrEdrSecurityMode(struct {
        bredr_security_mode sys.BrEdrSecurityMode;
    });

    /// Set the GAP LE Security Mode of the host. bt-host only supports encrypted, connection-based
    /// security modes, i.e. Mode 1 and Secure Connections Only mode. If the security mode is set
    /// to Secure Connections Only, any existing encrypted connections which do not meet the
    /// security requirements of Secure Connections Only mode will be disconnected.
    strict SetLeSecurityMode(struct {
        le_security_mode sys.LeSecurityMode;
    });

    /// Assigns the pairing delegate that will respond to authentication challenges using the given
    /// I/O capabilities. Calling this method cancels any on-going pairing procedure started
    /// using a previous delegate. Pairing requests will be rejected if no PairingDelegate has been
    /// assigned.
    strict SetPairingDelegate(resource struct {
        input sys.InputCapability;
        output sys.OutputCapability;
        delegate client_end:sys.PairingDelegate;
    });

    /// Restores existing bonded devices to the host. An authenticated session will be established
    /// for future connections using the provided bonding data.
    ///
    /// If bonding data for the LE transport is available, then the host will automatically
    /// establish a connection when the peer is in range and connectable.
    ///
    /// If any of the entries in `bonds` could not be restored, then they will be returned in
    /// `errors`. This can happen for entries that are malformed and for peers that are already
    /// known to the bt-host. An empty `errors` list indicates that all bonds were successfully
    /// restored.
    strict RestoreBonds(struct {
        bonds vector<sys.BondingData>:MAX;
    }) -> (struct {
        errors vector<sys.BondingData>:MAX;
    });

    // ===== Events =====

    /// Notifies when bonding data for a peer has been updated.
    strict -> OnNewBondingData(struct {
        data sys.BondingData;
    });

    // TODO(https://fxbug.dev/42158854): Introduce a "OnBondRemoved()" event to notify when existing
    // keys become stale.
};