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/* mbed Microcontroller Library
 * Copyright (c) 2006-2015 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef GATT_EXAMPLE_BLE_PROCESS_H_
#define GATT_EXAMPLE_BLE_PROCESS_H_

#include <stdint.h>
#include <stdio.h>

#include "events/EventQueue.h"
#include "platform/Callback.h"
#include "platform/NonCopyable.h"

#include "ble/BLE.h"
#include "ble/Gap.h"
#include "ble/GapAdvertisingParams.h"
#include "ble/GapAdvertisingData.h"
#include "ble/FunctionPointerWithContext.h"

/**
 * Handle initialization and shutdown of the BLE Instance.
 *
 * Setup advertising payload and manage advertising state.
 * Delegate to GattClientProcess once the connection is established.
 */
class BLEProcess : private mbed::NonCopyable<BLEProcess> {
public:
    /**
     * Construct a BLEProcess from an event queue and a ble interface.
     *
     * Call start() to initiate ble processing.
     */
    BLEProcess(events::EventQueue &event_queue, BLE &ble_interface) :
        _event_queue(event_queue),
        _ble_interface(ble_interface),
        _post_init_cb() {
    }

    ~BLEProcess()
    {
        stop();
    }

    /**
     * Initialize the ble interface, configure it and start advertising.
     */
    bool start()
    {
        printf("Ble process started.\r\n");

        if (_ble_interface.hasInitialized()) {
            printf("Error: the ble instance has already been initialized.\r\n");
            return false;
        }

        _ble_interface.onEventsToProcess(
            makeFunctionPointer(this, &BLEProcess::schedule_ble_events)
        );

        ble_error_t error = _ble_interface.init(
            this, &BLEProcess::when_init_complete
        );

        if (error) {
            printf("Error: %u returned by BLE::init.\r\n", error);
            return false;
        }

        return true;
    }

    /**
     * Close existing connections and stop the process.
     */
    void stop()
    {
        if (_ble_interface.hasInitialized()) {
            _ble_interface.shutdown();
            printf("Ble process stopped.");
        }
    }

    /**
     * Subscription to the ble interface initialization event.
     *
     * @param[in] cb The callback object that will be called when the ble
     * interface is initialized.
     */
    void on_init(mbed::Callback<void(BLE&, events::EventQueue&)> cb)
    {
        _post_init_cb = cb;
    }

private:
    /**
     * Sets up adverting payload and start advertising.
     *
     * This function is invoked when the ble interface is initialized.
     */
    void when_init_complete(BLE::InitializationCompleteCallbackContext *event)
    {
        if (event->error) {
            printf("Error %u during the initialization\r\n", event->error);
            return;
        }
        printf("Ble instance initialized\r\n");

        Gap &gap = _ble_interface.gap();
        ble_error_t error = gap.setAdvertisingPayload(make_advertising_data());
        if (error) {
            printf("Error %u during gap.setAdvertisingPayload\r\n", error);
            return;
        }

        gap.setAdvertisingParams(make_advertising_params());

        gap.onConnection(this, &BLEProcess::when_connection);
        gap.onDisconnection(this, &BLEProcess::when_disconnection);

        start_advertising();

        if (_post_init_cb) {
            _post_init_cb(_ble_interface, _event_queue);
        }
    }

    /**
     * Start the gatt client process when a connection event is received.
     */
    void when_connection(const Gap::ConnectionCallbackParams_t *connection_event)
    {
        printf("Connected.\r\n");
    }

    /**
     * Stop the gatt client process when the device is disconnected then restart
     * advertising.
     */
    void when_disconnection(const Gap::DisconnectionCallbackParams_t *event)
    {
        printf("Disconnected.\r\n");
        start_advertising();
    }

    /**
     * Setup the advertising parameters.
     */
    void setup_advertising()
    {
        Gap &gap = _ble_interface.gap();
        gap.setAdvertisingPayload(make_advertising_data());
        gap.setAdvertisingParams(make_advertising_params());
    }

    /**
     * Start the advertising process; it ends when a device connects.
     */
    void start_advertising()
    {
        ble_error_t error = _ble_interface.gap().startAdvertising();
        if (error) {
            printf("Error %u during gap.startAdvertising.\r\n", error);
        } else {
            printf("Advertising started.\r\n");
        }
    }

    /**
     * Schedule processing of events from the BLE middleware in the event queue.
     */
    void schedule_ble_events(BLE::OnEventsToProcessCallbackContext *event)
    {
        _event_queue.call(mbed::callback(&event->ble, &BLE::processEvents));
    }

    /**
     * Build data advertised by the BLE interface.
     */
    static GapAdvertisingData make_advertising_data(void)
    {
        static const uint8_t device_name[] = "GattClient";
        GapAdvertisingData advertising_data;

        // add advertising flags
        advertising_data.addFlags(
            GapAdvertisingData::LE_GENERAL_DISCOVERABLE |
            GapAdvertisingData::BREDR_NOT_SUPPORTED
        );

        // add device name
        advertising_data.addData(
            GapAdvertisingData::COMPLETE_LOCAL_NAME,
            device_name,
            sizeof(device_name)
        );

        return advertising_data;
    }

    /**
     * Build advertising parameters used by the BLE interface.
     */
    static GapAdvertisingParams make_advertising_params(void)
    {
        return GapAdvertisingParams(
            /* type */ GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED,
            /* interval */ GapAdvertisingParams::MSEC_TO_ADVERTISEMENT_DURATION_UNITS(500),
            /* timeout */ 0
        );
    }

    events::EventQueue &_event_queue;
    BLE &_ble_interface;
    mbed::Callback<void(BLE&, events::EventQueue&)> _post_init_cb;
};


#endif /* GATT_EXAMPLE_BLE_PROCESS_H_ */