/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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 CHRE_PLATFORM_HOST_LINK_H_
#define CHRE_PLATFORM_HOST_LINK_H_

#include <stddef.h>
#include <stdint.h>

#include "chre/target_platform/host_link_base.h"
#include "chre/util/non_copyable.h"

namespace chre {

struct HostMessage;
typedef HostMessage MessageToHost;

/**
 * Abstracts the platform-specific communications link between CHRE and the host
 * processor.
 *
 * The common-code HostCommsManager inherits from this class, so based on
 * later-established convention, a more fitting name for it would be
 * PlatformHostCommsManager. But the HostLink name is kept for compatibility
 * with legacy code.
 */
class HostLink : public HostLinkBase, public NonCopyable {
 public:
  /**
   * Flush (or purge) any messages sent by the given app ID that are currently
   * pending delivery to the host. At the point that this function is called, it
   * is guaranteed that no new messages will be generated from this nanoapp.
   *
   * This function must impose strict ordering constraints, such that after it
   * returns, it is guaranteed that HostCommsManager::onMessageToHostComplete
   * will not be invoked for the app with the given ID.
   */
  void flushMessagesSentByNanoapp(uint64_t appId);

  /**
   * Enqueues a message for sending to the host. Once sending the message is
   * complete (success or failure), the platform implementation must invoke
   * HostCommsManager::onMessageToHostComplete (can be called from any thread).
   * To meet the requirements of chreSendMessageToHostEndpoint(), this function
   * must wake up the host if it is suspended.
   *
   * @param message A non-null pointer to the message
   *
   * @return true if the message was successfully queued
   */
  bool sendMessage(const MessageToHost *message);

  /**
   * Sends a metric message to the host.
   *
   * @param metricId The ID of the metric being sent.
   * @param encodedMetric The non-null pointer to the metric being sent.
   * @param encodedMetricLen The length of the metric in bytes.
   *
   * @return true if the data was successfully queued for sending
   */
  bool sendMetricLog(uint32_t metricId, const uint8_t *encodedMetric,
                     size_t encodedMetricLen);
};

}  // namespace chre

#endif  // CHRE_PLATFORM_HOST_LINK_H_