//
// Copyright 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.
//

#include "h4_protocol.h"

#define LOG_TAG "android.hardware.bluetooth-hci-h4"
#include <android-base/logging.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <utils/Log.h>

namespace android {
namespace hardware {
namespace bluetooth {
namespace hci {

H4Protocol::H4Protocol(int fd, PacketReadCallback event_cb,
                       PacketReadCallback acl_cb, PacketReadCallback sco_cb,
                       PacketReadCallback iso_cb,
                       OnDisconnectCallback disconnect_cb)
    : uart_fd_(fd),
      event_cb_(std::move(event_cb)),
      acl_cb_(std::move(acl_cb)),
      sco_cb_(std::move(sco_cb)),
      iso_cb_(std::move(iso_cb)),
      disconnect_cb_(std::move(disconnect_cb)) {}

size_t H4Protocol::Send(uint8_t type, const uint8_t* data, size_t length) {
    /* For HCI communication over USB dongle, multiple write results in
     * response timeout as driver expect type + data at once to process
     * the command, so using "writev"(for atomicity) here.
     */
    struct iovec iov[2];
    ssize_t ret = 0;
    iov[0].iov_base = &type;
    iov[0].iov_len = sizeof(type);
    iov[1].iov_base = (void *)data;
    iov[1].iov_len = length;
    while (1) {
        ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, 2));
        if (ret == -1) {
            if (errno == EAGAIN) {
                ALOGE("%s error writing to UART (%s)", __func__, strerror(errno));
                continue;
            }
        } else if (ret == 0) {
            // Nothing written :(
            ALOGE("%s zero bytes written - something went wrong...", __func__);
            break;
        }
        break;
    }
    return ret;
}

size_t H4Protocol::on_packet_ready(const hidl_vec<uint8_t>& packet) {
  switch (hci_packet_type_) {
    case HCI_PACKET_TYPE_EVENT:
      event_cb_(packet);
      break;
    case HCI_PACKET_TYPE_ACL_DATA:
      acl_cb_(packet);
      break;
    case HCI_PACKET_TYPE_SCO_DATA:
      sco_cb_(packet);
      break;
    case HCI_PACKET_TYPE_ISO_DATA:
      iso_cb_(packet);
      break;
    default: {
      LOG_ALWAYS_FATAL("Unhandled packet of type 0x%x", hci_packet_type_);
    }
  }
  return packet.size();
}

void H4Protocol::send_data_to_packetizer(uint8_t* buffer, size_t length) {
  std::vector<uint8_t> input_buffer{buffer, buffer + length};
  size_t buffer_offset = 0;
  while (buffer_offset < input_buffer.size()) {
    if (hci_packet_type_ == HCI_PACKET_TYPE_UNKNOWN) {
      hci_packet_type_ =
          static_cast<HciPacketType>(input_buffer.data()[buffer_offset]);
      buffer_offset += 1;
    } else {
      bool packet_ready = hci_packetizer_.OnDataReady(
          hci_packet_type_, input_buffer, buffer_offset);
      if (packet_ready) {
        // Call packet callback and move offset.
        buffer_offset += on_packet_ready(hci_packetizer_.GetPacket());
        // Get ready for the next type byte.
        hci_packet_type_ = HCI_PACKET_TYPE_UNKNOWN;
      } else {
        // The data was consumed, but there wasn't a packet.
        buffer_offset = input_buffer.size();
      }
    }
  }
}

void H4Protocol::OnDataReady(int fd) {
  if (disconnected_) {
    return;
  }
  uint8_t buffer[kMaxPacketLength];
  ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, buffer, kMaxPacketLength));
  if (bytes_read == 0) {
    ALOGI("No bytes read, calling the disconnect callback");
    disconnected_ = true;
    disconnect_cb_();
    return;
  }
  if (bytes_read < 0) {
    ALOGW("error reading from UART (%s)", strerror(errno));
    return;
  }
  send_data_to_packetizer(buffer, bytes_read);
}

}  // namespace hci
}  // namespace bluetooth
}  // namespace hardware
}  // namespace android