// Copyright 2024 The Pigweed Authors
//
// 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
//
//     https://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 "pw_bluetooth_sapphire/central.h"

#include "pw_bluetooth_sapphire/internal/connection_options.h"
#include "pw_bluetooth_sapphire/internal/uuid.h"

namespace pw::bluetooth_sapphire {

bt::hci::DiscoveryFilter DiscoveryFilterFrom(const Central::ScanFilter& in) {
  bt::hci::DiscoveryFilter out;
  if (in.service_uuid.has_value()) {
    bt::UUID uuid = internal::UuidFrom(in.service_uuid.value());
    out.set_service_uuids({std::move(uuid)});
  }
  if (in.service_data_uuid.has_value()) {
    bt::UUID uuid = internal::UuidFrom(in.service_data_uuid.value());
    out.set_service_data_uuids({std::move(uuid)});
  }
  if (in.manufacturer_id.has_value()) {
    out.set_manufacturer_code(in.manufacturer_id.value());
  }
  if (in.connectable.has_value()) {
    out.set_connectable(in.connectable.value());
  }
  if (in.name.has_value()) {
    out.set_name_substring(std::string(in.name.value()));
  }
  if (in.max_path_loss.has_value()) {
    out.set_pathloss(in.max_path_loss.value());
  }
  if (in.solicitation_uuid.has_value()) {
    bt::UUID uuid = internal::UuidFrom(in.solicitation_uuid.value());
    out.set_solicitation_uuids({std::move(uuid)});
  }
  return out;
}

namespace {

pw::sync::Mutex g_peripheral_lock;

std::optional<Central::ScanResult> ScanResultFrom(
    const bt::gap::Peer& peer, pw::multibuf::MultiBufAllocator& allocator) {
  Central::ScanResult out;
  out.peer_id = peer.identifier().value();
  // TODO: https://pwbug.dev/377301546 - Report the "connectable" value of this
  // advertisement, not the Peer's dual-mode connectability.
  out.connectable = peer.connectable();
  out.rssi = peer.rssi();

  if (!peer.le()->parsed_advertising_data_timestamp().has_value()) {
    bt_log(DEBUG, "api", "failed to get advertising data time");
    return std::nullopt;
  }
  out.last_updated = peer.le()->parsed_advertising_data_timestamp().value();

  bt::BufferView data_view = peer.le()->advertising_data();
  std::optional<pw::multibuf::MultiBuf> data =
      allocator.Allocate(data_view.size());
  if (!data) {
    bt_log(DEBUG, "api", "failed to allocate buffer for advertising data");
    return std::nullopt;
  }
  StatusWithSize copy_status = data->CopyFrom(data_view.subspan());
  if (!copy_status.ok()) {
    bt_log(DEBUG,
           "api",
           "failed to copy scan result data: %s",
           copy_status.status().str());
    return std::nullopt;
  }
  out.data = std::move(data.value());

  if (peer.name().has_value()) {
    out.name.emplace();
    Status append_status =
        pw::string::Append(out.name.value(), peer.name().value());
    // RESOURCE_EXHAUSTED means that the name was truncated, which is OK.
    if (!append_status.ok() && !append_status.IsResourceExhausted()) {
      bt_log(DEBUG,
             "api",
             "failed to set scan result name: %s",
             append_status.str());
      return std::nullopt;
    }
  }

  return out;
}

}  // namespace

Central::Central(bt::gap::Adapter::WeakPtr adapter,
                 pw::async::Dispatcher& dispatcher,
                 pw::multibuf::MultiBufAllocator& allocator)
    : adapter_(std::move(adapter)),
      dispatcher_(dispatcher),
      heap_dispatcher_(dispatcher),
      allocator_(allocator),
      weak_factory_(this),
      self_(weak_factory_.GetWeakPtr()) {}

Central::~Central() {
  std::lock_guard guard(lock());
  scans_.clear();
}

async2::OnceReceiver<Central::ConnectResult> Central::Connect(
    pw::bluetooth::PeerId peer_id,
    bluetooth::low_energy::Connection2::ConnectionOptions options) {
  bt::PeerId internal_peer_id(peer_id);
  bt::gap::LowEnergyConnectionOptions connection_options =
      internal::ConnectionOptionsFrom(options);

  auto [result_sender, result_receiver] =
      async2::MakeOnceSenderAndReceiver<ConnectResult>();

  bt::gap::Adapter::LowEnergy::ConnectionResultCallback result_cb =
      [self = self_,
       peer = internal_peer_id,
       sender = std::move(result_sender)](
          bt::gap::Adapter::LowEnergy::ConnectionResult result) mutable {
        if (!self.is_alive()) {
          return;
        }
        self->OnConnectionResult(peer, std::move(result), std::move(sender));
      };

  async::TaskFunction task_fn = [self = self_,
                                 internal_peer_id,
                                 connection_options,
                                 cb = std::move(result_cb)](
                                    async::Context&, Status status) mutable {
    if (!status.ok() || !self.is_alive()) {
      return;
    }
    self->adapter_->le()->Connect(
        internal_peer_id, std::move(cb), connection_options);
  };
  Status post_status = heap_dispatcher_.Post(std::move(task_fn));
  PW_CHECK_OK(post_status);

  return std::move(result_receiver);
}

async2::OnceReceiver<Central::ScanStartResult> Central::Scan(
    const ScanOptions& options) {
  // TODO: https://pwbug.dev/377301546 - Support the different types of active
  // scans.
  bool active = (options.scan_type != ScanType::kPassive);

  if (options.filters.empty()) {
    return async2::OnceReceiver<ScanStartResult>(
        pw::unexpected(StartScanError::kInvalidParameters));
  }

  auto [result_sender, result_receiver] =
      async2::MakeOnceSenderAndReceiver<Central::ScanStartResult>();

  auto callback =
      [self = self_, sender = std::move(result_sender)](
          std::unique_ptr<bt::gap::LowEnergyDiscoverySession> session) mutable {
        // callback will always be run on the Bluetooth thread

        if (!self.is_alive()) {
          sender.emplace(pw::unexpected(StartScanError::kInternal));
          return;
        }

        if (!session) {
          bt_log(WARN, "api", "failed to start LE discovery session");
          sender.emplace(pw::unexpected(StartScanError::kInternal));
          return;
        }

        ScanHandleImpl* scan_handle_raw_ptr =
            new ScanHandleImpl(session->scan_id(), &self.get());
        ScanHandle::Ptr scan_handle_ptr(scan_handle_raw_ptr);
        {
          std::lock_guard guard(lock());
          auto [iter, emplaced] = self->scans_.try_emplace(session->scan_id(),
                                                           std::move(session),
                                                           scan_handle_raw_ptr,
                                                           session->scan_id(),
                                                           &self.get());
          PW_CHECK(emplaced);
        }

        sender.emplace(std::move(scan_handle_ptr));
      };

  // Convert options to filters now because options contains non-owning views
  // that won't be valid in callbacks.
  std::vector<bt::hci::DiscoveryFilter> discovery_filters;
  discovery_filters.reserve(options.filters.size());
  for (const ScanFilter& filter : options.filters) {
    discovery_filters.emplace_back(DiscoveryFilterFrom(filter));
  }

  async::TaskFunction task_fn = [self = self_,
                                 filters = std::move(discovery_filters),
                                 active,
                                 cb = std::move(callback)](
                                    async::Context&, Status status) mutable {
    if (status.ok()) {
      // TODO: https://pwbug.dev/377301546 - Support configuring interval,
      // window, and PHY.
      self->adapter_->le()->StartDiscovery(active, filters, std::move(cb));
    }
  };
  Status post_status = heap_dispatcher_.Post(std::move(task_fn));
  PW_CHECK_OK(post_status);

  return std::move(result_receiver);
}

pw::sync::Mutex& Central::lock() { return g_peripheral_lock; }

Central::ScanHandleImpl::~ScanHandleImpl() {
  std::lock_guard guard(lock());
  if (central_) {
    central_->StopScanLocked(scan_id_);
  }
}

void Central::ScanHandleImpl::QueueScanResultLocked(ScanResult&& result) {
  if (results_.size() == kMaxScanResultsQueueSize) {
    results_.pop();
  }
  results_.push(std::move(result));
  std::move(waker_).Wake();
}

async2::PollResult<Central::ScanResult> Central::ScanHandleImpl::PendResult(
    async2::Context& cx) {
  std::lock_guard guard(lock());
  if (!results_.empty()) {
    ScanResult result = std::move(results_.front());
    results_.pop();
    return async2::Ready(std::move(result));
  }

  if (!central_) {
    return async2::Ready(pw::Status::Cancelled());
  }

  PW_ASYNC_STORE_WAKER(cx, waker_, "scan result");
  return async2::Pending();
}

Central::ScanState::ScanState(
    std::unique_ptr<bt::gap::LowEnergyDiscoverySession> session,
    ScanHandleImpl* scan_handle,
    uint16_t scan_id,
    Central* central)
    : scan_id_(scan_id),
      scan_handle_(scan_handle),
      central_(central),
      session_(std::move(session)) {
  session_->SetResultCallback(
      [this](const bt::gap::Peer& peer) { OnScanResult(peer); });
  session_->set_error_callback([this]() { OnError(); });
}

Central::ScanState::~ScanState() {
  // lock() is expected to be held
  if (scan_handle_) {
    scan_handle_->OnScanErrorLocked();
    scan_handle_ = nullptr;
  }
}

void Central::ScanState::OnScanResult(const bt::gap::Peer& peer) {
  // TODO: https://pwbug.dev/377301546 - Getting only a Peer as a scan result is
  // awkward. Update LowEnergyDiscoverySession to give us the actual
  // LowEnergyScanResult.
  std::lock_guard guard(lock());
  if (!scan_handle_) {
    return;
  }

  std::optional<Central::ScanResult> scan_result =
      ScanResultFrom(peer, central_->allocator_);
  if (!scan_result.has_value()) {
    return;
  }

  scan_handle_->QueueScanResultLocked(std::move(scan_result.value()));
  scan_handle_->WakeLocked();
}

void Central::ScanState::OnError() {
  std::lock_guard guard(lock());
  if (scan_handle_) {
    scan_handle_->OnScanErrorLocked();
    scan_handle_ = nullptr;
  }
  central_->scans_.erase(scan_id_);
  // This object has been destroyed.
}

void Central::StopScanLocked(uint16_t scan_id) {
  auto iter = scans_.find(scan_id);
  if (iter == scans_.end()) {
    return;
  }
  iter->second.OnScanHandleDestroyedLocked();

  pw::Status post_status = heap_dispatcher_.Post(
      [self = self_, scan_id](pw::async::Context, pw::Status status) {
        if (!status.ok() || !self.is_alive()) {
          return;
        }
        std::lock_guard guard(lock());
        self->scans_.erase(scan_id);
      });
  PW_CHECK(post_status.ok());
}

void Central::OnConnectionResult(
    bt::PeerId peer_id,
    bt::gap::Adapter::LowEnergy::ConnectionResult result,
    async2::OnceSender<ConnectResult> result_sender) {
  if (result.is_error()) {
    if (result.error_value() == bt::HostError::kNotFound) {
      result_sender.emplace(pw::unexpected(ConnectError::kUnknownPeer));
    } else {
      result_sender.emplace(
          pw::unexpected(ConnectError::kCouldNotBeEstablished));
    }
    return;
  }

  pw::bluetooth::low_energy::Connection2::Ptr connection_ptr(
      new internal::Connection(
          peer_id, std::move(result.value()), dispatcher_));
  result_sender.emplace(std::move(connection_ptr));
}

}  // namespace pw::bluetooth_sapphire