/*
 * 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 ANDROID_HARDWARE_CONTEXTHUB_COMMON_CONTEXTHUB_H
#define ANDROID_HARDWARE_CONTEXTHUB_COMMON_CONTEXTHUB_H

#include <condition_variable>
#include <functional>
#include <mutex>
#include <optional>

#include <android/hardware/contexthub/1.0/IContexthub.h>
#include <hidl/MQDescriptor.h>
#include <hidl/Status.h>
#include <log/log.h>

#include "chre_host/fragmented_load_transaction.h"
#include "chre_host/host_protocol_host.h"
#include "chre_host/socket_client.h"

namespace android {
namespace hardware {
namespace contexthub {
namespace common {
namespace implementation {

using ::android::sp;
using ::android::chre::FragmentedLoadRequest;
using ::android::chre::FragmentedLoadTransaction;
using ::android::chre::getStringFromByteVector;
using ::android::chre::HostProtocolHost;
using ::android::hardware::hidl_handle;
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::Return;
using ::android::hardware::contexthub::V1_0::AsyncEventType;
using ::android::hardware::contexthub::V1_0::ContextHub;
using ::android::hardware::contexthub::V1_0::ContextHubMsg;
using ::android::hardware::contexthub::V1_0::HubAppInfo;
using ::android::hardware::contexthub::V1_0::IContexthubCallback;
using ::android::hardware::contexthub::V1_0::NanoAppBinary;
using ::android::hardware::contexthub::V1_0::Result;
using ::android::hardware::contexthub::V1_0::TransactionResult;
using ::flatbuffers::FlatBufferBuilder;

constexpr uint32_t kDefaultHubId = 0;

inline constexpr uint8_t extractChreApiMajorVersion(uint32_t chreVersion) {
  return static_cast<uint8_t>(chreVersion >> 24);
}

inline constexpr uint8_t extractChreApiMinorVersion(uint32_t chreVersion) {
  return static_cast<uint8_t>(chreVersion >> 16);
}

inline constexpr uint16_t extractChrePatchVersion(uint32_t chreVersion) {
  return static_cast<uint16_t>(chreVersion);
}

/**
 * @return file descriptor contained in the hidl_handle, or -1 if there is none
 */
inline int hidlHandleToFileDescriptor(const hidl_handle &hh) {
  const native_handle_t *handle = hh.getNativeHandle();
  return (handle != nullptr && handle->numFds >= 1) ? handle->data[0] : -1;
}

template <class IContexthubT>
class GenericContextHubBase : public IContexthubT {
 public:
  GenericContextHubBase() {
    constexpr char kChreSocketName[] = "chre";

    mSocketCallbacks = new SocketCallbacks(*this);
    if (!mClient.connectInBackground(kChreSocketName, mSocketCallbacks)) {
      ALOGE("Couldn't start socket client");
    }

    mDeathRecipient = new DeathRecipient(this);
  }

  Return<void> debug(const hidl_handle &fd,
                     const hidl_vec<hidl_string> & /* options */) override {
    // Timeout inside CHRE is typically 5 seconds, grant 500ms extra here to let
    // the data reach us
    constexpr auto kDebugDumpTimeout = std::chrono::milliseconds(5500);

    mDebugFd = hidlHandleToFileDescriptor(fd);
    if (mDebugFd < 0) {
      ALOGW("Can't dump debug info to invalid fd");
    } else {
      writeToDebugFile("-- Dumping CHRE/ASH debug info --\n");

      ALOGV("Sending debug dump request");
      FlatBufferBuilder builder;
      HostProtocolHost::encodeDebugDumpRequest(builder);
      std::unique_lock<std::mutex> lock(mDebugDumpMutex);
      mDebugDumpPending = true;
      if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
        ALOGW("Couldn't send debug dump request");
      } else {
        mDebugDumpCond.wait_for(lock, kDebugDumpTimeout,
                                [this]() { return !mDebugDumpPending; });
        if (mDebugDumpPending) {
          ALOGI("Timed out waiting on debug dump data");
          mDebugDumpPending = false;
        }
      }
      writeToDebugFile("\n-- End of CHRE/ASH debug info --\n");

      mDebugFd = kInvalidFd;
      ALOGV("Debug dump complete");
    }

    return Void();
  }

  // Methods from ::android::hardware::contexthub::V1_0::IContexthub follow.
  Return<void> getHubs(V1_0::IContexthub::getHubs_cb _hidl_cb) override {
    constexpr auto kHubInfoQueryTimeout = std::chrono::seconds(5);
    std::vector<ContextHub> hubs;
    ALOGV("%s", __func__);

    // If we're not connected yet, give it some time
    // TODO refactor from polling into conditional wait
    int maxSleepIterations = 250;
    while (!mHubInfoValid && !mClient.isConnected() &&
           --maxSleepIterations > 0) {
      std::this_thread::sleep_for(std::chrono::milliseconds(20));
    }

    if (!mClient.isConnected()) {
      ALOGE("Couldn't connect to hub daemon");
    } else if (!mHubInfoValid) {
      // We haven't cached the hub details yet, so send a request and block
      // waiting on a response
      std::unique_lock<std::mutex> lock(mHubInfoMutex);
      FlatBufferBuilder builder;
      HostProtocolHost::encodeHubInfoRequest(builder);

      ALOGD("Sending hub info request");
      if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
        ALOGE("Couldn't send hub info request");
      } else {
        mHubInfoCond.wait_for(lock, kHubInfoQueryTimeout,
                              [this]() { return mHubInfoValid; });
      }
    }

    if (mHubInfoValid) {
      hubs.push_back(mHubInfo);
    } else {
      ALOGE("Unable to get hub info from CHRE");
    }

    _hidl_cb(hubs);
    return Void();
  }

  Return<Result> registerCallback(uint32_t hubId,
                                  const sp<IContexthubCallback> &cb) override {
    Result result;
    ALOGV("%s", __func__);

    // TODO: currently we only support 1 hub behind this HAL implementation
    if (hubId == kDefaultHubId) {
      std::lock_guard<std::mutex> lock(mCallbacksLock);

      if (cb != nullptr) {
        if (mCallbacks != nullptr) {
          ALOGD("Modifying callback for hubId %" PRIu32, hubId);
          mCallbacks->unlinkToDeath(mDeathRecipient);
        }
        Return<bool> linkReturn = cb->linkToDeath(mDeathRecipient, hubId);
        if (!linkReturn.withDefault(false)) {
          ALOGW("Could not link death recipient to hubId %" PRIu32, hubId);
        }
      }

      mCallbacks = cb;
      result = Result::OK;
    } else {
      result = Result::BAD_PARAMS;
    }

    return result;
  }

  Return<Result> sendMessageToHub(uint32_t hubId,
                                  const ContextHubMsg &msg) override {
    Result result;
    ALOGV("%s", __func__);

    if (hubId != kDefaultHubId) {
      result = Result::BAD_PARAMS;
    } else {
      FlatBufferBuilder builder(1024);
      HostProtocolHost::encodeNanoappMessage(builder, msg.appName, msg.msgType,
                                             msg.hostEndPoint, msg.msg.data(),
                                             msg.msg.size());

      if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
        result = Result::UNKNOWN_FAILURE;
      } else {
        result = Result::OK;
      }
    }

    return result;
  }

  Return<Result> loadNanoApp(uint32_t hubId, const NanoAppBinary &appBinary,
                             uint32_t transactionId) override {
    Result result;
    ALOGV("%s", __func__);

    if (hubId != kDefaultHubId) {
      result = Result::BAD_PARAMS;
    } else {
      std::lock_guard<std::mutex> lock(mPendingLoadTransactionMutex);

      if (mPendingLoadTransaction.has_value()) {
        ALOGE("Pending load transaction exists. Overriding pending request");
      }

      uint32_t targetApiVersion = (appBinary.targetChreApiMajorVersion << 24) |
                                  (appBinary.targetChreApiMinorVersion << 16);
      mPendingLoadTransaction = FragmentedLoadTransaction(
          transactionId, appBinary.appId, appBinary.appVersion,
          targetApiVersion, appBinary.customBinary, kLoadFragmentSizeBytes);

      result =
          sendFragmentedLoadNanoAppRequest(mPendingLoadTransaction.value());
      if (result != Result::OK) {
        mPendingLoadTransaction.reset();
      }
    }

    ALOGD(
        "Attempted to send load nanoapp request for app of size %zu with ID "
        "0x%016" PRIx64 " as transaction ID %" PRIu32 ": result %" PRIu32,
        appBinary.customBinary.size(), appBinary.appId, transactionId, result);

    return result;
  }

  Return<Result> unloadNanoApp(uint32_t hubId, uint64_t appId,
                               uint32_t transactionId) override {
    Result result;
    ALOGV("%s", __func__);

    if (hubId != kDefaultHubId) {
      result = Result::BAD_PARAMS;
    } else {
      FlatBufferBuilder builder(64);
      HostProtocolHost::encodeUnloadNanoappRequest(
          builder, transactionId, appId, false /* allowSystemNanoappUnload */);
      if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
        result = Result::UNKNOWN_FAILURE;
      } else {
        result = Result::OK;
      }
    }

    ALOGD("Attempted to send unload nanoapp request for app ID 0x%016" PRIx64
          " as transaction ID %" PRIu32 ": result %" PRIu32,
          appId, transactionId, result);

    return result;
  }

  Return<Result> enableNanoApp(uint32_t /* hubId */, uint64_t appId,
                               uint32_t /* transactionId */) override {
    // TODO
    ALOGW("Attempted to enable app ID 0x%016" PRIx64 ", but not supported",
          appId);
    return Result::TRANSACTION_FAILED;
  }

  Return<Result> disableNanoApp(uint32_t /* hubId */, uint64_t appId,
                                uint32_t /* transactionId */) override {
    // TODO
    ALOGW("Attempted to disable app ID 0x%016" PRIx64 ", but not supported",
          appId);
    return Result::TRANSACTION_FAILED;
  }

  Return<Result> queryApps(uint32_t hubId) override {
    Result result;
    ALOGV("%s", __func__);

    if (hubId != kDefaultHubId) {
      result = Result::BAD_PARAMS;
    } else {
      FlatBufferBuilder builder(64);
      HostProtocolHost::encodeNanoappListRequest(builder);
      if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
        result = Result::UNKNOWN_FAILURE;
      } else {
        result = Result::OK;
      }
    }

    return result;
  }

 protected:
  ::android::chre::SocketClient mClient;
  sp<IContexthubCallback> mCallbacks;
  std::mutex mCallbacksLock;

  class SocketCallbacks : public ::android::chre::SocketClient::ICallbacks,
                          public ::android::chre::IChreMessageHandlers {
   public:
    explicit SocketCallbacks(GenericContextHubBase &parent) : mParent(parent) {}

    void onMessageReceived(const void *data, size_t length) override {
      if (!HostProtocolHost::decodeMessageFromChre(data, length, *this)) {
        ALOGE("Failed to decode message");
      }
    }

    void onConnected() override {
      if (mHaveConnected) {
        ALOGI("Reconnected to CHRE daemon");
        invokeClientCallback([&]() {
          return mParent.mCallbacks->handleHubEvent(AsyncEventType::RESTARTED);
        });
      }
      mHaveConnected = true;
    }

    void onDisconnected() override {
      ALOGW("Lost connection to CHRE daemon");
    }

    void handleNanoappMessage(
        const ::chre::fbs::NanoappMessageT &message) override {
      ContextHubMsg msg;
      msg.appName = message.app_id;
      msg.hostEndPoint = message.host_endpoint;
      msg.msgType = message.message_type;
      msg.msg = message.message;

      invokeClientCallback(
          [&]() { return mParent.mCallbacks->handleClientMsg(msg); });
    }

    void handleHubInfoResponse(
        const ::chre::fbs::HubInfoResponseT &response) override {
      ALOGD("Got hub info response");

      std::lock_guard<std::mutex> lock(mParent.mHubInfoMutex);
      if (mParent.mHubInfoValid) {
        ALOGI("Ignoring duplicate/unsolicited hub info response");
      } else {
        mParent.mHubInfo.name = getStringFromByteVector(response.name);
        mParent.mHubInfo.vendor = getStringFromByteVector(response.vendor);
        mParent.mHubInfo.toolchain =
            getStringFromByteVector(response.toolchain);
        mParent.mHubInfo.platformVersion = response.platform_version;
        mParent.mHubInfo.toolchainVersion = response.toolchain_version;
        mParent.mHubInfo.hubId = kDefaultHubId;

        mParent.mHubInfo.peakMips = response.peak_mips;
        mParent.mHubInfo.stoppedPowerDrawMw = response.stopped_power;
        mParent.mHubInfo.sleepPowerDrawMw = response.sleep_power;
        mParent.mHubInfo.peakPowerDrawMw = response.peak_power;

        mParent.mHubInfo.maxSupportedMsgLen = response.max_msg_len;
        mParent.mHubInfo.chrePlatformId = response.platform_id;

        uint32_t version = response.chre_platform_version;
        mParent.mHubInfo.chreApiMajorVersion =
            extractChreApiMajorVersion(version);
        mParent.mHubInfo.chreApiMinorVersion =
            extractChreApiMinorVersion(version);
        mParent.mHubInfo.chrePatchVersion = extractChrePatchVersion(version);

        mParent.mHubInfoValid = true;
        mParent.mHubInfoCond.notify_all();
      }
    }

    void handleNanoappListResponse(
        const ::chre::fbs::NanoappListResponseT &response) override {
      std::vector<HubAppInfo> appInfoList;

      ALOGV("Got nanoapp list response with %zu apps",
            response.nanoapps.size());
      for (const std::unique_ptr<::chre::fbs::NanoappListEntryT> &nanoapp :
           response.nanoapps) {
        // TODO: determine if this is really required, and if so, have
        // HostProtocolHost strip out null entries as part of decode
        if (nanoapp == nullptr) {
          continue;
        }

        ALOGV("App 0x%016" PRIx64 " ver 0x%" PRIx32 " enabled %d system %d",
              nanoapp->app_id, nanoapp->version, nanoapp->enabled,
              nanoapp->is_system);
        if (!nanoapp->is_system) {
          HubAppInfo appInfo;

          appInfo.appId = nanoapp->app_id;
          appInfo.version = nanoapp->version;
          appInfo.enabled = nanoapp->enabled;

          appInfoList.push_back(appInfo);
        }
      }

      invokeClientCallback(
          [&]() { return mParent.mCallbacks->handleAppsInfo(appInfoList); });
    }

    void handleLoadNanoappResponse(
        const ::chre::fbs::LoadNanoappResponseT &response) override {
      ALOGV("Got load nanoapp response for transaction %" PRIu32
            " fragment %" PRIu32 " with result %d",
            response.transaction_id, response.fragment_id, response.success);
      std::unique_lock<std::mutex> lock(mParent.mPendingLoadTransactionMutex);

      // TODO: Handle timeout in receiving load response
      if (!mParent.mPendingLoadTransaction.has_value()) {
        ALOGE(
            "Dropping unexpected load response (no pending transaction "
            "exists)");
      } else {
        FragmentedLoadTransaction &transaction =
            mParent.mPendingLoadTransaction.value();

        if (!mParent.isExpectedLoadResponseLocked(response)) {
          ALOGE(
              "Dropping unexpected load response, expected transaction %" PRIu32
              " fragment %" PRIu32 ", received transaction %" PRIu32
              " fragment %" PRIu32,
              transaction.getTransactionId(), mParent.mCurrentFragmentId,
              response.transaction_id, response.fragment_id);
        } else {
          TransactionResult result;
          bool continueLoadRequest = false;
          if (response.success && !transaction.isComplete()) {
            if (mParent.sendFragmentedLoadNanoAppRequest(transaction) ==
                Result::OK) {
              continueLoadRequest = true;
              result = TransactionResult::SUCCESS;
            } else {
              result = TransactionResult::FAILURE;
            }
          } else {
            result = (response.success) ? TransactionResult::SUCCESS
                                        : TransactionResult::FAILURE;
          }

          if (!continueLoadRequest) {
            mParent.mPendingLoadTransaction.reset();
            lock.unlock();
            invokeClientCallback([&]() {
              return mParent.mCallbacks->handleTxnResult(
                  response.transaction_id, result);
            });
          }
        }
      }
    }

    void handleUnloadNanoappResponse(
        const ::chre::fbs::UnloadNanoappResponseT &response) override {
      ALOGV("Got unload nanoapp response for transaction %" PRIu32
            " with result %d",
            response.transaction_id, response.success);

      invokeClientCallback([&]() {
        TransactionResult result = (response.success)
                                       ? TransactionResult::SUCCESS
                                       : TransactionResult::FAILURE;
        return mParent.mCallbacks->handleTxnResult(response.transaction_id,
                                                   result);
      });
    }

    void handleDebugDumpData(const ::chre::fbs::DebugDumpDataT &data) override {
      ALOGV("Got debug dump data, size %zu", data.debug_str.size());
      if (mParent.mDebugFd == kInvalidFd) {
        ALOGW("Got unexpected debug dump data message");
      } else {
        mParent.writeToDebugFile(
            reinterpret_cast<const char *>(data.debug_str.data()),
            data.debug_str.size());
      }
    }

    void handleDebugDumpResponse(
        const ::chre::fbs::DebugDumpResponseT &response) override {
      ALOGV("Got debug dump response, success %d, data count %" PRIu32,
            response.success, response.data_count);
      std::lock_guard<std::mutex> lock(mParent.mDebugDumpMutex);
      if (!mParent.mDebugDumpPending) {
        ALOGI("Ignoring duplicate/unsolicited debug dump response");
      } else {
        mParent.mDebugDumpPending = false;
        mParent.mDebugDumpCond.notify_all();
      }
    }

   private:
    GenericContextHubBase &mParent;
    bool mHaveConnected = false;

    /**
     * Acquires mParent.mCallbacksLock and invokes the synchronous callback
     * argument if mParent.mCallbacks is not null.
     */
    void invokeClientCallback(std::function<Return<void>()> callback) {
      std::lock_guard<std::mutex> lock(mParent.mCallbacksLock);
      if (mParent.mCallbacks != nullptr && !callback().isOk()) {
        ALOGE("Failed to invoke client callback");
      }
    }
  };

  class DeathRecipient : public hidl_death_recipient {
   public:
    explicit DeathRecipient(const sp<GenericContextHubBase> contexthub)
        : mGenericContextHub(contexthub) {}
    void serviceDied(
        uint64_t cookie,
        const wp<::android::hidl::base::V1_0::IBase> & /* who */) override {
      uint32_t hubId = static_cast<uint32_t>(cookie);
      mGenericContextHub->handleServiceDeath(hubId);
    }

   private:
    sp<GenericContextHubBase> mGenericContextHub;
  };

  sp<SocketCallbacks> mSocketCallbacks;
  sp<DeathRecipient> mDeathRecipient;

  // Cached hub info used for getHubs(), and synchronization primitives to make
  // that function call synchronous if we need to query it
  ContextHub mHubInfo;
  bool mHubInfoValid = false;
  std::mutex mHubInfoMutex;
  std::condition_variable mHubInfoCond;

  static constexpr int kInvalidFd = -1;
  int mDebugFd = kInvalidFd;
  bool mDebugDumpPending = false;
  std::mutex mDebugDumpMutex;
  std::condition_variable mDebugDumpCond;

  // The pending fragmented load request
  uint32_t mCurrentFragmentId = 0;
  std::optional<FragmentedLoadTransaction> mPendingLoadTransaction;
  std::mutex mPendingLoadTransactionMutex;

  // Use 30KB fragment size to fit within 32KB memory fragments at the kernel
  static constexpr size_t kLoadFragmentSizeBytes = 30 * 1024;

  // Write a string to mDebugFd
  void writeToDebugFile(const char *str) {
    writeToDebugFile(str, strlen(str));
  }

  void writeToDebugFile(const char *str, size_t len) {
    ssize_t written = write(mDebugFd, str, len);
    if (written != (ssize_t)len) {
      ALOGW(
          "Couldn't write to debug header: returned %zd, expected %zu (errno "
          "%d)",
          written, len, errno);
    }
  }

  // Unregisters callback when context hub service dies
  void handleServiceDeath(uint32_t hubId) {
    std::lock_guard<std::mutex> lock(mCallbacksLock);
    ALOGI("Context hub service died for hubId %" PRIu32, hubId);
    mCallbacks.clear();
  }

  /**
   * Checks to see if a load response matches the currently pending
   * fragmented load transaction. mPendingLoadTransactionMutex must
   * be acquired prior to calling this function.
   *
   * @param response the received load response
   *
   * @return true if the response matches a pending load transaction
   *         (if any), false otherwise
   */
  bool isExpectedLoadResponseLocked(
      const ::chre::fbs::LoadNanoappResponseT &response) {
    return mPendingLoadTransaction.has_value() &&
           (mPendingLoadTransaction->getTransactionId() ==
            response.transaction_id) &&
           (response.fragment_id == 0 ||
            mCurrentFragmentId == response.fragment_id);
  }

  /**
   * Sends a fragmented load request to CHRE. The caller must ensure that
   * transaction.isComplete() returns false prior to invoking this method.
   *
   * @param transaction the FragmentedLoadTransaction object
   *
   * @return the result of the request
   */
  Result sendFragmentedLoadNanoAppRequest(
      FragmentedLoadTransaction &transaction) {
    Result result;
    const FragmentedLoadRequest &request = transaction.getNextRequest();

    FlatBufferBuilder builder(128 + request.binary.size());
    HostProtocolHost::encodeFragmentedLoadNanoappRequest(builder, request);

    if (!mClient.sendMessage(builder.GetBufferPointer(), builder.GetSize())) {
      ALOGE("Failed to send load request message (fragment ID = %zu)",
            request.fragmentId);
      result = Result::UNKNOWN_FAILURE;
    } else {
      mCurrentFragmentId = request.fragmentId;
      result = Result::OK;
    }

    return result;
  }
};

}  // namespace implementation
}  // namespace common
}  // namespace contexthub
}  // namespace hardware
}  // namespace android

#endif  // ANDROID_HARDWARE_CONTEXTHUB_COMMON_CONTEXTHUB_H