/*
 * Copyright (C) 2019 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.
 */
#define LOG_TAG "BtGdModule"

#include "module.h"

#include <bluetooth/log.h>
#include <com_android_bluetooth_flags.h>

using ::bluetooth::os::Handler;
using ::bluetooth::os::Thread;

namespace bluetooth {

constexpr std::chrono::milliseconds kModuleStopTimeout = std::chrono::milliseconds(2000);

ModuleFactory::ModuleFactory(std::function<Module*()> ctor) : ctor_(ctor) {}

Handler* Module::GetHandler() const {
  log::assert_that(handler_ != nullptr, "Can't get handler when it's not started");
  return handler_;
}

const ModuleRegistry* Module::GetModuleRegistry() const { return registry_; }

Module* Module::GetDependency(const ModuleFactory* module) const {
  for (auto& dependency : dependencies_.list_) {
    if (dependency == module) {
      return registry_->Get(module);
    }
  }

  log::fatal("Module was not listed as a dependency in ListDependencies");
}

Module* ModuleRegistry::Get(const ModuleFactory* module) const {
  std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
  if (com::android::bluetooth::flags::fix_started_module_race()) {
    lock.lock();
  }

  auto instance = started_modules_.find(module);
  log::assert_that(instance != started_modules_.end(),
                   "Request for module not started up, maybe not in Start(ModuleList)?");
  return instance->second;
}

bool ModuleRegistry::IsStarted(const ModuleFactory* module) const {
  std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
  if (com::android::bluetooth::flags::fix_started_module_race()) {
    lock.lock();
  }
  return started_modules_.find(module) != started_modules_.end();
}

void ModuleRegistry::Start(ModuleList* modules, Thread* thread, Handler* handler) {
  for (auto it = modules->list_.begin(); it != modules->list_.end(); it++) {
    Start(*it, thread, handler);
  }
}

void ModuleRegistry::set_registry_and_handler(Module* instance, Thread* thread,
                                              Handler* handler) const {
  instance->registry_ = this;

  if (com::android::bluetooth::flags::same_handler_for_all_modules()) {
    // Use same handler for all modules initialization.
    // TODO: remove the dependency on the `thread` when the flag is removed.
    instance->handler_ = handler;
  } else {
    instance->handler_ = new Handler(thread);
  }
}

Module* ModuleRegistry::Start(const ModuleFactory* module, Thread* thread, Handler* handler) {
  {
    std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
    if (com::android::bluetooth::flags::fix_started_module_race()) {
      lock.lock();
    }
    auto started_instance = started_modules_.find(module);
    if (started_instance != started_modules_.end()) {
      return started_instance->second;
    }
  }

  log::info("Constructing next module");
  Module* instance = module->ctor_();
  set_registry_and_handler(instance, thread, handler);

  log::info("Starting dependencies of {}", instance->ToString());
  instance->ListDependencies(&instance->dependencies_);
  Start(&instance->dependencies_, thread, handler);

  log::info("Finished starting dependencies and calling Start() of {}", instance->ToString());

  last_instance_ = "starting " + instance->ToString();
  instance->Start();
  start_order_.push_back(module);
  {
    std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
    if (com::android::bluetooth::flags::fix_started_module_race()) {
      lock.lock();
    }
    started_modules_[module] = instance;
  }
  log::info("Started {}", instance->ToString());
  return instance;
}

void ModuleRegistry::StopAll() {
  // Since modules were brought up in dependency order, it is safe to tear down by going in reverse
  // order.
  for (auto it = start_order_.rbegin(); it != start_order_.rend(); it++) {
    auto module = Get(*it);
    last_instance_ = "stopping " + module->ToString();

    /*
     * b/393449774 since we have now shifted to a single handler for all modules, we don't need
     * to clear the handler here, it will be done in the respective teardown.
     * Since we have a single handler, we need to make sure that the handler instance is deleted
     * only once, otherwise we will see a crash as a handler can only be cleared once.
     */
    if (!com::android::bluetooth::flags::same_handler_for_all_modules()) {
      // Clear the handler before stopping the module to allow it to shut down gracefully.
      log::info("Stopping Handler of Module {}", module->ToString());
      module->handler_->Clear();
      module->handler_->WaitUntilStopped(kModuleStopTimeout);
    }
    log::info("Stopping Module {}", module->ToString());
    module->Stop();
  }

  std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
  if (com::android::bluetooth::flags::fix_started_module_race()) {
    lock.lock();
  }
  for (auto it = start_order_.rbegin(); it != start_order_.rend(); it++) {
    auto instance = started_modules_.find(*it);
    log::assert_that(instance != started_modules_.end(),
                     "assert failed: instance != started_modules_.end()");
    if (!com::android::bluetooth::flags::same_handler_for_all_modules()) {
      delete instance->second->handler_;
    }
    delete instance->second;
    started_modules_.erase(instance);
  }

  log::assert_that(started_modules_.empty(), "assert failed: started_modules_.empty()");
  start_order_.clear();
}

os::Handler* ModuleRegistry::GetModuleHandler(const ModuleFactory* module) const {
  std::unique_lock<std::mutex> lock(started_modules_guard_, std::defer_lock);
  if (com::android::bluetooth::flags::fix_started_module_race()) {
    lock.lock();
  }
  auto started_instance = started_modules_.find(module);
  if (started_instance != started_modules_.end()) {
    return started_instance->second->GetHandler();
  }
  return nullptr;
}

// Override the StopAll method to use the test thread and handler.
// This function will take care of releasing the handler instances.
void TestModuleRegistry::StopAll() {
  os::Handler* handler = GetTestHandler();
  handler->Clear();
  if (com::android::bluetooth::flags::same_handler_for_all_modules()) {
    handler->WaitUntilStopped(kHandlerStopTimeout);
  }
  ModuleRegistry::StopAll();  // call the base class StopAll
  delete handler;
}
}  // namespace bluetooth