// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "extensions/browser/api/idle/idle_manager.h"

#include <utility>

#include "base/memory/ptr_util.h"
#include "base/stl_util.h"
#include "content/public/browser/browser_context.h"
#include "extensions/browser/api/idle/idle_api_constants.h"
#include "extensions/browser/event_router.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/common/api/idle.h"
#include "extensions/common/extension.h"

namespace keys = extensions::idle_api_constants;
namespace idle = extensions::api::idle;

namespace extensions {

namespace {

const int kDefaultIdleThreshold = 60;
const int kPollInterval = 1;

class DefaultEventDelegate : public IdleManager::EventDelegate {
 public:
  explicit DefaultEventDelegate(content::BrowserContext* context);
  ~DefaultEventDelegate() override;

  void OnStateChanged(const std::string& extension_id,
                      ui::IdleState new_state) override;
  void RegisterObserver(EventRouter::Observer* observer) override;
  void UnregisterObserver(EventRouter::Observer* observer) override;

 private:
  content::BrowserContext* const context_;
};

DefaultEventDelegate::DefaultEventDelegate(content::BrowserContext* context)
    : context_(context) {
}

DefaultEventDelegate::~DefaultEventDelegate() {
}

void DefaultEventDelegate::OnStateChanged(const std::string& extension_id,
                                          ui::IdleState new_state) {
  std::unique_ptr<base::ListValue> args(new base::ListValue());
  args->Append(IdleManager::CreateIdleValue(new_state));
  std::unique_ptr<Event> event(new Event(events::IDLE_ON_STATE_CHANGED,
                                         idle::OnStateChanged::kEventName,
                                         std::move(args)));
  event->restrict_to_browser_context = context_;
  EventRouter::Get(context_)
      ->DispatchEventToExtension(extension_id, std::move(event));
}

void DefaultEventDelegate::RegisterObserver(EventRouter::Observer* observer) {
  EventRouter::Get(context_)
      ->RegisterObserver(observer, idle::OnStateChanged::kEventName);
}

void DefaultEventDelegate::UnregisterObserver(EventRouter::Observer* observer) {
  EventRouter::Get(context_)->UnregisterObserver(observer);
}

class DefaultIdleProvider : public IdleManager::IdleTimeProvider {
 public:
  DefaultIdleProvider();
  ~DefaultIdleProvider() override;

  void CalculateIdleState(int idle_threshold, ui::IdleCallback notify) override;
  void CalculateIdleTime(ui::IdleTimeCallback notify) override;
  bool CheckIdleStateIsLocked() override;
};

DefaultIdleProvider::DefaultIdleProvider() {
}

DefaultIdleProvider::~DefaultIdleProvider() {
}

void DefaultIdleProvider::CalculateIdleState(int idle_threshold,
                                             ui::IdleCallback notify) {
  ui::CalculateIdleState(idle_threshold, notify);
}

void DefaultIdleProvider::CalculateIdleTime(ui::IdleTimeCallback notify) {
  ui::CalculateIdleTime(notify);
}

bool DefaultIdleProvider::CheckIdleStateIsLocked() {
  return ui::CheckIdleStateIsLocked();
}

ui::IdleState IdleTimeToIdleState(bool locked,
                                  int idle_time,
                                  int idle_threshold) {
  ui::IdleState state;

  if (locked) {
    state = ui::IDLE_STATE_LOCKED;
  } else if (idle_time >= idle_threshold) {
    state = ui::IDLE_STATE_IDLE;
  } else {
    state = ui::IDLE_STATE_ACTIVE;
  }
  return state;
}

}  // namespace

IdleMonitor::IdleMonitor(ui::IdleState initial_state)
    : last_state(initial_state),
      listeners(0),
      threshold(kDefaultIdleThreshold) {
}

IdleManager::IdleManager(content::BrowserContext* context)
    : context_(context),
      last_state_(ui::IDLE_STATE_ACTIVE),
      idle_time_provider_(new DefaultIdleProvider()),
      event_delegate_(new DefaultEventDelegate(context)),
      extension_registry_observer_(this),
      weak_factory_(this) {
}

IdleManager::~IdleManager() {
}

void IdleManager::Init() {
  extension_registry_observer_.Add(ExtensionRegistry::Get(context_));
  event_delegate_->RegisterObserver(this);
}

void IdleManager::Shutdown() {
  DCHECK(thread_checker_.CalledOnValidThread());
  event_delegate_->UnregisterObserver(this);
}

void IdleManager::OnExtensionUnloaded(content::BrowserContext* browser_context,
                                      const Extension* extension,
                                      UnloadedExtensionInfo::Reason reason) {
  DCHECK(thread_checker_.CalledOnValidThread());
  monitors_.erase(extension->id());
}

void IdleManager::OnListenerAdded(const EventListenerInfo& details) {
  DCHECK(thread_checker_.CalledOnValidThread());

  ++GetMonitor(details.extension_id)->listeners;
  StartPolling();
}

void IdleManager::OnListenerRemoved(const EventListenerInfo& details) {
  DCHECK(thread_checker_.CalledOnValidThread());

  // During unload the monitor could already have been deleted. No need to do
  // anything in that case.
  MonitorMap::iterator it = monitors_.find(details.extension_id);
  if (it != monitors_.end()) {
    DCHECK_GT(it->second.listeners, 0);
    // Note: Deliberately leave the listener count as 0 rather than erase()ing
    // this record so that the threshold doesn't get reset when all listeners
    // are removed.
    --it->second.listeners;
  }
}

void IdleManager::QueryState(int threshold, const QueryStateCallback& notify) {
  DCHECK(thread_checker_.CalledOnValidThread());
  idle_time_provider_->CalculateIdleState(threshold, notify);
}

void IdleManager::SetThreshold(const std::string& extension_id, int threshold) {
  DCHECK(thread_checker_.CalledOnValidThread());
  GetMonitor(extension_id)->threshold = threshold;
}

// static
std::unique_ptr<base::StringValue> IdleManager::CreateIdleValue(
    ui::IdleState idle_state) {
  const char* description;

  if (idle_state == ui::IDLE_STATE_ACTIVE) {
    description = keys::kStateActive;
  } else if (idle_state == ui::IDLE_STATE_IDLE) {
    description = keys::kStateIdle;
  } else {
    description = keys::kStateLocked;
  }

  return base::MakeUnique<base::StringValue>(description);
}

void IdleManager::SetEventDelegateForTest(
    std::unique_ptr<EventDelegate> event_delegate) {
  DCHECK(thread_checker_.CalledOnValidThread());
  event_delegate_ = std::move(event_delegate);
}

void IdleManager::SetIdleTimeProviderForTest(
    std::unique_ptr<IdleTimeProvider> idle_time_provider) {
  DCHECK(thread_checker_.CalledOnValidThread());
  idle_time_provider_ = std::move(idle_time_provider);
}

IdleMonitor* IdleManager::GetMonitor(const std::string& extension_id) {
  DCHECK(thread_checker_.CalledOnValidThread());
  MonitorMap::iterator it = monitors_.find(extension_id);

  if (it == monitors_.end()) {
    it = monitors_.insert(std::make_pair(extension_id,
                                         IdleMonitor(last_state_))).first;
  }
  return &it->second;
}

void IdleManager::StartPolling() {
  DCHECK(thread_checker_.CalledOnValidThread());
  if (!poll_timer_.IsRunning()) {
    poll_timer_.Start(FROM_HERE, base::TimeDelta::FromSeconds(kPollInterval),
                      this, &IdleManager::UpdateIdleState);
  }
}

void IdleManager::StopPolling() {
  DCHECK(thread_checker_.CalledOnValidThread());
  poll_timer_.Stop();
}

void IdleManager::UpdateIdleState() {
  DCHECK(thread_checker_.CalledOnValidThread());
  idle_time_provider_->CalculateIdleTime(base::Bind(
      &IdleManager::UpdateIdleStateCallback, weak_factory_.GetWeakPtr()));
}

void IdleManager::UpdateIdleStateCallback(int idle_time) {
  DCHECK(thread_checker_.CalledOnValidThread());
  bool locked = idle_time_provider_->CheckIdleStateIsLocked();
  int listener_count = 0;

  // Remember this state for initializing new event listeners.
  last_state_ = IdleTimeToIdleState(locked, idle_time, kDefaultIdleThreshold);

  for (MonitorMap::iterator it = monitors_.begin(); it != monitors_.end();
       ++it) {
    IdleMonitor& monitor = it->second;
    ui::IdleState new_state =
        IdleTimeToIdleState(locked, idle_time, monitor.threshold);
    // TODO(kalman): Use EventRouter::HasListeners for these sorts of checks.
    if (monitor.listeners > 0 && monitor.last_state != new_state)
      event_delegate_->OnStateChanged(it->first, new_state);
    monitor.last_state = new_state;
    listener_count += monitor.listeners;
  }

  if (listener_count == 0)
    StopPolling();
}

}  // namespace extensions