// Copyright 2017 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.

#ifndef COMPONENTS_PREVIEWS_CONTENT_PREVIEWS_OPTIMIZATION_GUIDE_H_
#define COMPONENTS_PREVIEWS_CONTENT_PREVIEWS_OPTIMIZATION_GUIDE_H_

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "components/optimization_guide/optimization_guide_service.h"
#include "components/optimization_guide/optimization_guide_service_observer.h"
#include "components/previews/content/previews_optimization_guide.h"
#include "components/previews/core/previews_experiments.h"

class GURL;

namespace net {
class URLRequest;
}  // namespace net

namespace optimization_guide {
namespace proto {
class Configuration;
}  // namespace proto
}  // namespace optimization_guide

namespace previews {

class PreviewsHints;

// A Previews optimization guide that makes decisions guided by hints received
// from the OptimizationGuideService.
class PreviewsOptimizationGuide
    : public optimization_guide::OptimizationGuideServiceObserver {
 public:
  // The embedder guarantees |optimization_guide_service| outlives |this|.
  PreviewsOptimizationGuide(
      optimization_guide::OptimizationGuideService* optimization_guide_service,
      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);

  ~PreviewsOptimizationGuide() override;

  // Returns whether |type| is whitelisted for |request|.
  // Virtual so it can be mocked in tests.
  virtual bool IsWhitelisted(const net::URLRequest& request,
                             PreviewsType type) const;

  // Whether |url| is whitelisted for previews type |type|. The method may
  // make the decision based only on a partial comparison (e.g., only the
  // hostname of |url|). As such, the method may return true even if |type|
  // can't be used for the previews.
  bool IsHostWhitelistedAtNavigation(const GURL& url,
                                     previews::PreviewsType type) const;

  // optimization_guide::OptimizationGuideServiceObserver implementation:
  void OnHintsProcessed(
      const optimization_guide::proto::Configuration& config,
      const optimization_guide::ComponentInfo& component_info) override;

 private:
  // Updates the hints to the latest hints sent by the Component Updater.
  void UpdateHints(std::unique_ptr<PreviewsHints> hints);

  // The OptimizationGuideService that this guide is listening to. Not owned.
  optimization_guide::OptimizationGuideService* optimization_guide_service_;

  // Runner for IO thread tasks.
  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;

  // Background thread where hints processing should be performed.
  scoped_refptr<base::SequencedTaskRunner> background_task_runner_;

  // The current hints used for this optimization guide.
  std::unique_ptr<PreviewsHints> hints_;

  // Used to get |weak_ptr_| to self on the IO thread.
  base::WeakPtrFactory<PreviewsOptimizationGuide> io_weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(PreviewsOptimizationGuide);
};

}  // namespace previews

#endif  // COMPONENTS_PREVIEWS_CONTENT_PREVIEWS_OPTIMIZATION_GUIDE_H_