// 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_UPDATE_CLIENT_COMPONENT_H_
#define COMPONENTS_UPDATE_CLIENT_COMPONENT_H_

#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "base/version.h"
#include "components/update_client/crx_downloader.h"
#include "components/update_client/protocol_parser.h"
#include "components/update_client/update_client.h"
#include "url/gurl.h"


namespace update_client {

struct CrxUpdateItem;
struct UpdateContext;

// Describes a CRX component managed by the UpdateEngine. Each |Component| is
// associated with an UpdateContext.
class Component {
 public:
  using Events = UpdateClient::Observer::Events;

  using CallbackHandleComplete = base::Callback<void()>;

  Component(const UpdateContext& update_context, const std::string& id);
  ~Component();

  // Handles the current state of the component and makes it transition
  // to the next component state before |callback| is invoked.
  void Handle(CallbackHandleComplete callback);

  CrxUpdateItem GetCrxUpdateItem() const;

  // Called by the UpdateChecker to set the update response for this component.
  void SetParseResult(const ProtocolParser::Result& result);

  // Sets the uninstall state for this component.
  void Uninstall(const base::Version& cur_version, int reason);

  // Called by the UpdateEngine when an update check for this component is done.
  void UpdateCheckComplete() const;

  // Returns true if the component has reached a final state and no further
  // handling and state transitions are possible.
  bool IsHandled() const { return state_->IsFinal(); }

  // Returns true if an update is available for this component, meaning that
  // the update server has return a response containing an update.
  bool IsUpdateAvailable() const { return is_update_available_; }

  base::TimeDelta GetUpdateDuration() const;

  ComponentState state() const { return state_->state(); }

  std::string id() const { return id_; }

  const CrxComponent& crx_component() const { return crx_component_; }
  void set_crx_component(const CrxComponent& crx_component) {
    crx_component_ = crx_component;
  }

  const base::Version& previous_version() const { return previous_version_; }
  void set_previous_version(const base::Version& previous_version) {
    previous_version_ = previous_version;
  }

  const base::Version& next_version() const { return next_version_; }

  std::string previous_fp() const { return previous_fp_; }
  void set_previous_fp(const std::string& previous_fp) {
    previous_fp_ = previous_fp;
  }

  std::string next_fp() const { return next_fp_; }
  void set_next_fp(const std::string& next_fp) { next_fp_ = next_fp; }

  int update_check_error() const { return update_check_error_; }
  void set_update_check_error(int update_check_error) {
    update_check_error_ = update_check_error;
  }

  // Returns the time when processing of an update for this component has
  // begun, once the update has been discovered. Returns a null TimeTicks object
  // if the handling of an update has not happened.
  // base::TimeTicks update_begin() const { return update_begin_; }

  bool on_demand() const { return on_demand_; }
  void set_on_demand(bool on_demand) { on_demand_ = on_demand; }

  const std::vector<std::string>& events() const { return events_; }

  const std::vector<GURL>& crx_diffurls() const { return crx_diffurls_; }

  bool diff_update_failed() const { return !!diff_error_code_; }

  int error_category() const { return error_category_; }
  int error_code() const { return error_code_; }
  int extra_code1() const { return extra_code1_; }
  int diff_error_category() const { return diff_error_category_; }
  int diff_error_code() const { return diff_error_code_; }
  int diff_extra_code1() const { return diff_extra_code1_; }

 private:
  friend class FakePingManagerImpl;
  friend class UpdateCheckerTest;

  FRIEND_TEST_ALL_PREFIXES(PingManagerTest, SendPing);
  FRIEND_TEST_ALL_PREFIXES(PingManagerTest, RequiresEncryption);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, NoUpdateActionRun);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, UpdateCheckCupError);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, UpdateCheckError);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, UpdateCheckInvalidAp);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest,
                           UpdateCheckRequiresEncryptionError);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, UpdateCheckSuccess);
  FRIEND_TEST_ALL_PREFIXES(UpdateCheckerTest, UpdateCheckUpdateDisabled);

  // Describes an abstraction for implementing the behavior of a component and
  // the transition from one state to another.
  class State {
   public:
    using CallbackNextState =
        base::Callback<void(std::unique_ptr<State> next_state)>;

    State(Component* component, ComponentState state);
    virtual ~State();

    // Handles the current state and initiates a transition to a new state.
    // The transition to the new state is non-blocking and it is completed
    // by the outer component, after the current state is fully handled.
    void Handle(CallbackNextState callback);

    ComponentState state() const { return state_; }

    bool IsFinal() const { return is_final_; }

   protected:
    // Initiates the transition to the new state.
    void TransitionState(std::unique_ptr<State> new_state);

    Component& component() { return component_; }
    const Component& component() const { return component_; }

    CallbackNextState callback() const { return callback_; }

    base::ThreadChecker thread_checker_;

    const ComponentState state_;

   private:
    virtual void DoHandle() = 0;

    Component& component_;
    CallbackNextState callback_;

    bool is_final_ = false;
  };

  class StateNew : public State {
   public:
    explicit StateNew(Component* component);
    ~StateNew() override;

   private:
    // State overrides.
    void DoHandle() override;

    DISALLOW_COPY_AND_ASSIGN(StateNew);
  };

  class StateChecking : public State {
   public:
    explicit StateChecking(Component* component);
    ~StateChecking() override;

   private:
    // State overrides.
    void DoHandle() override;

    void UpdateCheckComplete();

    DISALLOW_COPY_AND_ASSIGN(StateChecking);
  };

  class StateUpdateError : public State {
   public:
    explicit StateUpdateError(Component* component);
    ~StateUpdateError() override;

   private:
    // State overrides.
    void DoHandle() override;

    DISALLOW_COPY_AND_ASSIGN(StateUpdateError);
  };

  class StateCanUpdate : public State {
   public:
    explicit StateCanUpdate(Component* component);
    ~StateCanUpdate() override;

   private:
    // State overrides.
    void DoHandle() override;
    bool CanTryDiffUpdate() const;

    DISALLOW_COPY_AND_ASSIGN(StateCanUpdate);
  };

  class StateUpToDate : public State {
   public:
    explicit StateUpToDate(Component* component);
    ~StateUpToDate() override;

   private:
    // State overrides.
    void DoHandle() override;

    DISALLOW_COPY_AND_ASSIGN(StateUpToDate);
  };

  class StateDownloadingDiff : public State {
   public:
    explicit StateDownloadingDiff(Component* component);
    ~StateDownloadingDiff() override;

   private:
    // State overrides.
    void DoHandle() override;

    // Called when progress is being made downloading a CRX. The progress may
    // not monotonically increase due to how the CRX downloader switches between
    // different downloaders and fallback urls.
    void DownloadProgress(const std::string& id,
                          const CrxDownloader::Result& download_result);

    void DownloadComplete(const std::string& id,
                          const CrxDownloader::Result& download_result);

    // Downloads updates for one CRX id only.
    std::unique_ptr<CrxDownloader> crx_downloader_;

    DISALLOW_COPY_AND_ASSIGN(StateDownloadingDiff);
  };

  class StateDownloading : public State {
   public:
    explicit StateDownloading(Component* component);
    ~StateDownloading() override;

   private:
    // State overrides.
    void DoHandle() override;

    // Called when progress is being made downloading a CRX. The progress may
    // not monotonically increase due to how the CRX downloader switches between
    // different downloaders and fallback urls.
    void DownloadProgress(const std::string& id,
                          const CrxDownloader::Result& download_result);

    void DownloadComplete(const std::string& id,
                          const CrxDownloader::Result& download_result);

    // Downloads updates for one CRX id only.
    std::unique_ptr<CrxDownloader> crx_downloader_;

    DISALLOW_COPY_AND_ASSIGN(StateDownloading);
  };

  class StateUpdatingDiff : public State {
   public:
    explicit StateUpdatingDiff(Component* component);
    ~StateUpdatingDiff() override;

   private:
    // State overrides.
    void DoHandle() override;

    void InstallComplete(int error_category, int error_code, int extra_code1);

    DISALLOW_COPY_AND_ASSIGN(StateUpdatingDiff);
  };

  class StateUpdating : public State {
   public:
    explicit StateUpdating(Component* component);
    ~StateUpdating() override;

   private:
    // State overrides.
    void DoHandle() override;

    void InstallComplete(int error_category, int error_code, int extra_code1);

    DISALLOW_COPY_AND_ASSIGN(StateUpdating);
  };

  class StateUpdated : public State {
   public:
    explicit StateUpdated(Component* component);
    ~StateUpdated() override;

   private:
    // State overrides.
    void DoHandle() override;

    DISALLOW_COPY_AND_ASSIGN(StateUpdated);
  };

  class StateUninstalled : public State {
   public:
    explicit StateUninstalled(Component* component);
    ~StateUninstalled() override;

   private:
    // State overrides.
    void DoHandle() override;

    DISALLOW_COPY_AND_ASSIGN(StateUninstalled);
  };

  // Returns true is the update payload for this component can be downloaded
  // by a downloader which can do bandwidth throttling on the client side.
  bool CanDoBackgroundDownload() const;

  void AppendEvent(const std::string& event);

  // Changes the component state and notifies the caller of the |Handle|
  // function that the handling of this component state is complete.
  void ChangeState(std::unique_ptr<State> next_state);

  // Notifies registered observers about changes in the state of the component.
  void NotifyObservers(Events event) const;

  base::ThreadChecker thread_checker_;

  const std::string id_;
  CrxComponent crx_component_;

  std::string status_;

  // Time when an update check for this CRX has happened.
  base::TimeTicks last_check_;

  // Time when the update of this CRX has begun.
  base::TimeTicks update_begin_;

  // A component can be made available for download from several urls.
  std::vector<GURL> crx_urls_;
  std::vector<GURL> crx_diffurls_;

  // The cryptographic hash values for the component payload.
  std::string hash_sha256_;
  std::string hashdiff_sha256_;

  // The from/to version and fingerprint values.
  base::Version previous_version_;
  base::Version next_version_;
  std::string previous_fp_;
  std::string next_fp_;

  // Contains the file name of the payload to run.
  std::string action_run_;

  // True if the update check response for this component includes an update.
  bool is_update_available_ = false;

  // True if the current update check cycle is on-demand.
  bool on_demand_ = false;

  // The error reported by the update checker.
  int update_check_error_ = 0;

  base::FilePath crx_path_;

  // The error information for full and differential updates.
  // The |error_category| contains a hint about which module in the component
  // updater generated the error. The |error_code| constains the error and
  // the |extra_code1| usually contains a system error, but it can contain
  // any extended information that is relevant to either the category or the
  // error itself.
  int error_category_ = 0;
  int error_code_ = 0;
  int extra_code1_ = 0;
  int diff_error_category_ = 0;
  int diff_error_code_ = 0;
  int diff_extra_code1_ = 0;

  // Contains the events which are serialized in the pings.
  std::vector<std::string> events_;

  CallbackHandleComplete callback_handle_complete_;
  std::unique_ptr<State> state_;
  const UpdateContext& update_context_;

  base::Closure update_check_complete_;

  DISALLOW_COPY_AND_ASSIGN(Component);
};

using IdToComponentPtrMap = std::map<std::string, std::unique_ptr<Component>>;

}  // namespace update_client

#endif  // COMPONENTS_UPDATE_CLIENT_COMPONENT_H_