// Copyright (c) 2006-2008 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.
//
// The Safe Browsing service is responsible for downloading anti-phishing and
// anti-malware tables and checking urls against them.

#ifndef CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H__
#define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H__

#include <deque>
#include <hash_map>
#include <set>
#include <string>
#include <vector>

#include "base/ref_counted.h"
#include "base/scoped_ptr.h"
#include "base/thread.h"
#include "base/time.h"
#include "chrome/browser/safe_browsing/safe_browsing_util.h"
#include "googleurl/src/gurl.h"
#include "webkit/glue/resource_type.h"

class MessageLoop;
class PrefService;
class SafeBrowsingBlockingPage;
class SafeBrowsingDatabase;
class SafeBrowsingProtocolManager;

// Construction needs to happen on the main thread.
class SafeBrowsingService
    : public base::RefCountedThreadSafe<SafeBrowsingService> {
 public:
  // Users of this service implement this interface to be notified
  // asynchronously of the result.
  enum UrlCheckResult {
    URL_SAFE,
    URL_PHISHING,
    URL_MALWARE,
  };

  class Client {
   public:
    virtual ~Client() {}

    // Called when the result of checking a URL is known.
    virtual void OnUrlCheckResult(const GURL& url, UrlCheckResult result) = 0;

    // Called when the user has made a decision about how to handle the
    // SafeBrowsing interstitial page.
    virtual void OnBlockingPageComplete(bool proceed) = 0;
  };

  // Creates the safe browsing service.  Need to initialize before using.
  SafeBrowsingService();
  ~SafeBrowsingService();

  // Initializes the service.  io_loop is the message loop that the
  // caller of this service (ResourceDispatcherHost) wants to be notified on
  // for check results.  db_loop is the message loop for the thread to do
  // the database work.
  void Initialize(MessageLoop* io_loop);

  // Called to initialize objects that are used on the io_thread.
  void OnIOInitialize(MessageLoop* notify_loop,
                      const std::string& client_key,
                      const std::string& wrapped_key);

  // Called to initialize objects that are used on the db_thread.
  void OnDBInitialize();

  // Called to shutdown operations on the io_thread.
  void OnIOShutdown();

  // Called on the main thread to let us know that the io_thread is going away.
  void ShutDown();

  // Called on the IO thread.

  // Returns true if the url's scheme can be checked.
  bool CanCheckUrl(const GURL& url) const;

  // Checks if the given url is safe or not.  If we can synchronously determine
  // that the url is safe, CheckUrl returns true.  Otherwise it returns false,
  // and "client" is called asynchronously with the result when it is ready.
  bool CheckUrl(const GURL& url, Client* client);

  // Cancels a pending check if the result is no longer needed.
  void CancelCheck(Client* client);

  // Displays an interstitial page.
  void DisplayBlockingPage(const GURL& url,
                           ResourceType::Type resource_type,
                           UrlCheckResult result,
                           Client* client,
                           MessageLoop* ui_loop,
                           int render_process_host_id,
                           int render_view_id);

  // Bundle of SafeBrowsing state for one URL check.
  // TODO(paulg): Make this struct private to SafeBrowsingService and maintain
  //              request mappings using CancelableRequests instead (which can
  //              store this state for us).
  struct SafeBrowsingCheck {
    GURL url;
    Client* client;
    bool need_get_hash;
    Time start;  // Time that check was sent to SB service.
    TimeDelta db_time;  // How long DB look-up took.
    UrlCheckResult result;
    std::vector<SBPrefix> prefix_hits;
    std::vector<SBFullHashResult> full_hits;
  };

  // API used by the SafeBrowsingProtocolManager to interface with the
  // SafeBrowsing storage system.
  void HandleGetHashResults(
      SafeBrowsingCheck* check,
      const std::vector<SBFullHashResult>& full_hashes);
  void HandleChunk(const std::string& list, std::deque<SBChunk>* chunks);
  void HandleChunkDelete(std::vector<SBChunkDelete>* chunk_deletes);
  void GetAllChunks();

  // The blocking page on the UI thread has completed.
  void OnBlockingPageDone(SafeBrowsingBlockingPage* page,
                          Client* client,
                          bool proceed);

  // Called when the SafeBrowsingProtocolManager has received updated MAC keys.
  void OnNewMacKeys(const std::string& client_key,
                    const std::string& wrapped_key);

  // Notification from the advanced options UI.
  void OnEnable(bool enabled);
  bool enabled() const { return enabled_; }

  // Called by the database (on the db thread) when a chunk insertion is
  // complete.
  void ChunkInserted();

  // Preference handling.
  static void RegisterUserPrefs(PrefService* prefs);

  // The SafeBrowsing system has instructed us to reset our database.
  void ResetDatabase();

  // Log the user perceived delay caused by SafeBrowsing. This delay is the time
  // delta starting from when we would have started reading data from the
  // network, and ending when the SafeBrowsing check completes indicating that
  // the current page is 'safe'.
  static void LogPauseDelay(TimeDelta time);

  // We defer SafeBrowsing work for a short duration when the computer comes
  // out of a suspend state to avoid thrashing the disk.
  void OnSuspend();
  void OnResume();

 private:
  // Should only be called on db thread as SafeBrowsingDatabase is not
  // threadsafe.
  SafeBrowsingDatabase* GetDatabase();

  // Called on the database thread to check a url.
  void CheckDatabase(SafeBrowsingCheck* info, Time last_update);

  // Called on the IO thread with the check result.
  void OnCheckDone(SafeBrowsingCheck* info);

  // Called on the database thread to retrieve chunks.
  void GetAllChunksFromDatabase();

  // Called on the IOthread with the results of all chunks.
  void OnGetAllChunksFromDatabase(const std::vector<SBListChunkRanges>& lists,
                                  bool database_error);

  // Called on the IO thread after the database reports that it added a chunk.
  void OnChunkInserted();

  // Called on the database thread to add/remove chunks and host keys.
  // Callee will free the data when it's done.
  void HandleChunkForDatabase(const std::string& list,
                              std::deque<SBChunk>* chunks);
  void DeleteChunks(std::vector<SBChunkDelete>* chunk_deletes);

  static UrlCheckResult GetResultFromListname(const std::string& list_name);

  void NotifyClientBlockingComplete(Client* client, bool proceed);

  void Start();
  void Stop();

  // Runs on the db thread to reset the database. We assume that resetting the
  // database is a synchronous operation.
  void OnResetDatabase();

  // Runs on the io thread when the reset is complete.
  void OnResetComplete();

  // Store the results of a GetHash request. Runs on the database thread.
  void CacheHashResults(const std::vector<SBFullHashResult>& full_hashes);

  // Internal worker function for processing full hashes.
  void OnHandleGetHashResults(SafeBrowsingCheck* check,
                              const std::vector<SBFullHashResult>& full_hashes);

  void HandleOneCheck(SafeBrowsingCheck* check,
                      const std::vector<SBFullHashResult>& full_hashes);

  // Runs on the database thread to inform the database we've resumed from a low
  // power state.
  void HandleResume();

  MessageLoop* io_loop_;

  typedef std::set<SafeBrowsingCheck*> CurrentChecks;
  CurrentChecks checks_;

  // Used for issuing only one GetHash request for a given prefix.
  typedef std::vector<SafeBrowsingCheck*> GetHashRequestors;
  typedef stdext::hash_map<SBPrefix, GetHashRequestors> GetHashRequests;
  GetHashRequests gethash_requests_;

  // The sqlite database.  We don't use a scoped_ptr because it needs to be
  // destructed on a different thread than this object.
  SafeBrowsingDatabase* database_;

  // Handles interaction with SafeBrowsing servers.
  SafeBrowsingProtocolManager* protocol_manager_;

  // Used for whitelisting a render view when the user ignores our warning.
  struct WhiteListedEntry {
    int render_process_host_id;
    int render_view_id;
    std::string domain;
    UrlCheckResult result;
  };

  std::vector<WhiteListedEntry> white_listed_entries_;

  // Whether the service is running. 'enabled_' is used by SafeBrowsingService
  // on the IO thread during normal operations.
  bool enabled_;

  // The SafeBrowsing thread that runs database operations.
  scoped_ptr<base::Thread> db_thread_;

  // Indicates if we are in the process of resetting the database.
  bool resetting_;

  DISALLOW_EVIL_CONSTRUCTORS(SafeBrowsingService);
};

#endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H__