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// Copyright 2014 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_SEARCH_PROVIDER_LOGOS_LOGO_TRACKER_H_
#define COMPONENTS_SEARCH_PROVIDER_LOGOS_LOGO_TRACKER_H_
#include <string>
#include <vector>
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/sequenced_task_runner.h"
#include "base/time/clock.h"
#include "base/time/time.h"
#include "components/search_provider_logos/logo_cache.h"
#include "components/search_provider_logos/logo_common.h"
#include "net/url_request/url_fetcher_delegate.h"
#include "url/gurl.h"
namespace net {
class URLFetcher;
class URLRequestContextGetter;
}
namespace search_provider_logos {
// Receives updates when the search provider's logo is available.
class LogoObserver {
public:
virtual ~LogoObserver() {}
// Called when the cached logo is available and possibly when a freshly
// downloaded logo is available. |logo| will be NULL if no logo is available.
// |from_cache| indicates whether the logo was loaded from the cache.
//
// If the fresh logo is the same as the cached logo, this will not be called
// again.
virtual void OnLogoAvailable(const Logo* logo, bool from_cache) = 0;
// Called when the LogoTracker will no longer send updates to this
// LogoObserver. For example: after the cached logo is validated, after
// OnFreshLogoAvailable() is called, or when the LogoTracker is destructed.
// This is not called when an observer is removed using
// LogoTracker::RemoveObserver().
virtual void OnObserverRemoved() = 0;
};
// Provides a LogoTracker with methods it needs to download and cache logos.
class LogoDelegate {
public:
virtual ~LogoDelegate() {}
// Decodes an untrusted image safely and returns it as an SkBitmap via
// |image_decoded_callback|. If image decoding fails, |image_decoded_callback|
// should be called with NULL. This will be called on the thread that
// LogoTracker lives on and |image_decoded_callback| must be called on the
// same thread.
virtual void DecodeUntrustedImage(
const scoped_refptr<base::RefCountedString>& encoded_image,
base::Callback<void(const SkBitmap&)> image_decoded_callback) = 0;
};
// Parses the response from the server and returns it as an EncodedLogo. Returns
// NULL if the response is invalid.
typedef base::Callback<
scoped_ptr<EncodedLogo>(const scoped_ptr<std::string>& response,
base::Time response_time)> ParseLogoResponse;
// Encodes the fingerprint of the cached logo in the logo URL. This enables the
// server to verify whether the cached logo is up-to-date.
typedef base::Callback<
GURL(const GURL& logo_url, const std::string& fingerprint)>
AppendFingerprintToLogoURL;
// This class provides the logo for a search provider. Logos are downloaded from
// the search provider's logo URL and cached on disk.
//
// Call SetServerAPI() at least once to specify how to get the logo from the
// server. Then call GetLogo() to trigger retrieval of the logo and receive
// updates once the cached and/or fresh logos are available.
class LogoTracker : public net::URLFetcherDelegate {
public:
// Constructs a LogoTracker with the given LogoDelegate. Takes ownership of
// |delegate|, which will be deleted at the same time as the LogoTracker.
//
// |cached_logo_directory| is the directory in which the cached logo and its
// metadata should be saved.
//
// |file_task_runner| is the SequencedTaskRunner that should be used to run
// file system operations.
//
// |background_task_runner| is the TaskRunner that should be used to for
// CPU-intensive background operations.
//
// |request_context_getter| is the URLRequestContextGetter used to download
// the logo.
explicit LogoTracker(
base::FilePath cached_logo_directory,
scoped_refptr<base::SequencedTaskRunner> file_task_runner,
scoped_refptr<base::TaskRunner> background_task_runner,
scoped_refptr<net::URLRequestContextGetter> request_context_getter,
scoped_ptr<LogoDelegate> delegate);
~LogoTracker() override;
// Defines the server API for downloading and parsing the logo. This must be
// called at least once before calling GetLogo().
//
// |logo_url| is the URL from which the logo will be downloaded. If |logo_url|
// is different than the current logo URL, any pending LogoObservers will be
// canceled.
//
// |parse_logo_response_func| is a callback that will be used to parse the
// server's response into a EncodedLogo object. |append_fingerprint_func| is a
// callback that will return the URL from which to download the logo if a
// cached logo with a fingerprint is already available. Note:
// |parse_logo_response_func| and |append_fingerprint_func| must be suitable
// for running multiple times, concurrently, and on multiple threads.
void SetServerAPI(const GURL& logo_url,
const ParseLogoResponse& parse_logo_response_func,
const AppendFingerprintToLogoURL& append_fingerprint_func);
// Retrieves the current search provider's logo from the local cache and/or
// over the network, and registers |observer| to be called when the cached
// and/or fresh logos are available.
void GetLogo(LogoObserver* observer);
// Prevents |observer| from receiving future updates. This is safe to call
// even when the observer is being notified of an update.
void RemoveObserver(LogoObserver* observer);
// Overrides the cache used to store logos.
void SetLogoCacheForTests(scoped_ptr<LogoCache> cache);
// Overrides the clock used to check the time.
void SetClockForTests(scoped_ptr<base::Clock> clock);
private:
// Cancels the current asynchronous operation, if any, and resets all member
// variables that change as the logo is fetched.
void ReturnToIdle();
// Called when the cached logo has been read from the cache. |cached_logo|
// will be NULL if there wasn't a valid, up-to-date logo in the cache.
void OnCachedLogoRead(scoped_ptr<EncodedLogo> cached_logo);
// Called when the cached logo has been decoded into an SkBitmap. |image| will
// be NULL if decoding failed.
void OnCachedLogoAvailable(const LogoMetadata& metadata,
const SkBitmap& image);
// Stores |logo| in the cache.
void SetCachedLogo(scoped_ptr<EncodedLogo> logo);
// Updates the metadata for the logo already stored in the cache.
void SetCachedMetadata(const LogoMetadata& metadata);
// Starts fetching the current logo over the network.
void FetchLogo();
// Called when the logo has been downloaded and parsed. |logo| will be NULL
// if the server's response was invalid.
void OnFreshLogoParsed(scoped_ptr<EncodedLogo> logo);
// Called when the fresh logo has been decoded into an SkBitmap. |image| will
// be NULL if decoding failed.
void OnFreshLogoAvailable(scoped_ptr<EncodedLogo> logo,
const SkBitmap& image);
// net::URLFetcherDelegate:
void OnURLFetchComplete(const net::URLFetcher* source) override;
void OnURLFetchDownloadProgress(const net::URLFetcher* source,
int64 current,
int64 total) override;
// The URL from which the logo is fetched.
GURL logo_url_;
// The function used to parse the logo response from the server.
ParseLogoResponse parse_logo_response_func_;
// The function used to include the cached logo's fingerprint in the logo URL.
AppendFingerprintToLogoURL append_fingerprint_func_;
// False if an asynchronous task is currently running.
bool is_idle_;
// The logo that's been read from the cache, or NULL if the cache is empty.
// Meaningful only if is_cached_logo_valid_ is true; NULL otherwise.
scoped_ptr<Logo> cached_logo_;
// Whether the value of |cached_logo_| reflects the actual cached logo.
// This will be false if the logo hasn't been read from the cache yet.
// |cached_logo_| may be NULL even if |is_cached_logo_valid_| is true, if no
// logo is cached.
bool is_cached_logo_valid_;
// The URLFetcher currently fetching the logo. NULL when not fetching.
scoped_ptr<net::URLFetcher> fetcher_;
// The list of observers to be notified when the logo is available. This
// should be empty when the state is IDLE.
ObserverList<LogoObserver> logo_observers_;
scoped_ptr<LogoDelegate> logo_delegate_;
// The cache used to persist the logo on disk. Used only on the file thread.
LogoCache* logo_cache_;
// Clock used to determine current time. Can be overridden in tests.
scoped_ptr<base::Clock> clock_;
// The SequencedTaskRunner on which file system operations will be run.
scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
// The TaskRunner on which the server's response will be parsed.
scoped_refptr<base::TaskRunner> background_task_runner_;
// The URLRequestContextGetter used for network requests.
scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
base::WeakPtrFactory<LogoTracker> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(LogoTracker);
};
} // namespace search_provider_logos
#endif // COMPONENTS_SEARCH_PROVIDER_LOGOS_LOGO_TRACKER_H_