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// 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_OFFLINE_ITEMS_COLLETION_CORE_OFFLINE_CONTENT_PROVIDER_H_
#define COMPONENTS_OFFLINE_ITEMS_COLLETION_CORE_OFFLINE_CONTENT_PROVIDER_H_
#include <string>
#include <vector>
#include "base/callback.h"
#include "base/macros.h"
#include "url/gurl.h"
namespace offline_items_collection {
struct ContentId;
struct OfflineItem;
struct OfflineItemVisuals;
// A provider of a set of OfflineItems that are meant to be exposed to the UI.
// The provider is required to notify all observers of OnItemsAvailable when the
// underlying data set is initialized. Without that call it should not expect
// nor have to support any other calls to this provider.
class OfflineContentProvider {
public:
using OfflineItemList = std::vector<OfflineItem>;
using VisualsCallback =
base::Callback<void(const ContentId&, const OfflineItemVisuals*)>;
// An observer class that should be notified of relevant changes to the
// underlying data source.
class Observer {
public:
// Called when the underlying data source for the provider has been
// initialized and the contents are able to be queried and interacted with.
// |provider| should be a reference to this OfflineContentProvider that is
// initialized.
virtual void OnItemsAvailable(OfflineContentProvider* provider) = 0;
// Called when one or more OfflineItems have been added and should be shown
// in the UI.
virtual void OnItemsAdded(const OfflineItemList& items) = 0;
// Called when the OfflineItem represented by |id| should be removed from
// the UI.
virtual void OnItemRemoved(const ContentId& id) = 0;
// Called when the contents of |item| have been updated and the UI should be
// refreshed for that item.
// TODO(dtrainor): Make this take a list of OfflineItems.
virtual void OnItemUpdated(const OfflineItem& item) = 0;
protected:
virtual ~Observer() = default;
};
// Returns whether or not the underlying data source for this provider has
// been initialized and is ready to start returning content. This provider
// should not need to support handling the other data query/manipulation
// methods if this returns false.
virtual bool AreItemsAvailable() = 0;
// Called to trigger opening an OfflineItem represented by |id|.
virtual void OpenItem(const ContentId& id) = 0;
// Called to trigger removal of an OfflineItem represented by |id|.
virtual void RemoveItem(const ContentId& id) = 0;
// Called to cancel a download of an OfflineItem represented by |id|.
virtual void CancelDownload(const ContentId& id) = 0;
// Called to pause a download of an OfflineItem represented by |id|.
virtual void PauseDownload(const ContentId& id) = 0;
// Called to resume a paused download of an OfflineItem represented by |id|.
virtual void ResumeDownload(const ContentId& id) = 0;
// Returns an OfflineItem represented by |id| or |nullptr| if none exists.
// The caller should not hold ownership of the returned item beyond the scope
// of the function call.
virtual const OfflineItem* GetItemById(const ContentId& id) = 0;
// Returns all OfflineItems for this particular provider.
virtual OfflineItemList GetAllItems() = 0;
// Asks for an OfflineItemVisuals struct for an OfflineItem represented by
// |id| or |nullptr| if one doesn't exist. The implementer should post any
// replies even if the results are available immediately to prevent reentrancy
// and for consistent behavior.
virtual void GetVisualsForItem(const ContentId& id,
const VisualsCallback& callback) = 0;
// Adds an observer that should be notified of OfflineItem list modifications.
// If the provider is already initialized OnItemsAvailable should be scheduled
// on this observer (suggested over calling the method directly to avoid
// reentrancy).
virtual void AddObserver(Observer* observer) = 0;
// Removes an observer. No further notifications should be sent to it.
virtual void RemoveObserver(Observer* observer) = 0;
protected:
virtual ~OfflineContentProvider() = default;
};
} // namespace offline_items_collection
#endif // COMPONENTS_OFFLINE_ITEMS_COLLETION_CORE_OFFLINE_CONTENT_PROVIDER_H_
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