Implement XEP-0448: Stateless File Sharing

This adds a file sharing manager that is capable of using multiple back
ends. Currently implemented are a normal HTTP File Upload backend and an
encrypted HTTP File Upload. Jingle File Transfer could be implemented
later.

Co-authored-by: Linus Jahn <lnj@kaidan.im>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/client/QXmppFileSharingProvider.h b/src/client/QXmppFileSharingProvider.h
new file mode 100644
index 00000000..cde719db
--- /dev/null
+++ b/src/client/QXmppFileSharingProvider.h
@@ -0,0 +1,52 @@
+// SPDX-FileCopyrightText: 2022 Jonah Brüchert <jbb@kaidan.im>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#ifndef QXMPPFILESHARINGPROVIDER_H
+#define QXMPPFILESHARINGPROVIDER_H
+
+#include "QXmppGlobal.h"
+
+#include <any>
+#include <memory>
+
+class QIODevice;
+class QXmppFileMetadata;
+class QXmppUpload;
+class QXmppDownload;
+
+///
+/// \brief The interface of a provider for the FileSharingManager
+///
+/// To use it, implement all the pure virtual functions,
+/// and add a using declaration for the type of source you want to handle.
+/// ```
+/// using SourceType = QXmppHttpFileSource;
+/// ```
+///
+class QXMPP_EXPORT QXmppFileSharingProvider
+{
+public:
+    /// \cond
+    virtual ~QXmppFileSharingProvider() = default;
+    /// \endcond
+
+    ///
+    /// \brief Handles the download of files for this provider
+    /// \param source A type-erased source object. The provider will only ever have to handle its own sources,
+    ///         so this can be safely casted to a concrete type.
+    /// \param target QIODevice into which the received data should be written
+    /// \return A subclass of QXmppDownload
+    ///
+    virtual auto downloadFile(const std::any &source, std::unique_ptr<QIODevice> &&target) -> std::shared_ptr<QXmppDownload> = 0;
+
+    ///
+    /// \brief Handles the upload of a file for this provider
+    /// \param source A QIODevice from which data for uploading should be read.
+    /// \param info Metadata of the file
+    /// \return A subclass of QXmppUpload
+    ///
+    virtual auto uploadFile(std::unique_ptr<QIODevice> source, const QXmppFileMetadata &info) -> std::shared_ptr<QXmppUpload> = 0;
+};
+
+#endif  // QXMPPFILESHARINGPROVIDER_H