Refactor EncryptedFile and EC::FileInfo::file

Besides having a misleading name (and it goes back to the spec),
EncryptedFile under `file` key preempts the `url` (or `thumbnail_url`)
string value so only one of the two should exist. This is a case for
using std::variant<> - despite its clumsy syntax, it can actually
simplify and streamline code when all the necessary bits are in place
(such as conversion to JSON and getting the common piece - the URL -
out of it). This commit replaces `FileInfo::url` and `FileInfo::file`
with a common field `source` of type `FileSourceInfo` that is an alias
for a variant type covering both underlying types; and `url()` is
reintroduced as a function instead, to allow simplified access
to whichever URL is available inside the variant.

Oh, and EncryptedFile is EncryptedFileMetadata now, to clarify that it
does not represent the file payload itself but rather the data necessary
to obtain that payload.

1 files changed, 24 insertions, 29 deletions

diff --git a/lib/events/eventcontent.h b/lib/events/eventcontent.h
index bbd35618..23281876 100644
--- a/lib/events/eventcontent.h
+++ b/lib/events/eventcontent.h
@@ -6,14 +6,14 @@
 // This file contains generic event content definitions, applicable to room
 // message events as well as other events (e.g., avatars).
 
-#include "encryptedfile.h"
+#include "filesourceinfo.h"
 #include "quotient_export.h"
 
 #include <QtCore/QJsonObject>
+#include <QtCore/QMetaType>
 #include <QtCore/QMimeType>
 #include <QtCore/QSize>
 #include <QtCore/QUrl>
-#include <QtCore/QMetaType>
 
 class QFileInfo;
 
@@ -50,7 +50,7 @@ namespace EventContent {
 
     // A quick classes inheritance structure follows (the definitions are
     // spread across eventcontent.h and roommessageevent.h):
-    // UrlBasedContent<InfoT> : InfoT + url and thumbnail data
+    // UrlBasedContent<InfoT> : InfoT + thumbnail data
     //   PlayableContent<InfoT> : + duration attribute
     // FileInfo
     //   FileContent = UrlBasedContent<FileInfo>
@@ -89,34 +89,32 @@ namespace EventContent {
         //!
         //! \param fi a QFileInfo object referring to an existing file
         explicit FileInfo(const QFileInfo& fi);
-        explicit FileInfo(QUrl mxcUrl, qint64 payloadSize = -1,
+        explicit FileInfo(FileSourceInfo sourceInfo, qint64 payloadSize = -1,
                           const QMimeType& mimeType = {},
-                          Omittable<EncryptedFile> encryptedFile = none,
                           QString originalFilename = {});
         //! \brief Construct from a JSON `info` payload
         //!
         //! Make sure to pass the `info` subobject of content JSON, not the
         //! whole JSON content.
-        FileInfo(QUrl mxcUrl, const QJsonObject& infoJson,
-                 Omittable<EncryptedFile> encryptedFile,
+        FileInfo(FileSourceInfo sourceInfo, const QJsonObject& infoJson,
                  QString originalFilename = {});
 
         bool isValid() const;
+        QUrl url() const;
 
         //! \brief Extract media id from the URL
         //!
         //! This can be used, e.g., to construct a QML-facing image://
         //! URI as follows:
         //! \code "image://provider/" + info.mediaId() \endcode
-        QString mediaId() const { return url.authority() + url.path(); }
+        QString mediaId() const { return url().authority() + url().path(); }
 
     public:
+        FileSourceInfo source;
         QJsonObject originalInfoJson;
         QMimeType mimeType;
-        QUrl url;
         qint64 payloadSize = 0;
         QString originalName;
-        Omittable<EncryptedFile> file = none;
     };
 
     QUOTIENT_API QJsonObject toInfoJson(const FileInfo& info);
@@ -126,12 +124,10 @@ namespace EventContent {
     public:
         ImageInfo() = default;
         explicit ImageInfo(const QFileInfo& fi, QSize imageSize = {});
-        explicit ImageInfo(const QUrl& mxcUrl, qint64 fileSize = -1,
+        explicit ImageInfo(FileSourceInfo sourceInfo, qint64 fileSize = -1,
                            const QMimeType& type = {}, QSize imageSize = {},
-                           Omittable<EncryptedFile> encryptedFile = none,
                            const QString& originalFilename = {});
-        ImageInfo(const QUrl& mxcUrl, const QJsonObject& infoJson,
-                  Omittable<EncryptedFile> encryptedFile,
+        ImageInfo(FileSourceInfo sourceInfo, const QJsonObject& infoJson,
                   const QString& originalFilename = {});
 
     public:
@@ -144,12 +140,13 @@ namespace EventContent {
     //!
     //! This class saves/loads a thumbnail to/from `info` subobject of
     //! the JSON representation of event content; namely, `info/thumbnail_url`
-    //! and `info/thumbnail_info` fields are used.
+    //! (or, in case of an encrypted thumbnail, `info/thumbnail_file`) and
+    //! `info/thumbnail_info` fields are used.
     class QUOTIENT_API Thumbnail : public ImageInfo {
     public:
         using ImageInfo::ImageInfo;
         Thumbnail(const QJsonObject& infoJson,
-                  Omittable<EncryptedFile> encryptedFile = none);
+                  const Omittable<EncryptedFileMetadata>& encryptedFile = none);
 
         //! \brief Add thumbnail information to the passed `info` JSON object
         void dumpTo(QJsonObject& infoJson) const;
@@ -169,10 +166,10 @@ namespace EventContent {
 
     //! \brief A template class for content types with a URL and additional info
     //!
-    //! Types that derive from this class template take `url` and,
-    //! optionally, `filename` values from the top-level JSON object and
-    //! the rest of information from the `info` subobject, as defined by
-    //! the parameter type.
+    //! Types that derive from this class template take `url` (or, if the file
+    //! is encrypted, `file`) and, optionally, `filename` values from
+    //! the top-level JSON object and the rest of information from the `info`
+    //! subobject, as defined by the parameter type.
     //! \tparam InfoT base info class - FileInfo or ImageInfo
     template <class InfoT>
     class UrlBasedContent : public TypedBase, public InfoT {
@@ -181,10 +178,12 @@ namespace EventContent {
         explicit UrlBasedContent(const QJsonObject& json)
             : TypedBase(json)
             , InfoT(QUrl(json["url"].toString()), json["info"].toObject(),
-                    fromJson<Omittable<EncryptedFile>>(json["file"]),
                     json["filename"].toString())
             , thumbnail(FileInfo::originalInfoJson)
         {
+            const auto efmJson = json.value("file"_ls).toObject();
+            if (!efmJson.isEmpty())
+                InfoT::source = fromJson<EncryptedFileMetadata>(efmJson);
             // Two small hacks on originalJson to expose mediaIds to QML
             originalJson.insert("mediaId", InfoT::mediaId());
             originalJson.insert("thumbnailMediaId", thumbnail.mediaId());
@@ -204,11 +203,7 @@ namespace EventContent {
 
         void fillJson(QJsonObject& json) const override
         {
-            if (!InfoT::file.has_value()) {
-                json.insert("url", InfoT::url.toString());
-            } else {
-                json.insert("file", Quotient::toJson(*InfoT::file));
-            }
+            Quotient::fillJson(json, { "url"_ls, "file"_ls }, InfoT::source);
             if (!InfoT::originalName.isEmpty())
                 json.insert("filename", InfoT::originalName);
             auto infoJson = toInfoJson(*this);
@@ -223,7 +218,7 @@ namespace EventContent {
     //!
     //! Available fields:
     //! - corresponding to the top-level JSON:
-    //!   - url
+    //!   - source (corresponding to `url` or `file` in JSON)
     //!   - filename (extension to the spec)
     //! - corresponding to the `info` subobject:
     //!   - payloadSize (`size` in JSON)
@@ -241,12 +236,12 @@ namespace EventContent {
     //!
     //! Available fields:
     //! - corresponding to the top-level JSON:
-    //!   - url
+    //!   - source (corresponding to `url` or `file` in JSON)
     //!   - filename
     //! - corresponding to the `info` subobject:
     //!   - payloadSize (`size` in JSON)
     //!   - mimeType (`mimetype` in JSON)
-    //!   - thumbnail.url (`thumbnail_url` in JSON)
+    //!   - thumbnail.source (`thumbnail_url` or `thumbnail_file` in JSON)
     //! - corresponding to the `info/thumbnail_info` subobject:
     //!   - thumbnail.payloadSize
     //!   - thumbnail.mimeType