Merge pull request #72 from QMatrixClient/kitsune-send-events

Events creation and sending

4 files changed, 493 insertions, 112 deletions

diff --git a/events/event.cpp b/events/event.cpp
index bd7e1b03..653396bd 100644
--- a/events/event.cpp
+++ b/events/event.cpp
@@ -95,6 +95,7 @@ RoomEvent::RoomEvent(Type type, const QJsonObject& rep)
     , _serverTimestamp(toTimestamp(rep["origin_server_ts"]))
     , _roomId(rep["room_id"].toString())
     , _senderId(rep["sender"].toString())
+    , _txnId(rep["unsigned"].toObject().value("transactionId").toString())
 {
     if (_id.isEmpty())
     {
@@ -103,14 +104,22 @@ RoomEvent::RoomEvent(Type type, const QJsonObject& rep)
     }
     if (!rep.contains("origin_server_ts"))
     {
-        qCWarning(EVENTS) << "Event: can't find server timestamp in a room event";
+        qCWarning(EVENTS) << "Can't find server timestamp in a room event";
         qCWarning(EVENTS) << formatJson << rep;
     }
     if (_senderId.isEmpty())
     {
-        qCWarning(EVENTS) << "user_id not found in a room event";
+        qCWarning(EVENTS) << "Can't find sender in a room event";
         qCWarning(EVENTS) << formatJson << rep;
     }
+    if (!_txnId.isEmpty())
+        qCDebug(EVENTS) << "Event transactionId:" << _txnId;
+}
+
+void RoomEvent::addId(const QString& id)
+{
+    Q_ASSERT(_id.isEmpty()); Q_ASSERT(!id.isEmpty());
+    _id = id;
 }
 
 RoomEvent* RoomEvent::fromJson(const QJsonObject& obj)
diff --git a/events/event.h b/events/event.h
index fd2f6feb..8760aa28 100644
--- a/events/event.h
+++ b/events/event.h
@@ -37,14 +37,16 @@ namespace QMatrixClient
                 RoomMember, RoomTopic, Typing, Receipt, Unknown
             };
 
-            explicit Event(Type type, const QJsonObject& rep);
+            explicit Event(Type type) : _type(type) { }
+            Event(Type type, const QJsonObject& rep);
             Event(const Event&) = delete;
 
             Type type() const { return _type; }
             QByteArray originalJson() const;
 
-            // Every event also has a "content" object but since its structure is
-            // different for different types, we're implementing it per-event type
+            // According to the CS API spec, every event also has
+            // a "content" object; but since its structure is different for
+            // different types, we're implementing it per-event type
             // (and in most cases it will be a combination of other fields
             // instead of "content" field).
 
@@ -61,6 +63,8 @@ namespace QMatrixClient
             QJsonObject _originalJson;
 
             REGISTER_ENUM(Type)
+            Q_PROPERTY(Type type READ type CONSTANT)
+            Q_PROPERTY(QJsonObject contentJson READ contentJson CONSTANT)
     };
     using EventType = Event::Type;
     template <typename EventT>
@@ -91,13 +95,42 @@ namespace QMatrixClient
 
     class RoomEvent : public Event
     {
+            Q_GADGET
+            Q_PROPERTY(QString id READ id)
+            Q_PROPERTY(QDateTime timestamp READ timestamp CONSTANT)
+            Q_PROPERTY(QString roomId READ roomId CONSTANT)
+            Q_PROPERTY(QString senderId READ senderId CONSTANT)
+            Q_PROPERTY(QString transactionId READ transactionId CONSTANT)
         public:
+            explicit RoomEvent(Type type) : Event(type) { }
             RoomEvent(Type type, const QJsonObject& rep);
 
-            const QString& id() const          { return _id; }
+            const QString& id() const { return _id; }
             const QDateTime& timestamp() const { return _serverTimestamp; }
-            const QString& roomId() const      { return _roomId; }
-            const QString& senderId() const    { return _senderId; }
+            const QString& roomId() const { return _roomId; }
+            const QString& senderId() const { return _senderId; }
+            const QString& transactionId() const { return _txnId; }
+
+            /**
+             * Sets the transaction id for locally created events. This should be
+             * done before the event is exposed to any code using the respective
+             * Q_PROPERTY.
+             *
+             * \param txnId - transaction id, normally obtained from
+             * Connection::generateTxnId()
+             */
+            void setTransactionId(const QString& txnId) { _txnId = txnId; }
+
+            /**
+             * Sets event id for locally created events
+             *
+             * When a new event is created locally, it has no server id yet.
+             * This function allows to add the id once the confirmation from
+             * the server is received. There should be no id set previously
+             * in the event. It's the responsibility of the code calling addId()
+             * to notify clients that use Q_PROPERTY(id) about its change
+             */
+            void addId(const QString& id);
 
             // "Static override" of the one in Event
             static RoomEvent* fromJson(const QJsonObject& obj);
@@ -107,6 +140,11 @@ namespace QMatrixClient
             QDateTime _serverTimestamp;
             QString _roomId;
             QString _senderId;
+            QString _txnId;
     };
     using RoomEvents = EventsBatch<RoomEvent>;
 }  // namespace QMatrixClient
+Q_DECLARE_OPAQUE_POINTER(QMatrixClient::Event*)
+Q_DECLARE_METATYPE(QMatrixClient::Event*)
+Q_DECLARE_OPAQUE_POINTER(QMatrixClient::RoomEvent*)
+Q_DECLARE_METATYPE(QMatrixClient::RoomEvent*)
diff --git a/events/roommessageevent.cpp b/events/roommessageevent.cpp
index 19da8827..179eac77 100644
--- a/events/roommessageevent.cpp
+++ b/events/roommessageevent.cpp
@@ -25,57 +25,78 @@
 using namespace QMatrixClient;
 using namespace MessageEventContent;
 
-using ContentPair = std::pair<CType, Base*>;
+using MsgType = RoomMessageEvent::MsgType;
 
-template <CType EnumType, typename ContentT>
-ContentPair make(const QJsonObject& json)
+template <typename ContentT>
+Base* make(const QJsonObject& json)
 {
-    return { EnumType, new ContentT(json) };
+    return new ContentT(json);
 }
 
-ContentPair makeVideo(const QJsonObject& json)
+struct MsgTypeDesc
 {
-    auto c = new VideoContent(json);
-    // Only for m.video, the spec puts a thumbnail inside "info" JSON key. Once
-    // this is fixed, VideoContent creation will switch to make<>().
-    const QJsonObject infoJson = json["info"].toObject();
-    if (infoJson.contains("thumbnail_url"))
-    {
-        c->thumbnail = ImageInfo(infoJson["thumbnail_url"].toString(),
-                                 infoJson["thumbnail_info"].toObject());
-    }
-    return { CType::Video, c };
+    QString jsonType;
+    MsgType enumType;
+    Base* (*maker)(const QJsonObject&);
 };
 
-ContentPair makeUnknown(const QJsonObject& json)
+const std::vector<MsgTypeDesc> msgTypes =
+    { { QStringLiteral("m.text"), MsgType::Text, make<TextContent> }
+    , { QStringLiteral("m.emote"), MsgType::Emote, make<TextContent> }
+    , { QStringLiteral("m.notice"), MsgType::Notice, make<TextContent> }
+    , { QStringLiteral("m.image"), MsgType::Image, make<ImageContent> }
+    , { QStringLiteral("m.file"), MsgType::File, make<FileContent> }
+    , { QStringLiteral("m.location"), MsgType::Location, make<LocationContent> }
+    , { QStringLiteral("m.video"), MsgType::Video, make<VideoContent> }
+    , { QStringLiteral("m.audio"), MsgType::Audio, make<AudioContent> }
+    };
+
+QString msgTypeToJson(MsgType enumType)
 {
-    qCDebug(EVENTS) << "RoomMessageEvent: couldn't resolve msgtype, JSON follows:";
-    qCDebug(EVENTS) << json;
-    return { CType::Unknown, new Base() };
+    auto it = std::find_if(msgTypes.begin(), msgTypes.end(),
+        [=](const MsgTypeDesc& mtd) { return mtd.enumType == enumType; });
+    if (it != msgTypes.end())
+        return it->jsonType;
+
+    qCCritical(EVENTS) << "Unknown msgtype:" << enumType;
+    return {};
 }
 
+MsgType jsonToMsgType(const QString& jsonType)
+{
+    auto it = std::find_if(msgTypes.begin(), msgTypes.end(),
+        [=](const MsgTypeDesc& mtd) { return mtd.jsonType == jsonType; });
+    if (it != msgTypes.end())
+        return it->enumType;
+
+    qCCritical(EVENTS) << "Unknown msgtype:" << jsonType;
+    return {};
+}
+
+RoomMessageEvent::RoomMessageEvent(const QString& plainBody,
+                                   MsgType msgType, Base* content)
+    : RoomMessageEvent(plainBody, msgTypeToJson(msgType), content)
+{ }
+
 RoomMessageEvent::RoomMessageEvent(const QJsonObject& obj)
-    : RoomEvent(Type::RoomMessage, obj), _msgtype(CType::Unknown)
-    , _content(nullptr)
+    : RoomEvent(Type::RoomMessage, obj), _content(nullptr)
 {
     const QJsonObject content = contentJson();
     if ( content.contains("msgtype") && content.contains("body") )
     {
         _plainBody = content["body"].toString();
 
-        auto factory = lookup(content["msgtype"].toString(),
-                            "m.text", &make<CType::Text, TextContent>,
-                            "m.emote", &make<CType::Emote, TextContent>,
-                            "m.notice", &make<CType::Notice, TextContent>,
-                            "m.image", &make<CType::Image, ImageContent>,
-                            "m.file", &make<CType::File, FileContent>,
-                            "m.location", &make<CType::Location, LocationContent>,
-                            "m.video", &makeVideo,
-                            "m.audio", &make<CType::Audio, AudioContent>,
-                            // Insert new message types before this line
-                            &makeUnknown
-                        );
-        std::tie(_msgtype, _content) = factory(content);
+        _msgtype = content["msgtype"].toString();
+        for (auto mt: msgTypes)
+            if (mt.jsonType == _msgtype)
+                _content.reset(mt.maker(content));
+
+        if (!_content)
+        {
+            qCWarning(EVENTS) << "RoomMessageEvent: couldn't load content,"
+                              << " full content dump follows";
+            qCWarning(EVENTS) << formatJson << content;
+        }
     }
     else
     {
@@ -84,12 +105,43 @@ RoomMessageEvent::RoomMessageEvent(const QJsonObject& obj)
     }
 }
 
-RoomMessageEvent::~RoomMessageEvent()
+RoomMessageEvent::MsgType RoomMessageEvent::msgtype() const
+{
+    return jsonToMsgType(_msgtype);
+}
+
+QMimeType RoomMessageEvent::mimeType() const
+{
+    return _content ? _content->mimeType :
+                      QMimeDatabase().mimeTypeForName("text/plain");
+}
+
+QJsonObject RoomMessageEvent::toJson() const
 {
-    if (_content)
-        delete _content;
+    QJsonObject obj = _content ? _content->toJson() : QJsonObject();
+    obj.insert("msgtype", msgTypeToJson(msgtype()));
+    obj.insert("body", plainBody());
+    return obj;
 }
 
+QJsonObject Base::toJson() const
+{
+    QJsonObject o;
+    fillJson(&o);
+    return o;
+}
+
+QJsonObject InfoBase::toInfoJson() const
+{
+    QJsonObject info;
+    fillInfoJson(&info);
+    return info;
+}
+
+TextContent::TextContent(const QString& text, const QString& contentType)
+    : Base(QMimeDatabase().mimeTypeForName(contentType)), body(text)
+{ }
+
 TextContent::TextContent(const QJsonObject& json)
 {
     QMimeDatabase db;
@@ -103,39 +155,82 @@ TextContent::TextContent(const QJsonObject& json)
     } else {
         // Falling back to plain text, as there's no standard way to describe
         // rich text in messages.
-        body = json["body"].toString();
         mimeType = db.mimeTypeForName("text/plain");
+        body = json["body"].toString();
     }
 }
 
-FileInfo::FileInfo(QUrl u, const QJsonObject& infoJson, QString originalFilename)
-    : url(u)
-    , fileSize(infoJson["size"].toInt())
-    , mimetype(QMimeDatabase().mimeTypeForName(infoJson["mimetype"].toString()))
+void TextContent::fillJson(QJsonObject* json) const
+{
+    Q_ASSERT(json);
+    json->insert("format", QStringLiteral("org.matrix.custom.html"));
+    json->insert("formatted_body", body);
+}
+
+FileInfo::FileInfo(const QUrl& u, int payloadSize, const QMimeType& mimeType,
+                 const QString& originalFilename)
+    : InfoBase(mimeType), url(u), payloadSize(payloadSize)
     , originalName(originalFilename)
+{ }
+
+FileInfo::FileInfo(const QUrl& u, const QJsonObject& infoJson,
+                 const QString& originalFilename)
+    : FileInfo(u, infoJson["size"].toInt(),
+              QMimeDatabase().mimeTypeForName(infoJson["mimetype"].toString()),
+              originalFilename)
+{
+    if (!mimeType.isValid())
+        mimeType = QMimeDatabase().mimeTypeForData(QByteArray());
+}
+
+void FileInfo::fillInfoJson(QJsonObject* infoJson) const
 {
-    if (!mimetype.isValid())
-        mimetype = QMimeDatabase().mimeTypeForData(QByteArray());
+    Q_ASSERT(infoJson);
+    infoJson->insert("size", payloadSize);
+    infoJson->insert("mimetype", mimeType.name());
 }
 
-ImageInfo::ImageInfo(QUrl u, const QJsonObject& infoJson)
-    : FileInfo(u, infoJson)
-    , imageSize(infoJson["w"].toInt(), infoJson["h"].toInt())
+void FileInfo::fillJson(QJsonObject* json) const
+{
+    Q_ASSERT(json);
+    json->insert("url", url.toString());
+    if (!originalName.isEmpty())
+        json->insert("filename", originalName);
+    json->insert("info", toInfoJson());
+}
+
+LocationContent::LocationContent(const QString& geoUri,
+                                 const ImageInfo<>& thumbnail)
+    : Thumbnailed<>(thumbnail), geoUri(geoUri)
 { }
 
 LocationContent::LocationContent(const QJsonObject& json)
-    : geoUri(json["geo_uri"].toString())
-    , thumbnail(json["thumbnail_url"].toString(),
-                json["thumbnail_info"].toObject())
+    : Thumbnailed<>(json["info"].toObject())
+    , geoUri(json["geo_uri"].toString())
 { }
 
-VideoInfo::VideoInfo(QUrl u, const QJsonObject& infoJson)
-    : FileInfo(u, infoJson)
-    , duration(infoJson["duration"].toInt())
-    , imageSize(infoJson["w"].toInt(), infoJson["h"].toInt())
+void LocationContent::fillJson(QJsonObject* o) const
+{
+    Q_ASSERT(o);
+    o->insert("geo_uri", geoUri);
+    o->insert("info", Thumbnailed::toInfoJson());
+}
+
+PlayableInfo::PlayableInfo(const QUrl& u, int fileSize,
+                           const QMimeType& mimeType, int duration,
+                           const QString& originalFilename)
+    : FileInfo(u, fileSize, mimeType, originalFilename)
+    , duration(duration)
 { }
 
-AudioInfo::AudioInfo(QUrl u, const QJsonObject& infoJson)
-    : FileInfo(u, infoJson)
+PlayableInfo::PlayableInfo(const QUrl& u, const QJsonObject& infoJson,
+                           const QString& originalFilename)
+    : FileInfo(u, infoJson, originalFilename)
     , duration(infoJson["duration"].toInt())
 { }
+
+void PlayableInfo::fillInfoJson(QJsonObject* infoJson) const
+{
+    FileInfo::fillInfoJson(infoJson);
+    infoJson->insert("duration", duration);
+}
diff --git a/events/roommessageevent.h b/events/roommessageevent.h
index 299b1b19..74e0defb 100644
--- a/events/roommessageevent.h
+++ b/events/roommessageevent.h
@@ -24,122 +24,361 @@
 #include <QtCore/QMimeType>
 #include <QtCore/QSize>
 
-#include <memory>
-
 namespace QMatrixClient
 {
     namespace MessageEventContent
     {
+        /**
+         * A base class for all content types that can be stored
+         * in a RoomMessageEvent
+         *
+         * Each content type class should have a constructor taking
+         * a QJsonObject and override fillJson() with an implementation
+         * that will fill the target QJsonObject with stored values. It is
+         * assumed but not required that a content object can also be created
+         * from plain data. fillJson() should only fill the main JSON object
+         * but not the "info" subobject if it exists for a certain content type;
+         * use \p InfoBase to de/serialize "info" parts with an optional URL
+         * on the top level.
+         */
         class Base
         {
-            Q_GADGET
             public:
-                enum class Type
-                {
-                    Text, Emote, Notice, Image, File, Location, Video, Audio, Unknown
-                };
-
                 virtual ~Base() = default;
 
-                REGISTER_ENUM(Type)
+                QJsonObject toJson() const;
+
+                QMimeType mimeType;
+
+            protected:
+                Base() = default;
+                explicit Base(const QMimeType& type) : mimeType(type) { }
+
+                virtual void fillJson(QJsonObject* o) const = 0;
+        };
+
+        /**
+         * A base class for content types that have an "info" object in their
+         * JSON representation
+         *
+         * These include most multimedia types currently in the CS API spec.
+         * Derived classes should override fillInfoJson() to fill the "info"
+         * subobject, BUT NOT the main JSON object. Most but not all "info"
+         * classes (specifically, those deriving from UrlInfo) should also
+         * have a constructor that accepts two parameters, QUrl and QJsonObject,
+         * in order to load the URL+info part from JSON.
+         */
+        class InfoBase: public Base
+        {
+            public:
+                QJsonObject toInfoJson() const;
+
+            protected:
+                using Base::Base;
+
+                virtual void fillInfoJson(QJsonObject* infoJson) const { }
         };
-        using CType = Base::Type;
     }  // namespace MessageEventContent
-    using MessageEventType = MessageEventContent::CType;
 
+    /**
+     * The event class corresponding to m.room.message events
+     */
     class RoomMessageEvent: public RoomEvent
     {
+            Q_GADGET
         public:
+            enum class MsgType
+            {
+                Text, Emote, Notice, Image, File, Location, Video, Audio, Unknown
+            };
+
+            RoomMessageEvent(const QString& plainBody,
+                             const QString& jsonMsgType,
+                             MessageEventContent::Base* content = nullptr)
+                : RoomEvent(Type::RoomMessage)
+                , _msgtype(jsonMsgType), _plainBody(plainBody), _content(content)
+            { }
+            explicit RoomMessageEvent(const QString& plainBody,
+                                      MsgType msgType = MsgType::Text,
+                                      MessageEventContent::Base* content = nullptr);
             explicit RoomMessageEvent(const QJsonObject& obj);
-            ~RoomMessageEvent();
 
-            MessageEventType msgtype() const                 { return _msgtype; }
-            const QString& plainBody() const                 { return _plainBody; }
-            const MessageEventContent::Base* content() const { return _content; }
+            MsgType msgtype() const;
+            QString rawMsgtype() const       { return _msgtype; }
+            const QString& plainBody() const { return _plainBody; }
+            const MessageEventContent::Base* content() const
+                                             { return _content.data(); }
+            QMimeType mimeType() const;
+
+            QJsonObject toJson() const;
+
+            static constexpr const char* TypeId = "m.room.message";
 
         private:
-            MessageEventType _msgtype;
+            QString _msgtype;
             QString _plainBody;
-            MessageEventContent::Base* _content;
+            QScopedPointer<MessageEventContent::Base> _content;
+
+            REGISTER_ENUM(MsgType)
     };
+    using MessageEventType = RoomMessageEvent::MsgType;
 
     namespace MessageEventContent
     {
         // The below structures fairly follow CS spec 11.2.1.6. The overall
         // set of attributes for each content types is a superset of the spec
-        // but specific aggregation structure is altered.
+        // but specific aggregation structure is altered. See doc comments to
+        // each type for the list of available attributes.
 
+        /**
+         * Rich text content for m.text, m.emote, m.notice
+         *
+         * Available fields: mimeType, body. The body can be either rich text
+         * or plain text, depending on what mimeType specifies.
+         */
         class TextContent: public Base
         {
             public:
+                TextContent(const QString& text, const QString& contentType);
                 explicit TextContent(const QJsonObject& json);
 
-                QMimeType mimeType;
+                void fillJson(QJsonObject* json) const override;
+
                 QString body;
         };
 
-        class FileInfo: public Base
+        /**
+         * Base class for content types that consist of a URL along with
+         * additional information
+         *
+         * All message types except the (hyper)text mentioned above and
+         * m.location fall under this category.
+         */
+        class FileInfo: public InfoBase
         {
             public:
-                FileInfo(QUrl u, const QJsonObject& infoJson,
-                         QString originalFilename = QString());
+                explicit FileInfo(const QUrl& u, int payloadSize = -1,
+                                 const QMimeType& mimeType = {},
+                                 const QString& originalFilename = {});
+                FileInfo(const QUrl& u, const QJsonObject& infoJson,
+                        const QString& originalFilename = {});
 
                 QUrl url;
-                int fileSize;
-                QMimeType mimetype;
+                int payloadSize;
                 QString originalName;
+
+            protected:
+                void fillJson(QJsonObject* json) const override;
+                void fillInfoJson(QJsonObject* infoJson) const override;
         };
 
-        class ImageInfo: public FileInfo
+        /**
+         * A base class for image info types: image, thumbnail, video
+         *
+         * \tparam InfoT base info class; should derive from \p InfoBase
+         */
+        template <class InfoT = FileInfo>
+        class ImageInfo : public InfoT
         {
             public:
-                ImageInfo(QUrl u, const QJsonObject& infoJson);
+                explicit ImageInfo(const QUrl& u, int fileSize = -1,
+                                   QMimeType mimeType = {},
+                                   const QSize& imageSize = {})
+                    : InfoT(u, fileSize, mimeType), imageSize(imageSize)
+                { }
+                ImageInfo(const QUrl& u, const QJsonObject& infoJson,
+                          const QString& originalFilename = {})
+                    : InfoT(u, infoJson, originalFilename)
+                    , imageSize(infoJson["w"].toInt(), infoJson["h"].toInt())
+                { }
+
+                void fillInfoJson(QJsonObject* infoJson) const /* override */
+                {
+                    InfoT::fillInfoJson(infoJson);
+                    infoJson->insert("w", imageSize.width());
+                    infoJson->insert("h", imageSize.height());
+                }
 
                 QSize imageSize;
         };
 
-        template <class ContentInfoT>
-        class ThumbnailedContent: public ContentInfoT
+        /**
+         * A base class for an info type that carries a thumbnail
+         *
+         * This class provides a means to save/load a thumbnail to/from "info"
+         * subobject of the JSON representation of a message; namely,
+         * "info/thumbnail_url" and "info/thumbnail_info" fields are used.
+         *
+         * \tparam InfoT base info class; should derive from \p InfoBase
+         */
+        template <class InfoT = InfoBase>
+        class Thumbnailed : public InfoT
         {
             public:
-                explicit ThumbnailedContent(const QJsonObject& json)
-                    : ContentInfoT(json["url"].toString(), json["info"].toObject())
-                    , thumbnail(json["thumbnail_url"].toString(),
-                                json["thumbnail_info"].toObject())
+                template <typename... ArgTs>
+                explicit Thumbnailed(const ImageInfo<>& thumbnail,
+                                     ArgTs&&... infoArgs)
+                    : InfoT(std::forward<ArgTs>(infoArgs)...)
+                    , thumbnail(thumbnail)
                 { }
 
-                ImageInfo thumbnail;
+                explicit Thumbnailed(const QJsonObject& infoJson)
+                    : thumbnail(infoJson["thumbnail_url"].toString(),
+                                infoJson["thumbnail_info"].toObject())
+                { }
+
+                Thumbnailed(const QUrl& u, const QJsonObject& infoJson,
+                            const QString& originalFilename = {})
+                    : InfoT(u, infoJson, originalFilename)
+                    , thumbnail(infoJson["thumbnail_url"].toString(),
+                                infoJson["thumbnail_info"].toObject())
+                { }
+
+                void fillInfoJson(QJsonObject* infoJson) const /* override */
+                {
+                    InfoT::fillInfoJson(infoJson);
+                    infoJson->insert("thumbnail_url", thumbnail.url.toString());
+                    infoJson->insert("thumbnail_info", thumbnail.toInfoJson());
+                }
+
+                ImageInfo<> thumbnail;
+        };
+
+        /**
+         * One more facility base class for content types that have a URL and
+         * additional info
+         *
+         * The assumed layout for types enabled by a combination of UrlInfo and
+         * UrlWith<> is the following: "url" and, optionally, "filename" in the
+         * top-level JSON and the rest of information inside the "info" subobject.
+         *
+         * \tparam InfoT base info class; should derive from \p UrlInfo or
+         * provide a constructor with a compatible signature
+         */
+        template <class InfoT> // InfoT : public FileInfo
+        class UrlWith : public InfoT
+        {
+            public:
+                using InfoT::InfoT;
+                explicit UrlWith(const QJsonObject& json)
+                    : InfoT(json["url"].toString(), json["info"].toObject(),
+                            json["filename"].toString())
+                { }
         };
 
-        using ImageContent = ThumbnailedContent<ImageInfo>;
-        using FileContent = ThumbnailedContent<FileInfo>;
+        /**
+         * Content class for m.image
+         *
+         * Available fields:
+         * - corresponding to the top-level JSON:
+         *   - url
+         *   - filename (extension to the spec)
+         * - corresponding to the "info" subobject:
+         *   - payloadSize ("size" in JSON)
+         *   - mimeType ("mimetype" in JSON)
+         *   - imageSize (QSize for a combination of "h" and "w" in JSON)
+         *   - thumbnail.url ("thumbnail_url" in JSON)
+         * - corresponding to the "info/thumbnail_info" subobject: contents of
+         *   thumbnail field, in the same vein as for the main image:
+         *   - payloadSize
+         *   - mimeType
+         *   - imageSize
+         */
+        using ImageContent = UrlWith<Thumbnailed<ImageInfo<>>>;
 
-        class LocationContent: public Base
+        /**
+         * Content class for m.file
+         *
+         * Available fields:
+         * - corresponding to the top-level JSON:
+         *   - url
+         *   - filename
+         * - corresponding to the "info" subobject:
+         *   - payloadSize ("size" in JSON)
+         *   - mimeType ("mimetype" in JSON)
+         *   - thumbnail.url ("thumbnail_url" in JSON)
+         * - corresponding to the "info/thumbnail_info" subobject:
+         *   - thumbnail.payloadSize
+         *   - thumbnail.mimeType
+         *   - thumbnail.imageSize (QSize for "h" and "w" in JSON)
+         */
+        using FileContent = UrlWith<Thumbnailed<FileInfo>>;
+
+        /**
+         * Content class for m.location
+         *
+         * Available fields:
+         * - corresponding to the top-level JSON:
+         *   - geoUri ("geo_uri" in JSON)
+         * - corresponding to the "info" subobject:
+         *   - thumbnail.url ("thumbnail_url" in JSON)
+         * - corresponding to the "info/thumbnail_info" subobject:
+         *   - thumbnail.payloadSize
+         *   - thumbnail.mimeType
+         *   - thumbnail.imageSize
+         */
+        class LocationContent: public Thumbnailed<>
         {
             public:
+                LocationContent(const QString& geoUri,
+                                const ImageInfo<>& thumbnail);
                 explicit LocationContent(const QJsonObject& json);
 
+                void fillJson(QJsonObject* o) const override;
+
                 QString geoUri;
-                ImageInfo thumbnail;
         };
 
-        class VideoInfo: public FileInfo
+        /**
+         * A base class for "playable" info types: audio and video
+         */
+        class PlayableInfo : public FileInfo
         {
             public:
-                VideoInfo(QUrl u, const QJsonObject& infoJson);
+                explicit PlayableInfo(const QUrl& u, int fileSize,
+                                      const QMimeType& mimeType, int duration,
+                                      const QString& originalFilename = {});
+                PlayableInfo(const QUrl& u, const QJsonObject& infoJson,
+                             const QString& originalFilename = {});
+
+                void fillInfoJson(QJsonObject* infoJson) const override;
 
                 int duration;
-                QSize imageSize;
         };
-        using VideoContent = ThumbnailedContent<VideoInfo>;
 
-        class AudioInfo: public FileInfo
-        {
-            public:
-                AudioInfo(QUrl u, const QJsonObject& infoJson);
+        /**
+         * Content class for m.video
+         *
+         * Available fields:
+         * - corresponding to the top-level JSON:
+         *   - url
+         *   - filename (extension to the CS API spec)
+         * - corresponding to the "info" subobject:
+         *   - payloadSize ("size" in JSON)
+         *   - mimeType ("mimetype" in JSON)
+         *   - duration
+         *   - imageSize (QSize for a combination of "h" and "w" in JSON)
+         *   - thumbnail.url ("thumbnail_url" in JSON)
+         * - corresponding to the "info/thumbnail_info" subobject: contents of
+         *   thumbnail field, in the same vein as for "info":
+         *   - payloadSize
+         *   - mimeType
+         *   - imageSize
+         */
+        using VideoContent = UrlWith<Thumbnailed<ImageInfo<PlayableInfo>>>;
 
-                int duration;
-        };
-        using AudioContent = ThumbnailedContent<AudioInfo>;
+        /**
+         * Content class for m.audio
+         *
+         * Available fields:
+         * - corresponding to the top-level JSON:
+         *   - url
+         *   - filename (extension to the CS API spec)
+         * - corresponding to the "info" subobject:
+         *   - payloadSize ("size" in JSON)
+         *   - mimeType ("mimetype" in JSON)
+         *   - duration
+         */
+        using AudioContent = UrlWith<PlayableInfo>;
     }  // namespace MessageEventContent
 }  // namespace QMatrixClient