[SMS App] Basic plain-text MMS support

## Summary

Desktop companion to https://invent.kde.org/kde/kdeconnect-android/merge_requests/78

Give desktop SMS app a basic understanding of the MMSes coming from Android:
- Show a fake body if we get an attachment we can't display (for now, any attachment)
- Display a fake contact header for multi-target messages since Android does not yet export multi-target address information
- Disable attempting to reply to multi-target messages

BUG: 398889

## Test Plan
### Before:
MMS messages were silently dropped, meaning:
 - Group MMS conversations were not visible
 - Single-target conversations with the most-recent message an MMS were not visible

### After:
 - Install https://invent.kde.org/kde/kdeconnect-android/merge_requests/78
 - Multi-target conversations are displayed (kind of ugly, since they have no contact information
 - Single-target conversations which end with an MMS are displayed
 - Plain-text MMS is displayed nicely
 - MMS attachments don't show
   - MMS which are only an attachment with no body are displayed with a dummy body

interfaces/conversationmessage.h

@@ -47,6 +47,7 @@ public:
      */
     enum Events {
         EventTextMessage = 0x1, // This message has a body field which contains pure, human-readable text
+        EventMultiTarget = 0x2, // This is a multitarget (group) message which has an "addresses" field which is a list of participants in the group
     };
 
     /**
@@ -77,6 +78,7 @@ public:
     QVariantMap toVariant() const;
 
     bool containsTextBody() const { return (eventField() & ConversationMessage::EventTextMessage); }
+    bool isMultitarget() const { return (eventField() & ConversationMessage::EventMultiTarget); }
 
 protected:
     /**

plugins/sms/smsplugin.cpp

@@ -107,8 +107,8 @@ bool SmsPlugin::handleBatchMessages(const NetworkPacket& np)
         ConversationMessage message(body.toMap());
         if (message.containsTextBody()) {
             forwardToTelepathy(message);
-        messagesList.append(message);
         }
+        messagesList.append(message);
     }
 
     m_conversationInterface->addMessages(messagesList);

smsapp/conversationlistmodel.cpp

@@ -23,6 +23,9 @@
 
 #include <QString>
 #include <QLoggingCategory>
+
+#include <KLocalizedString>
+
 #include "interfaces/conversationmessage.h"
 #include "interfaces/dbusinterfaces.h"
 #include "smshelper.h"
@@ -42,6 +45,7 @@ ConversationListModel::ConversationListModel(QObject* parent)
     roles.insert(AddressRole, "address");
     roles.insert(PersonUriRole, "personUri");
     roles.insert(ConversationIdRole, "conversationId");
+    roles.insert(MultitargetRole, "isMultitarget");
     roles.insert(DateRole, "date");
     setItemRoleNames(roles);
 
@@ -159,6 +163,14 @@ void ConversationListModel::createRowFromMessage(const QVariantMap& msg)
         item->setData(message.threadID(), ConversationIdRole);
     }
 
+    // TODO: Upgrade to support other kinds of media
+    // Get the body that we should display
+    QString displayBody = message.containsTextBody() ? message.body() : i18n("(Unsupported Message Type)");
+
+    // TODO: Upgrade with multitarget support
+    if (message.isMultitarget()) {
+        item->setText(i18n("(Multitarget Message)"));
+    }
     // Update the message if the data is newer
     // This will be true if a conversation receives a new message, but false when the user
     // does something to trigger past conversation history loading
@@ -168,8 +180,9 @@ void ConversationListModel::createRowFromMessage(const QVariantMap& msg)
         // If there was no old data or incoming data is newer, update the record
         item->setData(message.address(), AddressRole);
         item->setData(message.type() == ConversationMessage::MessageTypeSent, FromMeRole);
-        item->setData(message.body(), Qt::ToolTipRole);
+        item->setData(displayBody, Qt::ToolTipRole);
         item->setData(message.date(), DateRole);
+        item->setData(message.isMultitarget(), MultitargetRole);
     }
 
     if (toadd)

smsapp/conversationlistmodel.h

@@ -83,6 +83,7 @@ public:
         AddressRole,
         ConversationIdRole,
         DateRole,
+        MultitargetRole, // Indicate that this conversation is multitarget
     };
     Q_ENUM(Roles)
 

smsapp/conversationmodel.cpp

@@ -21,6 +21,9 @@
 
 #include "conversationmodel.h"
 #include <QLoggingCategory>
+
+#include <KLocalizedString>
+
 #include "interfaces/conversationmessage.h"
 
 Q_LOGGING_CATEGORY(KDECONNECT_SMS_CONVERSATION_MODEL, "kdeconnect.sms.conversation")
@@ -110,8 +113,12 @@ void ConversationModel::createRowFromMessage(const QVariantMap& msg, int pos)
         return;
     }
 
+    // TODO: Upgrade to support other kinds of media
+    // Get the body that we should display
+    QString displayBody = message.containsTextBody() ? message.body() : i18n("(Unsupported Message Type)");
+
     auto item = new QStandardItem;
-    item->setText(message.body());
+    item->setText(displayBody);
     item->setData(message.type() == ConversationMessage::MessageTypeSent, FromMeRole);
     item->setData(message.date(), DateRole);
     insertRow(pos, item);

smsapp/qml/ConversationDisplay.qml

@@ -40,6 +40,7 @@ Kirigami.ScrollablePage
     property string deviceId
 //     property QtObject device
     property string conversationId
+    property bool isMultitarget
     property string initialMessage
 
     property string phoneNumber
@@ -127,7 +128,7 @@ Kirigami.ScrollablePage
 
     footer: Pane {
         id: sendingArea
-        enabled: page.deviceConnected
+        enabled: page.deviceConnected && !page.isMultitarget
         layer.enabled: sendingArea.enabled
         layer.effect: DropShadow {
             verticalOffset: 1
@@ -148,7 +149,7 @@ Kirigami.ScrollablePage
             TextArea {
                 id: messageField
                 Layout.fillWidth: true
-                placeholderText: i18n("Compose message")
+                placeholderText: page.isMultitarget ? i18n("Replying to multitarget messages is not supported") : i18n("Compose message")
                 wrapMode: TextArea.Wrap
                 topPadding: Kirigami.Units.gridUnit * 0.5
                 bottomPadding: topPadding

smsapp/qml/ConversationList.qml

@@ -149,6 +149,7 @@ Kirigami.ScrollablePage
                                                        personUri: model.personUri,
                                                        phoneNumber: address,
                                                        conversationId: model.conversationId,
+                                                       isMultitarget: isMultitarget,
                                                        initialMessage: page.initialMessage,
                                                        device: device})
                 initialMessage = ""