[Technical] Open stickers using the thumbnail url if the main url is empty (#2157)

* Explicitely use the thumbnail url to show stickers if the content's url is an empty string

---------

Signed-off-by: Marco Antonio Alvarez <surakin@gmail.com>

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesFlowNode.kt

@@ -255,17 +255,21 @@ class MessagesFlowNode @AssistedInject constructor(
                 overlay.show(navTarget)
             }
             is TimelineItemStickerContent -> {
-                val navTarget = NavTarget.MediaViewer(
-                    mediaInfo = MediaInfo(
-                        name = event.content.body,
-                        mimeType = event.content.mimeType,
-                        formattedFileSize = event.content.formattedFileSize,
-                        fileExtension = event.content.fileExtension
-                    ),
-                    mediaSource = event.content.mediaSource,
-                    thumbnailSource = event.content.thumbnailSource,
-                )
-                overlay.show(navTarget)
+                /* Sticker may have an empty url and no thumbnail
+                   if encrypted on certain bridges */
+                if (event.content.preferredMediaSource != null) {
+                    val navTarget = NavTarget.MediaViewer(
+                        mediaInfo = MediaInfo(
+                            name = event.content.body,
+                            mimeType = event.content.mimeType,
+                            formattedFileSize = event.content.formattedFileSize,
+                            fileExtension = event.content.fileExtension
+                        ),
+                        mediaSource = event.content.preferredMediaSource,
+                        thumbnailSource = event.content.thumbnailSource,
+                    )
+                    overlay.show(navTarget)
+                }
             }
             is TimelineItemVideoContent -> {
                 val navTarget = NavTarget.MediaViewer(

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/event/TimelineItemStickerContent.kt

@@ -16,7 +16,6 @@
 
 package io.element.android.features.messages.impl.timeline.model.event
 
-import io.element.android.libraries.core.mimetype.MimeTypes
 import io.element.android.libraries.matrix.api.media.MediaSource
 
 data class TimelineItemStickerContent(
@@ -33,9 +32,7 @@ data class TimelineItemStickerContent(
 ) : TimelineItemEventContent {
     override val type: String = "TimelineItemStickerContent"
 
-    val preferredMediaSource = if (mimeType == MimeTypes.Gif) {
-        mediaSource
-    } else {
-        thumbnailSource ?: mediaSource
-    }
+    /* Stickers are supposed to be small images so
+       we allow using the mediaSource (unless the url is empty) */
+    val preferredMediaSource = if (mediaSource.url.isEmpty()) thumbnailSource else mediaSource
 }