Implements attachments display in transcript

src/models/attachment.vala

@@ -0,0 +1,74 @@
+public class AttributionInfo : Object {
+    // Picture width
+    public int64 width;
+    
+    // Picture height
+    public int64 height;
+
+    public static AttributionInfo from_variant(Variant variant) {
+        var attribution_info = new AttributionInfo();
+
+        VariantDict dict = new VariantDict(variant);
+        attribution_info.width = dict.lookup_value("width", VariantType.INT32)?.get_int32() ?? 0;
+        attribution_info.height = dict.lookup_value("height", VariantType.INT32)?.get_int32() ?? 0;
+
+        return attribution_info;
+    }
+}
+
+public class AttachmentMetadata : Object {
+    public AttributionInfo? attribution_info = null;
+
+    public static AttachmentMetadata from_variant(Variant variant) {
+        var metadata = new AttachmentMetadata();
+        
+        VariantDict dict = new VariantDict(variant);
+        metadata.attribution_info = AttributionInfo.from_variant(dict.lookup_value("attribution_info", VariantType.DICTIONARY));
+
+        return metadata;
+    }
+}
+
+public class Attachment : Object {
+    public string guid;
+    public string path;
+    public string preview_path;
+    public bool downloaded;
+    public bool preview_downloaded;
+    public AttachmentMetadata? metadata;
+
+    public Attachment(string guid, AttachmentMetadata? metadata) {
+        this.guid = guid;
+        this.metadata = metadata;
+    }
+
+    public Attachment.from_variant(Variant variant) {
+        VariantIter iter;
+        variant.get("a{sv}", out iter);
+        
+        string key;
+        Variant val;
+        while (iter.next("{sv}", out key, out val)) {
+            switch (key) {
+                case "guid":
+                    this.guid = val.get_string();
+                    break;
+                case "path":
+                    this.path = val.get_string();
+                    break;
+                case "preview_path":
+                    this.preview_path = val.get_string();
+                    break;
+                case "downloaded":
+                    this.downloaded = val.get_boolean();
+                    break;
+                case "preview_downloaded":
+                    this.preview_downloaded = val.get_boolean();
+                    break;
+                case "metadata":
+                    this.metadata = AttachmentMetadata.from_variant(val);
+                    break;
+            }
+        }
+    }
+}