Add json methods to PreviousMessage

lib/pangea/choreographer/controllers/choreographer.dart

@@ -71,28 +71,36 @@ class Choreographer {
 
   List<PreviousMessage> prevMessages() {
     const int howFarBack = 5;
-    final List<Event> events = chatController.timeline?.events ?? [];
+    final List<Event> events = chatController.timeline?.events
+            .where(
+              (e) =>
+                  e.messageType == MessageTypes.Text ||
+                  e.messageType == MessageTypes.Audio,
+            )
+            .toList() ??
+        [];
+    // Sort from most recent to least
+    events.sort(
+      (a, b) => b.originServerTs.compareTo(a.originServerTs),
+    );
     final List<PreviousMessage> messages = [];
     for (final Event event in events) {
-      if (event.messageType == MessageTypes.Text ||
-          event.messageType == MessageTypes.Audio) {
-        final Map<String, Object?>? content =
-            (event.messageType == MessageTypes.Text)
-                ? event.content
-                : (event as PangeaMessageEvent)
-                    .getSpeechToTextLocalOnly(l1LangCode, l2LangCode)
-                    ?.toJson();
-        if (content != null) {
-          messages.add(
-            PreviousMessage(
-              event.content,
-              event.senderId,
-              event.originServerTs,
-            ),
-          );
-          if (messages.length >= howFarBack) {
-            return messages;
-          }
+      final Map<String, Object?>? content =
+          (event.messageType == MessageTypes.Text)
+              ? event.content
+              : (event as PangeaMessageEvent)
+                  .getSpeechToTextLocalOnly(l1LangCode, l2LangCode)
+                  ?.toJson();
+      if (content != null) {
+        messages.add(
+          PreviousMessage(
+            event.content,
+            event.senderId,
+            event.originServerTs,
+          ),
+        );
+        if (messages.length >= howFarBack) {
+          return messages;
         }
       }
     }

lib/pangea/constants/model_keys.dart

@@ -70,6 +70,9 @@ class ModelKey {
   static const String enableIGC = "enable_igc";
   static const String enableIT = "enable_it";
   static const String prevMessages = "prev_messages";
+  static const String prevContent = "prev_content";
+  static const String prevSender = "prev_sender";
+  static const String prevTimestamp = "prev_timestamp";
 
   static const String originalSent = "original_sent";
   static const String originalWritten = "original_written";

lib/pangea/repo/igc_repo.dart

@@ -95,18 +95,33 @@ class IgcRepo {
   }
 }
 
-/// Previous text/audio messages sent in chat
+/// Previous text/audio message sent in chat
 /// Contain message content, sender, and timestamp
 class PreviousMessage {
   Map<String, Object?> content;
   String sender;
   DateTime timestamp;
 
-  PreviousMessage(
-    this.content,
-    this.sender,
-    this.timestamp,
-  );
+  PreviousMessage({
+    required this.content,
+    required this.sender,
+    required this.timestamp,
+  });
+
+  factory PreviousMessage.fromJson(Map<String, dynamic> json) =>
+      PreviousMessage(
+        content: jsonDecode(json[ModelKey.prevContent]) ?? <String, Object?>{},
+        sender: json[ModelKey.prevSender] ?? "",
+        timestamp: json[ModelKey.prevTimestamp] == null
+            ? DateTime.now()
+            : DateTime.parse(json[ModelKey.prevTimestamp]),
+      );
+
+  Map<String, dynamic> toJson() => {
+        ModelKey.prevContent: jsonEncode(content),
+        ModelKey.prevSender: sender,
+        ModelKey.prevTimestamp: timestamp.toIso8601String(),
+      };
 }
 
 class IGCRequestBody {
@@ -132,6 +147,7 @@ class IGCRequestBody {
         ModelKey.userL2: userL2,
         "enable_it": enableIT,
         "enable_igc": enableIGC,
-        "prev_messages": prevMessages,
+        ModelKey.prevMessages:
+            jsonEncode(prevMessages.map((x) => x.toJson()).toList()),
       };
 }