Fix AI messages not being taken into account when saving a draft in some cases

The bug would happen in this situation:

* When generating a message with AI, as AiPropositionFragment is navigated to, NewMessageFragment would export his body in the `subjectAndBodyChannel`.
* When inserting the AI proposition, we would navigate back to NewMessageFragment.
* When we want to now save or send the draft we will receive values through the channel but the channel's value was never consumed and the previous body is still there even though we want to wait for the new body.

This commit introduces a `channelExpirationIdTarget` that will let us know if a message is too old and needs to be discarded while we wait for the correct message to get through the channel

Author: LunarX

app/src/main/java/com/infomaniak/mail/ui/newMessage/NewMessageFragment.kt

@@ -582,6 +582,11 @@ class NewMessageFragment : Fragment() {
         }
     }
 
+    override fun onStart() {
+        super.onStart()
+        newMessageViewModel.discardOldBodyAndSubjectChannelMessages()
+    }
+
     override fun onStop() {
         /**
          * When the Activity is being stopped, we save the Draft.

app/src/main/java/com/infomaniak/mail/ui/newMessage/NewMessageViewModel.kt

@@ -116,8 +116,13 @@ class NewMessageViewModel @Inject constructor(
 
     val editorBodyLoader = SingleLiveEvent<BodyContentPayload>()
 
-    private val _subjectAndBodyChannel: Channel<Pair<String, String>> = Channel(capacity = CONFLATED)
-    private val subjectAndBodyChannel: ReceiveChannel<Pair<String, String>> = _subjectAndBodyChannel
+    // 1. Navigating to AiPropositionFragment causes NewMessageFragment to export its body to `subjectAndBodyChannel`.
+    // 2. Inserting the AI proposition navigates back to NewMessageFragment.
+    // 3. When saving or sending the draft now, the channel still holds the previous body as it wasn't consumed.
+    // channelExpirationIdTarget lets us identify and discard outdated messages, ensuring the correct message is processed.
+    private var channelExpirationIdTarget = 0
+    private val _subjectAndBodyChannel: Channel<Triple<String, String, Int>> = Channel(capacity = CONFLATED)
+    private val subjectAndBodyChannel: ReceiveChannel<Triple<String, String, Int>> = _subjectAndBodyChannel
     private var subjectAndBodyJob: Job? = null
 
     var isAutoCompletionOpened = false
@@ -754,14 +759,28 @@ class NewMessageViewModel @Inject constructor(
 
     fun saveBodyAndSubject(subject: String, html: String) {
         globalCoroutineScope.launch {
-            _subjectAndBodyChannel.send(subject to html)
+            _subjectAndBodyChannel.send(Triple(subject, html, channelExpirationIdTarget))
         }
     }
 
+    fun discardOldBodyAndSubjectChannelMessages() {
+        channelExpirationIdTarget++
+    }
+
     fun waitForBodyAndSubjectToExecuteDraftAction(draftSaveConfiguration: DraftSaveConfiguration) {
         subjectAndBodyJob?.cancel()
         subjectAndBodyJob = globalCoroutineScope.launch {
-            val (subject, body) = subjectAndBodyChannel.receive()
+            val subject: String
+            val body: String
+            while (true) {
+                val (receivedSubject, receivedBody, expirationId) = subjectAndBodyChannel.receive()
+                if (expirationId == channelExpirationIdTarget) {
+                    subject = receivedSubject
+                    body = receivedBody
+                    break
+                }
+            }
+
             draftSaveConfiguration.addSubjectAndBody(subject, body)
             executeDraftAction(draftSaveConfiguration)
         }