fix: Correctly handle setting / editing a status' language (#780)

Previous code set the initial status text, and then set up the callbacks
which meant that the status' length was initially 0, even when editing a
status.

This meant that, e.g., editing a status to change its language would
erroneously report the status body was empty. It also meant that editing
a status and changing just the language would not prompt to save or
discard the changes if moving back.

Fix this.

First, only set the status content after the callbacks that compute the
status length.

Second, provide a function that sets the status' language, and update
the close confirmation state when the language changes. Modify isDirty()
to compare the original and current language when determining if the
status is dirty.

Fixes #701

app/src/main/java/app/pachli/components/compose/ComposeActivity.kt

@@ -413,6 +413,13 @@ class ComposeActivity :
         )
         binding.composeEditField.setTokenizer(ComposeTokenizer())
 
+        val mentionColour = binding.composeEditField.linkTextColors.defaultColor
+        highlightSpans(binding.composeEditField.text, mentionColour)
+        binding.composeEditField.doAfterTextChanged { editable ->
+            highlightSpans(editable!!, mentionColour)
+            viewModel.onContentChanged(editable)
+        }
+
         binding.composeEditField.setText(startingText)
 
         when (composeOptions?.initialCursorPosition ?: InitialCursorPosition.END) {
@@ -422,13 +429,6 @@ class ComposeActivity :
             )
         }
 
-        val mentionColour = binding.composeEditField.linkTextColors.defaultColor
-        highlightSpans(binding.composeEditField.text, mentionColour)
-        binding.composeEditField.doAfterTextChanged { editable ->
-            highlightSpans(editable!!, mentionColour)
-            viewModel.onContentChanged(editable)
-        }
-
         // work around Android platform bug -> https://issuetracker.google.com/issues/67102093
         if (Build.VERSION.SDK_INT == Build.VERSION_CODES.O ||
             Build.VERSION.SDK_INT == Build.VERSION_CODES.O_MR1
@@ -594,7 +594,7 @@ class ComposeActivity :
     private fun setupLanguageSpinner(initialLanguages: List<String>) {
         binding.composePostLanguageButton.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
             override fun onItemSelected(parent: AdapterView<*>, view: View?, position: Int, id: Long) {
-                viewModel.postLanguage = (parent.adapter.getItem(position) as Locale).modernLanguageCode
+                viewModel.onLanguageChanged((parent.adapter.getItem(position) as Locale).modernLanguageCode)
             }
 
             override fun onNothingSelected(parent: AdapterView<*>) {
@@ -927,7 +927,7 @@ class ComposeActivity :
 
     @VisibleForTesting
     val selectedLanguage: String?
-        get() = viewModel.postLanguage
+        get() = viewModel.language
 
     private fun updateVisibleCharactersLeft(textLength: Int) {
         val remainingLength = maximumTootCharacters - textLength

app/src/main/java/app/pachli/components/compose/ComposeViewModel.kt

@@ -89,7 +89,11 @@ class ComposeViewModel @Inject constructor(
     /** The initial content warning for this status, before any edits */
     private var initialContentWarning: String = ""
 
-    internal var postLanguage: String? = null
+    /** The initial language for this status, before any changes */
+    private var initialLanguage: String? = null
+
+    /** The current language for this status. */
+    internal var language: String? = null
 
     /** If editing a draft then the ID of the draft, otherwise 0 */
     private var draftId: Int = 0
@@ -279,6 +283,12 @@ class ComposeViewModel @Inject constructor(
         _statusVisibility.value = newVisibility
     }
 
+    /** Call this to change the status' language */
+    fun onLanguageChanged(newLanguage: String) {
+        language = newLanguage
+        updateCloseConfirmation()
+    }
+
     @VisibleForTesting
     fun updateStatusLength() {
         _statusLength.value = statusLength(content, effectiveContentWarning, instanceInfo.value.charactersReservedPerUrl)
@@ -317,8 +327,9 @@ class ComposeViewModel @Inject constructor(
         val contentWarningChanged = effectiveContentWarning != initialContentWarning
         val mediaChanged = media.value.isNotEmpty()
         val pollChanged = poll.value != null
+        val languageChanged = initialLanguage != language
 
-        return modifiedInitialState || contentChanged || contentWarningChanged || mediaChanged || pollChanged || scheduledTimeChanged
+        return modifiedInitialState || contentChanged || contentWarningChanged || mediaChanged || pollChanged || languageChanged || scheduledTimeChanged
     }
 
     private fun isEmpty(content: CharSequence, contentWarning: CharSequence): Boolean {
@@ -375,7 +386,7 @@ class ComposeViewModel @Inject constructor(
             failedToSend = false,
             failedToSendAlert = false,
             scheduledAt = scheduledAt.value,
-            language = postLanguage,
+            language = language,
             statusId = originalStatusId,
         )
     }
@@ -418,7 +429,7 @@ class ComposeViewModel @Inject constructor(
             draftId = draftId,
             idempotencyKey = randomAlphanumericString(16),
             retries = 0,
-            language = postLanguage,
+            language = language,
             statusId = originalStatusId,
         )
 
@@ -538,7 +549,8 @@ class ComposeViewModel @Inject constructor(
         scheduledTootId = composeOptions?.scheduledTootId
         originalStatusId = composeOptions?.statusId
         initialContent = composeOptions?.content ?: ""
-        postLanguage = composeOptions?.language
+        initialLanguage = composeOptions?.language
+        language = initialLanguage
 
         val tootVisibility = composeOptions?.visibility ?: Status.Visibility.UNKNOWN
         if (tootVisibility != Status.Visibility.UNKNOWN) {