move duck.ai input screen return button, improve input string management (#6308)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/1208671518894266/task/1210659642047207?focus=true

### Description
- Moves the return button in the Duck.ai input screen to the side of the
submit button.
- Fixes an issue where the submit button was visible when only new lines
were in the input field.
- Fixes an issue where return key didn't replace selected text.
- Fixes voice input button's background color.

### Steps to test this PR
- [ ] Verify that even if voice input is enabled, return key is next to
submit button.
- [ ] Open the input screen, clear text, add new lines. Verify the
submit button is not visible.
- [ ] Input some text, select all or portion of it, click the return key
and verify that the whole selection is replaced.

Author: LukasPaczos

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/ui/DuckChatOmnibarLayout.kt

@@ -85,7 +85,7 @@ class DuckChatOmnibarLayout @JvmOverloads constructor(
     var onSendMessageAvailable: ((Boolean) -> Unit)? = null
         set(value) {
             field = value
-            value?.invoke(!duckChatInput.text.isNullOrEmpty())
+            value?.invoke(duckChatInput.text.getTextToSubmit() != null)
         }
 
     @IdRes
@@ -139,9 +139,9 @@ class DuckChatOmnibarLayout @JvmOverloads constructor(
         }
 
         doOnTextChanged { text, _, _, _ ->
+            onSendMessageAvailable?.invoke(duckChatInput.text.getTextToSubmit() != null)
             val isNullOrEmpty = text.isNullOrEmpty()
             fade(duckChatClearText, !isNullOrEmpty)
-            onSendMessageAvailable?.invoke(!isNullOrEmpty)
 
             if (isNullOrEmpty && duckChatInput.minLines > 1) {
                 duckChatInput.post {
@@ -201,12 +201,13 @@ class DuckChatOmnibarLayout @JvmOverloads constructor(
     }
 
     fun submitMessage(message: String? = null) {
-        val text = message?.also(duckChatInput::setText) ?: duckChatInput.text.toString().trim()
-        if (text.isNotBlank()) {
+        val text = message?.also(duckChatInput::setText) ?: duckChatInput.text
+        val textToSubmit = text.getTextToSubmit()?.toString()
+        if (textToSubmit != null) {
             if (duckChatTabLayout.selectedTabPosition == 0) {
-                onSearchSent?.invoke(text)
+                onSearchSent?.invoke(textToSubmit)
             } else {
-                onDuckChatSent?.invoke(text)
+                onDuckChatSent?.invoke(textToSubmit)
             }
             duckChatInput.clearFocus()
         }
@@ -291,10 +292,16 @@ class DuckChatOmnibarLayout @JvmOverloads constructor(
 
     fun printNewLine() {
         val currentText = duckChatInput.text.toString()
-        val currentSelection = duckChatInput.selectionStart
-        val newText = currentText.substring(0, currentSelection) + "\n" + currentText.substring(currentSelection)
+        val selectionStart = duckChatInput.selectionStart
+        val selectionEnd = duckChatInput.selectionEnd
+        val newText = currentText.substring(0, selectionStart) + "\n" + currentText.substring(selectionEnd)
         duckChatInput.setText(newText)
-        duckChatInput.setSelection(currentSelection + 1)
+        duckChatInput.setSelection(selectionStart + 1)
+    }
+
+    private fun CharSequence.getTextToSubmit(): CharSequence? {
+        val text = this.trim()
+        return text.ifBlank { null }
     }
 
     companion object {

duckchat/duckchat-impl/src/main/res/layout/fragment_search_interstitial.xml

@@ -63,19 +63,19 @@
         app:layout_constraintEnd_toEndOf="parent"/>
 
     <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
-        android:id="@+id/actionVoice"
+        android:id="@+id/actionNewLine"
         android:layout_width="40dp"
         android:layout_height="40dp"
         android:minWidth="0dp"
         android:minHeight="0dp"
-        android:backgroundTint="?attr/daxColorSurface"
+        android:backgroundTint="?attr/daxColorWindow"
         android:layout_marginBottom="@dimen/keyline_3"
         android:layout_marginEnd="@dimen/keyline_3"
         android:importantForAccessibility="no"
         android:text="&#8203;"
         android:textColor="@android:color/transparent"
-        android:visibility="gone"
-        app:icon="@drawable/ic_microphone_24"
+        android:visibility="visible"
+        app:icon="@drawable/ic_return_24"
         app:iconTint="?attr/daxColorPrimaryIcon"
         app:iconPadding="0dp"
         app:iconGravity="textStart"
@@ -84,7 +84,7 @@
         app:layout_constraintEnd_toStartOf="@id/actionSend"/>
 
     <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
-        android:id="@+id/actionNewLine"
+        android:id="@+id/actionVoice"
         android:layout_width="40dp"
         android:layout_height="40dp"
         android:minWidth="0dp"
@@ -95,13 +95,13 @@
         android:importantForAccessibility="no"
         android:text="&#8203;"
         android:textColor="@android:color/transparent"
-        android:visibility="visible"
-        app:icon="@drawable/ic_return_24"
+        android:visibility="gone"
+        app:icon="@drawable/ic_microphone_24"
         app:iconTint="?attr/daxColorPrimaryIcon"
         app:iconPadding="0dp"
         app:iconGravity="textStart"
         app:rippleColor="?attr/daxColorRipple"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toStartOf="@id/actionVoice"/>
+        app:layout_constraintEnd_toStartOf="@id/actionNewLine"/>
 
 </androidx.constraintlayout.widget.ConstraintLayout>