For #5047 - Addresses nits

- Changes MainScope to viewLifecycleScope
- Fixes string name/comment to better describe what it is
- Adds disabled state to the add button

app/src/main/java/org/mozilla/fenix/shortcut/CreateShortcutFragment.kt

@@ -8,9 +8,10 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import androidx.core.widget.addTextChangedListener
 import androidx.fragment.app.DialogFragment
+import androidx.lifecycle.lifecycleScope
 import kotlinx.android.synthetic.main.fragment_create_shortcut.*
-import kotlinx.coroutines.MainScope
 import kotlinx.coroutines.launch
 import org.mozilla.fenix.R
 import org.mozilla.fenix.ext.loadIntoView
@@ -30,16 +31,37 @@ class CreateShortcutFragment : DialogFragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        val session = requireComponents.core.sessionManager.selectedSession!!
-        requireComponents.core.icons.loadIntoView(favicon_image, session.url)
-        shortcut_text.setText(session.title)
 
-        cancel_button.setOnClickListener { dismiss() }
-        add_button.setOnClickListener {
-            val text = shortcut_text.text.toString()
-            MainScope().launch {
-                requireComponents.useCases.webAppUseCases.addToHomescreen(text)
-            }.invokeOnCompletion { dismiss() }
+        val session = requireComponents.core.sessionManager.selectedSession
+
+        if (session == null) {
+            dismiss()
+        } else {
+            requireComponents.core.icons.loadIntoView(favicon_image, session.url)
+
+            cancel_button.setOnClickListener { dismiss() }
+            add_button.setOnClickListener {
+                val text = shortcut_text.text.toString()
+                viewLifecycleOwner.lifecycleScope.launch {
+                    requireComponents.useCases.webAppUseCases.addToHomescreen(text)
+                }.invokeOnCompletion { dismiss() }
+            }
+
+            shortcut_text.addTextChangedListener {
+                updateAddButtonEnabledState()
+            }
+
+            shortcut_text.setText(session.title)
         }
     }
+
+    private fun updateAddButtonEnabledState() {
+        add_button.isEnabled = shortcut_text.text.isNotEmpty()
+        add_button.alpha = if (shortcut_text.text.isNotEmpty()) ENABLED_ALPHA else DISABLED_ALPHA
+    }
+
+    companion object {
+        private const val ENABLED_ALPHA = 1.0f
+        private const val DISABLED_ALPHA = 0.4f
+    }
 }

app/src/main/res/layout/fragment_create_shortcut.xml

@@ -45,7 +45,7 @@
             android:id="@+id/shortcut_text"
             android:inputType="text"
             android:importantForAutofill="no"
-            android:hint="@string/add_to_homescreen_text_description"
+            android:hint="@string/add_to_homescreen_text_placeholder"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_marginStart="8dp"

app/src/main/res/values/strings.xml

@@ -871,6 +871,6 @@
     <string name="add_to_homescreen_cancel">Cancel</string>
     <!-- Add button text for the Add to Homescreen dialog -->
     <string name="add_to_homescreen_add">Add</string>
-    <!-- Content description (not visible, for screen readers etc.): Text field for shortcut name-->
-    <string name="add_to_homescreen_text_description">Shortcut name</string>
+    <!-- Placeholder text for the TextView in the Add to Homescreen dialog -->
+    <string name="add_to_homescreen_text_placeholder">Shortcut name</string>
 </resources>