add dialog to prevent accidentally dismissing poll changes

app/src/main/java/com/keylesspalace/tusky/components/compose/dialog/AddPollDialog.kt

@@ -50,6 +50,7 @@ fun showAddPollDialog(
         .setBackgroundInsetStart(inset)
         .setNegativeButton(android.R.string.cancel, null)
         .setPositiveButton(android.R.string.ok, null)
+        .setCancelable(false)
         .create()
 
     val adapter = AddPollOptionsAdapter(
@@ -96,19 +97,36 @@ fun showAddPollDialog(
 
     binding.multipleChoicesCheckBox.isChecked = poll?.multiple == true
 
+    fun newPoll() = NewPoll(
+        options = adapter.pollOptions,
+        expiresIn = durations[selectedDurationIndex],
+        multiple = binding.multipleChoicesCheckBox.isChecked
+    )
+
+    val existingPoll = newPoll()
+
     dialog.setOnShowListener {
-        val button = dialog.getButton(AlertDialog.BUTTON_POSITIVE)
-        button.setOnClickListener {
+        dialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener {
             onUpdatePoll(
-                NewPoll(
-                    options = adapter.pollOptions,
-                    expiresIn = durations[selectedDurationIndex],
-                    multiple = binding.multipleChoicesCheckBox.isChecked
-                )
+                newPoll()
             )
 
             dialog.dismiss()
         }
+
+        dialog.getButton(AlertDialog.BUTTON_NEGATIVE)?.setOnClickListener {
+            if (existingPoll != newPoll()) {
+                MaterialAlertDialogBuilder(context)
+                    .setMessage(R.string.confirm_dismiss_caption)
+                    .setPositiveButton(R.string.yes) { _, _ ->
+                        dialog.dismiss()
+                    }
+                    .setNegativeButton(R.string.no, null)
+                    .show()
+            } else {
+                dialog.dismiss()
+            }
+        }
     }
 
     dialog.show()

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

@@ -915,6 +915,7 @@
     <string name="yes">Yes</string>
     <string name="no">No</string>
     <string name="confirm_dismiss_caption">Discard caption changes?</string>
+    <string name="confirm_dismiss_poll">Discard poll changes?</string>
 
     <string name="unblock_success">Unblocked %1$s</string>
     <string name="unmute_success">Unmuted %1$s</string>