Support pasting in verification code view.

app/src/main/java/org/thoughtcrime/securesms/components/registration/VerificationCodeView.kt

@@ -1,6 +1,8 @@
 package org.thoughtcrime.securesms.components.registration
 
 import android.content.Context
+import android.text.Editable
+import android.text.TextWatcher
 import android.util.AttributeSet
 import android.widget.FrameLayout
 import com.google.android.material.textfield.TextInputLayout
@@ -9,6 +11,7 @@ import org.thoughtcrime.securesms.R
 class VerificationCodeView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0, defStyleRes: Int = 0) :
   FrameLayout(context, attrs, defStyleAttr, defStyleRes) {
   private val containers: MutableList<TextInputLayout> = ArrayList(6)
+  private val textWatcher = PasteTextWatcher()
   private var listener: OnCodeEnteredListener? = null
   private var index = 0
 
@@ -22,6 +25,7 @@ class VerificationCodeView @JvmOverloads constructor(context: Context, attrs: At
     containers.add(findViewById(R.id.container_five))
 
     containers.forEach { it.editText?.showSoftInputOnFocus = false }
+    containers.forEach { it.editText?.addTextChangedListener(textWatcher) }
   }
 
   fun setOnCompleteListener(listener: OnCodeEnteredListener?) {
@@ -41,8 +45,9 @@ class VerificationCodeView @JvmOverloads constructor(context: Context, attrs: At
   }
 
   fun delete() {
-    if (index <= 0) return
-    containers[--index].editText?.setText("")
+    if (index < 0) return
+    val editText = if (index == 0) containers[index].editText else containers[--index].editText
+    editText?.setText("")
     containers[index].editText?.requestFocus()
   }
 
@@ -57,4 +62,29 @@ class VerificationCodeView @JvmOverloads constructor(context: Context, attrs: At
   interface OnCodeEnteredListener {
     fun onCodeComplete(code: String)
   }
+
+  inner class PasteTextWatcher : TextWatcher {
+    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
+
+    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
+
+    override fun afterTextChanged(s: Editable?) {
+      if (s == null) {
+        return
+      }
+
+      if (s.length > 1) {
+        val enteredText = s.toList()
+        enteredText.forEach {
+          val castInt = it.digitToIntOrNull()
+          if (castInt == null) {
+            s.clear()
+            return@forEach
+          } else {
+            append(castInt)
+          }
+        }
+      }
+    }
+  }
 }