From cd873bcb3ff431e73edcb70b6f7d7ec0716b7668 Mon Sep 17 00:00:00 2001
From: Michael Shafrir <45020849+mshafrir-stripe@users.noreply.github.com>
Date: Wed, 18 Mar 2020 14:50:41 -0400
Subject: [PATCH] Add BecsDebitWidget.ValidParamsCallback (#2297)

When `BecsDebitWidget.validParamsCallback` is set,
`onInputChanged(isValid)` will be called on that instance.
---
 example/res/layout/becs_debit_activity.xml    |  1 +
 .../BecsDebitPaymentMethodActivity.kt         |  7 ++++
 .../stripe/android/view/BecsDebitWidget.kt    | 40 ++++++++++++++++++
 .../android/view/BecsDebitWidgetTest.kt       | 42 +++++++++++++++++++
 4 files changed, 90 insertions(+)

diff --git a/example/res/layout/becs_debit_activity.xml b/example/res/layout/becs_debit_activity.xml
index e6333916f6d..41ac0c6afa4 100644
--- a/example/res/layout/becs_debit_activity.xml
+++ b/example/res/layout/becs_debit_activity.xml
@@ -27,6 +27,7 @@
             android:layout_height="wrap_content"
             android:layout_gravity="center_horizontal"
             android:layout_marginTop="20dp"
+            android:enabled="false"
             android:text="@string/create_becs_debit_params" />
 
         <TextView
diff --git a/example/src/main/java/com/stripe/example/activity/BecsDebitPaymentMethodActivity.kt b/example/src/main/java/com/stripe/example/activity/BecsDebitPaymentMethodActivity.kt
index d983718b18b..29ba8891e45 100644
--- a/example/src/main/java/com/stripe/example/activity/BecsDebitPaymentMethodActivity.kt
+++ b/example/src/main/java/com/stripe/example/activity/BecsDebitPaymentMethodActivity.kt
@@ -6,6 +6,7 @@ import com.stripe.android.ApiResultCallback
 import com.stripe.android.PaymentConfiguration
 import com.stripe.android.Stripe
 import com.stripe.android.model.PaymentMethod
+import com.stripe.android.view.BecsDebitWidget
 import com.stripe.example.databinding.BecsDebitActivityBinding
 
 class BecsDebitPaymentMethodActivity : AppCompatActivity() {
@@ -23,6 +24,12 @@ class BecsDebitPaymentMethodActivity : AppCompatActivity() {
         super.onCreate(savedInstanceState)
         setContentView(viewBinding.root)
 
+        viewBinding.element.validParamsCallback = object : BecsDebitWidget.ValidParamsCallback {
+            override fun onInputChanged(isValid: Boolean) {
+                viewBinding.submit.isEnabled = isValid
+            }
+        }
+
         viewBinding.mandateAcceptance.merchantName = "Rocketship Inc."
 
         viewBinding.submit.setOnClickListener {
diff --git a/stripe/src/main/java/com/stripe/android/view/BecsDebitWidget.kt b/stripe/src/main/java/com/stripe/android/view/BecsDebitWidget.kt
index 7260340eae5..55ceb35d59f 100644
--- a/stripe/src/main/java/com/stripe/android/view/BecsDebitWidget.kt
+++ b/stripe/src/main/java/com/stripe/android/view/BecsDebitWidget.kt
@@ -30,12 +30,45 @@ class BecsDebitWidget @JvmOverloads constructor(
         )
     }
 
+    var validParamsCallback: ValidParamsCallback = object : ValidParamsCallback {
+        override fun onInputChanged(isValid: Boolean) {
+            // no-op default implementation
+        }
+    }
+
+    private val validParamsTextWatcher = object : StripeTextWatcher() {
+        override fun afterTextChanged(s: Editable?) {
+            super.afterTextChanged(s)
+            validParamsCallback.onInputChanged(isInputValid)
+        }
+    }
+
+    private val isInputValid: Boolean
+        get() {
+            val name = viewBinding.nameEditText.fieldText
+            val email = viewBinding.emailEditText.email
+            val bsbNumber = viewBinding.bsbEditText.bsb
+            val accountNumber = viewBinding.accountNumberEditText.accountNumber
+
+            return !(name.isBlank() || email.isNullOrBlank() || bsbNumber.isNullOrBlank() ||
+                accountNumber.isNullOrBlank())
+        }
+
     init {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             viewBinding.nameEditText.setAutofillHints(View.AUTOFILL_HINT_NAME)
             viewBinding.emailEditText.setAutofillHints(View.AUTOFILL_HINT_EMAIL_ADDRESS)
         }
 
+        setOf(
+            viewBinding.nameEditText,
+            viewBinding.emailEditText,
+            viewBinding.bsbEditText,
+            viewBinding.accountNumberEditText
+        ).forEach {
+            it.addTextChangedListener(validParamsTextWatcher)
+        }
+
         viewBinding.bsbEditText.onBankChangedCallback = { bank ->
             if (bank != null) {
                 viewBinding.bsbTextInputLayout.helperText = bank.name
@@ -145,4 +178,11 @@ class BecsDebitWidget @JvmOverloads constructor(
                 )
             )
         }
+
+    interface ValidParamsCallback {
+        /**
+         * @param isValid if the current input is valid
+         */
+        fun onInputChanged(isValid: Boolean)
+    }
 }
diff --git a/stripe/src/test/java/com/stripe/android/view/BecsDebitWidgetTest.kt b/stripe/src/test/java/com/stripe/android/view/BecsDebitWidgetTest.kt
index f1a23e1a2d8..933f1ba7a7c 100644
--- a/stripe/src/test/java/com/stripe/android/view/BecsDebitWidgetTest.kt
+++ b/stripe/src/test/java/com/stripe/android/view/BecsDebitWidgetTest.kt
@@ -112,6 +112,48 @@ internal class BecsDebitWidgetTest : BaseViewTest<BecsDebitWidgetTestActivity>(
             .isEqualTo(4)
     }
 
+    @Test
+    fun validParamsCallback_shouldBeCalledWhenInputChanges() {
+        var isValidArg = false
+        var callbacks = 0
+        becsDebitWidget.validParamsCallback = object : BecsDebitWidget.ValidParamsCallback {
+            override fun onInputChanged(isValid: Boolean) {
+                callbacks++
+                isValidArg = isValid
+            }
+        }
+
+        assertThat(isValidArg)
+            .isFalse()
+        assertThat(callbacks)
+            .isEqualTo(0)
+
+        nameEditText.setText("Jenny Rosen")
+        assertThat(isValidArg)
+            .isFalse()
+        assertThat(callbacks)
+            .isEqualTo(1)
+
+        emailEditText.setText("jrosen@example.com")
+        assertThat(isValidArg)
+            .isFalse()
+        assertThat(callbacks)
+            .isEqualTo(2)
+
+        bsbEditText.setText("000000")
+        assertThat(isValidArg)
+            .isFalse()
+        // there is an additional callback because "000000" is formatted to "000-000"
+        assertThat(callbacks)
+            .isEqualTo(4)
+
+        accountNumberEditText.setText("000123456")
+        assertThat(isValidArg)
+            .isTrue()
+        assertThat(callbacks)
+            .isEqualTo(5)
+    }
+
     private companion object {
         private const val VALID_BSB_NUMBER = "000000"
         private const val VALID_ACCOUNT_NUMBER = "000123456"