Add CardValidCallback and add support in card forms

example/src/main/java/com/stripe/example/activity/CreateCardPaymentMethodActivity.kt

@@ -11,6 +11,7 @@ import androidx.recyclerview.widget.RecyclerView
 import com.stripe.android.PaymentConfiguration
 import com.stripe.android.Stripe
 import com.stripe.android.model.PaymentMethod
+import com.stripe.android.view.CardValidCallback
 import com.stripe.example.R
 import io.reactivex.Observable
 import io.reactivex.android.schedulers.AndroidSchedulers
@@ -40,6 +41,15 @@ class CreateCardPaymentMethodActivity : AppCompatActivity() {
         rv_payment_methods.layoutManager = LinearLayoutManager(this)
         rv_payment_methods.adapter = adapter
 
+        card_multiline_widget.setCardValidCallback(object : CardValidCallback {
+            override fun onInputChanged(
+                isValid: Boolean,
+                invalidFields: Set<CardValidCallback.Fields>
+            ) {
+                // added as an example - no-op
+            }
+        })
+
         btn_create_payment_method.setOnClickListener { createPaymentMethod() }
     }
 

example/src/main/java/com/stripe/example/activity/CreateCardTokenActivity.kt

@@ -20,6 +20,7 @@ import com.stripe.android.PaymentConfiguration
 import com.stripe.android.Stripe
 import com.stripe.android.model.Card
 import com.stripe.android.model.Token
+import com.stripe.android.view.CardValidCallback
 import com.stripe.example.R
 import kotlinx.android.synthetic.main.card_token_activity.*
 
@@ -60,6 +61,15 @@ class CreateCardTokenActivity : AppCompatActivity() {
             }
         }
 
+        card_input_widget.setCardValidCallback(object : CardValidCallback {
+            override fun onInputChanged(
+                isValid: Boolean,
+                invalidFields: Set<CardValidCallback.Fields>
+            ) {
+                // added as an example - no-op
+            }
+        })
+
         card_input_widget.requestFocus()
     }
 

stripe/src/main/java/com/stripe/android/view/CardInputWidget.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.os.Build
 import android.os.Bundle
 import android.os.Parcelable
+import android.text.Editable
 import android.text.Layout
 import android.text.TextPaint
 import android.text.TextWatcher
@@ -62,6 +63,27 @@ class CardInputWidget @JvmOverloads constructor(
     private val postalCodeEditText: PostalCodeEditText
 
     private var cardInputListener: CardInputListener? = null
+    private var cardValidCallback: CardValidCallback? = null
+    private val cardValidTextWatcher = object : StripeTextWatcher() {
+        override fun afterTextChanged(s: Editable?) {
+            super.afterTextChanged(s)
+            cardValidCallback?.onInputChanged(invalidFields.isEmpty(), invalidFields)
+        }
+    }
+    private val invalidFields: Set<CardValidCallback.Fields>
+        get() {
+            return listOfNotNull(
+                CardValidCallback.Fields.Number.takeIf {
+                    cardNumberEditText.cardNumber == null
+                },
+                CardValidCallback.Fields.Expiry.takeIf {
+                    expiryDateEditText.validDateFields == null
+                },
+                CardValidCallback.Fields.Cvc.takeIf {
+                    this.cvcValue == null
+                }
+            ).toSet()
+        }
 
     @JvmSynthetic
     internal var cardNumberIsViewed = true
@@ -252,6 +274,19 @@ class CardInputWidget @JvmOverloads constructor(
         initView(attrs)
     }
 
+    override fun setCardValidCallback(callback: CardValidCallback?) {
+        this.cardValidCallback = callback
+        standardFields.forEach { it.removeTextChangedListener(cardValidTextWatcher) }
+
+        // only add the TextWatcher if it will be used
+        if (callback != null) {
+            standardFields.forEach { it.addTextChangedListener(cardValidTextWatcher) }
+        }
+
+        // call immediately after setting
+        cardValidCallback?.onInputChanged(invalidFields.isEmpty(), invalidFields)
+    }
+
     /**
      * Set a [CardInputListener] to be notified of card input events.
      *

stripe/src/main/java/com/stripe/android/view/CardMultilineWidget.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.graphics.Rect
 import android.graphics.drawable.Drawable
 import android.os.Build
+import android.text.Editable
 import android.text.TextWatcher
 import android.util.AttributeSet
 import android.view.View
@@ -52,6 +53,25 @@ class CardMultilineWidget @JvmOverloads constructor(
     private val postalInputLayout: TextInputLayout
 
     private var cardInputListener: CardInputListener? = null
+    private var cardValidCallback: CardValidCallback? = null
+    private val cardValidTextWatcher = object : StripeTextWatcher() {
+        override fun afterTextChanged(s: Editable?) {
+            super.afterTextChanged(s)
+            cardValidCallback?.onInputChanged(invalidFields.isEmpty(), invalidFields)
+        }
+    }
+    private val invalidFields: Set<CardValidCallback.Fields>
+        get() {
+            return listOfNotNull(
+                CardValidCallback.Fields.Number.takeIf {
+                    cardNumber == null
+                },
+                CardValidCallback.Fields.Expiry.takeIf {
+                    expiryDate == null
+                },
+                CardValidCallback.Fields.Cvc.takeUnless { isCvcLengthValid }
+            ).toSet()
+        }
 
     private var isEnabled: Boolean = false
     private var hasAdjustedDrawable: Boolean = false
@@ -75,7 +95,7 @@ class CardMultilineWidget @JvmOverloads constructor(
             return if (validateAllFields()) {
                 expiryDateEditText.validDateFields?.let { (month, year) ->
                     PaymentMethodCreateParams.Card(
-                        number = cardNumberEditText.cardNumber,
+                        number = cardNumber,
                         cvc = cvcEditText.text?.toString(),
                         expiryMonth = month,
                         expiryYear = year
@@ -139,7 +159,7 @@ class CardMultilineWidget @JvmOverloads constructor(
                 return null
             }
 
-            val cardNumber = cardNumberEditText.cardNumber
+            val cardNumber = cardNumber
             val cardDate = requireNotNull(expiryDateEditText.validDateFields)
             val cvcValue = cvcEditText.text?.toString()
             val postalCode = postalCodeEditText.text?.toString()
@@ -150,10 +170,24 @@ class CardMultilineWidget @JvmOverloads constructor(
                 .loggingTokens(listOf(CARD_MULTILINE_TOKEN))
         }
 
+    private val cardNumber: String?
+        get() {
+            return cardNumberEditText.cardNumber
+        }
+    private val expiryDate: Pair<Int, Int>?
+        get() {
+            return expiryDateEditText.validDateFields
+        }
     private val isCvcLengthValid: Boolean
         get() {
             return cardBrand.isValidCvc(cvcEditText.rawCvcValue)
         }
+    private val allFields: Collection<StripeEditText>
+        get() {
+            return listOf(
+                cardNumberEditText, expiryDateEditText, cvcEditText, postalCodeEditText
+            )
+        }
 
     private val cvcHelperText: Int
         @StringRes
@@ -279,6 +313,19 @@ class CardMultilineWidget @JvmOverloads constructor(
         this.cardInputListener = listener
     }
 
+    override fun setCardValidCallback(callback: CardValidCallback?) {
+        this.cardValidCallback = callback
+        allFields.forEach { it.removeTextChangedListener(cardValidTextWatcher) }
+
+        // only add the TextWatcher if it will be used
+        if (callback != null) {
+            allFields.forEach { it.addTextChangedListener(cardValidTextWatcher) }
+        }
+
+        // call immediately after setting
+        cardValidCallback?.onInputChanged(invalidFields.isEmpty(), invalidFields)
+    }
+
     override fun setCardHint(cardHint: String) {
         cardHintText = cardHint
     }
@@ -289,22 +336,14 @@ class CardMultilineWidget @JvmOverloads constructor(
      * @return `true` if all shown fields are valid, `false` otherwise
      */
     fun validateAllFields(): Boolean {
-        val cardNumberIsValid = CardUtils.isValidCardNumber(cardNumberEditText.cardNumber)
-        val expiryIsValid = expiryDateEditText.validDateFields != null
+        val cardNumberIsValid = CardUtils.isValidCardNumber(cardNumber)
+        val expiryIsValid = expiryDate != null
         val cvcIsValid = isCvcLengthValid
         cardNumberEditText.shouldShowError = !cardNumberIsValid
         expiryDateEditText.shouldShowError = !expiryIsValid
         cvcEditText.shouldShowError = !cvcIsValid
 
-        val fields = listOf(
-            cardNumberEditText, expiryDateEditText, cvcEditText, postalCodeEditText
-        )
-        for (field in fields) {
-            if (field.shouldShowError) {
-                field.requestFocus()
-                break
-            }
-        }
+        allFields.firstOrNull { it.shouldShowError }?.requestFocus()
 
         return cardNumberIsValid && expiryIsValid && cvcIsValid
     }
@@ -353,7 +392,7 @@ class CardMultilineWidget @JvmOverloads constructor(
      * Checks whether the current card number is valid
      */
     fun validateCardNumber(): Boolean {
-        val cardNumberIsValid = CardUtils.isValidCardNumber(cardNumberEditText.cardNumber)
+        val cardNumberIsValid = CardUtils.isValidCardNumber(cardNumber)
         cardNumberEditText.shouldShowError = !cardNumberIsValid
         return cardNumberIsValid
     }

stripe/src/main/java/com/stripe/android/view/CardValidCallback.kt

@@ -0,0 +1,17 @@
+package com.stripe.android.view
+
+interface CardValidCallback {
+    /**
+     * @param isValid if the current input is valid
+     * @param invalidFields if the current input is invalid, this [Set] will be populated with the
+     * fields that are invalid, represented by [Fields]; if the current input is valid,
+     * this [Set] will be empty
+     */
+    fun onInputChanged(isValid: Boolean, invalidFields: Set<Fields>)
+
+    enum class Fields {
+        Number,
+        Expiry,
+        Cvc
+    }
+}

stripe/src/main/java/com/stripe/android/view/CardWidget.kt

@@ -24,6 +24,8 @@ internal interface CardWidget {
      */
     val paymentMethodCreateParams: PaymentMethodCreateParams?
 
+    fun setCardValidCallback(callback: CardValidCallback?)
+
     fun setCardInputListener(listener: CardInputListener?)
 
     fun setCardHint(cardHint: String)

stripe/src/test/java/com/stripe/android/view/CardInputWidgetTest.kt

@@ -4,6 +4,7 @@ import android.os.Build
 import android.text.TextPaint
 import android.view.ViewGroup
 import android.widget.ImageView
+import com.nhaarman.mockitokotlin2.mock
 import com.nhaarman.mockitokotlin2.reset
 import com.nhaarman.mockitokotlin2.verify
 import com.stripe.android.CardNumberFixtures.VALID_AMEX_NO_SPACES
@@ -14,7 +15,6 @@ import com.stripe.android.CardNumberFixtures.VALID_VISA_NO_SPACES
 import com.stripe.android.CardNumberFixtures.VALID_VISA_WITH_SPACES
 import com.stripe.android.R
 import com.stripe.android.model.Address
-import com.stripe.android.model.Card
 import com.stripe.android.model.CardBrand
 import com.stripe.android.model.PaymentMethod
 import com.stripe.android.model.PaymentMethodCreateParams
@@ -36,8 +36,6 @@ import kotlin.test.assertNotNull
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
 import org.junit.runner.RunWith
-import org.mockito.Mock
-import org.mockito.MockitoAnnotations
 import org.robolectric.RobolectricTestRunner
 import org.robolectric.annotation.Config
 
@@ -66,14 +64,10 @@ internal class CardInputWidgetTest : BaseViewTest<CardInputTestActivity>(
     private val postalCodeEditText: PostalCodeEditText by lazy {
         cardInputWidget.findViewById<PostalCodeEditText>(R.id.et_postal_code)
     }
-
-    @Mock
-    private lateinit var cardInputListener: CardInputListener
+    private val cardInputListener: CardInputListener = mock()
 
     @BeforeTest
     fun setup() {
-        MockitoAnnotations.initMocks(this)
-
         cardInputWidget.setCardNumberTextWatcher(object : StripeTextWatcher() {})
         cardInputWidget.setExpiryDateTextWatcher(object : StripeTextWatcher() {})
         cardInputWidget.setCvcNumberTextWatcher(object : StripeTextWatcher() {})
@@ -1229,6 +1223,70 @@ internal class CardInputWidgetTest : BaseViewTest<CardInputTestActivity>(
         assertNotEquals(cardInputWidget.standardFields, cardInputWidget.allFields)
     }
 
+    @Test
+    fun testCardValidCallback() {
+        var currentIsValid = false
+        var currentInvalidFields = emptySet<CardValidCallback.Fields>()
+        cardInputWidget.setCardValidCallback(object : CardValidCallback {
+            override fun onInputChanged(
+                isValid: Boolean,
+                invalidFields: Set<CardValidCallback.Fields>
+            ) {
+                currentIsValid = isValid
+                currentInvalidFields = invalidFields
+            }
+        })
+
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(
+                CardValidCallback.Fields.Number,
+                CardValidCallback.Fields.Expiry,
+                CardValidCallback.Fields.Cvc
+            ),
+            currentInvalidFields
+        )
+
+        cardInputWidget.setCardNumber(VALID_VISA_NO_SPACES)
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(CardValidCallback.Fields.Expiry, CardValidCallback.Fields.Cvc),
+            currentInvalidFields
+        )
+
+        expiryEditText.append("12")
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(CardValidCallback.Fields.Expiry, CardValidCallback.Fields.Cvc),
+            currentInvalidFields
+        )
+
+        expiryEditText.append("50")
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(CardValidCallback.Fields.Cvc),
+            currentInvalidFields
+        )
+
+        cvcEditText.append("12")
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(CardValidCallback.Fields.Cvc),
+            currentInvalidFields
+        )
+
+        cvcEditText.append("3")
+        assertTrue(currentIsValid)
+        assertTrue(currentInvalidFields.isEmpty())
+
+        cvcEditText.setText("0")
+        assertFalse(currentIsValid)
+        assertEquals(
+            setOf(CardValidCallback.Fields.Cvc),
+            currentInvalidFields
+        )
+    }
+
     private companion object {
         // Every Card made by the CardInputView should have the card widget token.
         private val EXPECTED_LOGGING_ARRAY = arrayOf(LOGGING_TOKEN)