feat: MFA Enrollment (TOTP)

auth/src/main/java/com/firebase/ui/auth/compose/configuration/string_provider/AuthUIStringProvider.kt

@@ -224,4 +224,42 @@ interface AuthUIStringProvider {
 
     /** Unknown error recovery message */
     val unknownErrorRecoveryMessage: String
+
+    // MFA Enrollment Step Titles
+    /** Title for MFA factor selection step */
+    val mfaStepSelectFactorTitle: String
+
+    /** Title for SMS MFA configuration step */
+    val mfaStepConfigureSmsTitle: String
+
+    /** Title for TOTP MFA configuration step */
+    val mfaStepConfigureTotpTitle: String
+
+    /** Title for MFA verification step */
+    val mfaStepVerifyFactorTitle: String
+
+    /** Title for recovery codes step */
+    val mfaStepShowRecoveryCodesTitle: String
+
+    // MFA Enrollment Helper Text
+    /** Helper text for selecting MFA factor */
+    val mfaStepSelectFactorHelper: String
+
+    /** Helper text for SMS configuration */
+    val mfaStepConfigureSmsHelper: String
+
+    /** Helper text for TOTP configuration */
+    val mfaStepConfigureTotpHelper: String
+
+    /** Helper text for SMS verification */
+    val mfaStepVerifyFactorSmsHelper: String
+
+    /** Helper text for TOTP verification */
+    val mfaStepVerifyFactorTotpHelper: String
+
+    /** Generic helper text for factor verification */
+    val mfaStepVerifyFactorGenericHelper: String
+
+    /** Helper text for recovery codes */
+    val mfaStepShowRecoveryCodesHelper: String
 }

auth/src/main/java/com/firebase/ui/auth/compose/configuration/string_provider/DefaultAuthUIStringProvider.kt

@@ -213,4 +213,36 @@ class DefaultAuthUIStringProvider(
         get() = localizedContext.getString(R.string.fui_error_auth_cancelled_message)
     override val unknownErrorRecoveryMessage: String
         get() = localizedContext.getString(R.string.fui_error_unknown)
+
+    /**
+     * MFA Enrollment Step Titles
+     */
+    override val mfaStepSelectFactorTitle: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_select_factor_title)
+    override val mfaStepConfigureSmsTitle: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_configure_sms_title)
+    override val mfaStepConfigureTotpTitle: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_configure_totp_title)
+    override val mfaStepVerifyFactorTitle: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_verify_factor_title)
+    override val mfaStepShowRecoveryCodesTitle: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_show_recovery_codes_title)
+
+    /**
+     * MFA Enrollment Helper Text
+     */
+    override val mfaStepSelectFactorHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_select_factor_helper)
+    override val mfaStepConfigureSmsHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_configure_sms_helper)
+    override val mfaStepConfigureTotpHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_configure_totp_helper)
+    override val mfaStepVerifyFactorSmsHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_verify_factor_sms_helper)
+    override val mfaStepVerifyFactorTotpHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_verify_factor_totp_helper)
+    override val mfaStepVerifyFactorGenericHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_verify_factor_generic_helper)
+    override val mfaStepShowRecoveryCodesHelper: String
+        get() = localizedContext.getString(R.string.fui_mfa_step_show_recovery_codes_helper)
 }

auth/src/main/java/com/firebase/ui/auth/compose/mfa/MfaEnrollmentContentState.kt

@@ -0,0 +1,161 @@
+/*
+ * Copyright 2025 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.firebase.ui.auth.compose.mfa
+
+import com.firebase.ui.auth.compose.configuration.MfaFactor
+import com.firebase.ui.auth.compose.data.CountryData
+
+/**
+ * State class containing all the necessary information to render a custom UI for the
+ * Multi-Factor Authentication (MFA) enrollment flow.
+ *
+ * This class is passed to the content slot of the MfaEnrollmentScreen composable, providing
+ * access to the current step, user input values, callbacks for actions, and loading/error states.
+ *
+ * Use a `when` expression on [step] to determine which UI to render:
+ *
+ * ```kotlin
+ * MfaEnrollmentScreen(user, config, onComplete, onSkip) { state ->
+ *     when (state.step) {
+ *         MfaEnrollmentStep.SelectFactor -> {
+ *             // Render factor selection UI using state.availableFactors
+ *         }
+ *         MfaEnrollmentStep.ConfigureTotp -> {
+ *             // Render TOTP setup UI using state.totpSecret and state.totpQrCodeUrl
+ *         }
+ *         MfaEnrollmentStep.VerifyFactor -> {
+ *             // Render verification UI using state.verificationCode
+ *         }
+ *         // ... other steps
+ *     }
+ * }
+ * ```
+ *
+ * @property step The current step in the enrollment flow. Use this to determine which UI to display.
+ * @property isLoading `true` when an asynchronous operation (like generating a secret or verifying a code) is in progress. Use this to show loading indicators.
+ * @property error An optional error message to display to the user. Will be `null` if there's no error.
+ * @property onBackClick Callback to navigate to the previous step in the flow. Invoked when the user clicks a back button.
+ *
+ * @property availableFactors (Step: [MfaEnrollmentStep.SelectFactor]) A list of MFA factors the user can choose from (e.g., SMS, TOTP). Determined by [com.firebase.ui.auth.compose.configuration.MfaConfiguration.allowedFactors].
+ * @property onFactorSelected (Step: [MfaEnrollmentStep.SelectFactor]) Callback invoked when the user selects an MFA factor. Receives the selected [MfaFactor].
+ * @property onSkipClick (Step: [MfaEnrollmentStep.SelectFactor]) Callback for the "Skip" action. Will be `null` if MFA enrollment is required via [com.firebase.ui.auth.compose.configuration.MfaConfiguration.requireEnrollment].
+ *
+ * @property phoneNumber (Step: [MfaEnrollmentStep.ConfigureSms]) The current value of the phone number input field. Does not include country code prefix.
+ * @property onPhoneNumberChange (Step: [MfaEnrollmentStep.ConfigureSms]) Callback invoked when the phone number input changes. Receives the new phone number string.
+ * @property selectedCountry (Step: [MfaEnrollmentStep.ConfigureSms]) The currently selected country for phone number formatting. Contains dial code, country code, and flag.
+ * @property onCountrySelected (Step: [MfaEnrollmentStep.ConfigureSms]) Callback invoked when the user selects a different country. Receives the new [CountryData].
+ * @property onSendSmsCodeClick (Step: [MfaEnrollmentStep.ConfigureSms]) Callback to send the SMS verification code to the entered phone number.
+ *
+ * @property totpSecret (Step: [MfaEnrollmentStep.ConfigureTotp]) The TOTP secret containing the shared key and configuration. Use this to display the secret key or access the underlying Firebase TOTP secret.
+ * @property totpQrCodeUrl (Step: [MfaEnrollmentStep.ConfigureTotp]) A URI that can be rendered as a QR code or used as a deep link to open authenticator apps. Generated via [TotpSecret.generateQrCodeUrl].
+ * @property onContinueToVerifyClick (Step: [MfaEnrollmentStep.ConfigureTotp]) Callback to proceed to the verification step after the user has scanned the QR code or entered the secret.
+ *
+ * @property verificationCode (Step: [MfaEnrollmentStep.VerifyFactor]) The current value of the verification code input field. Should be a 6-digit string.
+ * @property onVerificationCodeChange (Step: [MfaEnrollmentStep.VerifyFactor]) Callback invoked when the verification code input changes. Receives the new code string.
+ * @property onVerifyClick (Step: [MfaEnrollmentStep.VerifyFactor]) Callback to verify the entered code and finalize MFA enrollment.
+ * @property selectedFactor (Step: [MfaEnrollmentStep.VerifyFactor]) The MFA factor being verified (SMS or TOTP). Use this to customize UI messages.
+ * @property onResendCodeClick (Step: [MfaEnrollmentStep.VerifyFactor], SMS only) Callback to resend the SMS verification code. Will be `null` for TOTP verification.
+ *
+ * @property recoveryCodes (Step: [MfaEnrollmentStep.ShowRecoveryCodes]) A list of one-time backup codes the user should save. Only present if [com.firebase.ui.auth.compose.configuration.MfaConfiguration.enableRecoveryCodes] is `true`.
+ * @property onCodesSavedClick (Step: [MfaEnrollmentStep.ShowRecoveryCodes]) Callback invoked when the user confirms they have saved their recovery codes. Completes the enrollment flow.
+ *
+ * @since 10.0.0
+ */
+data class MfaEnrollmentContentState(
+    /** The current step in the enrollment flow. Use this to determine which UI to display. */
+    val step: MfaEnrollmentStep,
+
+    /** `true` when an async operation is in progress. Use to show loading indicators. */
+    val isLoading: Boolean = false,
+
+    /** Optional error message to display. `null` if no error. */
+    val error: String? = null,
+
+    /** Callback to navigate to the previous step. */
+    val onBackClick: () -> Unit = {},
+
+    // SelectFactor step
+    val availableFactors: List<MfaFactor> = emptyList(),
+
+    val onFactorSelected: (MfaFactor) -> Unit = {},
+
+    val onSkipClick: (() -> Unit)? = null,
+
+    // ConfigureSms step
+    val phoneNumber: String = "",
+
+    val onPhoneNumberChange: (String) -> Unit = {},
+
+    val selectedCountry: CountryData? = null,
+
+    val onCountrySelected: (CountryData) -> Unit = {},
+
+    val onSendSmsCodeClick: () -> Unit = {},
+
+    // ConfigureTotp step
+    val totpSecret: TotpSecret? = null,
+
+    val totpQrCodeUrl: String? = null,
+
+    val onContinueToVerifyClick: () -> Unit = {},
+
+    // VerifyFactor step
+    val verificationCode: String = "",
+
+    val onVerificationCodeChange: (String) -> Unit = {},
+
+    val onVerifyClick: () -> Unit = {},
+
+    val selectedFactor: MfaFactor? = null,
+
+    val onResendCodeClick: (() -> Unit)? = null,
+
+    // ShowRecoveryCodes step
+    val recoveryCodes: List<String>? = null,
+
+    val onCodesSavedClick: () -> Unit = {}
+) {
+    /**
+     * Returns true if the current state is valid for the current step.
+     *
+     * This can be used to enable/disable action buttons in the UI.
+     */
+    val isValid: Boolean
+        get() = when (step) {
+            MfaEnrollmentStep.SelectFactor -> availableFactors.isNotEmpty()
+            MfaEnrollmentStep.ConfigureSms -> phoneNumber.isNotBlank()
+            MfaEnrollmentStep.ConfigureTotp -> totpSecret != null && totpQrCodeUrl != null
+            MfaEnrollmentStep.VerifyFactor -> verificationCode.length == 6
+            MfaEnrollmentStep.ShowRecoveryCodes -> !recoveryCodes.isNullOrEmpty()
+        }
+
+    /**
+     * Returns true if there is an error in the current state.
+     */
+    val hasError: Boolean
+        get() = !error.isNullOrBlank()
+
+    /**
+     * Returns true if the skip action is available (only for SelectFactor step when not required).
+     */
+    val canSkip: Boolean
+        get() = step == MfaEnrollmentStep.SelectFactor && onSkipClick != null
+
+    /**
+     * Returns true if the back action is available (for all steps except SelectFactor).
+     */
+    val canGoBack: Boolean
+        get() = step != MfaEnrollmentStep.SelectFactor
+}

auth/src/main/java/com/firebase/ui/auth/compose/mfa/MfaEnrollmentStep.kt

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2025 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.firebase.ui.auth.compose.mfa
+
+import com.firebase.ui.auth.compose.configuration.MfaFactor
+import com.firebase.ui.auth.compose.configuration.string_provider.AuthUIStringProvider
+
+/**
+ * Represents the different steps in the Multi-Factor Authentication (MFA) enrollment flow.
+ *
+ * This enum defines the sequence of UI states that users progress through when enrolling
+ * in MFA, from selecting a factor to completing the setup with recovery codes.
+ *
+ * @since 10.0.0
+ */
+enum class MfaEnrollmentStep {
+    /**
+     * The user is presented with a selection of available MFA factors to enroll in.
+     * The available factors are determined by the [com.firebase.ui.auth.compose.configuration.MfaConfiguration].
+     */
+    SelectFactor,
+
+    /**
+     * The user is configuring SMS-based MFA by entering their phone number.
+     * This step prepares to send an SMS verification code to the provided number.
+     */
+    ConfigureSms,
+
+    /**
+     * The user is configuring TOTP (Time-based One-Time Password) MFA.
+     * This step presents the TOTP secret (as both text and QR code) for the user
+     * to scan into their authenticator app.
+     */
+    ConfigureTotp,
+
+    /**
+     * The user is verifying their chosen MFA factor by entering a verification code.
+     * For SMS, this is the code received via text message.
+     * For TOTP, this is the code generated by their authenticator app.
+     */
+    VerifyFactor,
+
+    /**
+     * The enrollment is complete and recovery codes are displayed to the user.
+     * These backup codes can be used to sign in if the primary MFA method is unavailable.
+     * This step only appears if recovery codes are enabled in the configuration.
+     */
+    ShowRecoveryCodes
+}
+
+/**
+ * Returns the localized title text for this enrollment step.
+ *
+ * @param stringProvider The string provider for localized strings
+ * @return The localized title for this step
+ */
+fun MfaEnrollmentStep.getTitle(stringProvider: AuthUIStringProvider): String = when (this) {
+    MfaEnrollmentStep.SelectFactor -> stringProvider.mfaStepSelectFactorTitle
+    MfaEnrollmentStep.ConfigureSms -> stringProvider.mfaStepConfigureSmsTitle
+    MfaEnrollmentStep.ConfigureTotp -> stringProvider.mfaStepConfigureTotpTitle
+    MfaEnrollmentStep.VerifyFactor -> stringProvider.mfaStepVerifyFactorTitle
+    MfaEnrollmentStep.ShowRecoveryCodes -> stringProvider.mfaStepShowRecoveryCodesTitle
+}
+
+/**
+ * Returns localized helper text providing instructions for this step.
+ *
+ * @param stringProvider The string provider for localized strings
+ * @param selectedFactor The MFA factor being configured or verified. Used for [MfaEnrollmentStep.VerifyFactor]
+ *                       to provide factor-specific instructions. Ignored for other steps.
+ * @return Localized instructional text appropriate for this step
+ */
+fun MfaEnrollmentStep.getHelperText(
+    stringProvider: AuthUIStringProvider,
+    selectedFactor: MfaFactor? = null
+): String = when (this) {
+    MfaEnrollmentStep.SelectFactor -> stringProvider.mfaStepSelectFactorHelper
+    MfaEnrollmentStep.ConfigureSms -> stringProvider.mfaStepConfigureSmsHelper
+    MfaEnrollmentStep.ConfigureTotp -> stringProvider.mfaStepConfigureTotpHelper
+    MfaEnrollmentStep.VerifyFactor -> when (selectedFactor) {
+        MfaFactor.Sms -> stringProvider.mfaStepVerifyFactorSmsHelper
+        MfaFactor.Totp -> stringProvider.mfaStepVerifyFactorTotpHelper
+        null -> stringProvider.mfaStepVerifyFactorGenericHelper
+    }
+    MfaEnrollmentStep.ShowRecoveryCodes -> stringProvider.mfaStepShowRecoveryCodesHelper
+}