Basic recovery flow working

Signed-off-by: Iván Ávalos <avalos@disroot.org>

13 files changed, 594 insertions, 99 deletions

diff --git a/anastasis/src/main/java/net/taler/anastasis/MainActivity.kt b/anastasis/src/main/java/net/taler/anastasis/MainActivity.kt
index 3a4ddb8..bb0fd4d 100644
--- a/anastasis/src/main/java/net/taler/anastasis/MainActivity.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/MainActivity.kt
@@ -25,8 +25,10 @@ import net.taler.anastasis.ui.common.SelectCountryScreen
 import net.taler.anastasis.ui.common.SelectUserAttributesScreen
 import net.taler.anastasis.ui.dialogs.ErrorDialog
 import net.taler.anastasis.ui.home.HomeScreen
+import net.taler.anastasis.ui.recovery.RecoveryFinishedScreen
 import net.taler.anastasis.ui.recovery.SelectChallengeScreen
 import net.taler.anastasis.ui.recovery.SelectSecretScreen
+import net.taler.anastasis.ui.recovery.SolveChallengeScreen
 import net.taler.anastasis.ui.theme.AnastasisTheme
 import net.taler.anastasis.viewmodels.ReducerViewModel
 
@@ -113,6 +115,14 @@ fun MainNavHost(
                 SelectChallengeScreen()
             }
 
+            Routes.SolveChallenge.route -> {
+                SolveChallengeScreen()
+            }
+
+            Routes.RecoveryFinished.route -> {
+                RecoveryFinishedScreen()
+            }
+
             Routes.RestoreInit.route -> {
                 Text("This is the restore session screen!")
             }
diff --git a/anastasis/src/main/java/net/taler/anastasis/Routes.kt b/anastasis/src/main/java/net/taler/anastasis/Routes.kt
index 8b2d821..ac6e1d9 100644
--- a/anastasis/src/main/java/net/taler/anastasis/Routes.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/Routes.kt
@@ -20,6 +20,8 @@ sealed class Routes(
     // Recovery
     object SelectSecret: Routes("select_secret")
     object SelectChallenge: Routes("select_challenge")
+    object SolveChallenge: Routes("solve_challenge")
+    object RecoveryFinished: Routes("recovery_finished")
 
     // Restore
     object RestoreInit: Routes("restore")
diff --git a/anastasis/src/main/java/net/taler/anastasis/models/ChallengeFeedback.kt b/anastasis/src/main/java/net/taler/anastasis/models/ChallengeFeedback.kt
index 57496db..1368d9f 100644
--- a/anastasis/src/main/java/net/taler/anastasis/models/ChallengeFeedback.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/models/ChallengeFeedback.kt
@@ -9,76 +9,76 @@ import net.taler.common.Amount
 @OptIn(ExperimentalSerializationApi::class)
 @Serializable
 @JsonClassDiscriminator("state")
-abstract class ChallengeFeedback
+sealed class ChallengeFeedback {
+    @Serializable
+    @SerialName("solved")
+    object Solved: ChallengeFeedback()
 
-@Serializable
-@SerialName("solved")
-class ChallengeFeedbackSolved: ChallengeFeedback()
+    @Serializable
+    @SerialName("incorrect-answer")
+    object IncorrectAnswer: ChallengeFeedback()
 
-@Serializable
-@SerialName("incorrect-answer")
-class ChallengeFeedbackIncorrectAnswer: ChallengeFeedback()
+    @Serializable
+    @SerialName("code-in-file")
+    data class CodeInFile(
+        val filename: String,
+        @SerialName("display_hint")
+        val displayHint: String,
+    ): ChallengeFeedback()
 
-@Serializable
-@SerialName("code-in-file")
-data class ChallengeFeedbackCodeInFile(
-    val filename: String,
-    @SerialName("display_hint")
-    val displayHint: String,
-): ChallengeFeedback()
+    @Serializable
+    @SerialName("code-sent")
+    data class CodeSent(
+        @SerialName("display_hint")
+        val displayHint: String,
+        @SerialName("address_hint")
+        val addressHint: String,
+    ): ChallengeFeedback()
 
-@Serializable
-@SerialName("code-sent")
-data class ChallengeFeedbackCodeSent(
-    @SerialName("display_hint")
-    val displayHint: String,
-    @SerialName("address_hint")
-    val addressHint: String,
-): ChallengeFeedback()
+    @Serializable
+    @SerialName("unsupported")
+    data class Unsupported(
+        @SerialName("unsupported_method")
+        val unsupportedMethod: String,
+    ): ChallengeFeedback()
 
-@Serializable
-@SerialName("unsupported")
-data class ChallengeFeedbackUnsupported(
-    @SerialName("unsupported_method")
-    val unsupportedMethod: String,
-): ChallengeFeedback()
+    @Serializable
+    @SerialName("rate-limit-exceeded")
+    object RateLimitExceeded : ChallengeFeedback()
 
-@Serializable
-@SerialName("rate-limit-exceeded")
-class ChallengeFeedbackRateLimitExceeded: ChallengeFeedback()
+    @Serializable
+    @SerialName("iban-instructions")
+    data class BankTransferRequired(
+        @SerialName("challenge_amount")
+        val challengeAmount: Amount,
+        @SerialName("target_iban")
+        val targetIban: String,
+        @SerialName("target_business_name")
+        val targetBusinessName: String,
+        @SerialName("wire_transfer_subject")
+        val wireTransferSubject: String,
+        @SerialName("answer_code")
+        val answerCode: Int,
+    ): ChallengeFeedback()
 
-@Serializable
-@SerialName("iban-instructions")
-data class ChallengeFeedbackBankTransferRequired(
-    @SerialName("challenge_amount")
-    val challengeAmount: Amount,
-    @SerialName("target_iban")
-    val targetIban: String,
-    @SerialName("target_business_name")
-    val targetBusinessName: String,
-    @SerialName("wire_transfer_subject")
-    val wireTransferSubject: String,
-    @SerialName("answer_code")
-    val answerCode: Int,
-): ChallengeFeedback()
+    @Serializable
+    @SerialName("server-failure")
+    class ServerFailure(
+        val httpStatus: Int,
+        // TODO: error_response
+    ): ChallengeFeedback()
 
-@Serializable
-@SerialName("server-failure")
-class ChallengeFeedbackServerFailure(
-    // TODO: http_status
-    // TODO: error_response
-): ChallengeFeedback()
+    @Serializable
+    @SerialName("truth-unknown")
+    object TruthUnknown: ChallengeFeedback()
 
-@Serializable
-@SerialName("truth-unknown")
-class ChallengeFeedbackTruthUnknown: ChallengeFeedback()
-
-@Serializable
-@SerialName("taler-payment")
-class ChallengeFeedbackTalerPaymentRequired(
-    @SerialName("taler_pay_uri")
-    val talerPayUri: String,
-    val provider: String,
-    @SerialName("payment_secret")
-    val paymentSecret: String,
-): ChallengeFeedback()
\ No newline at end of file
+    @Serializable
+    @SerialName("taler-payment")
+    class TalerPaymentRequired(
+        @SerialName("taler_pay_uri")
+        val talerPayUri: String,
+        val provider: String,
+        @SerialName("payment_secret")
+        val paymentSecret: String,
+    ): ChallengeFeedback()
+}
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/models/ReducerState.kt b/anastasis/src/main/java/net/taler/anastasis/models/ReducerState.kt
index e12a176..72c1f48 100644
--- a/anastasis/src/main/java/net/taler/anastasis/models/ReducerState.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/models/ReducerState.kt
@@ -107,7 +107,9 @@ sealed class ReducerState {
         val selectedVersion: SelectedVersionInfo? = null,
         @SerialName("challenge_feedback")
         val challengeFeedback: Map<String, ChallengeFeedback>? = null,
-        // TODO: recovered_key_shares
+        @SerialName("recovered_key_shares")
+        val recoveredKeyShares: Map<String, String>? = null,
+        @SerialName("core_secret")
         val coreSecret: CoreSecret? = null,
         @SerialName("authentication_providers")
         val authenticationProviders: Map<String, AuthenticationProviderStatus>? = null,
diff --git a/anastasis/src/main/java/net/taler/anastasis/reducers/ReducerManager.kt b/anastasis/src/main/java/net/taler/anastasis/reducers/ReducerManager.kt
index 38b63e0..db9f5ff 100644
--- a/anastasis/src/main/java/net/taler/anastasis/reducers/ReducerManager.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/reducers/ReducerManager.kt
@@ -295,4 +295,15 @@ class ReducerManager(
                 .onError { this@ReducerManager.onError(it) }
         }
     }
+
+    fun solveChallenge(answer: String) = scope.launch {
+        state.value?.let { initialState ->
+            addTask()
+            api.reduceAction(initialState, "solve_challenge") {
+                put("answer", answer)
+            }
+                .onSuccess { this@ReducerManager.onSuccess(it) }
+                .onError { this@ReducerManager.onError(it) }
+        }
+    }
 }
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/shared/Utils.kt b/anastasis/src/main/java/net/taler/anastasis/shared/Utils.kt
index 916dd36..ee3799d 100644
--- a/anastasis/src/main/java/net/taler/anastasis/shared/Utils.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/shared/Utils.kt
@@ -17,9 +17,6 @@
 package net.taler.anastasis.shared
 
 import android.os.Build
-import io.matthewnelson.encoding.base32.Base32
-import io.matthewnelson.encoding.core.Decoder.Companion.decodeToByteArray
-import io.matthewnelson.encoding.core.Encoder.Companion.encodeToString
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.flow
 import kotlinx.datetime.Clock
@@ -31,7 +28,6 @@ import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import org.json.JSONArray
 import org.json.JSONObject
-import java.nio.charset.Charset
 import java.text.SimpleDateFormat
 import java.time.format.DateTimeFormatter
 import java.util.Locale
@@ -58,17 +54,6 @@ object Utils {
     inline fun <reified T> Json.encodeToNativeJson(value: Collection<T>): JSONArray =
         JSONArray(encodeToString(value))
 
-    fun encodeBase32 (input: String) = input
-        .toByteArray(Charset.defaultCharset())
-        .encodeToString(Base32.Crockford)
-
-    fun encodeBase32 (input: ByteArray) = input
-        .encodeToString(Base32.Crockford)
-
-    fun decodeBase32 (input: String) = input
-        .decodeToByteArray(Base32.Crockford)
-        .toString(Charset.defaultCharset())
-
     // Source: https://stackoverflow.com/questions/54827455/how-to-implement-timer-with-kotlin-coroutines/54828055#54828055
     fun tickerFlow(period: Duration, initialDelay: Duration = Duration.ZERO) = flow {
         delay(initialDelay)
@@ -77,4 +62,6 @@ object Utils {
             delay(period)
         }
     }
+
+    fun extractVerificationCode(code: String) = code.split('-').drop(1).joinToString("")
 }
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditAnswerForm.kt b/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditAnswerForm.kt
new file mode 100644
index 0000000..aacc8a6
--- /dev/null
+++ b/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditAnswerForm.kt
@@ -0,0 +1,121 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2023 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.anastasis.ui.forms
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.focus.FocusRequester
+import androidx.compose.ui.focus.focusRequester
+import androidx.compose.ui.platform.LocalFocusManager
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.tooling.preview.Preview
+import net.taler.anastasis.R
+import net.taler.anastasis.shared.FieldStatus
+import net.taler.anastasis.ui.theme.AnastasisTheme
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun EditAnswerForm(
+    questionLabel: String? = null,
+    question: String? = null,
+    answerLabel: String,
+    answer: String = "",
+    onAnswerEdited: (answer: String) -> Unit,
+    regex: String? = null,
+) {
+    val focusRequester1 = remember { FocusRequester() }
+    val focusManager = LocalFocusManager.current
+    val status = remember(answer) {
+        fieldStatus(answer, regex)
+    }
+
+    Column {
+        if (question != null) {
+            OutlinedTextField(
+                modifier = Modifier
+                    .focusRequester(focusRequester1)
+                    .fillMaxWidth(),
+                value = question,
+                maxLines = 1,
+                enabled = false,
+                label = { Text(questionLabel ?: stringResource(R.string.question)) },
+                onValueChange = {},
+            )
+        }
+
+        OutlinedTextField(
+            modifier = Modifier
+                .focusRequester(focusRequester1)
+                .fillMaxWidth(),
+            value = answer,
+            isError = status.error,
+            supportingText = {
+                status.msgRes?.let { Text(stringResource(it)) }
+            },
+            maxLines = 1,
+            keyboardOptions = KeyboardOptions(
+                keyboardType = KeyboardType.Email,
+                imeAction = ImeAction.Done,
+            ),
+            keyboardActions = KeyboardActions(onDone = { focusManager.clearFocus() }),
+            onValueChange = onAnswerEdited,
+            label = { Text(answerLabel) },
+        )
+    }
+
+    LaunchedEffect(Unit) {
+        focusRequester1.requestFocus()
+    }
+}
+
+private fun fieldStatus(answer: String, regex: String? = null): FieldStatus = if (answer.isBlank()) {
+    FieldStatus.Blank
+} else if (regex?.toRegex()?.matches(answer) != false) {
+    FieldStatus.Valid
+} else {
+    FieldStatus.Invalid
+}
+
+@Preview
+@Composable
+fun EditCodeFormPreview() {
+    var code by remember { mutableStateOf("A-65611-546-7467-369") }
+    AnastasisTheme {
+        Surface {
+            EditAnswerForm(
+                answer = code,
+                answerLabel = stringResource(R.string.code),
+                onAnswerEdited = { code = it },
+            )
+        }
+    }
+}
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditQuestionForm.kt b/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditQuestionForm.kt
index fb17088..cac228c 100644
--- a/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditQuestionForm.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/ui/forms/EditQuestionForm.kt
@@ -39,6 +39,7 @@ import net.taler.anastasis.models.AuthMethod
 @Composable
 fun EditQuestionForm(
     method: AuthMethod? = null,
+    isAnswer: Boolean = false,
     onMethodEdited: (method: AuthMethod) -> Unit,
 ) {
     val localMethod = method ?: AuthMethod(
@@ -59,6 +60,7 @@ fun EditQuestionForm(
                 .fillMaxWidth(),
             value = localMethod.instructions,
             maxLines = 1,
+            enabled = !isAnswer,
             keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
             keyboardActions = KeyboardActions(onNext = { focusRequester2.requestFocus() }),
             onValueChange = {
diff --git a/anastasis/src/main/java/net/taler/anastasis/ui/recovery/RecoveryFinishedScreen.kt b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/RecoveryFinishedScreen.kt
new file mode 100644
index 0000000..9cc58e5
--- /dev/null
+++ b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/RecoveryFinishedScreen.kt
@@ -0,0 +1,142 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2023 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.anastasis.ui.recovery
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.aspectRatio
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material.Icon
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.CloudDone
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.hilt.navigation.compose.hiltViewModel
+import net.taler.anastasis.R
+import net.taler.anastasis.models.CoreSecret
+import net.taler.anastasis.models.RecoveryInternalData
+import net.taler.anastasis.models.RecoveryStates
+import net.taler.anastasis.models.ReducerState
+import net.taler.anastasis.ui.reusable.pages.WizardPage
+import net.taler.anastasis.ui.theme.LocalSpacing
+import net.taler.anastasis.viewmodels.FakeReducerViewModel
+import net.taler.anastasis.viewmodels.ReducerViewModel
+import net.taler.anastasis.viewmodels.ReducerViewModelI
+import net.taler.common.CryptoUtils
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun RecoveryFinishedScreen(
+    viewModel: ReducerViewModelI = hiltViewModel<ReducerViewModel>(),
+) {
+    val state by viewModel.reducerState.collectAsState()
+    val reducerState = state as? ReducerState.Recovery
+        ?: error("invalid reducer state type")
+
+    val recoveryDocument = reducerState.recoveryDocument!!
+    val coreSecret = reducerState.coreSecret!!
+
+    WizardPage(
+        title = stringResource(R.string.recovery_finished_title),
+        onBackClicked = { viewModel.goHome() },
+        showNext = false,
+        showPrev = false,
+    ) {
+        LazyColumn(
+            modifier = Modifier
+                .fillMaxSize()
+                .nestedScroll(it),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            item {
+                Box(
+                    modifier = Modifier
+                        .padding(LocalSpacing.current.large)
+                        .background(MaterialTheme.colorScheme.primary, shape = CircleShape)
+                        .fillMaxWidth(0.4f)
+                        .aspectRatio(1f),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    Icon(
+                        Icons.Default.CloudDone,
+                        modifier = Modifier.fillMaxSize(0.5f),
+                        tint = MaterialTheme.colorScheme.onPrimary,
+                        contentDescription = stringResource(R.string.success),
+                    )
+                }
+            }
+
+            item {
+                Text(
+                    recoveryDocument.secretName,
+                    modifier = Modifier.padding(LocalSpacing.current.medium),
+                    style = MaterialTheme.typography.titleLarge,
+                )
+            }
+
+            item {
+                OutlinedTextField(
+                    modifier = Modifier
+                        .padding(
+                            start = LocalSpacing.current.medium,
+                            end = LocalSpacing.current.medium,
+                            bottom = LocalSpacing.current.small,
+                        ).fillMaxWidth(),
+                    value = CryptoUtils.decodeCrock(coreSecret.value).toString(Charsets.UTF_8),
+                    readOnly = true,
+                    onValueChange = {},
+                    label = { Text(stringResource(R.string.secret_text)) },
+                )
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+fun RecoveryFinishedScreenPreview() {
+    RecoveryFinishedScreen(
+        viewModel = FakeReducerViewModel(
+            state = ReducerState.Recovery(
+                recoveryState = RecoveryStates.RecoveryFinished,
+                recoveryDocument = RecoveryInternalData(
+                    secretName = "Secret",
+                    providerUrl = "http://localhost:8089",
+                    version = 1,
+                ),
+                coreSecret = CoreSecret(
+                    mime = "text/plain",
+                    value = CryptoUtils.encodeCrock("Taler".toByteArray(Charsets.UTF_8)),
+                )
+            ),
+        ),
+    )
+}
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SelectChallengeScreen.kt b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SelectChallengeScreen.kt
index 9060e22..df7afdf 100644
--- a/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SelectChallengeScreen.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SelectChallengeScreen.kt
@@ -16,18 +16,24 @@
 
 package net.taler.anastasis.ui.recovery
 
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Check
 import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.ElevatedCard
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedCard
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -40,6 +46,7 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.hilt.navigation.compose.hiltViewModel
 import net.taler.anastasis.R
 import net.taler.anastasis.models.AuthMethod
+import net.taler.anastasis.models.ChallengeFeedback
 import net.taler.anastasis.models.ChallengeInfo
 import net.taler.anastasis.models.RecoveryInformation
 import net.taler.anastasis.models.RecoveryStates
@@ -60,6 +67,7 @@ fun SelectChallengeScreen(
 
     val policies = reducerState.recoveryInformation?.policies ?: emptyList()
     val challenges = reducerState.recoveryInformation?.challenges ?: emptyList()
+    val challengeFeedback = reducerState.challengeFeedback ?: emptyMap()
 
     WizardPage(
         title = stringResource(R.string.select_challenge_title),
@@ -83,6 +91,7 @@ fun SelectChallengeScreen(
                     policy = policies[index],
                     policyIndex = index,
                     challenges = challenges,
+                    challengeFeedback = challengeFeedback,
                     onChallengeClick = { uuid ->
                         viewModel.reducerManager?.selectChallenge(uuid)
                     }
@@ -98,6 +107,7 @@ fun PolicyCard(
     policy: List<RecoveryInformation.Policy>,
     policyIndex: Int,
     challenges: List<ChallengeInfo>,
+    challengeFeedback: Map<String, ChallengeFeedback>,
     onChallengeClick: (uuid: String) -> Unit,
 ) {
     ElevatedCard(
@@ -119,6 +129,7 @@ fun PolicyCard(
                             .padding(top = LocalSpacing.current.small)
                             .fillMaxWidth(),
                         challenge = challenge,
+                        challengeFeedback = challengeFeedback[challenge.uuid],
                         onClick = { onChallengeClick(uuid) },
                     )
                 }
@@ -131,34 +142,85 @@ fun PolicyCard(
 fun ChallengeCard(
     modifier: Modifier = Modifier,
     challenge: ChallengeInfo,
+    challengeFeedback: ChallengeFeedback? = null,
     onClick: () -> Unit,
 ) {
     OutlinedCard(
         modifier = modifier,
     ) {
-        Row(
-            modifier = Modifier.padding(LocalSpacing.current.medium),
-            verticalAlignment = Alignment.CenterVertically,
+        Column(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalAlignment = Alignment.End,
         ) {
-            Icon(
-                challenge.type.icon,
-                tint = MaterialTheme.colorScheme.onBackground,
-                contentDescription = stringResource(challenge.type.nameRes),
-            )
-            Spacer(Modifier.width(LocalSpacing.current.medium))
-            Text(
-                challenge.instructions,
-                modifier = Modifier.weight(1f),
-                style = MaterialTheme.typography.labelLarge,
-            )
-            Spacer(Modifier.width(LocalSpacing.current.medium))
-            Button(onClick = onClick) {
-                Text(stringResource(R.string.challenge_solve))
+            Row(
+                modifier = Modifier.padding(LocalSpacing.current.medium),
+                verticalAlignment = Alignment.CenterVertically,
+            ) {
+                Icon(
+                    challenge.type.icon,
+                    tint = MaterialTheme.colorScheme.onBackground,
+                    contentDescription = stringResource(challenge.type.nameRes),
+                )
+                Spacer(Modifier.width(LocalSpacing.current.medium))
+                Text(
+                    challenge.instructions,
+                    modifier = Modifier.weight(1f),
+                    style = MaterialTheme.typography.labelLarge,
+                )
+                Spacer(Modifier.width(LocalSpacing.current.medium))
+                when (challengeFeedback) {
+                    is ChallengeFeedback.Solved -> FeedbackSolvedButton()
+                    else -> Button(onClick = onClick) {
+                        Text(stringResource(R.string.challenge_solve))
+                    }
+                }
+            }
+
+            if (challengeFeedback != null && challengeFeedback !is ChallengeFeedback.Solved) {
+                Box(Modifier.padding(
+                    end = LocalSpacing.current.medium,
+                    bottom = LocalSpacing.current.medium,
+                    start = LocalSpacing.current.medium,
+                )) {
+                    Text(
+                        when (challengeFeedback) {
+                            is ChallengeFeedback.Solved -> return@Box
+                            is ChallengeFeedback.IncorrectAnswer -> stringResource(R.string.challenge_feedback_incorrect_answer)
+                            is ChallengeFeedback.CodeInFile -> challengeFeedback.displayHint
+                            is ChallengeFeedback.CodeSent -> challengeFeedback.displayHint
+                            is ChallengeFeedback.Unsupported -> stringResource(R.string.challenge_feedback_unsupported)
+                            is ChallengeFeedback.RateLimitExceeded -> stringResource(R.string.challenge_feedback_rate_limit_exceeded)
+                            is ChallengeFeedback.BankTransferRequired -> stringResource(R.string.challenge_feedback_bank_transfer_required)
+                            is ChallengeFeedback.ServerFailure -> stringResource(R.string.challenge_feedback_server_failure)
+                            is ChallengeFeedback.TruthUnknown -> stringResource(R.string.challenge_feedback_truth_unknown)
+                            is ChallengeFeedback.TalerPaymentRequired -> stringResource(R.string.challenge_feedback_taler_payment_required)
+                        },
+                        style = MaterialTheme.typography.labelMedium
+                            .copy(color = MaterialTheme.colorScheme.error),
+                    )
+                }
             }
         }
     }
 }
 
+@Composable
+fun FeedbackSolvedButton() {
+    OutlinedButton(
+        onClick = {},
+        enabled = false,
+    ) {
+        val label = stringResource(R.string.challenge_feedback_solved)
+        Icon(
+            imageVector = Icons.Default.Check,
+            contentDescription = label,
+            modifier = Modifier.size(ButtonDefaults.IconSize),
+        )
+        Spacer(Modifier.size(ButtonDefaults.IconSpacing))
+        Text(label)
+    }
+}
+
 @Preview
 @Composable
 fun SelectChallengeScreenPreview() {
@@ -186,6 +248,10 @@ fun SelectChallengeScreenPreview() {
                         ),
                     ),
                 ),
+                challengeFeedback = mapOf(
+                    "RNB84NQZPCM3MZWF9D5FFMSYYN07J2NAT5N8Q0DBHHT7R3GJ4AA0" to ChallengeFeedback.IncorrectAnswer,
+                    "ZA6T35B8XAR0DNKS5H100GK8PDPTA7Q8ST2FPQSYAZ4QRAA9XKK0" to ChallengeFeedback.Solved,
+                ),
             ),
         ),
     )
diff --git a/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SolveChallengeScreen.kt b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SolveChallengeScreen.kt
new file mode 100644
index 0000000..ece93d5
--- /dev/null
+++ b/anastasis/src/main/java/net/taler/anastasis/ui/recovery/SolveChallengeScreen.kt
@@ -0,0 +1,141 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2023 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.anastasis.ui.recovery
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.hilt.navigation.compose.hiltViewModel
+import net.taler.anastasis.R
+import net.taler.anastasis.models.AuthMethod
+import net.taler.anastasis.models.ChallengeFeedback
+import net.taler.anastasis.models.ReducerState
+import net.taler.anastasis.shared.Utils
+import net.taler.anastasis.ui.forms.EditAnswerForm
+import net.taler.anastasis.ui.reusable.pages.WizardPage
+import net.taler.anastasis.ui.theme.LocalSpacing
+import net.taler.anastasis.viewmodels.ReducerViewModel
+import net.taler.anastasis.viewmodels.ReducerViewModelI
+
+@Composable
+fun SolveChallengeScreen(
+    viewModel: ReducerViewModelI = hiltViewModel<ReducerViewModel>(),
+) {
+    val state by viewModel.reducerState.collectAsState()
+    val reducerState = state as? ReducerState.Recovery
+        ?: error("invalid reducer state type")
+
+    val selectedChallengeUuid = reducerState.selectedChallengeUuid
+    val challenge = remember(selectedChallengeUuid) {
+        reducerState.recoveryInformation?.challenges?.find {
+            it.uuid == selectedChallengeUuid
+        } ?: error("empty challenge")
+    }
+    val challengeFeedback = remember(selectedChallengeUuid) {
+        reducerState.challengeFeedback?.get(challenge.uuid)
+    }
+
+    val question by remember { mutableStateOf(challenge.instructions) }
+    var answer by remember { mutableStateOf("") }
+
+    WizardPage(
+        title = stringResource(R.string.solve_challenge_title),
+        onBackClicked = { viewModel.goHome() },
+        onPrevClicked = { viewModel.goBack() },
+        onNextClicked = {
+            when (challenge.type) {
+                AuthMethod.Type.Question -> {
+                    viewModel.reducerManager?.solveChallenge(answer)
+                }
+                AuthMethod.Type.Sms, AuthMethod.Type.Email -> {
+                    viewModel.reducerManager?.solveChallenge(Utils.extractVerificationCode(answer))
+                }
+                // TODO: handle other challenge types
+                else -> {}
+            }
+        },
+    ) {
+        Column {
+            if (challengeFeedback != null && challengeFeedback !is ChallengeFeedback.Solved) {
+                Box(
+                    Modifier
+                        .fillMaxWidth()
+                        .background(MaterialTheme.colorScheme.primary),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    Text(
+                        when (challengeFeedback) {
+                            is ChallengeFeedback.Solved -> return@Box
+                            is ChallengeFeedback.IncorrectAnswer -> stringResource(R.string.challenge_feedback_incorrect_answer)
+                            is ChallengeFeedback.CodeInFile -> challengeFeedback.displayHint
+                            is ChallengeFeedback.CodeSent -> challengeFeedback.displayHint
+                            is ChallengeFeedback.Unsupported -> stringResource(R.string.challenge_feedback_unsupported)
+                            is ChallengeFeedback.RateLimitExceeded -> stringResource(R.string.challenge_feedback_rate_limit_exceeded)
+                            is ChallengeFeedback.BankTransferRequired -> stringResource(R.string.challenge_feedback_bank_transfer_required)
+                            is ChallengeFeedback.ServerFailure -> stringResource(R.string.challenge_feedback_server_failure)
+                            is ChallengeFeedback.TruthUnknown -> stringResource(R.string.challenge_feedback_truth_unknown)
+                            is ChallengeFeedback.TalerPaymentRequired -> stringResource(R.string.challenge_feedback_taler_payment_required)
+                        },
+                        modifier = Modifier.padding(LocalSpacing.current.small),
+                        style = MaterialTheme.typography.labelLarge,
+                        color = MaterialTheme.colorScheme.onPrimary,
+                    )
+                }
+            }
+            Box(Modifier.padding(LocalSpacing.current.medium)) {
+                when (challenge.type) {
+                    AuthMethod.Type.Question -> EditAnswerForm(
+                        question = question,
+                        answerLabel = stringResource(R.string.answer),
+                        answer = answer,
+                        onAnswerEdited = { answer = it }
+                    )
+
+                    AuthMethod.Type.Sms, AuthMethod.Type.Email -> EditAnswerForm(
+                        answerLabel = stringResource(R.string.code),
+                        answer = answer,
+                        onAnswerEdited = { answer = it },
+                        regex = "^A-\\d{5}-\\d{3}-\\d{4}-\\d{3}$",
+                    )
+
+                    // TODO: handle other challenge types
+                    else -> {}
+                }
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+fun SolveChallengeScreenPreview() {
+    SolveChallengeScreen()
+}
\ No newline at end of file
diff --git a/anastasis/src/main/java/net/taler/anastasis/viewmodels/ReducerViewModel.kt b/anastasis/src/main/java/net/taler/anastasis/viewmodels/ReducerViewModel.kt
index 24c17d6..faba94a 100644
--- a/anastasis/src/main/java/net/taler/anastasis/viewmodels/ReducerViewModel.kt
+++ b/anastasis/src/main/java/net/taler/anastasis/viewmodels/ReducerViewModel.kt
@@ -92,8 +92,8 @@ class ReducerViewModel @Inject constructor(): ViewModel(), ReducerViewModelI {
                             Routes.SelectChallenge.route
                         }
                         RecoveryStates.ChallengePaying -> TODO()
-                        RecoveryStates.ChallengeSolving -> TODO()
-                        RecoveryStates.RecoveryFinished -> TODO()
+                        RecoveryStates.ChallengeSolving -> Routes.SolveChallenge.route
+                        RecoveryStates.RecoveryFinished -> Routes.RecoveryFinished.route
                     }
                     else -> Routes.Home.route
                 }
diff --git a/anastasis/src/main/res/values/strings.xml b/anastasis/src/main/res/values/strings.xml
index 9aeebb5..b7dfed7 100644
--- a/anastasis/src/main/res/values/strings.xml
+++ b/anastasis/src/main/res/values/strings.xml
@@ -32,6 +32,7 @@
     <string name="field_empty">This field is required</string>
     <string name="field_invalid">This field is invalid</string>
     <string name="field_optional">This field is optional</string>
+    <string name="code">Verification code</string>
 
     <!-- Common -->
     <string name="select_continent_title">Where do you live?</string>
@@ -70,5 +71,15 @@
     <!-- Recovery -->
     <string name="select_secret_title">Select secret</string>
     <string name="select_challenge_title">Select challenge</string>
+    <string name="solve_challenge_title">Solve challenge</string>
+    <string name="recovery_finished_title">Your secret was recovered</string>
     <string name="challenge_solve">Solve</string>
+    <string name="challenge_feedback_solved">Solved</string>
+    <string name="challenge_feedback_incorrect_answer">Incorrect answer</string>
+    <string name="challenge_feedback_unsupported">Method unsupported</string>
+    <string name="challenge_feedback_rate_limit_exceeded">Rate limit exceeded</string>
+    <string name="challenge_feedback_bank_transfer_required">Bank transfer required</string>
+    <string name="challenge_feedback_server_failure">There was a server failure</string>
+    <string name="challenge_feedback_taler_payment_required">Taler payment required</string>
+    <string name="challenge_feedback_truth_unknown">Can\'t solve challenge</string>
 </resources>
\ No newline at end of file