feat: add export to eml action

.gitignore

@@ -46,3 +46,5 @@ captures/
 
 # Screenshots
 adb-screenshots/
+# Extracted eml files
+eml-files/

app-common/build.gradle.kts

@@ -47,6 +47,9 @@ dependencies {
     implementation(projects.feature.notification.impl)
     implementation(projects.feature.widget.messageList)
 
+    implementation(projects.feature.mail.message.export.api)
+    implementation(projects.feature.mail.message.export.implEml)
+
     implementation(projects.mail.protocols.imap)
     implementation(projects.backend.imap)
 

app-common/src/main/kotlin/net/thunderbird/app/common/feature/mail/FeatureMailModule.kt

@@ -2,6 +2,7 @@ package net.thunderbird.app.common.feature.mail
 
 import com.fsck.k9.mailstore.DefaultSpecialFolderUpdater
 import com.fsck.k9.mailstore.LegacyAccountDtoSpecialFolderUpdaterFactory
+import net.thunderbird.app.common.feature.mail.message.mailMessageModule
 import net.thunderbird.backend.api.BackendFactory
 import net.thunderbird.backend.api.BackendStorageFactory
 import net.thunderbird.backend.api.folder.RemoteFolderCreator
@@ -13,6 +14,8 @@ import org.koin.dsl.module
 
 internal val appCommonFeatureMailModule = module {
 
+    includes(mailMessageModule)
+
     single<BackendStorageFactory<BaseAccount>> {
         BaseAccountBackendStorageFactory(
             legacyFactory = get(),

app-common/src/main/kotlin/net/thunderbird/app/common/feature/mail/message/MailMessageModule.kt

@@ -0,0 +1,17 @@
+package net.thunderbird.app.common.feature.mail.message
+
+import net.thunderbird.feature.mail.message.export.DefaultMessageFileNameSuggester
+import net.thunderbird.feature.mail.message.export.MessageExporter
+import net.thunderbird.feature.mail.message.export.MessageFileNameSuggester
+import net.thunderbird.feature.mail.message.export.eml.EmlMessageExporter
+import org.koin.dsl.module
+
+internal val mailMessageModule = module {
+    single<MessageFileNameSuggester> { DefaultMessageFileNameSuggester() }
+
+    single<MessageExporter> {
+        EmlMessageExporter(
+            fileManager = get(),
+        )
+    }
+}

app-k9mail/src/debug/kotlin/app/k9mail/featureflag/K9FeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package app.k9mail.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -18,6 +19,7 @@ class K9FeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = false),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = false),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = true),
         )
     }
 }

app-k9mail/src/release/kotlin/app/k9mail/featureflag/K9FeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package app.k9mail.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -22,6 +23,7 @@ class K9FeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = false),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = false),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = false),
         )
     }
 }

app-thunderbird/src/beta/kotlin/net/thunderbird/android/featureflag/TbFeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.android.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -21,6 +22,7 @@ class TbFeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = false),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = false),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = false),
         )
     }
 }

app-thunderbird/src/daily/kotlin/net/thunderbird/android/featureflag/TbFeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.android.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -21,6 +22,7 @@ class TbFeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = true),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = false),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = true),
         )
     }
 }

app-thunderbird/src/debug/kotlin/net/thunderbird/android/featureflag/TbFeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.android.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -21,6 +22,7 @@ class TbFeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = true),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = true),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = true),
         )
     }
 }

app-thunderbird/src/release/kotlin/net/thunderbird/android/featureflag/TbFeatureFlagFactory.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.android.featureflag
 
 import com.fsck.k9.ui.messagelist.MessageListFeatureFlags
+import com.fsck.k9.ui.messageview.MessageViewFeatureFlags
 import net.thunderbird.core.featureflag.FeatureFlag
 import net.thunderbird.core.featureflag.FeatureFlagFactory
 import net.thunderbird.core.featureflag.FeatureFlagKey
@@ -21,6 +22,7 @@ class TbFeatureFlagFactory : FeatureFlagFactory {
             FeatureFlag(FeatureFlagKey.DisplayInAppNotifications, enabled = false),
             FeatureFlag(FeatureFlagKey.UseNotificationSenderForSystemNotifications, enabled = false),
             FeatureFlag(MessageListFeatureFlags.UseComposeForMessageListItems, enabled = false),
+            FeatureFlag(MessageViewFeatureFlags.ActionExportEml, enabled = false),
         )
     }
 }

feature/mail/message/export/api/build.gradle.kts

@@ -0,0 +1,16 @@
+plugins {
+    id(ThunderbirdPlugins.Library.kmp)
+}
+
+kotlin {
+    sourceSets {
+        commonMain.dependencies {
+            implementation(libs.uri)
+            implementation(projects.core.outcome)
+        }
+    }
+}
+
+android {
+    namespace = "net.thunderbird.feature.mail.message.export"
+}

feature/mail/message/export/api/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/DefaultMessageFileNameSuggester.kt

@@ -0,0 +1,37 @@
+package net.thunderbird.feature.mail.message.export
+
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.format.char
+
+/**
+ * Default, format-agnostic implementation for [MessageFileNameSuggester].
+ */
+class DefaultMessageFileNameSuggester : MessageFileNameSuggester {
+    override fun suggestFileName(subject: String, sentDateTime: LocalDateTime, extension: String): String {
+        val normalizedSubject = subject.trim()
+            .lowercase()
+            .replace(nonAlphanumericRegex, "-")
+            .replace(consecutiveDashesRegex, "-")
+            .trim('-')
+            .ifEmpty { "message" }
+
+        return "${fileNameDateFormat.format(sentDateTime)}_$normalizedSubject.$extension"
+    }
+
+    private companion object {
+        val fileNameDateFormat = LocalDateTime.Format {
+            year()
+            char('-')
+            monthNumber()
+            char('-')
+            day()
+            char('_')
+            hour()
+            char('-')
+            minute()
+        }
+
+        val nonAlphanumericRegex = Regex("[^a-z0-9-]+")
+        val consecutiveDashesRegex = Regex("-+")
+    }
+}

feature/mail/message/export/api/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/MessageExportError.kt

@@ -0,0 +1,19 @@
+package net.thunderbird.feature.mail.message.export
+
+import com.eygraber.uri.Uri
+
+/**
+ * Error type for message export failures.
+ *
+ * Keep this minimal and format-agnostic. Additional cases can be added later if needed.
+ */
+sealed interface MessageExportError {
+    /** Source or destination couldn't be opened or accessed. */
+    data class Unavailable(val uri: Uri, val message: String? = null) : MessageExportError
+
+    /** Generic I/O error while copying/exporting. */
+    data class Io(val message: String? = null) : MessageExportError
+
+    /** Fallback when the error type can't be determined. */
+    data class Unknown(val message: String? = null) : MessageExportError
+}

feature/mail/message/export/api/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/MessageExportResult.kt

@@ -0,0 +1,10 @@
+package net.thunderbird.feature.mail.message.export
+
+import net.thunderbird.core.outcome.Outcome
+
+/**
+ * Result type for message export using the shared Outcome abstraction.
+ *
+ * Success carries Unit. Failure carries an [MessageExportError].
+ */
+typealias MessageExportResult = Outcome<Unit, MessageExportError>

feature/mail/message/export/api/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/MessageExporter.kt

@@ -0,0 +1,23 @@
+package net.thunderbird.feature.mail.message.export
+
+import com.eygraber.uri.Uri
+
+/**
+ * API for exporting messages in a format-agnostic way, decoupled from platform specifics.
+ *
+ * The exporter operates on URIs so the UI/platform can select a source and destination.
+ * Implementations handle the I/O using platform-provided file system access.
+ */
+interface MessageExporter {
+    /**
+     * Export a message from the given source URI to the destination URI.
+     *
+     * @param sourceUri Uri of the source message
+     * @param destinationUri Uri of the destination for the exported message
+     * @return [MessageExportResult] indicating success or failure of the export operation
+     */
+    suspend fun export(
+        sourceUri: Uri,
+        destinationUri: Uri,
+    ): MessageExportResult
+}

feature/mail/message/export/api/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/MessageFileNameSuggester.kt

@@ -0,0 +1,17 @@
+package net.thunderbird.feature.mail.message.export
+
+import kotlinx.datetime.LocalDateTime
+
+/**
+ * Responsible for suggesting filesystem-friendly file names for exported messages.
+ */
+interface MessageFileNameSuggester {
+    /**
+     * Suggest a filename using a subject and (local) date & time, plus a required file extension.
+     *
+     * @param subject Subject to include in the file name. Callers should pass a reasonable default if the message has no subject.
+     * @param sentDateTime (local) date & time to include as a prefix in the file name.
+     * @param extension File extension without the leading dot, e.g., "eml".
+     */
+    fun suggestFileName(subject: String, sentDateTime: LocalDateTime, extension: String): String
+}

feature/mail/message/export/api/src/commonTest/kotlin/net/thunderbird/feature/mail/message/export/DefaultMessageFileNameSuggesterTest.kt

@@ -0,0 +1,54 @@
+package net.thunderbird.feature.mail.message.export
+
+import assertk.assertThat
+import assertk.assertions.isEqualTo
+import kotlin.test.Test
+import kotlinx.datetime.LocalDateTime
+
+class DefaultMessageFileNameSuggesterTest {
+
+    private val testSubject = DefaultMessageFileNameSuggester()
+
+    @Test
+    fun `suggestFileName should format date and time, normalize subject, and append extension`() {
+        // Arrange
+        val dt = LocalDateTime(2025, 10, 15, 14, 1)
+        val subject = "Meeting Reminder: Project Kickoff @ 10am!"
+        val extension = "eml"
+
+        // Act
+        val result = testSubject.suggestFileName(subject = subject, sentDateTime = dt, extension = extension)
+
+        // Assert
+        assertThat(result)
+            .isEqualTo("2025-10-15_14-01_meeting-reminder-project-kickoff-10am.eml")
+    }
+
+    @Test
+    fun `suggestFileName should normalize mixed case and non-alphanumeric characters`() {
+        // Arrange
+        val dt = LocalDateTime(2023, 1, 2, 3, 4)
+        val subject = "  HeLLo___World!!  -@-  ###Thunderbird!!!  "
+        val extension = "eml"
+
+        // Act
+        val result = testSubject.suggestFileName(subject = subject, sentDateTime = dt, extension = extension)
+
+        // Assert
+        assertThat(result).isEqualTo("2023-01-02_03-04_hello-world-thunderbird.eml")
+    }
+
+    @Test
+    fun `suggestFileName should fall back to message when subject is blank or symbols only`() {
+        // Arrange
+        val dt = LocalDateTime(1999, 12, 31, 23, 59)
+
+        // Act
+        val resultBlank = testSubject.suggestFileName(subject = "\t \n  ", sentDateTime = dt, extension = "eml")
+        val resultSymbols = testSubject.suggestFileName(subject = "*** ### !!!", sentDateTime = dt, extension = "log")
+
+        // Assert
+        assertThat(resultBlank).isEqualTo("1999-12-31_23-59_message.eml")
+        assertThat(resultSymbols).isEqualTo("1999-12-31_23-59_message.log")
+    }
+}

feature/mail/message/export/impl-eml/build.gradle.kts

@@ -0,0 +1,20 @@
+plugins {
+    id(ThunderbirdPlugins.Library.kmp)
+}
+
+kotlin {
+    sourceSets {
+        commonMain.dependencies {
+            api(projects.feature.mail.message.export.api)
+            implementation(projects.core.outcome)
+            implementation(projects.core.file)
+
+            implementation(libs.kotlinx.io.core)
+            implementation(libs.uri)
+        }
+    }
+}
+
+android {
+    namespace = "net.thunderbird.feature.mail.message.export.eml"
+}

feature/mail/message/export/impl-eml/src/commonMain/kotlin/net/thunderbird/feature/mail/message/export/eml/EmlMessageExporter.kt

@@ -0,0 +1,41 @@
+package net.thunderbird.feature.mail.message.export.eml
+
+import com.eygraber.uri.Uri
+import net.thunderbird.core.file.FileManager
+import net.thunderbird.core.file.FileOperationError
+import net.thunderbird.core.outcome.Outcome
+import net.thunderbird.feature.mail.message.export.MessageExportError
+import net.thunderbird.feature.mail.message.export.MessageExportResult
+import net.thunderbird.feature.mail.message.export.MessageExporter
+
+class EmlMessageExporter(
+    private val fileManager: FileManager,
+) : MessageExporter {
+    override suspend fun export(
+        sourceUri: Uri,
+        destinationUri: Uri,
+    ): MessageExportResult {
+        val outcome = fileManager.copy(sourceUri = sourceUri, destinationUri = destinationUri)
+        return when (outcome) {
+            is Outcome.Success -> Outcome.Success(Unit)
+            is Outcome.Failure -> Outcome.Failure(
+                error = mapError(outcome.error),
+                cause = outcome.cause,
+            )
+        }
+    }
+
+    private fun mapError(
+        error: FileOperationError,
+    ): MessageExportError {
+        return when (error) {
+            is FileOperationError.Unavailable -> MessageExportError.Unavailable(
+                error.uri,
+                error.message,
+            )
+            is FileOperationError.ReadFailed -> MessageExportError.Io(error.message)
+            is FileOperationError.WriteFailed -> MessageExportError.Io(error.message)
+            is FileOperationError.Unknown -> MessageExportError.Unknown(error.message)
+        }
+    }
+}