Implemented saving message UID so that on next app run fetchAllEmails() can continue on last downloaded message

e-invoice-domain/src/main/kotlin/net/codinux/invoicing/email/EmailsFetcher.kt

@@ -6,6 +6,7 @@ import jakarta.mail.Multipart
 import jakarta.mail.Part
 import jakarta.mail.Session
 import jakarta.mail.Store
+import jakarta.mail.UIDFolder
 import jakarta.mail.event.MessageCountAdapter
 import jakarta.mail.event.MessageCountEvent
 import kotlinx.coroutines.*
@@ -116,19 +117,23 @@ open class EmailsFetcher(
             return@runBlocking emptyList()
         }
 
-        IntRange(1, messageCount).mapNotNull { messageNumber -> // message numbers start at 1
-            async(coroutineDispatcher) {
-                try {
-                    getEmail(folder.getMessage(messageNumber), status)
-                } catch (e: Throwable) {
-                    log.error(e) { "Could not get email with messageNumber $messageNumber" }
-                    status.addError(FetchEmailsErrorType.GetEmail, messageNumber, e)
-                    null
+        async(coroutineDispatcher) {
+            val startUid = max(status.options.lastRetrievedMessageId?.let { it + 1 } ?: 0, 1) // message numbers start at 1
+
+            folder.getMessagesByUID(startUid, UIDFolder.MAXUID).mapNotNull { message ->
+                async(coroutineDispatcher) {
+                    try {
+                        getEmail(message, status)
+                    } catch (e: Throwable) {
+                        log.error(e) { "Could not get email $message" }
+                        status.addError(FetchEmailsErrorType.GetEmail, message, e)
+                        null
+                    }
                 }
             }
-        }
-            .awaitAll()
-            .filterNotNull()
+                .awaitAll()
+                .filterNotNull()
+        }.await()
     }
 
     protected open fun getEmail(message: Message, status: FetchEmailsStatus): Email? {

e-invoice-domain/src/main/kotlin/net/codinux/invoicing/email/FetchEmailsOptions.kt

@@ -4,6 +4,11 @@ import net.codinux.invoicing.email.model.Email
 import java.io.File
 
 open class FetchEmailsOptions(
+    /**
+     * The ID of the last retrieved message. If set, only messages newer than this ID will be fetched.
+     */
+    val lastRetrievedMessageId: Long? = null,
+
     val downloadMessageBody: Boolean = false,
     /**
      * Set the extension (without the dot) of files that should be downloaded.

e-invoice-domain/src/main/kotlin/net/codinux/invoicing/email/ListenForNewMailsOptions.kt

@@ -16,4 +16,4 @@ open class ListenForNewMailsOptions(
 
     onError: ((FetchEmailsError) -> Unit)? = null,
     onEmailReceived: (Email) -> Unit
-) : FetchEmailsOptions(downloadMessageBody, downloadAttachmentsWithExtensions, attachmentsDownloadDirectory, emailFolderName, connectTimeoutSeconds, onError, onEmailReceived)
+) : FetchEmailsOptions(null, downloadMessageBody, downloadAttachmentsWithExtensions, attachmentsDownloadDirectory, emailFolderName, connectTimeoutSeconds, onError, onEmailReceived)

e-invoice-domain/src/test/kotlin/net/codinux/invoicing/email/EmailsFetcherTest.kt

@@ -27,7 +27,7 @@ class EmailsFetcherTest {
 
     @Test
     fun fetchAllEmails() {
-        val result = underTest.fetchAllEmails(emailAccount, FetchEmailsOptions(true))
+        val result = underTest.fetchAllEmails(emailAccount, FetchEmailsOptions(downloadMessageBody = true))
 
         assertThat(result.overallError).isNull()
         assertThat(result.emails).isNotEmpty()