Check mail for missing attachment

src/components/NewMessageModal.vue

@@ -30,20 +30,27 @@
 		<Loading v-else-if="sending"
 			:hint="t('mail', 'Sending …')"
 			role="alert" />
-		<EmptyContent v-else-if="warning" :title="t('mail', 'Warning sending your message')" role="alert">
-			<p>{{ warning }}</p>
-			<ButtonVue
-				type="tertiary"
-				:aria-label="t('mail', 'Go back')"
-				@click="warning = undefined">
-				{{ t('mail', 'Go back') }}
-			</ButtonVue>
-			<ButtonVue
-				type="tertiary"
-				:aria-label="t('mail', 'Send anyway')"
-				@click="onForceSend">
-				{{ t('mail', 'Send anyway') }}
-			</ButtonVue>
+		<EmptyContent v-else-if="warning"
+			:title="t('mail', 'Warning sending your message')"
+			class="centered-content"
+			role="alert">
+			<template #description>
+				{{ warning }}
+			</template>
+			<template #action>
+				<ButtonVue
+					type="tertiary"
+					:aria-label="t('mail', 'Go back')"
+					@click="warning = undefined">
+					{{ t('mail', 'Go back') }}
+				</ButtonVue>
+				<ButtonVue
+					type="tertiary"
+					:aria-label="t('mail', 'Send anyway')"
+					@click="onForceSend">
+					{{ t('mail', 'Send anyway') }}
+				</ButtonVue>
+			</template>
 		</EmptyContent>
 		<template v-else>
 			<NcActions class="minimize-button">
@@ -114,6 +121,7 @@ import { UNDO_DELAY } from '../store/constants'
 import { matchError } from '../errors/match'
 import NoSentMailboxConfiguredError from '../errors/NoSentMailboxConfiguredError'
 import ManyRecipientsError from '../errors/ManyRecipientsError'
+import AttachmentMissingError from '../errors/AttachmentMissingError.js'
 import Loading from './Loading'
 import { mapGetters } from 'vuex'
 import MinimizeIcon from 'vue-material-design-icons/Minus.vue'
@@ -290,7 +298,7 @@ export default {
 				.then(() => logger.debug('attachments uploaded'))
 				.catch((error) => logger.error('could not upload attachments', { error }))
 		},
-		async onSend(data) {
+		async onSend(data, force = false) {
 			logger.debug('sending message', { data })
 
 			await this.attachmentsPromise
@@ -313,6 +321,20 @@ export default {
 					dataForServer.sendAt = Math.floor((now + UNDO_DELAY) / 1000)
 				}
 
+				if (!force && data.attachments.length === 0) {
+					const lines = toPlain(data.body).value.toLowerCase().split('\n')
+					const wordAttachment = t('mail', 'attachment').toLowerCase()
+					const wordAttached = t('mail', 'attached').toLowerCase()
+					for (const line of lines) {
+						if (line.startsWith('>') || line.startsWith('--')) {
+							break
+						}
+						if (line.includes(wordAttachment) || line.includes(wordAttached)) {
+							throw new AttachmentMissingError()
+						}
+					}
+				}
+
 				if (!this.composerData.id) {
 					// This is a new message
 					const { id } = await saveDraft(dataForServer)
@@ -357,10 +379,18 @@ export default {
 					[ManyRecipientsError.getName()]() {
 						return t('mail', 'You are trying to send to many recipients in To and/or Cc. Consider using Bcc to hide recipient addresses.')
 					},
+					// eslint-disable-next-line node/handle-callback-err
 					default(error) {
-						if (error && error.toString) {
-							return error.toString()
-						}
+						return undefined
+					},
+				})
+				this.warning = await matchError(error, {
+					[AttachmentMissingError.getName()]() {
+						return t('mail', 'You mentioned an attachment. Did you forget to add it?')
+					},
+					// eslint-disable-next-line node/handle-callback-err
+					default(error) {
+						return undefined
 					},
 				})
 			} finally {
@@ -380,7 +410,7 @@ export default {
 			}
 		},
 		async onForceSend() {
-			await this.onSend(null, true)
+			await this.onSend(this.cookedComposerData, true)
 		},
 		recipientToRfc822(recipient) {
 			if (recipient.email === recipient.label) {

src/errors/AttachmentMissingError.js

@@ -0,0 +1,32 @@
+/**
+ * @author 2023 Maximilian Martin <maximilian_martin@gmx.de>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+export default class AttachmentMissingError extends Error {
+
+	constructor(message) {
+		super(message)
+		this.name = AttachmentMissingError.getName()
+		this.message = message
+	}
+
+	static getName() {
+		return 'AttachmentMissingError'
+	}
+
+}