fix: Address PR nextcloud#3098 review comments on confirmation emails

- Allow form creators to explicitly select which email field to use for confirmations via the `confirmationEmailRecipient` property.
- Update `FormsService` to rely on the explicit recipient field when multiple email fields are present.
- Display relevant warnings in the settings tab if recipient fields are misconfigured.
- Replace basic email validation with Nextcloud's internal `\OCP\Mail\IEmailValidator`.
- Expand unit tests to verify explicit recipient selection and multi-email field validation logic.

Author: dtretyakov

lib/Constants.php

@@ -147,6 +147,7 @@ class Constants {
 	];
 
 	public const EXTRA_SETTINGS_SHORT = [
+		'confirmationEmailRecipient' => ['boolean'],
 		'validationType' => ['string'],
 		'validationRegex' => ['string'],
 	];

lib/ResponseDefinitions.php

@@ -26,6 +26,7 @@
  *   dateMax?: int,
  *   dateMin?: int,
  *   dateRange?: bool,
+ *   confirmationEmailRecipient?: bool,
  *   maxAllowedFilesCount?: int,
  *   maxFileSize?: int,
  *   optionsHighest?: 2|3|4|5|6|7|8|9|10,

lib/Service/FormsService.php

@@ -35,6 +35,7 @@
 use OCP\IUser;
 use OCP\IUserManager;
 use OCP\IUserSession;
+use OCP\Mail\IEmailValidator;
 use OCP\Mail\IMailer;
 use OCP\Search\ISearchQuery;
 use OCP\Security\ISecureRandom;
@@ -70,6 +71,7 @@ public function __construct(
 		private LoggerInterface $logger,
 		private IEventDispatcher $eventDispatcher,
 		private IMailer $mailer,
+		private IEmailValidator $emailValidator,
 		private AnswerMapper $answerMapper,
 	) {
 		$this->currentUser = $userSession->getUser();
@@ -771,12 +773,6 @@ private function sendConfirmationEmail(Form $form, Submission $submission): void
 		$questions = $this->getQuestions($form->getId());
 		$answers = $this->answerMapper->findBySubmission($submission->getId());
 
-		// Build a map of question IDs to questions and answers
-		$questionMap = [];
-		foreach ($questions as $question) {
-			$questionMap[$question['id']] = $question;
-		}
-
 		$answerMap = [];
 		foreach ($answers as $answer) {
 			$questionId = $answer->getQuestionId();
@@ -786,49 +782,25 @@ private function sendConfirmationEmail(Form $form, Submission $submission): void
 			$answerMap[$questionId][] = $answer->getText();
 		}
 
-		// Find email address from answers
-		$recipientEmails = [];
-		foreach ($questions as $question) {
-			if ($question['type'] !== Constants::ANSWER_TYPE_SHORT) {
-				continue;
-			}
-
-			$extraSettings = (array)($question['extraSettings'] ?? []);
-			$validationType = $extraSettings['validationType'] ?? null;
-			if ($validationType !== 'email') {
-				continue;
-			}
-
-			$questionId = $question['id'];
-			if (empty($answerMap[$questionId])) {
-				continue;
-			}
-
-			$emailValue = $answerMap[$questionId][0];
-			if ($this->mailer->validateMailAddress($emailValue)) {
-				$recipientEmails[] = $emailValue;
-			}
-		}
-
-		// If no email found, cannot send confirmation
-		if (empty($recipientEmails)) {
-			$this->logger->debug('No valid email address found in submission for confirmation email', [
+		$recipientQuestion = $this->getConfirmationEmailRecipientQuestion($questions);
+		if ($recipientQuestion === null) {
+			$this->logger->debug('No confirmation email recipient question is available', [
 				'formId' => $form->getId(),
 				'submissionId' => $submission->getId(),
 			]);
 			return;
 		}
 
-		if (count($recipientEmails) > 1) {
-			$this->logger->debug('Multiple email fields found in submission for confirmation email, using first match', [
+		$recipientQuestionId = $recipientQuestion['id'];
+		$recipientEmail = $answerMap[$recipientQuestionId][0] ?? null;
+		if ($recipientEmail === null || !$this->emailValidator->isValid($recipientEmail)) {
+			$this->logger->debug('No valid email address found in submission for confirmation email', [
 				'formId' => $form->getId(),
 				'submissionId' => $submission->getId(),
-				'emailCount' => count($recipientEmails),
 			]);
+			return;
 		}
 
-		$recipientEmail = $recipientEmails[0];
-
 		// Replace placeholders in subject and body
 		$replacements = [
 			'{formTitle}' => $form->getTitle(),
@@ -886,6 +858,55 @@ private function sendConfirmationEmail(Form $form, Submission $submission): void
 		}
 	}
 
+	/**
+	 * @param list<FormsQuestion> $questions
+	 * @return FormsQuestion|null
+	 */
+	private function getConfirmationEmailRecipientQuestion(array $questions): ?array {
+		$emailQuestions = array_values(array_filter(
+			$questions,
+			fn (array $question): bool => $this->isConfirmationEmailQuestion($question),
+		));
+
+		if ($emailQuestions === []) {
+			return null;
+		}
+
+		$explicitRecipients = array_values(array_filter(
+			$emailQuestions,
+			function (array $question): bool {
+				$extraSettings = (array)($question['extraSettings'] ?? []);
+				return !empty($extraSettings['confirmationEmailRecipient']);
+			},
+		));
+
+		if (count($explicitRecipients) === 1) {
+			return $explicitRecipients[0];
+		}
+
+		if (count($explicitRecipients) > 1) {
+			return null;
+		}
+
+		if (count($emailQuestions) === 1) {
+			return $emailQuestions[0];
+		}
+
+		return null;
+	}
+
+	/**
+	 * @param FormsQuestion $question
+	 */
+	private function isConfirmationEmailQuestion(array $question): bool {
+		if (($question['type'] ?? null) !== Constants::ANSWER_TYPE_SHORT) {
+			return false;
+		}
+
+		$extraSettings = (array)($question['extraSettings'] ?? []);
+		return ($extraSettings['validationType'] ?? null) === 'email';
+	}
+
 	/**
 	 * Return shares of a form shared with given user
 	 *

src/components/Questions/QuestionShort.vue

@@ -69,12 +69,19 @@
 					/^[a-z]{3}$/i
 					<!-- ^ Some example RegExp for the placeholder text -->
 				</NcActionInput>
+				<NcActionCheckbox
+					v-if="validationType === 'email'"
+					:model-value="isConfirmationEmailRecipient"
+					@update:model-value="onConfirmationEmailRecipientChange">
+					{{ t('forms', 'Use for confirmation emails') }}
+				</NcActionCheckbox>
 			</NcActions>
 		</div>
 	</Question>
 </template>
 
 <script>
+import NcActionCheckbox from '@nextcloud/vue/components/NcActionCheckbox'
 import NcActionInput from '@nextcloud/vue/components/NcActionInput'
 import NcActionRadio from '@nextcloud/vue/components/NcActionRadio'
 import NcActions from '@nextcloud/vue/components/NcActions'
@@ -89,6 +96,7 @@ export default {
 
 	components: {
 		IconRegex,
+		NcActionCheckbox,
 		NcActions,
 		NcActionInput,
 		NcActionRadio,
@@ -146,6 +154,10 @@ export default {
 		validationRegex() {
 			return this.extraSettings?.validationRegex || ''
 		},
+
+		isConfirmationEmailRecipient() {
+			return this.extraSettings?.confirmationEmailRecipient ?? false
+		},
 	},
 
 	methods: {
@@ -185,19 +197,32 @@ export default {
 			if (validationType === 'regex') {
 				// Make sure to also submit a regex (even if empty)
 				this.onExtraSettingsChange({
+					confirmationEmailRecipient: undefined,
 					validationType,
 					validationRegex: this.validationRegex,
 				})
 			} else {
 				// For all other types except regex we close the menu (for regex we keep it open to allow entering a regex)
 				this.isValidationTypeMenuOpen = false
 				this.onExtraSettingsChange({
+					confirmationEmailRecipient:
+						validationType === 'email'
+							? this.isConfirmationEmailRecipient || undefined
+							: undefined,
 					validationType:
 						validationType === 'text' ? undefined : validationType,
 				})
 			}
 		},
 
+		onConfirmationEmailRecipientChange(confirmationEmailRecipient) {
+			this.onExtraSettingsChange({
+				confirmationEmailRecipient: confirmationEmailRecipient
+					? true
+					: undefined,
+			})
+		},
+
 		/**
 		 * Validate and save regex if valid
 		 *

src/components/SidebarTabs/SettingsSidebarTab.vue

@@ -182,7 +182,7 @@
 				{{
 					t(
 						'forms',
-						'Requires an email field in the form. Available placeholders: {formTitle}, {formDescription}, and field names like {name}.',
+						'Requires an email field in the form. If the form has multiple email fields, mark one question with “Use for confirmation emails”. Available placeholders: {formTitle}, {formDescription}, and field names like {name}.',
 					)
 				}}
 			</p>
@@ -196,12 +196,28 @@
 					)
 				" />
 			<NcNoteCard
-				v-else-if="form.confirmationEmailEnabled && emailQuestionCount > 1"
-				type="info"
+				v-else-if="
+					form.confirmationEmailEnabled
+					&& emailQuestionCount > 1
+					&& confirmationEmailRecipientCount === 0
+				"
+				type="error"
 				:text="
 					t(
 						'forms',
-						'Multiple email fields found. The first email field in the form order will be used.',
+						'Select one email field and enable “Use for confirmation emails” on that question.',
+					)
+				" />
+			<NcNoteCard
+				v-else-if="
+					form.confirmationEmailEnabled
+					&& confirmationEmailRecipientCount > 1
+				"
+				type="error"
+				:text="
+					t(
+						'forms',
+						'Only one email field can be used for confirmation emails.',
 					)
 				" />
 			<label class="confirmation-email__label">
@@ -221,7 +237,7 @@
 			<textarea
 				:value="confirmationEmailBody"
 				:disabled="locked"
-				:placeholder="t('forms', 'Thank you for submitting the form.')"
+				:placeholder="emailBodyPlaceholder"
 				class="confirmation-email__textarea"
 				@input="onConfirmationEmailBodyInput"
 				@blur="onConfirmationEmailBodyChange"></textarea>
@@ -390,11 +406,21 @@ export default {
 		},
 
 		emailQuestionCount() {
+			return this.confirmationEmailQuestions.length
+		},
+
+		confirmationEmailQuestions() {
 			const questions = this.form?.questions || []
 			return questions.filter(
 				(question) =>
 					question.type === 'short'
 					&& question.extraSettings?.validationType === 'email',
+			)
+		},
+
+		confirmationEmailRecipientCount() {
+			return this.confirmationEmailQuestions.filter(
+				(question) => question.extraSettings?.confirmationEmailRecipient,
 			).length
 		},
 	},