<?php

declare(strict_types=1);

namespace OCA\WorkflowDeckAutomation\Service;

use OCA\Deck\Db\Card;
use OCA\WorkflowDeckAutomation\Db\Workflow;
use OCP\IL10N;
use OCP\IURLGenerator;
use OCP\IUser;
use OCP\Mail\IEMailTemplate;
use OCP\Mail\IMailer;
use OCP\Util;
use Psr\Log\LoggerInterface;
use Throwable;

class NotificationMailer {
	/**
	 * Descriptions are unbounded in Deck; keep the mail readable and well
	 * clear of any MTA size limits.
	 */
	private const MAX_DESCRIPTION_LENGTH = 2000;

	public function __construct(
		private IMailer $mailer,
		private IURLGenerator $urlGenerator,
		private IL10N $l10n,
		private LoggerInterface $logger,
	) {
	}

	/**
	 * @param array{board: string, sourceStack: string, targetStack: string} $targets
	 *        titles resolved by DeckIntegrationService::describeTargets()
	 */
	public function sendCardMovedNotification(IUser $user, Workflow $workflow, Card $card, array $targets): void {
		$email = $user->getEMailAddress();
		if ($email === null || $email === '') {
			$this->logger->info('Skipping notification for workflow ' . $workflow->getId() . ': user ' . $user->getUID() . ' has no email address', [
				'app' => 'workflow_deck_automation',
			]);
			return;
		}

		try {
			$cardLink = $this->urlGenerator->getAbsoluteURL(
				'/apps/deck/board/' . $workflow->getBoardId() . '/card/' . $card->getId(),
			);

			$template = $this->mailer->createEMailTemplate('workflow_deck_automation.CardMoved', [
				'cardTitle' => $card->getTitle(),
				'workflowTitle' => $workflow->getTitle(),
			]);
			$template->setSubject($this->l10n->t('Deck card moved: %s', [$card->getTitle()]));
			$template->addHeader();
			$template->addHeading($this->l10n->t('A card was moved automatically'), false);
			$template->addBodyText($this->l10n->t(
				'The card "%1$s" was moved because it is overdue (workflow "%2$s").',
				[$card->getTitle(), $workflow->getTitle()],
			));
			// Single-argument addBodyText() runs htmlspecialchars() itself, so
			// these board- and stack-titles (user input) are safe as-is —
			// unlike the description below, which passes both parts.
			$template->addBodyText($this->l10n->t(
				'Board "%1$s": moved from "%2$s" to "%3$s".',
				[$targets['board'], $targets['sourceStack'], $targets['targetStack']],
			));
			$this->addCardDescription($template, $card);
			$template->addBodyButton($this->l10n->t('Open card'), $cardLink);
			$template->addFooter();

			$message = $this->mailer->createMessage();
			$message->setTo([$email => $user->getDisplayName()]);
			$message->setFrom([Util::getDefaultEmailAddress('noreply') => $this->l10n->t('Deck Workflow Automation')]);
			$message->useTemplate($template);

			$failedRecipients = $this->mailer->send($message);
			if (!empty($failedRecipients)) {
				$this->logger->error('Notification mail for card ' . $card->getId() . ' failed for: ' . implode(', ', $failedRecipients), [
					'app' => 'workflow_deck_automation',
				]);
			}
		} catch (Throwable $e) {
			$this->logger->error('Could not send notification mail for card ' . $card->getId() . ': ' . $e->getMessage(), [
				'app' => 'workflow_deck_automation',
				'exception' => $e,
			]);
		}
	}

	/**
	 * One-off notice that a workflow was switched off because the board or
	 * stack it points at is gone.
	 *
	 * @param WorkflowRunner::TARGET_* $brokenTarget
	 */
	public function sendWorkflowDisabledNotification(IUser $user, Workflow $workflow, string $brokenTarget): void {
		$email = $user->getEMailAddress();
		if ($email === null || $email === '') {
			$this->logger->info('Cannot notify about disabled workflow ' . $workflow->getId() . ': user ' . $user->getUID() . ' has no email address', [
				'app' => 'workflow_deck_automation',
			]);
			return;
		}

		$reason = match ($brokenTarget) {
			WorkflowRunner::TARGET_SOURCE_STACK => $this->l10n->t('its source stack no longer exists'),
			WorkflowRunner::TARGET_TARGET_STACK => $this->l10n->t('its target stack no longer exists'),
			default => $this->l10n->t('its board no longer exists or is no longer available to you'),
		};

		try {
			$settingsLink = $this->urlGenerator->getAbsoluteURL('/settings/user/workflow_deck_automation');

			$template = $this->mailer->createEMailTemplate('workflow_deck_automation.WorkflowDisabled', [
				'workflowTitle' => $workflow->getTitle(),
			]);
			$template->setSubject($this->l10n->t('Deck workflow deactivated: %s', [$workflow->getTitle()]));
			$template->addHeader();
			$template->addHeading($this->l10n->t('A workflow was deactivated'), false);
			$template->addBodyText($this->l10n->t(
				'The workflow "%1$s" was switched off automatically because %2$s. No cards are being moved by it any more.',
				[$workflow->getTitle(), $reason],
			));
			$template->addBodyText($this->l10n->t(
				'Delete the workflow or point it at an existing board and stack to reactivate it. You will not be reminded about this workflow again.',
			));
			$template->addBodyButton($this->l10n->t('Open settings'), $settingsLink);
			$template->addFooter();

			$message = $this->mailer->createMessage();
			$message->setTo([$email => $user->getDisplayName()]);
			$message->setFrom([Util::getDefaultEmailAddress('noreply') => $this->l10n->t('Deck Workflow Automation')]);
			$message->useTemplate($template);

			$failedRecipients = $this->mailer->send($message);
			if (!empty($failedRecipients)) {
				$this->logger->error('Deactivation mail for workflow ' . $workflow->getId() . ' failed for: ' . implode(', ', $failedRecipients), [
					'app' => 'workflow_deck_automation',
				]);
			}
		} catch (Throwable $e) {
			$this->logger->error('Could not send deactivation mail for workflow ' . $workflow->getId() . ': ' . $e->getMessage(), [
				'app' => 'workflow_deck_automation',
				'exception' => $e,
			]);
		}
	}

	/**
	 * Appends the card's description, if it has one.
	 *
	 * Deck stores the description as Markdown. It is sent as-is rather than
	 * rendered: pulling a Markdown parser in just for the mail would be a
	 * lot of machinery, and unrendered Markdown still reads fine.
	 */
	private function addCardDescription(IEMailTemplate $template, Card $card): void {
		$description = trim((string)$card->getDescription());
		if ($description === '') {
			return;
		}

		if (mb_strlen($description) > self::MAX_DESCRIPTION_LENGTH) {
			$description = mb_substr($description, 0, self::MAX_DESCRIPTION_LENGTH) . ' […]';
		}

		$template->addBodyText($this->l10n->t('Card content:'));

		// addBodyText() only runs htmlspecialchars() when it has to build the
		// plain-text part itself. Passing both parts means escaping is on us
		// -- and it has to be, because a card description is user input that
		// would otherwise land unescaped in the HTML mail.
		$template->addBodyText(
			nl2br(htmlspecialchars($description, ENT_QUOTES, 'UTF-8'), false),
			$description,
		);
	}
}