import CronExpressionParser from "cron-parser";
import path from "node:path";
import type { BackupSchedule } from "~/server/db/schema";
import { toMessage } from "~/server/utils/errors";
import { logger } from "~/server/utils/logger";

export const calculateNextRun = (cronExpression: string) => {
	try {
		const interval = CronExpressionParser.parse(cronExpression, {
			currentDate: new Date(),
			tz: Intl.DateTimeFormat().resolvedOptions().timeZone,
		});
		return interval.next().getTime();
	} catch (error) {
		logger.error(`Failed to parse cron expression "${cronExpression}": ${toMessage(error)}`);
		const fallback = new Date();
		fallback.setMinutes(fallback.getMinutes() + 1);
		return fallback.getTime();
	}
};

export const processPattern = (pattern: string, volumePath: string) => {
	const isNegated = pattern.startsWith("!");
	const p = isNegated ? pattern.slice(1) : pattern;

	const relative = path.relative(volumePath, p);
	const isInsideVolume = !relative.startsWith("..") && !path.isAbsolute(relative);

	if (isInsideVolume || !p.startsWith("/")) {
		return pattern;
	}

	const processed = path.join(volumePath, p.slice(1));
	return isNegated ? `!${processed}` : processed;
};

export const createBackupOptions = (schedule: BackupSchedule, volumePath: string, signal: AbortSignal) => ({
	tags: [schedule.shortId],
	oneFileSystem: schedule.oneFileSystem,
	signal,
	exclude: schedule.excludePatterns ? schedule.excludePatterns.map((p) => processPattern(p, volumePath)) : undefined,
	excludeIfPresent: schedule.excludeIfPresent ?? undefined,
	include: schedule.includePatterns ? schedule.includePatterns.map((p) => processPattern(p, volumePath)) : undefined,
});