import { type ClassValue, clsx } from "clsx";
import { twMerge } from "tailwind-merge";

// Regex patterns for slugify
const DIACRITICS_PATTERN = /[\u0300-\u036f]/g;
const WHITESPACE_UNDERSCORE_PATTERN = /[\s_]+/g;
const NON_ALPHANUMERIC_HYPHEN_PATTERN = /[^a-z0-9-]/g;
const MULTIPLE_HYPHENS_PATTERN = /-+/g;
const LEADING_TRAILING_HYPHEN_PATTERN = /^-|-$/g;

/**
 * Merge class names with Tailwind CSS support
 */
export function cn(...inputs: ClassValue[]) {
	return twMerge(clsx(inputs));
}

/**
 * Convert a string to a URL-friendly slug.
 *
 * Handles unicode by normalizing to NFD and stripping diacritics.
 */
export function formatRelativeTime(dateString: string): string {
	const date = new Date(dateString);
	const now = new Date();
	const diffMs = now.getTime() - date.getTime();
	const diffSecs = Math.floor(diffMs / 1000);
	const diffMins = Math.floor(diffSecs / 60);
	const diffHours = Math.floor(diffMins / 60);
	const diffDays = Math.floor(diffHours / 24);

	if (diffSecs < 60) return "just now";
	if (diffMins < 60) return `${diffMins} min${diffMins === 1 ? "" : "s"} ago`;
	if (diffHours < 24) return `${diffHours} hour${diffHours === 1 ? "" : "s"} ago`;
	if (diffDays < 7) return `${diffDays} day${diffDays === 1 ? "" : "s"} ago`;

	return date.toLocaleDateString(undefined, {
		month: "short",
		day: "numeric",
		year: date.getFullYear() !== now.getFullYear() ? "numeric" : undefined,
	});
}

export function slugify(text: string): string {
	return text
		.toLowerCase()
		.normalize("NFD")
		.replace(DIACRITICS_PATTERN, "")
		.replace(WHITESPACE_UNDERSCORE_PATTERN, "-")
		.replace(NON_ALPHANUMERIC_HYPHEN_PATTERN, "")
		.replace(MULTIPLE_HYPHENS_PATTERN, "-")
		.replace(LEADING_TRAILING_HYPHEN_PATTERN, "");
}