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

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs));
}

export function formatDate(dateString: string): string {
  if (!dateString) return 'N/A';
  const date = new Date(dateString);
  return date.toLocaleDateString('en-ZA', {
    day: '2-digit',
    month: 'short',
    year: 'numeric',
  });
}

export function formatDateTime(dateString: string): string {
  if (!dateString) return 'N/A';
  const date = new Date(dateString);
  return date.toLocaleString('en-ZA', {
    day: '2-digit',
    month: 'short',
    year: 'numeric',
    hour: '2-digit',
    minute: '2-digit',
  });
}

export function formatCurrency(amount: number): string {
  return new Intl.NumberFormat('en-ZA', {
    style: 'currency',
    currency: 'ZAR',
  }).format(amount);
}

export function getRelativeTime(dateString: string): string {
  const date = new Date(dateString);
  const now = new Date();
  const diffInSeconds = Math.floor((now.getTime() - date.getTime()) / 1000);

  if (diffInSeconds < 60) return 'Just now';
  if (diffInSeconds < 3600) return `${Math.floor(diffInSeconds / 60)}m ago`;
  if (diffInSeconds < 86400) return `${Math.floor(diffInSeconds / 3600)}h ago`;
  if (diffInSeconds < 604800) return `${Math.floor(diffInSeconds / 86400)}d ago`;
  return formatDate(dateString);
}

export function debounce<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number
): (...args: Parameters<T>) => void {
  let timeout: ReturnType<typeof setTimeout>;
  return (...args: Parameters<T>) => {
    clearTimeout(timeout);
    timeout = setTimeout(() => func(...args), wait);
  };
}

export function groupBy<T>(array: T[], key: keyof T): Record<string, T[]> {
  return array.reduce((result, item) => {
    const groupKey = String(item[key]);
    if (!result[groupKey]) {
      result[groupKey] = [];
    }
    result[groupKey].push(item);
    return result;
  }, {} as Record<string, T[]>);
}

export function calculateDistance(
  lat1: number,
  lon1: number,
  lat2: number,
  lon2: number
): number {
  const R = 6371; // Earth's radius in km
  const dLat = (lat2 - lat1) * Math.PI / 180;
  const dLon = (lon2 - lon1) * Math.PI / 180;
  const a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(lat1 * Math.PI / 180) * Math.cos(lat2 * Math.PI / 180) *
    Math.sin(dLon / 2) * Math.sin(dLon / 2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  return R * c;
}

/**
 * Parse coordinates from a text field.
 * Supports formats like:
 *   "-33.9249, 18.4241"
 *   "-33.9249 18.4241"
 *   "lat: -33.9249, lng: 18.4241"
 * Returns null if parsing fails.
 */
export function parseCoordinates(coordString: string | undefined): { latitude: number; longitude: number } | null {
  if (!coordString) return null;

  // Try to extract two numbers that look like lat/lng
  const matches = coordString.match(/-?\d+\.?\d*/g);
  if (matches && matches.length >= 2) {
    const lat = parseFloat(matches[0]);
    const lng = parseFloat(matches[1]);
    if (!isNaN(lat) && !isNaN(lng)) {
      return { latitude: lat, longitude: lng };
    }
  }

  return null;
}