src/lib/utils/slug.ts

// Story 7.3: Slug generation utility for creator URLs

/**
 * Generate a URL-safe slug from a channel name
 * 
 * Rules:
 * - Convert to lowercase
 * - Replace spaces with hyphens
 * - Remove special characters (keep only alphanumeric and hyphens)
 * - Remove consecutive hyphens
 * - Trim hyphens from start/end
 * 
 * @param channelName - The YouTube channel name
 * @returns URL-safe slug
 * 
 * @example
 * generateCreatorSlug("Tech Reviews Pro") // "tech-reviews-pro"
 * generateCreatorSlug("Mr. Beast!!!") // "mr-beast"
 * generateCreatorSlug("  Spaces  Everywhere  ") // "spaces-everywhere"
 */
export function generateCreatorSlug(channelName: string): string {
  return channelName
    .toLowerCase()
    .trim()
    // Replace spaces with hyphens
    .replace(/\s+/g, '-')
    // Remove special characters (keep only alphanumeric and hyphens)
    .replace(/[^a-z0-9-]/g, '')
    // Remove consecutive hyphens
    .replace(/-+/g, '-')
    // Trim hyphens from start/end
    .replace(/^-+|-+$/g, '');
}

/**
 * Generate a unique slug by appending a number if collision detected
 * 
 * @param baseSlug - The base slug to make unique
 * @param existingSlugs - Array of existing slugs to check against
 * @returns Unique slug
 * 
 * @example
 * ensureUniqueSlug("tech-reviews", ["tech-reviews"]) // "tech-reviews-2"
 * ensureUniqueSlug("tech-reviews", ["tech-reviews", "tech-reviews-2"]) // "tech-reviews-3"
 */
export function ensureUniqueSlug(baseSlug: string, existingSlugs: string[]): string {
  let slug = baseSlug;
  let counter = 2;
  
  while (existingSlugs.includes(slug)) {
    slug = `${baseSlug}-${counter}`;
    counter++;
  }
  
  return slug;
}

/**
 * Validate if a string is a valid slug format
 * 
 * @param slug - The slug to validate
 * @returns True if valid slug format
 */
export function isValidSlug(slug: string): boolean {
  // Must be lowercase alphanumeric with hyphens only
  // Cannot start or end with hyphen
  // Cannot have consecutive hyphens
  const slugRegex = /^[a-z0-9]+(-[a-z0-9]+)*$/;
  return slugRegex.test(slug);
}