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

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

export function generateSlug(title: string): string {
  return title
    .toLowerCase()
    .trim()
    .replace(/[^\w\s-]/g, "") // Remove special characters
    .replace(/[\s_-]+/g, "-") // Replace spaces and underscores with hyphens
    .replace(/^-+|-+$/g, "") // Remove leading/trailing hyphens
}

export function generateExcerpt(content: string, maxLength = 160): string {
  // Remove HTML tags
  const plainText = content.replace(/<[^>]*>/g, "")

  if (plainText.length <= maxLength) {
    return plainText
  }

  // Find the last complete word within the limit
  const truncated = plainText.substring(0, maxLength)
  const lastSpaceIndex = truncated.lastIndexOf(" ")

  if (lastSpaceIndex > 0) {
    return truncated.substring(0, lastSpaceIndex) + "..."
  }

  return truncated + "..."
}

export function formatDate(date: Date): string {
  return new Intl.DateTimeFormat("en-US", {
    year: "numeric",
    month: "long",
    day: "numeric",
  }).format(date)
}

export function formatRelativeDate(date: Date | string): string {
  const dateObj = typeof date === 'string' ? new Date(date) : date
  
  // Check if the date is valid
  if (isNaN(dateObj.getTime())) {
    return "recently"
  }
  
  const now = new Date()
  const diffInSeconds = Math.floor((now.getTime() - dateObj.getTime()) / 1000)

  if (diffInSeconds < 60) {
    return "just now"
  }

  const diffInMinutes = Math.floor(diffInSeconds / 60)
  if (diffInMinutes < 60) {
    return `${diffInMinutes} minute${diffInMinutes > 1 ? "s" : ""} ago`
  }

  const diffInHours = Math.floor(diffInMinutes / 60)
  if (diffInHours < 24) {
    return `${diffInHours} hour${diffInHours > 1 ? "s" : ""} ago`
  }

  const diffInDays = Math.floor(diffInHours / 24)
  if (diffInDays < 7) {
    return `${diffInDays} day${diffInDays > 1 ? "s" : ""} ago`
  }

  const diffInWeeks = Math.floor(diffInDays / 7)
  if (diffInWeeks < 4) {
    return `${diffInWeeks} week${diffInWeeks > 1 ? "s" : ""} ago`
  }

  const diffInMonths = Math.floor(diffInDays / 30)
  if (diffInMonths < 12) {
    return `${diffInMonths} month${diffInMonths > 1 ? "s" : ""} ago`
  }

  const diffInYears = Math.floor(diffInDays / 365)
  return `${diffInYears} year${diffInYears > 1 ? "s" : ""} ago`
}

export function getReadingTime(content: string): number {
  const wordsPerMinute = 200
  const words = content.trim().split(/\s+/).length
  const readingTime = Math.ceil(words / wordsPerMinute)
  return Math.max(1, readingTime)
}

export function debounce<T extends (...args: any[]) => any>(func: T, wait: number): (...args: Parameters<T>) => void {
  let timeout: NodeJS.Timeout | null = null

  return (...args: Parameters<T>) => {
    if (timeout) {
      clearTimeout(timeout)
    }

    timeout = setTimeout(() => {
      func(...args)
    }, wait)
  }
}

export function truncateText(text: string, maxLength: number): string {
  if (text.length <= maxLength) {
    return text
  }

  return text.substring(0, maxLength).trim() + "..."
}

export function validateEmail(email: string): boolean {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
  return emailRegex.test(email)
}

export function validatePassword(password: string): {
  isValid: boolean
  errors: string[]
} {
  const errors: string[] = []

  if (password.length < 8) {
    errors.push("Password must be at least 8 characters long")
  }

  if (!/[A-Z]/.test(password)) {
    errors.push("Password must contain at least one uppercase letter")
  }

  if (!/[a-z]/.test(password)) {
    errors.push("Password must contain at least one lowercase letter")
  }

  if (!/\d/.test(password)) {
    errors.push("Password must contain at least one number")
  }

  return {
    isValid: errors.length === 0,
    errors,
  }
}

export function sanitizeHtml(html: string): string {
  // Basic HTML sanitization - in production, use a proper library like DOMPurify
  return html
    .replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, "")
    .replace(/<iframe\b[^<]*(?:(?!<\/iframe>)<[^<]*)*<\/iframe>/gi, "")
    .replace(/javascript:/gi, "")
    .replace(/on\w+\s*=/gi, "")
}

export function formatFileSize(bytes: number): string {
  if (bytes === 0) return "0 Bytes"

  const k = 1024
  const sizes = ["Bytes", "KB", "MB", "GB"]
  const i = Math.floor(Math.log(bytes) / Math.log(k))

  return Number.parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + " " + sizes[i]
}

export function generateRandomId(): string {
  return Math.random().toString(36).substring(2) + Date.now().toString(36)
}

export function capitalizeFirst(str: string): string {
  return str.charAt(0).toUpperCase() + str.slice(1)
}

export function pluralize(count: number, singular: string, plural?: string): string {
  if (count === 1) {
    return `${count} ${singular}`
  }
  return `${count} ${plural || singular + "s"}`
}