package utils

import (
	"crypto/md5"
	"fmt"
	"path/filepath"
	"regexp"
	"strings"
	"time"
	"unicode"

	"golang.org/x/text/runes"
	"golang.org/x/text/transform"
	"golang.org/x/text/unicode/norm"
)

// Contains 检查字符串切片是否包含指定字符串
func Contains(slice []string, item string) bool {
	for _, s := range slice {
		if s == item {
			return true
		}
	}
	return false
}

// ContainsUint 检查 uint 切片是否包含指定值
func ContainsUint(slice []uint, item uint) bool {
	for _, s := range slice {
		if s == item {
			return true
		}
	}
	return false
}

// GenerateUniqueFilename 生成唯一文件名
func GenerateUniqueFilename(originalFilename string) string {
	ext := filepath.Ext(originalFilename)
	name := strings.TrimSuffix(originalFilename, ext)
	
	// 生成时间戳和哈希
	timestamp := time.Now().Unix()
	hash := md5.Sum([]byte(fmt.Sprintf("%s%d", name, timestamp)))
	
	return fmt.Sprintf("%d_%x%s", timestamp, hash[:8], ext)
}

// GenerateSlug 生成 URL 友好的 slug
func GenerateSlug(text string) string {
	// 转换为小写
	slug := strings.ToLower(text)
	
	// 移除重音符号
	t := transform.Chain(norm.NFD, runes.Remove(runes.In(unicode.Mn)), norm.NFC)
	slug, _, _ = transform.String(t, slug)
	
	// 只保留字母、数字、连字符和下划线
	reg := regexp.MustCompile(`[^a-z0-9\-_\s]`)
	slug = reg.ReplaceAllString(slug, "")
	
	// 将空格替换为连字符
	slug = regexp.MustCompile(`\s+`).ReplaceAllString(slug, "-")
	
	// 移除多余的连字符
	slug = regexp.MustCompile(`-+`).ReplaceAllString(slug, "-")
	
	// 移除开头和结尾的连字符
	slug = strings.Trim(slug, "-")
	
	return slug
}

// ValidateEmail 验证邮箱格式
func ValidateEmail(email string) bool {
	emailRegex := regexp.MustCompile(`^[a-z0-9._%+\-]+@[a-z0-9.\-]+\.[a-z]{2,}$`)
	return emailRegex.MatchString(strings.ToLower(email))
}

// ValidatePassword 验证密码强度
func ValidatePassword(password string) bool {
	if len(password) < 8 {
		return false
	}
	
	hasLower := regexp.MustCompile(`[a-z]`).MatchString(password)
	hasUpper := regexp.MustCompile(`[A-Z]`).MatchString(password)
	hasDigit := regexp.MustCompile(`\d`).MatchString(password)
	
	return hasLower && hasUpper && hasDigit
}

// Paginate 计算分页参数
func Paginate(page, limit int) (offset int) {
	if page <= 0 {
		page = 1
	}
	if limit <= 0 {
		limit = 20
	}
	if limit > 100 {
		limit = 100
	}
	
	offset = (page - 1) * limit
	return offset
}

// CalculatePages 计算总页数
func CalculatePages(total int64, limit int) int {
	if limit <= 0 {
		return 0
	}
	return int((total + int64(limit) - 1) / int64(limit))
}

// TruncateString 截断字符串
func TruncateString(s string, maxLength int) string {
	if len(s) <= maxLength {
		return s
	}
	return s[:maxLength] + "..."
}

// FormatFileSize 格式化文件大小
func FormatFileSize(bytes int64) string {
	const unit = 1024
	if bytes < unit {
		return fmt.Sprintf("%d B", bytes)
	}
	
	div, exp := int64(unit), 0
	for n := bytes / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	
	sizes := []string{"KB", "MB", "GB", "TB", "PB"}
	return fmt.Sprintf("%.1f %s", float64(bytes)/float64(div), sizes[exp])
}

// ParseSortOrder 解析排序方向
func ParseSortOrder(order string) string {
	order = strings.ToLower(strings.TrimSpace(order))
	if order == "asc" || order == "desc" {
		return order
	}
	return "desc" // 默认降序
}

// SanitizeSearchQuery 清理搜索查询
func SanitizeSearchQuery(query string) string {
	// 移除特殊字符，只保留字母、数字、空格和常用标点
	reg := regexp.MustCompile(`[^\w\s\-\.\_\@]`)
	query = reg.ReplaceAllString(query, "")
	
	// 移除多余的空格
	query = regexp.MustCompile(`\s+`).ReplaceAllString(query, " ")
	
	return strings.TrimSpace(query)
}

// GenerateRandomString 生成随机字符串
func GenerateRandomString(length int) string {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	
	// 使用当前时间作为种子
	timestamp := time.Now().UnixNano()
	
	result := make([]byte, length)
	for i := range result {
		result[i] = charset[(timestamp+int64(i))%int64(len(charset))]
	}
	
	return string(result)
}

// IsValidImageExtension 检查是否为有效的图片扩展名
func IsValidImageExtension(filename string) bool {
	ext := strings.ToLower(filepath.Ext(filename))
	validExts := []string{".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp", ".tiff"}
	return Contains(validExts, ext)
}

// GetImageMimeType 根据文件扩展名获取 MIME 类型
func GetImageMimeType(filename string) string {
	ext := strings.ToLower(filepath.Ext(filename))
	mimeTypes := map[string]string{
		".jpg":  "image/jpeg",
		".jpeg": "image/jpeg",
		".png":  "image/png",
		".gif":  "image/gif",
		".webp": "image/webp",
		".bmp":  "image/bmp",
		".tiff": "image/tiff",
	}
	
	if mimeType, exists := mimeTypes[ext]; exists {
		return mimeType
	}
	return "application/octet-stream"
}

// RemoveEmptyStrings 移除字符串切片中的空字符串
func RemoveEmptyStrings(slice []string) []string {
	var result []string
	for _, s := range slice {
		if strings.TrimSpace(s) != "" {
			result = append(result, strings.TrimSpace(s))
		}
	}
	return result
}

// UniqueStrings 去重字符串切片
func UniqueStrings(slice []string) []string {
	keys := make(map[string]bool)
	var result []string
	
	for _, item := range slice {
		if !keys[item] {
			keys[item] = true
			result = append(result, item)
		}
	}
	
	return result
}

// UniqueUints 去重 uint 切片
func UniqueUints(slice []uint) []uint {
	keys := make(map[uint]bool)
	var result []uint
	
	for _, item := range slice {
		if !keys[item] {
			keys[item] = true
			result = append(result, item)
		}
	}
	
	return result
}