package utils

import (
	"fmt"
	"regexp"
	"strings"
)

var (
	slugRegex     = regexp.MustCompile(`^[a-z0-9-]+$`)
	reservedSlugs = map[string]bool{
		"admin":      true,
		"api":        true,
		"auth":       true,
		"system":     true,
		"root":       true,
		"super":      true,
		"public":     true,
		"internal":   true,
		"baron":      true,
		"sso":        true,
		"login":      true,
		"logout":     true,
		"signup":     true,
		"register":   true,
		"tenant":     true,
		"user":       true,
		"dev":        true,
		"stage":      true,
		"prod":       true,
		"test":       true,
		"static":     true,
		"assets":     true,
		"image":      true,
		"img":        true,
		"mail":       true,
		"smtp":       true,
		"pop":        true,
		"imap":       true,
		"ns":         true,
		"mx":         true,
		"webmaster":  true,
		"security":   true,
		"support":    true,
		"help":       true,
		"billing":    true,
		"account":    true,
		"config":     true,
		"status":     true,
		"health":     true,
		"metrics":    true,
		"grafana":    true,
		"prometheus": true,
	}
)

// ValidateSlug checks if a slug meets requirements and is not reserved.
func ValidateSlug(slug string) (bool, string) {
	s := strings.ToLower(strings.TrimSpace(slug))

	if len(s) < 3 || len(s) > 32 {
		return false, "slug must be between 3 and 32 characters"
	}

	if !slugRegex.MatchString(s) {
		return false, "slug can only contain lowercase letters, numbers, and hyphens"
	}

	if strings.HasPrefix(s, "-") || strings.HasSuffix(s, "-") {
		return false, "slug cannot start or end with a hyphen"
	}

	if reservedSlugs[s] {
		return false, "slug is a reserved keyword"
	}

	return true, ""
}

// GenerateSlug generates a base slug from a given string.
// It removes special characters, replaces spaces with hyphens, and converts to lowercase.
func GenerateSlug(name string) string {
	// Convert to lowercase
	s := strings.ToLower(strings.TrimSpace(name))

	// Replace non-alphanumeric characters (including spaces) with a hyphen
	re := regexp.MustCompile(`[^a-z0-9]+`)
	s = re.ReplaceAllString(s, "-")

	// Remove leading and trailing hyphens
	s = strings.Trim(s, "-")

	// Handle empty slug
	if s == "" {
		s = "tenant"
	}

	// Truncate to maximum length of 32 (reserving space for suffixes)
	if len(s) > 25 {
		s = s[:25]
		s = strings.TrimSuffix(s, "-")
	}

	return s
}

// GenerateUniqueSlug generates a unique slug by appending a suffix if the base slug exists.
// It takes the base name and a checker function that returns true if the slug already exists.
func GenerateUniqueSlug(name string, exists func(string) bool) string {
	baseSlug := GenerateSlug(name)

	slug := baseSlug
	counter := 1

	for reservedSlugs[slug] || exists(slug) {
		slug = fmt.Sprintf("%s-%d", baseSlug, counter)
		counter++
	}

	return slug
}