package services

import (
	"strings"
	"sync"
)

var publicAssetURLRuntime struct {
	sync.RWMutex
	resolver func(string) string
}

// SetPublicAssetURLResolver configures how host-owned asset keys are exposed
// to standalone customer-service clients. A nil resolver keeps absolute URLs
// and legacy values unchanged.
func SetPublicAssetURLResolver(resolver func(string) string) {
	publicAssetURLRuntime.Lock()
	publicAssetURLRuntime.resolver = resolver
	publicAssetURLRuntime.Unlock()
}

// SetPublicAssetURLSettings applies the same object-key joining rule used by
// the management frontend: cloud material keys use the active oss_domain,
// while absolute and same-origin URLs stay unchanged.
func SetPublicAssetURLSettings(settings map[string]string) {
	engine := strings.TrimSpace(settings["oss_default_engine"])
	if engine == "" || engine == "local" {
		SetPublicAssetURLResolver(nil)
		return
	}
	domain := strings.TrimSpace(settings["oss_"+engine+"_domain"])
	SetPublicAssetURLResolver(func(value string) string {
		return resolvePublicAssetURLWithDomain(value, domain)
	})
}

func resolvePublicAssetURLWithDomain(value, domain string) string {
	value = strings.TrimSpace(value)
	if value == "" || strings.HasPrefix(value, "/") {
		return value
	}
	lower := strings.ToLower(value)
	if strings.HasPrefix(lower, "http://") || strings.HasPrefix(lower, "https://") || strings.HasPrefix(lower, "data:") {
		return value
	}
	domain = strings.TrimSpace(domain)
	if domain == "" {
		return value
	}
	if !strings.HasPrefix(strings.ToLower(domain), "http://") && !strings.HasPrefix(strings.ToLower(domain), "https://") {
		domain = "https://" + domain
	}
	return strings.TrimRight(domain, "/") + "/" + strings.TrimLeft(value, "/")
}

// ResolvePublicAssetURL converts a host-owned object key into a browser-ready
// URL. Resolver failures must fall back to the stored value so message delivery
// is never affected by an optional avatar.
func ResolvePublicAssetURL(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return value
	}
	publicAssetURLRuntime.RLock()
	resolver := publicAssetURLRuntime.resolver
	publicAssetURLRuntime.RUnlock()
	if resolver == nil {
		return value
	}
	resolved := strings.TrimSpace(resolver(value))
	if resolved == "" {
		return value
	}
	return resolved
}