package search

import (
	"net/url"
	"strings"
)

// CanonicalURL lowercases scheme+host, strips default ports and fragments,
// and drops a trailing slash on the path. www. is left as-is.
func CanonicalURL(raw string) string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return ""
	}
	u, err := url.Parse(raw)
	if err != nil || u.Host == "" && u.Opaque == "" {
		return strings.TrimRight(raw, "/")
	}
	u.Fragment = ""
	u.Scheme = strings.ToLower(u.Scheme)
	host := strings.ToLower(u.Hostname())
	port := u.Port()
	switch {
	case port == "80" && u.Scheme == "http":
		port = ""
	case port == "443" && u.Scheme == "https":
		port = ""
	}
	if port != "" {
		u.Host = host + ":" + port
	} else {
		u.Host = host
	}
	if u.Path == "/" {
		u.Path = ""
	} else if len(u.Path) > 1 && strings.HasSuffix(u.Path, "/") {
		u.Path = strings.TrimSuffix(u.Path, "/")
	}
	return u.String()
}