package deadlinks

import (
	"errors"
	"fmt"
	"net/url"
)

// URL is a standard universal resource identifier, normalized particularly for
// this package.
type URL string

// ParseURL parses and returns a URL based on the given string, or an error.
func ParseURL(urlStr string) (URL, error) {
	u, err := url.Parse(urlStr)
	if err != nil {
		return "", err
	}
	return URL(u.String()), nil
}

func parseURLs(urlStrs []string) ([]URL, error) {
	var (
		res  = make([]URL, 0, len(urlStrs))
		errs []error
	)
	for _, urlStr := range urlStrs {
		u, err := ParseURL(urlStr)
		if err == nil {
			res = append(res, u)
		} else {
			errs = append(errs, err)
		}
	}
	return res, errors.Join(errs...)
}

func (u URL) toStd() *url.URL {
	uu, err := url.Parse(string(u))
	if err != nil {
		panic(fmt.Sprintf("parsing URL %q: %v", u, err))
	}
	return uu
}

// ResolveReference is equivalend to the method of the same name in `net/url`.
func (u URL) ResolveReference(u2 URL) URL {
	return URL(u.toStd().ResolveReference(u2.toStd()).String())
}