package naive

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

// NormalizeProxyURI converts share links and aliases into a naive --proxy URI.
//
// Supported inputs:
//   - https://user:pass@host:443
//   - quic://user:pass@host
//   - naive+https://user:pass@host:443#remark
//   - naive+quic://user:pass@host#remark
func NormalizeProxyURI(raw string) (string, error) {
	uri, _, err := ParseShareLink(raw)
	return uri, err
}

// ParseShareLink returns a normalized proxy URI and optional remark from #fragment.
func ParseShareLink(raw string) (proxyURI, remark string, err error) {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return "", "", fmt.Errorf("empty proxy URI")
	}

	if i := strings.IndexByte(raw, '#'); i >= 0 {
		remark = strings.TrimSpace(raw[i+1:])
		raw = raw[:i]
	}

	lower := strings.ToLower(raw)
	switch {
	case strings.HasPrefix(lower, "naive+https://"):
		raw = "https://" + raw[len("naive+https://"):]
	case strings.HasPrefix(lower, "naive+quic://"):
		raw = "quic://" + raw[len("naive+quic://"):]
	case strings.HasPrefix(lower, "naive://"):
		raw = "https://" + raw[len("naive://"):]
	}

	u, err := url.Parse(raw)
	if err != nil {
		return "", "", fmt.Errorf("parse proxy URI: %w", err)
	}
	switch strings.ToLower(u.Scheme) {
	case "https", "quic", "http":
	default:
		return "", "", fmt.Errorf("unsupported proxy scheme %q (use https://, quic:// or naive+https://)", u.Scheme)
	}
	if u.Host == "" {
		return "", "", fmt.Errorf("proxy URI missing host")
	}
	if u.User == nil || u.User.Username() == "" {
		return "", "", fmt.Errorf("proxy URI missing username")
	}
	if _, ok := u.User.Password(); !ok {
		return "", "", fmt.Errorf("proxy URI missing password")
	}

	out := &url.URL{
		Scheme: strings.ToLower(u.Scheme),
		User:   u.User,
		Host:   u.Host,
	}
	return out.String(), remark, nil
}