package config

import "strings"

// DetectProtocol infers protocol from a share/proxy URI or config body.
func DetectProtocol(raw string) Protocol {
	raw = stripShareNoise(raw)
	lower := strings.ToLower(strings.TrimSpace(raw))
	switch {
	case strings.HasPrefix(lower, "hysteria2://"), strings.HasPrefix(lower, "hy2://"):
		return ProtocolHysteria2
	case strings.HasPrefix(lower, "vless://"):
		return ProtocolVLESS
	case strings.HasPrefix(lower, "vmess://"):
		return ProtocolVMess
	case strings.HasPrefix(lower, "trojan://"):
		return ProtocolTrojan
	case strings.HasPrefix(lower, "awg://"), strings.HasPrefix(lower, "amneziawg://"),
		strings.HasPrefix(lower, "wireguard://"), strings.HasPrefix(lower, "vpn://"):
		return ProtocolAWG
	case strings.Contains(lower, "[interface]") && (strings.Contains(lower, "privatekey") || strings.Contains(lower, "private_key") || strings.Contains(lower, "private key")):
		return ProtocolAWG
	case strings.HasPrefix(strings.TrimSpace(raw), "{") && (strings.Contains(lower, "client_priv_key") || strings.Contains(lower, "server_pub_key")):
		return ProtocolAWG
	case strings.HasPrefix(lower, "naive+"), strings.HasPrefix(lower, "naive://"),
		strings.HasPrefix(lower, "https://"), strings.HasPrefix(lower, "quic://"),
		strings.HasPrefix(lower, "http://"):
		return ProtocolNaive
	default:
		return ""
	}
}

func stripShareNoise(raw string) string {
	raw = strings.TrimPrefix(raw, "\ufeff")
	var b strings.Builder
	for _, r := range raw {
		switch r {
		case '\u200b', '\u200c', '\u200d', '\u2060', '\ufeff',
			'\u2066', '\u2067', '\u2068', '\u2069',
			'\u200e', '\u200f',
			'\u202a', '\u202b', '\u202c', '\u202d', '\u202e':
			continue
		}
		if r < 0x20 && r != '\n' && r != '\r' && r != '\t' {
			continue
		}
		b.WriteRune(r)
	}
	return strings.TrimSpace(b.String())
}