package environment

import (
	"errors"
	"net/url"
	"regexp"
	"strconv"
	"strings"
)

// Fingerprint 是 fingerprint-chromium 的结构化启动参数集合。
// 参数契约来源：https://github.com/adryfish/fingerprint-chromium（BSD-3-clause）。
// 零值字段表示不传递该命令行开关。
type Fingerprint struct {
	Seed                 int64  `json:"seed"`
	Platform             string `json:"platform,omitempty"`
	PlatformVersion      string `json:"platform_version,omitempty"`
	Brand                string `json:"brand,omitempty"`
	BrandVersion         string `json:"brand_version,omitempty"`
	HardwareConcurrency  int64  `json:"hardware_concurrency,omitempty"`
	Lang                 string `json:"lang,omitempty"`
	AcceptLang           string `json:"accept_lang,omitempty"`
	Timezone             string `json:"timezone,omitempty"`
	ProxyServer          string `json:"proxy_server,omitempty"`
	DisableNonProxiedUDP bool   `json:"disable_non_proxied_udp,omitempty"`
	DisableSpoofing      string `json:"disable_spoofing,omitempty"`
}

var (
	platforms         = map[string]bool{"windows": true, "linux": true, "macos": true}
	brands            = map[string]bool{"Chrome": true, "Edge": true, "Opera": true, "Vivaldi": true}
	spoofings         = map[string]bool{"font": true, "audio": true, "canvas": true, "clientrects": true, "gpu": true}
	langPattern       = regexp.MustCompile(`^[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})?$`)
	acceptLangPattern = regexp.MustCompile(
		`^[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})?(, ?[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})*){0,7}$`)
	timezonePattern    = regexp.MustCompile(`^[A-Za-z0-9_+\-/]{1,64}$`)
	shortVersionPatten = regexp.MustCompile(`^[A-Za-z0-9._+~-]{1,32}$`)
)

// Validate 校验全量指纹参数；只做值域校验，参数作为独立 argv 传入容器，无 shell 注入面。
func (f Fingerprint) Validate() error {
	if f.Seed < 1 || f.Seed > 2147483647 {
		return errors.New("seed must be 1..2147483647")
	}
	if !optionalIn(f.Platform, platforms) {
		return errors.New("platform must be one of windows, linux, macos")
	}
	if !optionalIn(f.Brand, brands) {
		return errors.New("brand must be one of Chrome, Edge, Opera, Vivaldi")
	}
	if !optionalMatch(f.PlatformVersion, shortVersionPatten) {
		return errors.New("platform_version must be a short version like 11.0.0")
	}
	if !optionalMatch(f.BrandVersion, shortVersionPatten) {
		return errors.New("brand_version must be a short version like 132.0.6834.159")
	}
	if f.HardwareConcurrency < 0 || f.HardwareConcurrency > 128 {
		return errors.New("hardware_concurrency must be 0..128, 0 omits the flag")
	}
	if !optionalMatch(f.Lang, langPattern) {
		return errors.New("lang must be a language code like zh-CN")
	}
	if !optionalMatch(f.AcceptLang, acceptLangPattern) {
		return errors.New("accept_lang must be a comma separated language list like zh-CN,en-US")
	}
	if !optionalMatch(f.Timezone, timezonePattern) {
		return errors.New("timezone must be an IANA timezone like Asia/Shanghai")
	}
	if f.ProxyServer != "" && !validProxyURL(f.ProxyServer) {
		return errors.New("proxy_server must be an http/https/socks4/socks5 URL with a host")
	}
	if f.DisableSpoofing != "" && !validDisableSpoofing(f.DisableSpoofing) {
		return errors.New("disable_spoofing must be a comma separated subset of font,audio,canvas,clientrects,gpu")
	}
	return nil
}

// Args 生成 fingerprint-chromium 命令行参数（不含 URL 尾参）。
func (f Fingerprint) Args() []string {
	args := []string{"--fingerprint=" + strconv.FormatInt(f.Seed, 10)}
	value := func(flag, setting string) {
		if setting != "" {
			args = append(args, "--"+flag+"="+setting)
		}
	}
	value("fingerprint-platform", f.Platform)
	value("fingerprint-platform-version", f.PlatformVersion)
	value("fingerprint-brand", f.Brand)
	value("fingerprint-brand-version", f.BrandVersion)
	if f.HardwareConcurrency > 0 {
		value("fingerprint-hardware-concurrency", strconv.FormatInt(f.HardwareConcurrency, 10))
	}
	value("lang", f.Lang)
	value("accept-lang", f.AcceptLang)
	value("timezone", f.Timezone)
	value("proxy-server", f.ProxyServer)
	if f.DisableNonProxiedUDP {
		args = append(args, "--disable-non-proxied-udp")
	}
	value("disable-spoofing", f.DisableSpoofing)
	return args
}

func optionalIn(value string, allowed map[string]bool) bool {
	return value == "" || allowed[value]
}

func optionalMatch(value string, pattern *regexp.Regexp) bool {
	return value == "" || pattern.MatchString(value)
}

func validProxyURL(raw string) bool {
	parsed, err := url.Parse(raw)
	if err != nil || parsed.Host == "" || parsed.User != nil {
		return false
	}
	switch parsed.Scheme {
	case "http", "https", "socks4", "socks5":
		return true
	default:
		return false
	}
}

func validDisableSpoofing(value string) bool {
	seen := make(map[string]bool, len(spoofings))
	for _, part := range strings.Split(value, ",") {
		part = strings.TrimSpace(part)
		if !spoofings[part] || seen[part] {
			return false
		}
		seen[part] = true
	}
	return true
}