package audit

import (
	"strings"
)

// DeviceInfo 从 User-Agent 解析出的设备信息。
type DeviceInfo struct {
	OS      string // Windows/macOS/Android/iOS/Linux/Unknown
	Browser string // Chrome/Firefox/Safari/Edge/Other
	Type    string // desktop/mobile/tablet/bot/other
}

// 动作常量。
const (
	ActionUpload   = "upload"
	ActionDownload = "download"
	// ActionAdmin 管理端敏感操作（登录/登出/配置/密码/引擎切换/文件删除等），
	// L5：纳入审计以便追溯登录失败与配置变更。
	ActionAdmin = "admin"
)

// 角色常量。
const (
	ActorAdmin = "admin"
	ActorGuest = "guest"
)

// botKeywords 常见爬虫/机器人标识。
var botKeywords = []string{"bot", "spider", "crawl", "slurp", "curl/", "wget", "python-requests", "go-http-client"}

// ParseUserAgent 解析 User-Agent 为设备信息（轻量规则，避免引入重依赖）。
func ParseUserAgent(ua string) DeviceInfo {
	ua = strings.TrimSpace(ua)
	lower := strings.ToLower(ua)
	if ua == "" {
		return DeviceInfo{OS: "Unknown", Browser: "Other", Type: "other"}
	}
	for _, kw := range botKeywords {
		if strings.Contains(lower, kw) {
			return DeviceInfo{OS: "Unknown", Browser: "Other", Type: "bot"}
		}
	}

	info := DeviceInfo{OS: "Unknown", Browser: "Other", Type: "desktop"}

	// 操作系统
	switch {
	case strings.Contains(lower, "windows"):
		info.OS = "Windows"
	case strings.Contains(lower, "iphone"), strings.Contains(lower, "ipod"):
		info.OS = "iOS"
		info.Type = "mobile"
	case strings.Contains(lower, "ipad"):
		info.OS = "iOS"
		info.Type = "tablet"
	case strings.Contains(lower, "mac os x"), strings.Contains(lower, "macintosh"):
		info.OS = "macOS"
	case strings.Contains(lower, "android"):
		info.OS = "Android"
		info.Type = "mobile"
		if strings.Contains(lower, "tablet") || !strings.Contains(lower, "mobile") {
			info.Type = "tablet"
		}
	case strings.Contains(lower, "linux"), strings.Contains(lower, "ubuntu"), strings.Contains(lower, "fedora"):
		info.OS = "Linux"
	}

	// 浏览器（顺序重要：Edge/OPR 必须在 Chrome 之前判断）
	switch {
	case strings.Contains(lower, "edg/"), strings.Contains(lower, "edge/"):
		info.Browser = "Edge"
	case strings.Contains(lower, "opr/"), strings.Contains(lower, "opera"):
		info.Browser = "Opera"
	case strings.Contains(lower, "chrome/"), strings.Contains(lower, "crios/"):
		info.Browser = "Chrome"
	case strings.Contains(lower, "firefox/"), strings.Contains(lower, "fxios/"):
		info.Browser = "Firefox"
	case strings.Contains(lower, "safari/"):
		info.Browser = "Safari"
	}

	return info
}