package utils

import (
	"strings"

	"github.com/gin-gonic/gin"
)

// GetClientIP 获取客户端 IP 地址（考虑代理情况）
func GetClientIP(c *gin.Context) string {
	// 优先从 X-Forwarded-For 获取（适用于代理/负载均衡）
	// 标准格式为「客户端, 代理1, 代理2」；数据库存 varchar 时整串会超长，只取第一项。
	xff := strings.TrimSpace(c.GetHeader("X-Forwarded-For"))
	if xff != "" {
		if first := firstXForwardedForClient(xff); first != "" {
			return sanitizeIPForDB(first)
		}
	}
	ip := strings.TrimSpace(c.GetHeader("X-Real-IP"))
	if ip != "" {
		return sanitizeIPForDB(ip)
	}
	return sanitizeIPForDB(c.ClientIP())
}

func firstXForwardedForClient(xff string) string {
	for _, part := range strings.Split(xff, ",") {
		s := strings.TrimSpace(part)
		if s != "" {
			return s
		}
	}
	return ""
}

// sanitizeIPForDB 限制长度，避免异常头或未来字段变更再次撑爆列。
func sanitizeIPForDB(ip string) string {
	ip = strings.TrimSpace(ip)
	const maxLen = 255
	if len(ip) > maxLen {
		return ip[:maxLen]
	}
	return ip
}

// ParseUserAgent 从 User-Agent 字符串中解析浏览器和操作系统
func ParseUserAgent(userAgent string) (browser string, os string) {
	browser = "Unknown"
	os = "Unknown"

	ua := strings.ToLower(userAgent)
	if ua == "" {
		return
	}

	switch {
	case strings.Contains(ua, "edg/"):
		browser = "Edge"
	case strings.Contains(ua, "chrome/"):
		browser = "Chrome"
	case strings.Contains(ua, "firefox/"):
		browser = "Firefox"
	case strings.Contains(ua, "safari/"):
		browser = "Safari"
	}

	switch {
	case strings.Contains(ua, "windows nt"):
		os = "Windows"
	case strings.Contains(ua, "mac os x") || strings.Contains(ua, "macintosh"):
		os = "macOS"
	case strings.Contains(ua, "android"):
		os = "Android"
	case strings.Contains(ua, "iphone") || strings.Contains(ua, "ipad"):
		os = "iOS"
	case strings.Contains(ua, "linux"):
		os = "Linux"
	}

	return
}