package middleware

import (
	"net/http"
	"strings"
	"time"

	"github.com/zeromicro/go-zero/core/logx"
)

// CORSConfig CORS 配置
type CORSConfig struct {
	AllowOrigins     []string      // 允许的来源
	AllowMethods     []string      // 允许的方法
	AllowHeaders     []string      // 允许的头部
	ExposeHeaders    []string      // 暴露的头部
	AllowCredentials bool          // 是否允许携带凭证
	MaxAge           time.Duration // 预检请求缓存时间
}

// DefaultCORSConfig 默认 CORS 配置
func DefaultCORSConfig() CORSConfig {
	return CORSConfig{
		AllowOrigins: []string{
			"http://localhost:3000",
			"http://localhost:3001",
			"http://localhost:5173",
			"http://localhost:8080",
		},
		AllowMethods: []string{
			"GET",
			"POST",
			"PUT",
			"DELETE",
			"OPTIONS",
			"HEAD",
		},
		AllowHeaders: []string{
			"Origin",
			"Content-Type",
			"Content-Length",
			"Accept-Encoding",
			"X-CSRF-Token",
			"Authorization",
			"accept",
			"origin",
			"Cache-Control",
			"X-Requested-With",
		},
		ExposeHeaders: []string{
			"Content-Length",
			"Content-Type",
		},
		AllowCredentials: true,
		MaxAge:           12 * time.Hour,
	}
}

// ProductionCORSConfig 生产环境 CORS 配置
func ProductionCORSConfig(allowedOrigins []string) CORSConfig {
	config := DefaultCORSConfig()
	if len(allowedOrigins) > 0 {
		config.AllowOrigins = allowedOrigins
	} else {
		// 生产环境默认只允许 HTTPS
		config.AllowOrigins = []string{
			"https://photography.iriver.top",
			"https://admin.photography.iriver.top",
		}
	}
	return config
}

// CORSMiddleware CORS 中间件
type CORSMiddleware struct {
	config CORSConfig
}

// NewCORSMiddleware 创建 CORS 中间件
func NewCORSMiddleware(config CORSConfig) *CORSMiddleware {
	return &CORSMiddleware{
		config: config,
	}
}

// Handle 处理 CORS
func (m *CORSMiddleware) Handle(next http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		origin := r.Header.Get("Origin")

		// 检查来源是否被允许
		if origin != "" && m.isOriginAllowed(origin) {
			w.Header().Set("Access-Control-Allow-Origin", origin)
		}

		// 设置允许的方法
		if len(m.config.AllowMethods) > 0 {
			w.Header().Set("Access-Control-Allow-Methods", strings.Join(m.config.AllowMethods, ", "))
		}

		// 设置允许的头部
		if len(m.config.AllowHeaders) > 0 {
			w.Header().Set("Access-Control-Allow-Headers", strings.Join(m.config.AllowHeaders, ", "))
		}

		// 设置暴露的头部
		if len(m.config.ExposeHeaders) > 0 {
			w.Header().Set("Access-Control-Expose-Headers", strings.Join(m.config.ExposeHeaders, ", "))
		}

		// 设置是否允许携带凭证
		if m.config.AllowCredentials {
			w.Header().Set("Access-Control-Allow-Credentials", "true")
		}

		// 设置预检请求缓存时间
		if m.config.MaxAge > 0 {
			w.Header().Set("Access-Control-Max-Age", m.config.MaxAge.String())
		}

		// 添加安全头部
		m.setSecurityHeaders(w)

		// 处理预检请求
		if r.Method == "OPTIONS" {
			w.WriteHeader(http.StatusOK)
			return
		}

		// 记录跨域请求
		if origin != "" {
			logx.Infof("CORS request from origin: %s, method: %s, path: %s", origin, r.Method, r.URL.Path)
		}

		next(w, r)
	})
}

// isOriginAllowed 检查来源是否被允许
func (m *CORSMiddleware) isOriginAllowed(origin string) bool {
	for _, allowedOrigin := range m.config.AllowOrigins {
		if allowedOrigin == "*" {
			return true
		}
		if allowedOrigin == origin {
			return true
		}
		// 支持通配符匹配
		if strings.HasSuffix(allowedOrigin, "*") {
			prefix := strings.TrimSuffix(allowedOrigin, "*")
			if strings.HasPrefix(origin, prefix) {
				return true
			}
		}
	}
	return false
}

// setSecurityHeaders 设置安全头部
func (m *CORSMiddleware) setSecurityHeaders(w http.ResponseWriter) {
	// 防止点击劫持
	w.Header().Set("X-Frame-Options", "DENY")

	// 防止 MIME 类型嗅探
	w.Header().Set("X-Content-Type-Options", "nosniff")

	// XSS 保护
	w.Header().Set("X-XSS-Protection", "1; mode=block")

	// 引用者策略
	w.Header().Set("Referrer-Policy", "strict-origin-when-cross-origin")

	// 内容安全策略 (基础版)
	w.Header().Set("Content-Security-Policy", "default-src 'self'; img-src 'self' data: https:; style-src 'self' 'unsafe-inline'; script-src 'self'")
}