package grpcwebserver

import (
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
	log "github.com/sirupsen/logrus"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
)

type WebServer struct {
	GrpcWebServer   *GrpcWebServer
	Router          *gin.Engine
	h2Handler       http.Handler
	rESTfulHandeler *RESTfulMux
}

type RESTfulMux struct {
	Mux    *runtime.ServeMux //实现RESTful风格api处理复用
	Prefix string
}

type HttpsConf struct {
	BindAddr string
	HostName string //cert hostname
	CertFile string
	KeyFile  string
}

func NewServer(grpcWebServer *GrpcWebServer, allowCross bool) *WebServer {
	//gin.SetMode(gin.ReleaseMode)

	var weserver = &WebServer{
		GrpcWebServer: grpcWebServer,
		Router:        gin.New(), // 初始化一个空Gin路由
	}
	if allowCross {
		weserver.Router.Use(Cors())
	}

	return weserver
}

func (s *WebServer) Serve(httpBind string, https *HttpsConf) error {

	// 监听端口并处理服务分流
	s.h2Handler = h2c.NewHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		//if s.GrpcWebServer.WrappedGrpc.IsGrpcWebRequest(r) ||
		//	r.Method == http.MethodOptions {
		if s.GrpcWebServer.WrappedGrpc.IsGrpcWebRequest(r) {
			// 判断协议是否为grpc-web
			s.GrpcWebServer.WrappedGrpc.ServeHTTP(w, r)
		} else if r.ProtoMajor == 2 &&
			strings.HasPrefix(r.Header.Get("Content-Type"), "application/grpc") {
			// 判断协议是否为http/2 && 是grpc
			s.GrpcWebServer.GrpcServer.ServeHTTP(w, r)
		} else if strings.HasPrefix(r.RequestURI, s.rESTfulHandeler.Prefix) && s.rESTfulHandeler != nil {
			//grpc-gateway 实现RESTful风格api
			s.rESTfulHandeler.Mux.ServeHTTP(w, r)
		} else {
			// 当作普通http api
			s.Router.ServeHTTP(w, r)
		}
	}), &http2.Server{})

	if https != nil {
		go func() {
			err := http.ListenAndServeTLS(https.BindAddr, https.CertFile, https.KeyFile, s.h2Handler)
			if err != nil {
				log.Errorln(err)
			}
		}()
	}

	if httpBind != "" {
		if err := http.ListenAndServe(httpBind, s.h2Handler); err != nil {
			log.Println("http server done:", err.Error())
			return err
		}
	}

	return nil
}

func (s *WebServer) SetRESTfulMux(mux *RESTfulMux) {
	s.rESTfulHandeler = mux
}

func Cors() gin.HandlerFunc {
	return func(c *gin.Context) {
		method := c.Request.Method
		origin := c.Request.Header.Get("Origin") //请求头部
		if origin != "" {
			//接收客户端发送的origin （重要！）
			c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
			//服务器支持的所有跨域请求的方法
			c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE,UPDATE")
			//允许跨域设置可以返回其他子段，可以自定义字段
			c.Header("Access-Control-Allow-Headers", "Authorization, Content-Length, X-CSRF-Token, Token,session,X_Requested_With,Accept, Origin, Host, Connection, Accept-Encoding, Accept-Language,DNT, X-CustomHeader, Keep-Alive, User-Agent, X-Requested-With, If-Modified-Since, Cache-Control, Content-Type, Pragma, Authorization, Content-Type, Grpc-Timeout, X-Grpc-Web")
			// 允许浏览器（客户端）可以解析的头部 （重要）
			c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers")
			//设置缓存时间
			c.Header("Access-Control-Max-Age", "172800")
			//允许客户端传递校验信息比如 cookie (重要)
			c.Header("Access-Control-Allow-Credentials", "true")
		}

		//允许类型校验
		if method == "OPTIONS" {
			c.JSON(http.StatusOK, "ok!")
		}

		defer func() {
			if err := recover(); err != nil {
				log.Printf("Panic info is: %v", err)
			}
		}()
		c.Next()
	}
}