package logic

import (
	"context"
	"fmt"
	"github.com/gin-gonic/gin"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/resolver"
	"google.golang.org/protobuf/types/known/emptypb"
	"net/http"
	"sonet/api/gen/postal"
	"sonet/internal/gateway_http/config"
	"sonet/pkg/grpc/balancer"
	"sonet/pkg/grpc/discovery"
	"sonet/pkg/utils/resp"
)

type PostalBalancer struct {
	postalClient postal.PostalClient
}

func NewPostalBalancer() *PostalBalancer {
	return &PostalBalancer{}
}

func (h *PostalBalancer) Init(ctx context.Context, resolver resolver.Builder) {
	balancer.InitConsistentHashBuilder()

	postalUrl := discovery.EtcdDialUrl(postal.Postal_ServiceDesc.ServiceName)
	conn, err := grpc.DialContext(ctx, postalUrl,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
		// consistent hash lb
		grpc.WithDefaultServiceConfig(fmt.Sprintf(`{"loadBalancingPolicy":"%s"}`, balancer.ConsistentHash)),
		grpc.WithResolvers(resolver),
	)
	if err != nil {
		return
	}
	h.postalClient = postal.NewPostalClient(conn)
}

// Endpoint 根据consistent hash负载均衡策略调用到 postal 集群的一个节点，拿到节点的客户端连接地址
func (h *PostalBalancer) Endpoint(c *gin.Context) {
	subject, err := config.GetSubject(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, resp.Fail(err.Error()))
		return
	}
	ctx := context.WithValue(context.Background(), balancer.ConsistentHashKey, subject.Uid)
	res, err := h.postalClient.Endpoint(ctx, &emptypb.Empty{})
	if err != nil {
		c.JSON(http.StatusInternalServerError, resp.Error(err.Error()))
		return
	}
	c.JSON(http.StatusOK, resp.Success(resp.H{"ws": res.Endpoint}))
}