package app

import (
	"errors"
	"net"
	"net/http"
	"os"
	"sync"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"hyapp/services/gateway-service/internal/auth"
	"hyapp/services/gateway-service/internal/client"
	"hyapp/services/gateway-service/internal/config"
	"hyapp/services/gateway-service/internal/healthcheck"
	httptransport "hyapp/services/gateway-service/internal/transport/http"
)

// App 装配 gateway 的 HTTP 入口。
type App struct {
	server    *http.Server
	listener  net.Listener
	roomConn  *grpc.ClientConn
	userConn  *grpc.ClientConn
	health    *healthcheck.State
	closeOnce sync.Once
}

// New 初始化 gateway 应用。
func New(cfg config.Config) (*App, error) {
	roomConn, err := grpc.Dial(cfg.RoomServiceAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		return nil, err
	}

	userConn, err := grpc.Dial(cfg.UserServiceAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		_ = roomConn.Close()
		return nil, err
	}

	var roomClient client.RoomClient = client.NewGRPCRoomClient(roomConn)
	var userClient client.UserAuthClient = client.NewGRPCUserAuthClient(userConn)
	var userIdentityClient client.UserIdentityClient = client.NewGRPCUserIdentityClient(userConn)
	handler := httptransport.NewHandlerWithClients(roomClient, userClient, userIdentityClient)
	verifier := auth.NewVerifier(cfg.JWTSecret)
	healthState := healthcheck.NewState(nodeID(), cfg.JWTSecret, roomConn)

	mux := http.NewServeMux()
	healthHandler := healthcheck.NewHTTPHandler(healthState)
	mux.HandleFunc("/healthz/live", healthHandler.Live)
	mux.HandleFunc("/healthz/ready", healthHandler.Ready)
	mux.Handle("/", handler.Routes(verifier))

	listener, err := net.Listen("tcp", cfg.HTTPAddr)
	if err != nil {
		_ = roomConn.Close()
		_ = userConn.Close()
		return nil, err
	}

	server := &http.Server{
		Handler: mux,
	}

	return &App{
		server:   server,
		listener: listener,
		roomConn: roomConn,
		userConn: userConn,
		health:   healthState,
	}, nil
}

// Run 启动 HTTP 服务。
func (a *App) Run() error {
	a.health.MarkHTTPServing()
	err := a.server.Serve(a.listener)
	a.health.MarkHTTPStopped()
	if errors.Is(err, http.ErrServerClosed) {
		return nil
	}

	return err
}

// Close 关闭 HTTP 服务。
func (a *App) Close() error {
	var err error
	a.closeOnce.Do(func() {
		a.health.MarkDraining()
		if a.roomConn != nil {
			_ = a.roomConn.Close()
		}
		if a.userConn != nil {
			_ = a.userConn.Close()
		}

		err = a.server.Close()
	})

	return err
}

func nodeID() string {
	hostname, err := os.Hostname()
	if err != nil || hostname == "" {
		return "gateway-service"
	}

	return hostname
}