feat: enhance API and session management with Nacos and Redis integration

- Add Nacos registry for service registration and deregistration.
- Implement Redis registry for session management with heartbeat and session claiming.
- Improve completion service with session handling and request validation.
- Enhance WebSocket handling for completion requests with JSON-RPC support.
- Add tests for new registry implementations and completion manager functionalities.
- Refactor existing code for better readability and maintainability.

backend/internal/cluster/nacos_registry.go

@@ -0,0 +1,186 @@
+package cluster
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/nacos-group/nacos-sdk-go/v2/clients"
+	"github.com/nacos-group/nacos-sdk-go/v2/clients/naming_client"
+	"github.com/nacos-group/nacos-sdk-go/v2/common/constant"
+	"github.com/nacos-group/nacos-sdk-go/v2/vo"
+)
+
+type NacosRegistryConfig struct {
+	ServerAddr  string            // Nacos 地址，例如 10.0.0.10:8848。
+	Namespace   string            // Nacos namespace，可为空表示 public。
+	Group       string            // 服务组，默认 DEFAULT_GROUP。
+	ServiceName string            // 注册服务名，例如 lsp-gateway。
+	ClusterName string            // 可选集群名。
+	Username    string            // Nacos 用户名，可为空。
+	Password    string            // Nacos 密码，可为空。
+	IP          string            // 实例注册 IP，建议注入可达内网地址。
+	Port        uint64            // 实例注册端口（服务监听端口）。
+	Metadata    map[string]string // 实例元数据。
+	Ephemeral   bool              // 是否临时实例，默认 true。
+	Weight      float64           // 实例权重，默认 1。
+	TimeoutMs   uint64            // SDK 请求超时，默认 5000ms。
+}
+
+// NacosRegistry 负责将当前实例注册到 Nacos，并在退出时反注册。
+type NacosRegistry struct {
+	client      naming_client.INamingClient
+	serviceName string
+	groupName   string
+	clusterName string
+	ip          string
+	port        uint64
+	ephemeral   bool
+
+	closeOnce sync.Once
+}
+
+func NewNacosRegistry(cfg NacosRegistryConfig) (*NacosRegistry, error) {
+	serverHost, serverPort, err := parseServerAddr(cfg.ServerAddr)
+	if err != nil {
+		return nil, err
+	}
+	if strings.TrimSpace(cfg.ServiceName) == "" {
+		return nil, errors.New("nacos service name is required")
+	}
+	if strings.TrimSpace(cfg.IP) == "" {
+		return nil, errors.New("nacos register ip is required")
+	}
+	if cfg.Port == 0 {
+		return nil, errors.New("nacos register port is required")
+	}
+	if strings.TrimSpace(cfg.Group) == "" {
+		cfg.Group = "DEFAULT_GROUP"
+	}
+	if cfg.Weight <= 0 {
+		cfg.Weight = 1
+	}
+	if cfg.TimeoutMs == 0 {
+		cfg.TimeoutMs = 5000
+	}
+
+	clientConfig := constant.NewClientConfig(
+		constant.WithNamespaceId(strings.TrimSpace(cfg.Namespace)),
+		constant.WithTimeoutMs(cfg.TimeoutMs),
+		constant.WithUsername(strings.TrimSpace(cfg.Username)),
+		constant.WithPassword(strings.TrimSpace(cfg.Password)),
+	)
+
+	namingClient, err := clients.NewNamingClient(vo.NacosClientParam{
+		ClientConfig: clientConfig,
+		ServerConfigs: []constant.ServerConfig{
+			{
+				IpAddr: serverHost,
+				Port:   serverPort,
+			},
+		},
+	})
+	if err != nil {
+		return nil, fmt.Errorf("create nacos naming client failed: %w", err)
+	}
+
+	registry := &NacosRegistry{
+		client:      namingClient,
+		serviceName: strings.TrimSpace(cfg.ServiceName),
+		groupName:   strings.TrimSpace(cfg.Group),
+		clusterName: strings.TrimSpace(cfg.ClusterName),
+		ip:          strings.TrimSpace(cfg.IP),
+		port:        cfg.Port,
+		ephemeral:   cfg.Ephemeral,
+	}
+
+	ok, err := registry.client.RegisterInstance(vo.RegisterInstanceParam{
+		Ip:          registry.ip,
+		Port:        registry.port,
+		Weight:      cfg.Weight,
+		Enable:      true,
+		Healthy:     true,
+		Metadata:    cfg.Metadata,
+		ClusterName: registry.clusterName,
+		ServiceName: registry.serviceName,
+		GroupName:   registry.groupName,
+		Ephemeral:   registry.ephemeral,
+	})
+	if err != nil {
+		registry.client.CloseClient()
+		return nil, fmt.Errorf("register nacos instance failed: %w", err)
+	}
+	if !ok {
+		registry.client.CloseClient()
+		return nil, errors.New("register nacos instance returned false")
+	}
+
+	return registry, nil
+}
+
+func (r *NacosRegistry) Close() error {
+	var closeErr error
+	r.closeOnce.Do(func() {
+		ok, err := r.client.DeregisterInstance(vo.DeregisterInstanceParam{
+			Ip:          r.ip,
+			Port:        r.port,
+			Cluster:     r.clusterName,
+			ServiceName: r.serviceName,
+			GroupName:   r.groupName,
+			Ephemeral:   r.ephemeral,
+		})
+		if err != nil {
+			closeErr = fmt.Errorf("deregister nacos instance failed: %w", err)
+		} else if !ok {
+			closeErr = errors.New("deregister nacos instance returned false")
+		}
+		r.client.CloseClient()
+	})
+	return closeErr
+}
+
+func parseServerAddr(addr string) (string, uint64, error) {
+	trimmed := strings.TrimSpace(addr)
+	if trimmed == "" {
+		return "", 0, errors.New("nacos server addr is required")
+	}
+
+	host := trimmed
+	port := uint64(8848)
+	if strings.Contains(trimmed, ":") {
+		parsedHost, parsedPort, err := net.SplitHostPort(trimmed)
+		if err != nil {
+			return "", 0, fmt.Errorf("invalid nacos server addr %q: %w", addr, err)
+		}
+		host = parsedHost
+		rawPort, err := strconv.ParseUint(parsedPort, 10, 64)
+		if err != nil {
+			return "", 0, fmt.Errorf("invalid nacos server port %q: %w", parsedPort, err)
+		}
+		port = rawPort
+	}
+
+	host = strings.TrimSpace(host)
+	if host == "" {
+		return "", 0, errors.New("nacos server host is required")
+	}
+	return host, port, nil
+}
+
+func ResolveRegisterIP(explicitIP, instanceURL string) string {
+	if ip := strings.TrimSpace(explicitIP); ip != "" {
+		return ip
+	}
+
+	u, err := url.Parse(strings.TrimSpace(instanceURL))
+	if err == nil {
+		if host := strings.TrimSpace(u.Hostname()); host != "" {
+			return host
+		}
+	}
+	return ""
+}