router

var Module = fx.Options(fx.Provide(
	Codec,
	func(p RouterParams) (grpc.StreamHandler, error) {
		conns := make(map[string]*grpc.ClientConn, len(p.Config.Upstreams))
		for i := range p.Config.Upstreams {
			upstream := &p.Config.Upstreams[i]
			sockPath, err := socket.UnixPath(upstream.Listen.HostPort)
			if err != nil {
				return nil, fmt.Errorf("failed to resolve proxy socket path[%q]: %w", upstream.Name, err)
			}

			sock := "unix://" + sockPath
			conn, err := p.Pool.ConnOrCreate(sock, sock, grpc.WithTransportCredentials(insecure.NewCredentials()))
			if err != nil {
				return nil, fmt.Errorf("failed to create upstream client[%q]: %w", upstream.Name, err)
			}

			conns[upstream.Name] = conn
		}

		return Handler(
			&director{
				conns:    conns,
				mux:      p.Mux,
				reporter: p.Reporter,
			},
			p.Extractor,
			p.Reporter,
		), nil
	},
	func(c *config.Config, f *metrics.Factory) *Reporter {
		names := make([]string, 0, len(c.Upstreams))
		for i := range c.Upstreams {
			names = append(names, c.Upstreams[i].Name)
		}

		return NewReporter(f.ForSubsystem("router"), names)
	},
	func(c *config.Config) (*Mux, error) {
		rules := make([]Rule, 0, len(c.Routing.Rules))
		for i, r := range c.Routing.Rules {
			p := r.Match.Namespace
			if p == "" {
				p = "*"
			}

			ns, err := match.Compile(p)
			if err != nil {
				return nil, fmt.Errorf("routing: rules[%d].match.namespace: %w", i, err)
			}

			meta := make(map[string]Matcher, len(r.Match.Metadata))
			seen := make(map[string]string, len(r.Match.Metadata))
			for k, v := range r.Match.Metadata {
				lk := strings.ToLower(k)
				if prev, ok := seen[lk]; ok {
					return nil, fmt.Errorf(
						"routing: rules[%d].match.metadata: keys %q and %q both map to %q when lowercased",
						i, prev, k, lk,
					)
				}

				seen[lk] = k
				m, err := match.Compile(v)
				if err != nil {
					return nil, fmt.Errorf("routing: rules[%d].match.metadata[%q]: %w", i, k, err)
				}

				meta[lk] = m
			}

			rules = append(rules, Rule{
				upstream: r.Upstream,
				ns:       ns,
				meta:     meta,
			})
		}

		return New(
			c.Routing.DefaultUpstream,
			c.Routing.SystemUpstream,
			rules...,
		), nil
	},
))