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| 1 | +package clientmanager |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "fmt" |
| 6 | + "log/slog" |
| 7 | + "net/http" |
| 8 | + "os/exec" |
| 9 | + "sort" |
| 10 | + |
| 11 | + "github.com/modelcontextprotocol/go-sdk/mcp" |
| 12 | + "skillful-mcp/internal/config" |
| 13 | +) |
| 14 | + |
| 15 | +type Manager struct { |
| 16 | + sessions map[string]*mcp.ClientSession |
| 17 | +} |
| 18 | + |
| 19 | +// ConnectAll creates a Manager by connecting to all servers in the config. |
| 20 | +func ConnectAll(ctx context.Context, cfg *config.Config) (*Manager, error) { |
| 21 | + m := &Manager{sessions: make(map[string]*mcp.ClientSession)} |
| 22 | + |
| 23 | + for name, srv := range cfg.MCPServers { |
| 24 | + session, err := connect(ctx, name, &srv) |
| 25 | + if err != nil { |
| 26 | + // Close any sessions we already opened before returning. |
| 27 | + m.Close() |
| 28 | + return nil, fmt.Errorf("connecting to %q: %w", name, err) |
| 29 | + } |
| 30 | + m.sessions[name] = session |
| 31 | + tt, _ := srv.TransportType() // already validated |
| 32 | + slog.Info("connected to server", "skill", name, "transport", tt) |
| 33 | + } |
| 34 | + |
| 35 | + return m, nil |
| 36 | +} |
| 37 | + |
| 38 | +// NewFromSessions creates a Manager from pre-built sessions (useful for testing). |
| 39 | +func NewFromSessions(sessions map[string]*mcp.ClientSession) *Manager { |
| 40 | + return &Manager{sessions: sessions} |
| 41 | +} |
| 42 | + |
| 43 | +func connect(ctx context.Context, name string, srv *config.ServerConfig) (*mcp.ClientSession, error) { |
| 44 | + client := mcp.NewClient(&mcp.Implementation{ |
| 45 | + Name: "skillful-mcp", |
| 46 | + Version: "0.1.0", |
| 47 | + }, nil) |
| 48 | + |
| 49 | + var transport mcp.Transport |
| 50 | + |
| 51 | + tt, err := srv.TransportType() |
| 52 | + if err != nil { |
| 53 | + return nil, err |
| 54 | + } |
| 55 | + |
| 56 | + switch tt { |
| 57 | + case config.TransportSTDIO: |
| 58 | + cmd := exec.Command(srv.Command, srv.Args...) |
| 59 | + cmd.Env = toEnv(srv.Env) |
| 60 | + transport = &mcp.CommandTransport{Command: cmd} |
| 61 | + |
| 62 | + case config.TransportHTTP: |
| 63 | + httpClient := httpClientWithHeaders(srv.Headers) |
| 64 | + transport = &mcp.StreamableClientTransport{ |
| 65 | + Endpoint: srv.URL, |
| 66 | + HTTPClient: httpClient, |
| 67 | + } |
| 68 | + |
| 69 | + case config.TransportSSE: |
| 70 | + httpClient := httpClientWithHeaders(srv.Headers) |
| 71 | + transport = &mcp.SSEClientTransport{ |
| 72 | + Endpoint: srv.URL, |
| 73 | + HTTPClient: httpClient, |
| 74 | + } |
| 75 | + } |
| 76 | + |
| 77 | + session, err := client.Connect(ctx, transport, nil) |
| 78 | + if err != nil { |
| 79 | + return nil, err |
| 80 | + } |
| 81 | + return session, nil |
| 82 | +} |
| 83 | + |
| 84 | +func (m *Manager) GetSession(name string) (*mcp.ClientSession, error) { |
| 85 | + s, ok := m.sessions[name] |
| 86 | + if !ok { |
| 87 | + return nil, fmt.Errorf("unknown skill: %q", name) |
| 88 | + } |
| 89 | + return s, nil |
| 90 | +} |
| 91 | + |
| 92 | +func (m *Manager) ListServerNames() []string { |
| 93 | + names := make([]string, 0, len(m.sessions)) |
| 94 | + for name := range m.sessions { |
| 95 | + names = append(names, name) |
| 96 | + } |
| 97 | + sort.Strings(names) |
| 98 | + return names |
| 99 | +} |
| 100 | + |
| 101 | +func (m *Manager) Close() { |
| 102 | + for name, s := range m.sessions { |
| 103 | + if err := s.Close(); err != nil { |
| 104 | + slog.Warn("error closing session", "skill", name, "error", err) |
| 105 | + } |
| 106 | + } |
| 107 | +} |
| 108 | + |
| 109 | +// toEnv converts the configured env map to a slice for exec.Cmd. |
| 110 | +// Only the explicitly specified vars are passed to the child process. |
| 111 | +// If no env vars are configured, returns nil (child inherits nothing). |
| 112 | +func toEnv(env map[string]string) []string { |
| 113 | + if len(env) == 0 { |
| 114 | + return nil |
| 115 | + } |
| 116 | + result := make([]string, 0, len(env)) |
| 117 | + for k, v := range env { |
| 118 | + result = append(result, k+"="+v) |
| 119 | + } |
| 120 | + return result |
| 121 | +} |
| 122 | + |
| 123 | +// headerTransport injects custom HTTP headers into every request. |
| 124 | +type headerTransport struct { |
| 125 | + base http.RoundTripper |
| 126 | + headers map[string]string |
| 127 | +} |
| 128 | + |
| 129 | +func (t *headerTransport) RoundTrip(req *http.Request) (*http.Response, error) { |
| 130 | + for k, v := range t.headers { |
| 131 | + req.Header.Set(k, v) |
| 132 | + } |
| 133 | + return t.base.RoundTrip(req) |
| 134 | +} |
| 135 | + |
| 136 | +func httpClientWithHeaders(headers map[string]string) *http.Client { |
| 137 | + if len(headers) == 0 { |
| 138 | + return http.DefaultClient |
| 139 | + } |
| 140 | + return &http.Client{ |
| 141 | + Transport: &headerTransport{ |
| 142 | + base: http.DefaultTransport, |
| 143 | + headers: headers, |
| 144 | + }, |
| 145 | + } |
| 146 | +} |
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