1package agent
  2
  3import (
  4	"cmp"
  5	"context"
  6	"encoding/json"
  7	"errors"
  8	"fmt"
  9	"io"
 10	"log/slog"
 11	"maps"
 12	"net/http"
 13	"os/exec"
 14	"strings"
 15	"sync"
 16	"time"
 17
 18	"github.com/charmbracelet/crush/internal/config"
 19	"github.com/charmbracelet/crush/internal/csync"
 20	"github.com/charmbracelet/crush/internal/home"
 21	"github.com/charmbracelet/crush/internal/llm/tools"
 22	"github.com/charmbracelet/crush/internal/permission"
 23	"github.com/charmbracelet/crush/internal/pubsub"
 24	"github.com/charmbracelet/crush/internal/version"
 25	"github.com/modelcontextprotocol/go-sdk/mcp"
 26)
 27
 28// MCPState represents the current state of an MCP client
 29type MCPState int
 30
 31const (
 32	MCPStateDisabled MCPState = iota
 33	MCPStateStarting
 34	MCPStateConnected
 35	MCPStateError
 36)
 37
 38func (s MCPState) String() string {
 39	switch s {
 40	case MCPStateDisabled:
 41		return "disabled"
 42	case MCPStateStarting:
 43		return "starting"
 44	case MCPStateConnected:
 45		return "connected"
 46	case MCPStateError:
 47		return "error"
 48	default:
 49		return "unknown"
 50	}
 51}
 52
 53// MCPEventType represents the type of MCP event
 54type MCPEventType string
 55
 56const (
 57	MCPEventStateChanged     MCPEventType = "state_changed"
 58	MCPEventToolsListChanged MCPEventType = "tools_list_changed"
 59)
 60
 61// MCPEvent represents an event in the MCP system
 62type MCPEvent struct {
 63	Type      MCPEventType
 64	Name      string
 65	State     MCPState
 66	Error     error
 67	ToolCount int
 68}
 69
 70// MCPClientInfo holds information about an MCP client's state
 71type MCPClientInfo struct {
 72	Name        string
 73	State       MCPState
 74	Error       error
 75	Client      *mcp.ClientSession
 76	ToolCount   int
 77	ConnectedAt time.Time
 78}
 79
 80var (
 81	mcpToolsOnce    sync.Once
 82	mcpTools        = csync.NewMap[string, tools.BaseTool]()
 83	mcpClient2Tools = csync.NewMap[string, []tools.BaseTool]()
 84	mcpClients      = csync.NewMap[string, *mcp.ClientSession]()
 85	mcpStates       = csync.NewMap[string, MCPClientInfo]()
 86	mcpBroker       = pubsub.NewBroker[MCPEvent]()
 87)
 88
 89type McpTool struct {
 90	mcpName     string
 91	tool        *mcp.Tool
 92	permissions permission.Service
 93	workingDir  string
 94}
 95
 96func (b *McpTool) Name() string {
 97	return fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name)
 98}
 99
100func (b *McpTool) Info() tools.ToolInfo {
101	input := b.tool.InputSchema.(map[string]any)
102	required, _ := input["required"].([]string)
103	parameters, _ := input["properties"].(map[string]any)
104	return tools.ToolInfo{
105		Name:        fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name),
106		Description: b.tool.Description,
107		Parameters:  parameters,
108		Required:    required,
109	}
110}
111
112func runTool(ctx context.Context, name, toolName string, input string) (tools.ToolResponse, error) {
113	var args map[string]any
114	if err := json.Unmarshal([]byte(input), &args); err != nil {
115		return tools.NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
116	}
117
118	c, err := getOrRenewClient(ctx, name)
119	if err != nil {
120		return tools.NewTextErrorResponse(err.Error()), nil
121	}
122	result, err := c.CallTool(ctx, &mcp.CallToolParams{
123		Name:      toolName,
124		Arguments: args,
125	})
126	if err != nil {
127		return tools.NewTextErrorResponse(err.Error()), nil
128	}
129
130	output := make([]string, 0, len(result.Content))
131	for _, v := range result.Content {
132		if vv, ok := v.(*mcp.TextContent); ok {
133			output = append(output, vv.Text)
134		} else {
135			output = append(output, fmt.Sprintf("%v", v))
136		}
137	}
138	return tools.NewTextResponse(strings.Join(output, "\n")), nil
139}
140
141func getOrRenewClient(ctx context.Context, name string) (*mcp.ClientSession, error) {
142	sess, ok := mcpClients.Get(name)
143	if !ok {
144		return nil, fmt.Errorf("mcp '%s' not available", name)
145	}
146
147	cfg := config.Get()
148	m := cfg.MCP[name]
149	state, _ := mcpStates.Get(name)
150
151	timeout := mcpTimeout(m)
152	pingCtx, cancel := context.WithTimeout(ctx, timeout)
153	defer cancel()
154	err := sess.Ping(pingCtx, nil)
155	if err == nil {
156		return sess, nil
157	}
158	updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, state.ToolCount)
159
160	sess, err = createMCPSession(ctx, name, m, cfg.Resolver())
161	if err != nil {
162		return nil, err
163	}
164
165	updateMCPState(name, MCPStateConnected, nil, sess, state.ToolCount)
166	mcpClients.Set(name, sess)
167	return sess, nil
168}
169
170func (b *McpTool) Run(ctx context.Context, params tools.ToolCall) (tools.ToolResponse, error) {
171	sessionID, messageID := tools.GetContextValues(ctx)
172	if sessionID == "" || messageID == "" {
173		return tools.ToolResponse{}, fmt.Errorf("session ID and message ID are required for creating a new file")
174	}
175	permissionDescription := fmt.Sprintf("execute %s with the following parameters:", b.Info().Name)
176	p := b.permissions.Request(
177		permission.CreatePermissionRequest{
178			SessionID:   sessionID,
179			ToolCallID:  params.ID,
180			Path:        b.workingDir,
181			ToolName:    b.Info().Name,
182			Action:      "execute",
183			Description: permissionDescription,
184			Params:      params.Input,
185		},
186	)
187	if !p {
188		return tools.ToolResponse{}, permission.ErrorPermissionDenied
189	}
190
191	return runTool(ctx, b.mcpName, b.tool.Name, params.Input)
192}
193
194func getTools(ctx context.Context, name string, permissions permission.Service, c *mcp.ClientSession, workingDir string) ([]tools.BaseTool, error) {
195	result, err := c.ListTools(ctx, &mcp.ListToolsParams{})
196	if err != nil {
197		return nil, err
198	}
199	mcpTools := make([]tools.BaseTool, 0, len(result.Tools))
200	for _, tool := range result.Tools {
201		mcpTools = append(mcpTools, &McpTool{
202			mcpName:     name,
203			tool:        tool,
204			permissions: permissions,
205			workingDir:  workingDir,
206		})
207	}
208	return mcpTools, nil
209}
210
211// SubscribeMCPEvents returns a channel for MCP events
212func SubscribeMCPEvents(ctx context.Context) <-chan pubsub.Event[MCPEvent] {
213	return mcpBroker.Subscribe(ctx)
214}
215
216// GetMCPStates returns the current state of all MCP clients
217func GetMCPStates() map[string]MCPClientInfo {
218	return maps.Collect(mcpStates.Seq2())
219}
220
221// GetMCPState returns the state of a specific MCP client
222func GetMCPState(name string) (MCPClientInfo, bool) {
223	return mcpStates.Get(name)
224}
225
226// updateMCPState updates the state of an MCP client and publishes an event
227func updateMCPState(name string, state MCPState, err error, client *mcp.ClientSession, toolCount int) {
228	info := MCPClientInfo{
229		Name:      name,
230		State:     state,
231		Error:     err,
232		Client:    client,
233		ToolCount: toolCount,
234	}
235	switch state {
236	case MCPStateConnected:
237		info.ConnectedAt = time.Now()
238	case MCPStateError:
239		updateMcpTools(name, nil)
240		mcpClients.Del(name)
241	}
242	mcpStates.Set(name, info)
243
244	// Publish state change event
245	mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
246		Type:      MCPEventStateChanged,
247		Name:      name,
248		State:     state,
249		Error:     err,
250		ToolCount: toolCount,
251	})
252}
253
254// CloseMCPClients closes all MCP clients. This should be called during application shutdown.
255func CloseMCPClients() error {
256	var errs []error
257	for name, c := range mcpClients.Seq2() {
258		if err := c.Close(); err != nil &&
259			!errors.Is(err, io.EOF) &&
260			!errors.Is(err, context.Canceled) &&
261			err.Error() != "signal: killed" {
262			errs = append(errs, fmt.Errorf("close mcp: %s: %w", name, err))
263		}
264	}
265	mcpBroker.Shutdown()
266	return errors.Join(errs...)
267}
268
269func doGetMCPTools(ctx context.Context, permissions permission.Service, cfg *config.Config) {
270	var wg sync.WaitGroup
271	// Initialize states for all configured MCPs
272	for name, m := range cfg.MCP {
273		if m.Disabled {
274			updateMCPState(name, MCPStateDisabled, nil, nil, 0)
275			slog.Debug("skipping disabled mcp", "name", name)
276			continue
277		}
278
279		// Set initial starting state
280		updateMCPState(name, MCPStateStarting, nil, nil, 0)
281
282		wg.Add(1)
283		go func(name string, m config.MCPConfig) {
284			defer func() {
285				wg.Done()
286				if r := recover(); r != nil {
287					var err error
288					switch v := r.(type) {
289					case error:
290						err = v
291					case string:
292						err = fmt.Errorf("panic: %s", v)
293					default:
294						err = fmt.Errorf("panic: %v", v)
295					}
296					updateMCPState(name, MCPStateError, err, nil, 0)
297					slog.Error("panic in mcp client initialization", "error", err, "name", name)
298				}
299			}()
300
301			ctx, cancel := context.WithTimeout(ctx, mcpTimeout(m))
302			defer cancel()
303
304			c, err := createMCPSession(ctx, name, m, cfg.Resolver())
305			if err != nil {
306				return
307			}
308
309			mcpClients.Set(name, c)
310
311			tools, err := getTools(ctx, name, permissions, c, cfg.WorkingDir())
312			if err != nil {
313				slog.Error("error listing tools", "error", err)
314				updateMCPState(name, MCPStateError, err, nil, 0)
315				c.Close()
316				return
317			}
318
319			updateMcpTools(name, tools)
320			mcpClients.Set(name, c)
321			updateMCPState(name, MCPStateConnected, nil, c, len(tools))
322		}(name, m)
323	}
324	wg.Wait()
325}
326
327// updateMcpTools updates the global mcpTools and mcpClient2Tools maps
328func updateMcpTools(mcpName string, tools []tools.BaseTool) {
329	if len(tools) == 0 {
330		mcpClient2Tools.Del(mcpName)
331	} else {
332		mcpClient2Tools.Set(mcpName, tools)
333	}
334	for _, tools := range mcpClient2Tools.Seq2() {
335		for _, t := range tools {
336			mcpTools.Set(t.Name(), t)
337		}
338	}
339}
340
341func createMCPSession(ctx context.Context, name string, m config.MCPConfig, resolver config.VariableResolver) (*mcp.ClientSession, error) {
342	timeout := mcpTimeout(m)
343	mcpCtx, cancel := context.WithCancel(ctx)
344	cancelTimer := time.AfterFunc(timeout, cancel)
345
346	transport, err := createMCPTransport(mcpCtx, m, resolver)
347	if err != nil {
348		updateMCPState(name, MCPStateError, err, nil, 0)
349		slog.Error("error creating mcp client", "error", err, "name", name)
350		return nil, err
351	}
352
353	client := mcp.NewClient(
354		&mcp.Implementation{
355			Name:    "crush",
356			Version: version.Version,
357			Title:   "Crush",
358		},
359		&mcp.ClientOptions{
360			ToolListChangedHandler: func(context.Context, *mcp.ToolListChangedRequest) {
361				mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
362					Type: MCPEventToolsListChanged,
363					Name: name,
364				})
365			},
366			KeepAlive: time.Minute * 10,
367		},
368	)
369
370	session, err := client.Connect(mcpCtx, transport, nil)
371	if err != nil {
372		updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, 0)
373		slog.Error("error starting mcp client", "error", err, "name", name)
374		cancel()
375		return nil, err
376	}
377
378	cancelTimer.Stop()
379	slog.Info("Initialized mcp client", "name", name)
380	return session, nil
381}
382
383func maybeTimeoutErr(err error, timeout time.Duration) error {
384	if errors.Is(err, context.Canceled) {
385		return fmt.Errorf("timed out after %s", timeout)
386	}
387	return err
388}
389
390func createMCPTransport(ctx context.Context, m config.MCPConfig, resolver config.VariableResolver) (mcp.Transport, error) {
391	switch m.Type {
392	case config.MCPStdio:
393		command, err := resolver.ResolveValue(m.Command)
394		if err != nil {
395			return nil, fmt.Errorf("invalid mcp command: %w", err)
396		}
397		if strings.TrimSpace(command) == "" {
398			return nil, fmt.Errorf("mcp stdio config requires a non-empty 'command' field")
399		}
400		cmd := exec.CommandContext(ctx, home.Long(command), m.Args...)
401		cmd.Env = m.ResolvedEnv()
402		return &mcp.CommandTransport{
403			Command: cmd,
404		}, nil
405	case config.MCPHttp:
406		if strings.TrimSpace(m.URL) == "" {
407			return nil, fmt.Errorf("mcp http config requires a non-empty 'url' field")
408		}
409		client := &http.Client{
410			Transport: &headerRoundTripper{
411				headers: m.ResolvedHeaders(),
412			},
413		}
414		return &mcp.StreamableClientTransport{
415			Endpoint:   m.URL,
416			HTTPClient: client,
417		}, nil
418	case config.MCPSSE:
419		if strings.TrimSpace(m.URL) == "" {
420			return nil, fmt.Errorf("mcp sse config requires a non-empty 'url' field")
421		}
422		client := &http.Client{
423			Transport: &headerRoundTripper{
424				headers: m.ResolvedHeaders(),
425			},
426		}
427		return &mcp.SSEClientTransport{
428			Endpoint:   m.URL,
429			HTTPClient: client,
430		}, nil
431	default:
432		return nil, fmt.Errorf("unsupported mcp type: %s", m.Type)
433	}
434}
435
436type headerRoundTripper struct {
437	headers map[string]string
438}
439
440func (rt headerRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
441	for k, v := range rt.headers {
442		req.Header.Set(k, v)
443	}
444	return http.DefaultTransport.RoundTrip(req)
445}
446
447func mcpTimeout(m config.MCPConfig) time.Duration {
448	return time.Duration(cmp.Or(m.Timeout, 15)) * time.Second
449}