feat: add mcp client, convert eino tools

internal/mcp/config.go

@@ -0,0 +1,89 @@
+package mcp
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"time"
+)
+
+// MCPSettings represents the main configuration structure
+type MCPSettings struct {
+	MCPServers map[string]ServerConfig `json:"mcpServers"`
+}
+
+// ServerConfig represents configuration for a single MCP server
+type ServerConfig struct {
+	TransportType string        `json:"transportType,omitempty"` // "sse" or "stdio"
+	AutoApprove   []string      `json:"autoApprove,omitempty"`
+	Disabled      bool          `json:"disabled,omitempty"`
+	Timeout       time.Duration `json:"timeout,omitempty"`
+
+	// SSE specific config
+	URL string `json:"url,omitempty"`
+
+	// Stdio specific config
+	Command string            `json:"command"`
+	Args    []string          `json:"args"`
+	Env     map[string]string `json:"env,omitempty"`
+}
+
+const (
+	DefaultMCPTimeoutSeconds = 30
+	MinMCPTimeoutSeconds     = 5
+)
+
+// GetTimeoutDuration converts timeout seconds to time.Duration
+func (c *ServerConfig) GetTimeoutDuration() time.Duration {
+	if c.Timeout == 0 {
+		return time.Duration(DefaultMCPTimeoutSeconds) * time.Second
+	}
+	return c.Timeout
+}
+
+// LoadSettings loads MCP settings from the config file
+func LoadSettings(path string) (*MCPSettings, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read settings file: %w", err)
+	}
+
+	var settings MCPSettings
+	if err := json.Unmarshal(data, &settings); err != nil {
+		return nil, fmt.Errorf("failed to parse settings: %w", err)
+	}
+
+	if err := validateSettings(&settings); err != nil {
+		return nil, fmt.Errorf("invalid settings: %w", err)
+	}
+
+	return &settings, nil
+}
+
+// validateSettings validates the MCP settings
+func validateSettings(settings *MCPSettings) error {
+	if settings == nil {
+		return fmt.Errorf("settings cannot be nil")
+	}
+
+	for name, server := range settings.MCPServers {
+		if server.Timeout > 0 && server.Timeout < time.Duration(MinMCPTimeoutSeconds)*time.Second {
+			return fmt.Errorf("server %s: timeout must be at least %d seconds", name, MinMCPTimeoutSeconds)
+		}
+
+		switch server.TransportType {
+		case "sse":
+			if server.URL == "" {
+				return fmt.Errorf("server %s: URL is required for SSE transport", name)
+			}
+		case "stdio", "":
+			if server.Command == "" {
+				return fmt.Errorf("server %s: command is required for stdio transport", name)
+			}
+		default:
+			return fmt.Errorf("server %s: unsupported transport type: %s", name, server.TransportType)
+		}
+	}
+
+	return nil
+}