| 1 | import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js' |
| 2 | import { |
| 3 | ErrorCode, |
| 4 | ListResourcesRequestSchema, |
| 5 | ListResourceTemplatesRequestSchema, |
| 6 | McpError, |
| 7 | ReadResourceRequestSchema, |
| 8 | } from '@modelcontextprotocol/sdk/types.js' |
| 9 | import { Inject, Injectable, InjectionToken, Scope } from '@nestjs/common' |
| 10 | import { ContextIdFactory, ModuleRef } from '@nestjs/core' |
| 11 | import { getErrorMessage } from '@yikart/common' |
| 12 | import { Context } from '../../interfaces' |
| 13 | import { HttpRequest } from '../../interfaces/http-adapter.interface' |
| 14 | import { McpRegistryService } from '../mcp-registry.service' |
| 15 | import { McpHandlerBase } from './mcp-handler.base' |
| 16 | |
| 17 | @Injectable({ scope: Scope.REQUEST }) |
| 18 | export class McpResourcesHandler extends McpHandlerBase { |
| 19 | constructor( |
| 20 | moduleRef: ModuleRef, |
| 21 | registry: McpRegistryService, |
| 22 | @Inject('MCP_MODULE_ID') private readonly mcpModuleId: string, |
| 23 | ) { |
| 24 | super(moduleRef, registry, McpResourcesHandler.name) |
| 25 | } |
| 26 | |
| 27 | registerHandlers(mcpServer: McpServer, httpRequest: HttpRequest) { |
| 28 | const resources = this.registry.getResources(this.mcpModuleId) |
| 29 | const resourceTemplates = this.registry.getResourceTemplates( |
| 30 | this.mcpModuleId, |
| 31 | ) |
| 32 | if (resources.length === 0 && resourceTemplates.length === 0) { |
| 33 | this.logger.debug( |
| 34 | 'No resources or resource templates registered, skipping resource handlers', |
| 35 | ) |
| 36 | return |
| 37 | } |
| 38 | |
| 39 | mcpServer.server.setRequestHandler(ListResourcesRequestSchema, () => { |
| 40 | this.logger.debug('ListResourcesRequestSchema is being called') |
| 41 | return { |
| 42 | resources: this.registry |
| 43 | .getResources(this.mcpModuleId) |
| 44 | .map(resources => resources.metadata), |
| 45 | } |
| 46 | }) |
| 47 | |
| 48 | mcpServer.server.setRequestHandler( |
| 49 | ListResourceTemplatesRequestSchema, |
| 50 | () => { |
| 51 | this.logger.debug('ListResourceTemplatesRequestSchema is being called') |
| 52 | return { |
| 53 | resourceTemplates: this.registry |
| 54 | .getResourceTemplates(this.mcpModuleId) |
| 55 | .map(resourceTemplate => resourceTemplate.metadata), |
| 56 | } |
| 57 | }, |
| 58 | ) |
| 59 | |
| 60 | mcpServer.server.setRequestHandler( |
| 61 | ReadResourceRequestSchema, |
| 62 | async (request) => { |
| 63 | this.logger.debug('ReadResourceRequestSchema is being called') |
| 64 | |
| 65 | const uri = request.params.uri |
| 66 | const resourceInfo = this.registry.findResourceByUri( |
| 67 | this.mcpModuleId, |
| 68 | uri, |
| 69 | ) |
| 70 | const resourceTemplateInfo = this.registry.findResourceTemplateByUri( |
| 71 | this.mcpModuleId, |
| 72 | uri, |
| 73 | ) |
| 74 | |
| 75 | try { |
| 76 | let providerClass: InjectionToken |
| 77 | let params: Record<string, unknown> = {} |
| 78 | let methodName: string |
| 79 | if (resourceTemplateInfo) { |
| 80 | providerClass = resourceTemplateInfo.resourceTemplate.providerClass |
| 81 | params = { |
| 82 | ...resourceTemplateInfo.params, |
| 83 | ...request.params, |
| 84 | } |
| 85 | methodName = resourceTemplateInfo.resourceTemplate.methodName |
| 86 | } |
| 87 | else if (resourceInfo) { |
| 88 | providerClass = resourceInfo.resource.providerClass |
| 89 | |
| 90 | params = { |
| 91 | ...resourceInfo.params, |
| 92 | ...request.params, |
| 93 | } |
| 94 | methodName = resourceInfo.resource.methodName |
| 95 | } |
| 96 | else { |
| 97 | throw new McpError( |
| 98 | ErrorCode.MethodNotFound, |
| 99 | `Unknown resource: ${uri}`, |
| 100 | ) |
| 101 | } |
| 102 | return await this.handleRequest( |
| 103 | httpRequest, |
| 104 | providerClass, |
| 105 | uri, |
| 106 | this.createContext(mcpServer, request), |
| 107 | params, |
| 108 | methodName, |
| 109 | ) |
| 110 | } |
| 111 | catch (error) { |
| 112 | this.logger.error(error) |
| 113 | const errorMessage = getErrorMessage(error) |
| 114 | return { |
| 115 | contents: [{ uri, mimeType: 'text/plain', text: errorMessage }], |
| 116 | isError: true, |
| 117 | } |
| 118 | } |
| 119 | }, |
| 120 | ) |
| 121 | } |
| 122 | |
| 123 | private async handleRequest( |
| 124 | httpRequest: HttpRequest, |
| 125 | providerClass: InjectionToken, |
| 126 | uri: string, |
| 127 | context: Context, |
| 128 | requestParams: Record<string, unknown>, |
| 129 | methodName: string, |
| 130 | ) { |
| 131 | const contextId = ContextIdFactory.getByRequest(httpRequest) |
| 132 | this.moduleRef.registerRequestByContextId(httpRequest, contextId) |
| 133 | |
| 134 | const resourceInstance = await this.moduleRef.resolve( |
| 135 | providerClass, |
| 136 | contextId, |
| 137 | { strict: false }, |
| 138 | ) |
| 139 | |
| 140 | if (!resourceInstance) { |
| 141 | throw new McpError( |
| 142 | ErrorCode.MethodNotFound, |
| 143 | `Unknown resource template: ${uri}`, |
| 144 | ) |
| 145 | } |
| 146 | const result = await resourceInstance[methodName]( |
| 147 | requestParams, |
| 148 | context, |
| 149 | httpRequest, |
| 150 | ) |
| 151 | |
| 152 | this.logger.debug(result, 'ReadResourceRequestSchema result') |
| 153 | |
| 154 | return result |
| 155 | } |
| 156 | } |
| 157 |