printerCentral/server/api/mcp/index.post.ts

// MCP Server Endpoint - JSON-RPC 2.0 over HTTP
// Protocolo MCP para agentes de IA

import { MCP_TOOLS, handleToolCall } from '../../utils/mcp'

interface JsonRpcRequest {
  jsonrpc: '2.0'
  id: string | number
  method: string
  params?: any
}

interface JsonRpcResponse {
  jsonrpc: '2.0'
  id: string | number | null
  result?: any
  error?: {
    code: number
    message: string
    data?: any
  }
}

export default defineEventHandler(async (event) => {
  // Validar token de autenticación
  const authHeader = getHeader(event, 'Authorization')
  const expectedToken = process.env.MCP_AUTH_TOKEN

  if (expectedToken) {
    const providedToken = authHeader?.replace('Bearer ', '')
    if (!providedToken || providedToken !== expectedToken) {
      setResponseStatus(event, 401)
      return createJsonRpcError(null, -32000, 'Unauthorized: Invalid or missing token')
    }
  }

  try {
    const body = await readBody(event) as JsonRpcRequest

    // Validar JSON-RPC
    if (body.jsonrpc !== '2.0') {
      return createJsonRpcError(body.id, -32600, 'Invalid Request: jsonrpc must be "2.0"')
    }

    if (!body.method) {
      return createJsonRpcError(body.id, -32600, 'Invalid Request: method is required')
    }

    // Manejar métodos MCP
    switch (body.method) {
      case 'initialize': {
        // Handshake inicial del protocolo MCP
        return createJsonRpcResponse(body.id, {
          protocolVersion: '2024-11-05',
          capabilities: {
            tools: {}
          },
          serverInfo: {
            name: 'printercentral-mcp',
            version: '1.0.0'
          }
        })
      }

      case 'initialized': {
        // Notificación de que el cliente está listo
        return createJsonRpcResponse(body.id, {})
      }

      case 'tools/list': {
        // Listar todas las tools disponibles
        return createJsonRpcResponse(body.id, {
          tools: MCP_TOOLS
        })
      }

      case 'tools/call': {
        // Ejecutar una tool
        const { name, arguments: args } = body.params || {}

        if (!name) {
          return createJsonRpcError(body.id, -32602, 'Invalid params: tool name is required')
        }

        // Verificar que la tool existe
        const tool = MCP_TOOLS.find(t => t.name === name)
        if (!tool) {
          return createJsonRpcError(body.id, -32602, `Tool not found: ${name}`)
        }

        // Ejecutar la tool
        const result = await handleToolCall(name, args || {})
        return createJsonRpcResponse(body.id, result)
      }

      case 'ping': {
        return createJsonRpcResponse(body.id, {})
      }

      default:
        return createJsonRpcError(body.id, -32601, `Method not found: ${body.method}`)
    }
  } catch (err: any) {
    console.error('MCP Error:', err)
    return createJsonRpcError(null, -32603, `Internal error: ${err.message}`)
  }
})

function createJsonRpcResponse(id: string | number | null, result: any): JsonRpcResponse {
  return {
    jsonrpc: '2.0',
    id: id ?? null,
    result
  }
}

function createJsonRpcError(id: string | number | null, code: number, message: string, data?: any): JsonRpcResponse {
  return {
    jsonrpc: '2.0',
    id: id ?? null,
    error: {
      code,
      message,
      ...(data && { data })
    }
  }
}