Files
ca-marketplace-scraper/packages/mcp-server/src/protocol/handler.ts

281 lines
8.9 KiB
TypeScript

import { logger } from "../logger";
import { tools } from "./tools";
const API_BASE_URL = process.env.API_BASE_URL || "http://localhost:4005/api";
const API_TIMEOUT = Number(process.env.API_TIMEOUT) || 180000;
async function callMarketplaceApi(
marketplace: string,
params: URLSearchParams,
): Promise<unknown> {
const url = `${API_BASE_URL}/${marketplace}?${params.toString()}`;
logger.log(`[MCP] Calling ${marketplace} API`);
const response = await Promise.race([
fetch(url),
new Promise<Response>((_, reject) =>
setTimeout(
() => reject(new Error(`Request timed out after ${API_TIMEOUT}ms`)),
API_TIMEOUT,
),
),
]);
if (!response.ok) {
const errorText = await response.text();
logger.error(
`[MCP] ${marketplace} API error ${response.status}: ${errorText}`,
);
throw new Error(`API returned ${response.status}: ${errorText}`);
}
return response.json();
}
/**
* Handle MCP JSON-RPC 2.0 protocol requests
*/
export async function handleMcpRequest(req: Request): Promise<Response> {
try {
const body = await req.json();
// Validate JSON-RPC 2.0 format
if (!body.jsonrpc || body.jsonrpc !== "2.0" || !body.method) {
return Response.json(
{
jsonrpc: "2.0",
error: { code: -32600, message: "Invalid Request" },
id: body.id,
},
{ status: 400 },
);
}
const { method, params, id } = body;
// Handle initialize method
if (method === "initialize") {
return Response.json({
jsonrpc: "2.0",
id,
result: {
protocolVersion: "2025-06-18",
capabilities: {
tools: {
listChanged: true,
},
},
serverInfo: {
name: "marketplace-scrapers",
version: "1.0.0",
},
instructions:
"Use search_kijiji, search_facebook, or search_ebay tools to find listings across Canadian marketplaces",
},
});
}
// Handle tools/list method
if (method === "tools/list") {
return Response.json({
jsonrpc: "2.0",
id,
result: {
tools,
},
});
}
// Handle notifications (messages without id field should not get a response)
if (!id) {
// Notifications don't require a response
if (method === "notifications/initialized") {
// Client initialized successfully, no response needed
return new Response(null, { status: 204 });
}
if (method === "notifications/progress") {
// Progress notifications, no response needed
return new Response(null, { status: 204 });
}
// Unknown notification - still no response for notifications
return new Response(null, { status: 204 });
}
// Handle tools/call method
if (method === "tools/call") {
const { name, arguments: args } = params || {};
if (!name || !args) {
return Response.json(
{
jsonrpc: "2.0",
id,
error: {
code: -32602,
message: "Invalid params: name and arguments required",
},
},
{ status: 400 },
);
}
// Route tool calls to appropriate handlers
try {
let result: unknown;
if (name === "search_kijiji") {
const query = args.query;
if (!query) {
return Response.json({
jsonrpc: "2.0",
id,
error: { code: -32602, message: "query parameter is required" },
});
}
const params = new URLSearchParams({ q: query });
if (args.location) params.append("location", args.location);
if (args.category) params.append("category", args.category);
if (args.keywords) params.append("keywords", args.keywords);
if (args.sortBy) params.append("sortBy", args.sortBy);
if (args.sortOrder) params.append("sortOrder", args.sortOrder);
if (args.maxPages)
params.append("maxPages", args.maxPages.toString());
if (args.priceMin)
params.append("priceMin", args.priceMin.toString());
if (args.priceMax)
params.append("priceMax", args.priceMax.toString());
if (args.unstableFilter !== undefined)
params.append("unstableFilter", args.unstableFilter.toString());
logger.log(
`[MCP] Calling Kijiji API: ${API_BASE_URL}/kijiji?${params.toString()}`,
);
const response = await Promise.race([
fetch(`${API_BASE_URL}/kijiji?${params.toString()}`),
new Promise<Response>((_, reject) =>
setTimeout(
() =>
reject(new Error(`Request timed out after ${API_TIMEOUT}ms`)),
API_TIMEOUT,
),
),
]);
if (!response.ok) {
const errorText = await response.text();
logger.error(
`[MCP] Kijiji API error ${response.status}: ${errorText}`,
);
let errorMessage = `API returned ${response.status}: ${errorText}`;
try {
const errorJson = JSON.parse(errorText) as { message?: string };
if (errorJson.message) errorMessage = errorJson.message;
} catch {
// not JSON — use raw text
}
throw new Error(errorMessage);
}
result = await response.json();
logger.log(
`[MCP] Kijiji returned ${Array.isArray(result) ? result.length : 0} items`,
);
} else if (name === "search_facebook") {
const query = args.query;
if (!query) {
return Response.json({
jsonrpc: "2.0",
id,
error: { code: -32602, message: "query parameter is required" },
});
}
const params = new URLSearchParams({ q: query });
if (args.location) params.append("location", args.location);
if (args.maxItems)
params.append("maxItems", args.maxItems.toString());
if (args.unstableFilter !== undefined)
params.append("unstableFilter", args.unstableFilter.toString());
result = await callMarketplaceApi("facebook", params);
} else if (name === "search_ebay") {
const query = args.query;
if (!query) {
return Response.json({
jsonrpc: "2.0",
id,
error: { code: -32602, message: "query parameter is required" },
});
}
const params = new URLSearchParams({ q: query });
if (args.minPrice)
params.append("minPrice", args.minPrice.toString());
if (args.maxPrice)
params.append("maxPrice", args.maxPrice.toString());
if (args.strictMode !== undefined)
params.append("strictMode", args.strictMode.toString());
if (args.exclusions?.length)
params.append("exclusions", args.exclusions.join(","));
if (args.keywords?.length)
params.append("keywords", args.keywords.join(","));
if (args.buyItNowOnly !== undefined)
params.append("buyItNowOnly", args.buyItNowOnly.toString());
if (args.canadaOnly !== undefined)
params.append("canadaOnly", args.canadaOnly.toString());
if (args.maxItems)
params.append("maxItems", args.maxItems.toString());
if (args.unstableFilter !== undefined)
params.append("unstableFilter", args.unstableFilter.toString());
result = await callMarketplaceApi("ebay", params);
} else {
return Response.json({
jsonrpc: "2.0",
id,
error: { code: -32601, message: `Unknown tool: ${name}` },
});
}
return Response.json({
jsonrpc: "2.0",
id,
result: {
content: [
{
type: "text",
text: JSON.stringify(result, null, 2),
},
],
},
});
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : "Unknown error";
return Response.json({
jsonrpc: "2.0",
id,
error: {
code: -32603,
message: `Tool execution failed: ${errorMessage}`,
},
});
}
}
// Method not found
return Response.json(
{
jsonrpc: "2.0",
id,
error: { code: -32601, message: `Method not found: ${method}` },
},
{ status: 404 },
);
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : "Unknown error";
return Response.json(
{
jsonrpc: "2.0",
error: { code: -32700, message: `Parse error: ${errorMessage}` },
},
{ status: 400 },
);
}
}