/**
* @file Expenses Resource Handler
* @version 1.0.0
* @description Handles Brex expenses resource requests
*/
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { ReadResourceRequestSchema } from "@modelcontextprotocol/sdk/types.js";
import { ResourceTemplate } from "../models/resourceTemplate.js";
import { logDebug, logError } from "../utils/logger.js";
import { BrexClient } from "../services/brex/client.js";
import { isExpense, ListExpensesParams } from "../services/brex/expenses-types.js";
import { parseQueryParams } from "../models/common.js";
import { limitExpensesPayload } from "../utils/responseLimiter.js";
// Get Brex client
function getBrexClient(): BrexClient {
return new BrexClient();
}
// Define expenses resource template
const expensesTemplate = new ResourceTemplate("brex://expenses{/id}");
/**
* Registers the expenses resource handler with the server
* @param server The MCP server instance
*/
export function registerExpensesResource(server: Server): void {
server.registerCapabilities({
resources: {
"brex://expenses{/id}": {
description: "Brex expenses",
mimeTypes: ["application/json"],
}
}
});
// Use the standard approach with setRequestHandler
server.setRequestHandler(ReadResourceRequestSchema, async (request, _extra) => {
const uri = request.params.uri;
// Check if this handler should process this URI
if (!uri.startsWith("brex://expenses") || uri.includes("/card")) {
return { handled: false }; // Not handled by this handler (card expenses have their own handler)
}
logDebug(`Reading expenses resource: ${uri}`);
// Get Brex client
const brexClient = getBrexClient();
// Parse parameters from URI
const params = expensesTemplate.parse(uri);
if (!params.id) {
// List all expenses
try {
logDebug("Fetching all expenses from Brex API");
const listParams: ListExpensesParams = {
limit: 50,
expand: ['merchant', 'budget'] // Always expand merchant and budget information
};
const expenses = await brexClient.getExpenses(listParams);
const qp = parseQueryParams(uri);
const fields = qp.fields ? qp.fields.split(',').map(s => s.trim()).filter(Boolean) : undefined;
const summaryOnly = qp.summary_only === 'true';
const limited = limitExpensesPayload(expenses.items as any, { summaryOnly, fields, hardTokenLimit: 24000 });
logDebug(`Successfully fetched ${expenses.items.length} expenses (returned: ${limited.items.length})`);
return {
contents: [{
uri: uri,
mimeType: "application/json",
text: JSON.stringify(limited.items, null, 2)
}]
};
} catch (error) {
logError(`Failed to fetch expenses: ${error instanceof Error ? error.message : String(error)}`);
throw error;
}
} else {
// Get specific expense
try {
logDebug(`Fetching expense ${params.id} from Brex API`);
const expense = await brexClient.getExpense(params.id, {
expand: ['merchant', 'budget', 'location', 'department', 'receipts.download_uris'],
load_custom_fields: true
});
if (!isExpense(expense)) {
logError(`Invalid expense data received for expense ID: ${params.id}`);
throw new Error('Invalid expense data received');
}
const qp = parseQueryParams(uri);
const fields = qp.fields ? qp.fields.split(',').map(s => s.trim()).filter(Boolean) : undefined;
const summaryOnly = qp.summary_only === 'true';
const limited = limitExpensesPayload([expense] as any, { summaryOnly, fields, hardTokenLimit: 24000 });
logDebug(`Successfully fetched expense ${params.id} (summaryApplied=${limited.items.length === 1 && JSON.stringify(limited.items[0]) !== JSON.stringify(expense)})`);
return {
contents: [{
uri: uri,
mimeType: "application/json",
text: JSON.stringify(limited.items[0] || {}, null, 2)
}]
};
} catch (error) {
logError(`Failed to fetch expense ${params.id}: ${error instanceof Error ? error.message : String(error)}`);
throw error;
}
}
});
}
