/**
* Dashboard HTTP Handler
*
* Handles GET / requests and returns:
* - HTML dashboard when Accept header includes text/html or wildcard
* - JSON metrics when Accept header is application/json
*/
import { Request, Response } from "express";
import { collectMetrics, DashboardMetrics } from "./metrics.js";
import { renderDashboard } from "./html-template.js";
import { logDebug, logError } from "../logger.js";
// Determine if request prefers HTML response
//
// Returns true for:
// - Accept: text/html
// - Accept: */* (browser default)
// - No Accept header (treat as browser)
//
// Returns false for:
// - Accept: application/json
function prefersHtml(req: Request): boolean {
const accept = req.headers.accept ?? "*/*";
// Explicit JSON request
if (accept.includes("application/json") && !accept.includes("text/html")) {
return false;
}
// HTML or wildcard (browser default)
return accept.includes("text/html") || accept.includes("*/*");
}
/**
* Dashboard endpoint handler
*
* Returns server health dashboard as HTML or JSON based on Accept header.
* Safe for MCP clients - they use POST /mcp or SSE endpoints, not GET /.
*
* @param req - Express request
* @param res - Express response
*/
export function dashboardHandler(req: Request, res: Response): void {
try {
const metrics = collectMetrics();
logDebug("Dashboard request", {
accept: req.headers.accept,
prefersHtml: prefersHtml(req),
});
if (prefersHtml(req)) {
res.type("text/html").send(renderDashboard(metrics));
} else {
res.json(metrics);
}
} catch (error) {
logError("Dashboard error", { err: error });
res.status(500).json({ error: "Failed to generate dashboard" });
}
}
/**
* Get dashboard metrics without rendering
* Useful for programmatic access or testing
*/
export function getMetrics(): DashboardMetrics {
return collectMetrics();
}
