proxy-bun/src/lib/router.ts

import {
	normalizeTargetUrl,
	isAllowedTarget,
	isAllowedTargetAsync,
	isSsrfDnsCheckEnabled,
	filterRequestHeaders,
	buildRelayRequest,
	createRelayResponse,
	createErrorResponse,
	createCorsPreflightResponse,
	getCorsHeaders,
	classifyFetchError,
} from "./relay-utils";

import { checkBodySize } from "../middleware/body-limiter";
import { createRateLimiter } from "../middleware/rate-limiter";
import { logRelayEvent } from "../middleware/logger";
import { ProxyPool, SessionProxyPool } from "./proxy-pool";
import { handleChatCompletion, listModels } from "./ai-proxy";
import { handleAnthropicMessages } from "./anthropic-proxy";
import { fetchWithRetry } from "./fetch-utils";

// --- Types -------------------------------------------------------------------

export interface RouterEnv {
	PORT?: string;
	RELAY_TIMEOUT_MS?: string;
	BODY_MAX_BYTES?: string;
	RATE_LIMIT_MAX?: string;
	RATE_LIMIT_WINDOW_MS?: string;
	CORS_ORIGIN?: string;
	NODE_ENV?: string;
	API_KEY?: string;
	PROXY_LIST?: string; // Comma-separated list of proxies for serverless
	// Optional KV binding for rate limiter
	KV?: {
		get(key: string): Promise<any>;
		put(key: string, value: any, options?: { expirationTtl?: number }): Promise<void>;
	};
}

// --- Global singletons (survives warm starts) --------------------------------

let rateLimiter: ReturnType<typeof createRateLimiter> | null = null;
let proxyPool: ProxyPool | null = null;
let sessionPool: SessionProxyPool | null = null;

const SERVER_START_TIME = Date.now();
const RELAY_VERSION = "1.0.0";

// --- Helpers -----------------------------------------------------------------

function getNumericEnv(env: RouterEnv, key: keyof RouterEnv, fallback: number): number {
	const raw = env[key];
	const val = typeof raw === "string" ? raw : (typeof process !== "undefined" ? process.env[key as string] : undefined);
	return Number.parseInt(val ?? String(fallback), 10);
}

function getEnv(env: RouterEnv, key: keyof RouterEnv, fallback: string): string {
	const raw = env[key];
	const fromEnv = typeof raw === "string" ? raw : (typeof process !== "undefined" ? process.env[key as string] : undefined);
	return fromEnv ?? fallback;
}

function initGlobals(env: RouterEnv) {
	if (!rateLimiter) {
		const kvAdapter = env.KV ? {
			get: async (k: string) => {
				const val = await env.KV!.get(k);
				return val ? JSON.parse(val) : null;
			},
			set: async (k: string, v: number[], ttl?: number) => {
				await env.KV!.put(k, JSON.stringify(v), { expirationTtl: ttl });
			}
		} : undefined;

		rateLimiter = createRateLimiter({
			maxRequests: getNumericEnv(env, "RATE_LIMIT_MAX", 100),
			windowMs: getNumericEnv(env, "RATE_LIMIT_WINDOW_MS", 60000),
			kv: kvAdapter,
		});
	}

	if (!proxyPool) {
		proxyPool = new ProxyPool();
		// For Bun (process.env.PROXY_FILE) it's loaded in index.ts, but for serverless we can load from env
		const proxies = getEnv(env, "PROXY_LIST", "");
		if (proxies) {
			for (const p of proxies.split(",")) {
				const pt = p.trim();
				if (pt) proxyPool.addProxy(pt);
			}
		}
		sessionPool = new SessionProxyPool(proxyPool);
		sessionPool.setFailureThreshold(3);
	}
}

function requireAuth(req: Request, env: RouterEnv): Response | null {
	const API_KEY = getEnv(env, "API_KEY", "sk-dummy-key");
	const header = req.headers.get("authorization") ?? req.headers.get("x-api-key") ?? "";
	const key = header.replace(/^Bearer\s+/i, "").trim();
	if (key === API_KEY) return null;
	return new Response(
		JSON.stringify({ error: { message: "Unauthorized", type: "auth_error" } }),
		{
			status: 401,
			headers: { "Content-Type": "application/json", ...getCorsHeaders() },
		},
	);
}

// --- Static Handlers ---------------------------------------------------------

function handleHealth(): Response {
	return new Response(
		JSON.stringify({
			status: "ok",
			uptime: Date.now() - SERVER_START_TIME,
			version: RELAY_VERSION,
		}),
		{
			status: 200,
			headers: {
				"Content-Type": "application/json",
				...getCorsHeaders(),
			},
		},
	);
}

function handleIndex(): Response {
	const html = `<!DOCTYPE html>
	<html lang="en">
	<head>
	  <meta charset="UTF-8">
	  <meta name="viewport" content="width=device-width, initial-scale=1.0">
	  <title>Edge Proxy Relay</title>
	  <style>
	    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
	    body { font-family: system-ui, -apple-system, sans-serif; line-height: 1.6; color: #e1e4e8; background: #0d1117; display: flex; align-items: center; justify-content: center; min-height: 100vh; }
	    main { text-align: center; }
	    h1 { font-size: 2rem; color: #58a6ff; margin-bottom: 0.5rem; }
	    p { color: #8b949e; }
	    a { color: #58a6ff; }
	    .status { color: #3fb950; }
	  </style>
	</head>
	<body>
	<main>
	  <h1>Edge Proxy Relay</h1>
	  <p class="status">Server is running</p>
	  <p><a href="/health">/health</a> &middot; <a href="/docs">/docs</a></p>
	</main>
	</body>
	</html>`;

	return new Response(html, {
		status: 200,
		headers: {
			"Content-Type": "text/html; charset=utf-8",
		},
	});
}

function handleDocs(_isWebSocketSupported: boolean): Response {
	const html = `<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Edge Proxy — API Test</title>
  <style>
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    body { font-family: system-ui, -apple-system, sans-serif; background: #0d1117; color: #e1e4e8; padding: 1.5rem; }
    main { max-width: 960px; margin: 0 auto; }
    h1 { font-size: 1.5rem; color: #58a6ff; margin-bottom: 0.25rem; }
    .sub { color: #8b949e; margin-bottom: 1.5rem; font-size: 0.9rem; }
    .card { background: #161b22; border: 1px solid #30363d; border-radius: 8px; margin-bottom: 1rem; overflow: hidden; }
    .card-header { padding: 0.75rem 1rem; background: #1c2128; border-bottom: 1px solid #30363d; font-weight: 600; cursor: pointer; display: flex; align-items: center; gap: 0.5rem; user-select: none; }
    .card-header:hover { background: #21262d; }
    .card-header .method { font-size: 0.7rem; padding: 1px 6px; border-radius: 3px; font-weight: 600; text-transform: uppercase; }
    .get { background: #1f6feb33; color: #58a6ff; }
    .post { background: #23863633; color: #3fb950; }
    .card-body { padding: 1rem; display: none; }
    .card.open .card-body { display: block; }
    .card-header .arrow { margin-left: auto; transition: transform .15s; }
    .card.open .arrow { transform: rotate(90deg); }
    label { display: block; font-size: 0.8rem; color: #8b949e; margin-bottom: 0.25rem; }
    input, textarea, select { width: 100%; background: #0d1117; border: 1px solid #30363d; border-radius: 4px; color: #e1e4e8; padding: 0.5rem 0.75rem; font-family: inherit; font-size: 0.9rem; margin-bottom: 0.75rem; }
    input:focus, textarea:focus { border-color: #58a6ff; outline: none; }
    textarea { min-height: 60px; resize: vertical; font-family: 'SF Mono', 'Cascadia Code', monospace; font-size: 0.8rem; }
    textarea.code { min-height: 120px; }
    .row { display: flex; gap: 0.75rem; }
    .row > * { flex: 1; }
    .btn { background: #238636; color: #fff; border: none; border-radius: 6px; padding: 0.5rem 1.25rem; font-size: 0.85rem; cursor: pointer; font-weight: 500; }
    .btn:hover { background: #2ea043; }
    .btn:disabled { opacity: 0.5; cursor: not-allowed; }
    .output { background: #0d1117; border: 1px solid #30363d; border-radius: 4px; padding: 0.75rem; margin-top: 0.5rem; }
    .output pre { font-family: 'SF Mono', 'Cascadia Code', monospace; font-size: 0.78rem; white-space: pre-wrap; word-break: break-all; max-height: 300px; overflow: auto; color: #c9d1d9; }
    .output .meta { font-size: 0.75rem; color: #8b949e; margin-bottom: 0.5rem; }
    .output .meta .status.ok { color: #3fb950; }
    .output .meta .status.err { color: #f85149; }
    .toast { position: fixed; bottom: 1.5rem; right: 1.5rem; background: #1c2128; border: 1px solid #30363d; border-radius: 6px; padding: 0.75rem 1rem; font-size: 0.85rem; display: none; z-index: 100; }
  </style>
</head>
<body>
<main>
  <h1>Edge Proxy Relay — Interactive Test</h1>
  <p class="sub">Test all endpoints from the browser. Open a card, fill in the fields, and run.</p>

  <div class="card open">
    <div class="card-header">
      <span class="method get">AUTH</span> API Key
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <label>API Key (default: <code>sk-dummy-key</code>)</label>
      <div class="row">
        <input type="text" id="apiKey" value="sk-dummy-key" />
        <input type="text" id="baseUrl" value="" placeholder="(same origin)" />
      </div>
    </div>
  </div>

  <div class="card open">
    <div class="card-header" onclick="toggleCard(this)">
      <span class="method get">GET</span> /health
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <button class="btn" onclick="callHealth()">Ping Health</button>
      <div id="output-health" class="output" style="display:none"><pre></pre></div>
    </div>
  </div>

  <div class="card open">
    <div class="card-header" onclick="toggleCard(this)">
      <span class="method get">GET</span> /v1/models
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <button class="btn" onclick="callModels()">List Models</button>
      <div id="output-models" class="output" style="display:none"><pre></pre></div>
    </div>
  </div>

  <div class="card">
    <div class="card-header" onclick="toggleCard(this)">
      <span class="method post">POST</span> /v1/chat/completions
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <div class="row">
        <div><label>Model</label><input type="text" id="chatModel" value="deepseek-v4-flash-free" /></div>
        <div><label>Max Tokens</label><input type="number" id="chatMaxTokens" value="128" /></div>
      </div>
      <label>Messages (JSON array)</label>
      <textarea id="chatMessages" class="code">[{"role":"user","content":"Say hello in one word"}]</textarea>
      <label><input type="checkbox" id="chatStream" /> Stream (SSE)</label>
      <div style="margin-top:0.5rem"><button class="btn" onclick="callChat()">Send</button></div>
      <div id="output-chat" class="output" style="display:none"><pre></pre></div>
    </div>
  </div>

  <div class="card">
    <div class="card-header" onclick="toggleCard(this)">
      <span class="method post">POST</span> /v1/messages (Anthropic)
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <div class="row">
        <div><label>Model</label><input type="text" id="anthModel" value="deepseek-v4-flash-free" /></div>
        <div><label>Max Tokens</label><input type="number" id="anthMaxTokens" value="256" /></div>
      </div>
      <label>System Prompt (optional, with cache_control)</label>
      <textarea id="anthSystem" class="code" placeholder='[{"type":"text","text":"You are helpful.","cache_control":{"type":"ephemeral"}}]'></textarea>
      <label>Messages (JSON)</label>
      <textarea id="anthMessages" class="code">[{"role":"user","content":[{"type":"text","text":"Say hello in one word","cache_control":{"type":"ephemeral"}}]}]</textarea>
      <label><input type="checkbox" id="anthStream" /> Stream (SSE)</label>
      <div style="margin-top:0.5rem"><button class="btn" onclick="callAnthropic()">Send</button></div>
      <div id="output-anth" class="output" style="display:none"><pre></pre></div>
    </div>
  </div>

  <div class="card">
    <div class="card-header" onclick="toggleCard(this)">
      <span class="method post">RELAY</span> Generic HTTP Relay
      <span class="arrow">▶</span>
    </div>
    <div class="card-body">
      <label>Relay Target URL</label>
      <input type="text" id="relayTarget" value="https://httpbin.org" />
      <div class="row">
        <div><label>Relay Path</label><input type="text" id="relayPath" value="/get" /></div>
        <div><label>Method</label><select id="relayMethod"><option>GET</option><option>POST</option></select></div>
      </div>
      <label>Body (JSON, optional)</label>
      <textarea id="relayBody" class="code" placeholder='{"test":true}'></textarea>
      <div style="margin-top:0.5rem"><button class="btn" onclick="callRelay()">Send</button></div>
      <div id="output-relay" class="output" style="display:none"><pre></pre></div>
    </div>
  </div>

  <div id="toast" class="toast"></div>
</main>

<script>
function apiBase() { return document.getElementById('baseUrl').value || ''; }
function authHeaders() {
  const k = document.getElementById('apiKey').value || 'sk-dummy-key';
  return { 'Authorization': 'Bearer ' + k, 'Content-Type': 'application/json' };
}
function toggleCard(h) { h.parentElement.classList.toggle('open'); }
let toastTimer;
function showToast(msg, ok) {
  const el = document.getElementById('toast');
  el.textContent = (ok ? '✓ ' : '✗ ') + msg;
  el.style.display = 'block';
  el.style.borderColor = ok ? '#3fb950' : '#f85149';
  clearTimeout(toastTimer);
  toastTimer = setTimeout(() => el.style.display = 'none', 3000);
}
async function apiFetch(method, path, body) {
  const resp = await fetch((apiBase() || '') + path, { method, headers: authHeaders(), body: body ? JSON.stringify(body) : undefined });
  const text = await resp.text();
  try { var data = JSON.parse(text); } catch { data = text; }
  return { resp, data };
}
function showOutput(id, resp, data) {
  const el = document.getElementById('output-' + id);
  el.style.display = 'block';
  const ok = resp.status >= 200 && resp.status < 300;
  el.innerHTML = '<div class="meta"><span class="status ' + (ok ? 'ok' : 'err') + '">' + resp.status + ' ' + resp.statusText + '</span></div><pre>' + esc(typeof data === 'string' ? data : JSON.stringify(data, null, 2)).slice(0, 10000) + '</pre>';
  showToast(resp.status + ' ' + resp.statusText, ok);
}
function streamOutput(id, chunk) {
  const el = document.getElementById('output-' + id);
  el.style.display = 'block';
  let pre = el.querySelector('pre');
  if (!pre) { el.innerHTML = '<div class="meta">streaming…</div><pre></pre>'; pre = el.querySelector('pre'); }
  pre.textContent += chunk;
  pre.scrollTop = pre.scrollHeight;
}
let _t;
function elapsed() { return Date.now() - _t; }
function esc(s) { const d = document.createElement('div'); d.textContent = s; return d.innerHTML; }

async function callHealth() { _t = Date.now(); try { var r = await apiFetch('GET','/health'); showOutput('health',r.resp,r.data); } catch(e) { showOutput('health',{status:0,statusText:'Error'},e.message); showToast(e.message,0); } }
async function callModels() { _t = Date.now(); try { var r = await apiFetch('GET','/v1/models'); showOutput('models',r.resp,r.data); } catch(e) { showOutput('models',{status:0,statusText:'Error'},e.message); showToast(e.message,0); } }

async function callChat() {
  _t = Date.now();
  const stream = document.getElementById('chatStream').checked;
  try { var messages = JSON.parse(document.getElementById('chatMessages').value); } catch { showToast('Invalid messages JSON',0); return; }
  const body = { model: document.getElementById('chatModel').value || 'deepseek-v4-flash-free', messages, stream, max_tokens: parseInt(document.getElementById('chatMaxTokens').value) || 128 };
  try {
    if (stream) {
      var el = document.getElementById('output-chat'); el.style.display = 'block'; el.innerHTML = '<div class="meta">streaming…</div><pre></pre>';
      var resp = await fetch((apiBase()||'') + '/v1/chat/completions', { method: 'POST', headers: authHeaders(), body: JSON.stringify(body) });
      if (!resp.ok) { showOutput('chat',resp,await resp.text()); return; }
      var reader = resp.body.getReader(), decoder = new TextDecoder(), done;
      while (!done) { var v = await reader.read(); done = v.done; if (v.value) streamOutput('chat', decoder.decode(v.value)); }
      showToast('stream complete',1);
    } else { var r = await apiFetch('POST','/v1/chat/completions', body); showOutput('chat',r.resp,r.data); }
  } catch(e) { showOutput('chat',{status:0,statusText:'Error'},e.message); showToast(e.message,0); }
}

async function callAnthropic() {
  _t = Date.now();
  const stream = document.getElementById('anthStream').checked;
  try { var messages = JSON.parse(document.getElementById('anthMessages').value); } catch { showToast('Invalid messages JSON',0); return; }
  const body = { model: document.getElementById('anthModel').value || 'deepseek-v4-flash-free', max_tokens: parseInt(document.getElementById('anthMaxTokens').value) || 256, messages, stream };
  const sys = document.getElementById('anthSystem').value.trim();
  if (sys) { try { body.system = JSON.parse(sys); } catch { body.system = sys; } }
  try {
    if (stream) {
      var el = document.getElementById('output-anth'); el.style.display = 'block'; el.innerHTML = '<div class="meta">streaming…</div><pre></pre>';
      var resp = await fetch((apiBase()||'') + '/v1/messages', { method: 'POST', headers: authHeaders(), body: JSON.stringify(body) });
      if (!resp.ok) { showOutput('anth',resp,await resp.text()); return; }
      var reader = resp.body.getReader(), decoder = new TextDecoder(), done;
      while (!done) { var v = await reader.read(); done = v.done; if (v.value) streamOutput('anth', decoder.decode(v.value)); }
      showToast('stream complete',1);
    } else { var r = await apiFetch('POST','/v1/messages', body); showOutput('anth',r.resp,r.data); }
  } catch(e) { showOutput('anth',{status:0,statusText:'Error'},e.message); showToast(e.message,0); }
}

async function callRelay() {
  _t = Date.now();
  const target = document.getElementById('relayTarget').value;
  const path = document.getElementById('relayPath').value || '/';
  const method = document.getElementById('relayMethod').value;
  const rawBody = document.getElementById('relayBody').value;
  try {
    var resp = await fetch((apiBase()||'') + '/', { method, headers: { 'x-relay-target': target, 'x-relay-path': path, ...(rawBody ? {'Content-Type':'application/json'} : {}) }, body: rawBody || undefined });
    var text = await resp.text();
    try { var data = JSON.parse(text); } catch { data = text; }
    showOutput('relay', resp, data);
  } catch(e) { showOutput('relay',{status:0,statusText:'Error'},e.message); showToast(e.message,0); }
}
</script>
</body>
</html>`;

	return new Response(html, {
		status: 200,
		headers: {
			"Content-Type": "text/html; charset=utf-8",
			...getCorsHeaders(),
		},
	});
}

// --- Generic HTTP Relay ------------------------------------------------------

async function handleRelay(
	req: Request,
	env: RouterEnv,
	clientIP: string,
): Promise<Response> {
	const startTime = performance.now();
	const method = req.method;
	const requestUrl = req.url;

	const RELAY_TIMEOUT_MS = getNumericEnv(env, "RELAY_TIMEOUT_MS", 30000);

	// -- Pre-flight CORS
	if (method === "OPTIONS") {
		return createCorsPreflightResponse();
	}

	// -- Middleware: Body size check
	const bodyError = checkBodySize(req);
	if (bodyError) {
		logRelayEvent({
			method,
			url: requestUrl,
			status: bodyError.status,
			durationMs: Math.round(performance.now() - startTime),
			ip: clientIP,
		});
		return bodyError;
	}

	// -- Middleware: Rate limiting
	const rateCheck = await rateLimiter!.checkAsync(clientIP);
	if (!rateCheck.allowed) {
		logRelayEvent({
			method,
			url: requestUrl,
			status: 429,
			durationMs: Math.round(performance.now() - startTime),
			error: "rate_limit_exceeded",
			ip: clientIP,
		});
		return new Response(
			JSON.stringify({
				error: true,
				code: "RATE_LIMITED",
				message: "Too many requests",
				retryAfterMs: rateCheck.retryAfterMs,
			}),
			{
				status: 429,
				headers: {
					"Content-Type": "application/json",
					...getCorsHeaders(),
					"Retry-After": String(
						Math.ceil((rateCheck.retryAfterMs ?? 60_000) / 1000),
					),
				},
			},
		);
	}

	// -- Extract relay parameters from headers
	const target = req.headers.get("x-relay-target");
	const relayPath = req.headers.get("x-relay-path") ?? "/";

	// -- SSRF: Normalize and validate target URL
	const targetUrl = normalizeTargetUrl(target, relayPath);
	if (!targetUrl) {
		logRelayEvent({
			method,
			url: requestUrl,
			status: 400,
			durationMs: Math.round(performance.now() - startTime),
			error: "missing_target_header",
			ip: clientIP,
		});
		return createErrorResponse({
			code: "INVALID_TARGET",
			status: 400,
			message: "Missing or invalid x-relay-target header",
		});
	}

	if (!isAllowedTarget(targetUrl)) {
		logRelayEvent({
			method,
			url: requestUrl,
			status: 403,
			durationMs: Math.round(performance.now() - startTime),
			error: "target_not_allowed",
			ip: clientIP,
		});
		return createErrorResponse({
			code: "SSRF_BLOCKED",
			status: 403,
			message: "Target domain not allowed",
		});
	}

	// -- SSRF: DNS rebinding protection (optional, via SSRF_DNS_CHECK=true) -----
	if (isSsrfDnsCheckEnabled()) {
		const asyncAllowed = await isAllowedTargetAsync(targetUrl);
		if (!asyncAllowed) {
			logRelayEvent({
				method,
				url: requestUrl,
				status: 403,
				durationMs: Math.round(performance.now() - startTime),
				error: "ssrf_dns_rebinding",
				ip: clientIP,
			});
			return createErrorResponse({
				code: "SSRF_BLOCKED",
				status: 403,
				message: "Target resolves to private/internal IP",
			});
		}
	}

	// -- Build the upstream request
	const filteredHeaders = filterRequestHeaders(req.headers);
	const fetchOptions = buildRelayRequest(
		req,
		filteredHeaders,
		RELAY_TIMEOUT_MS,
	) as RequestInit & { proxy?: string };

	const targetUrlString = targetUrl.toString();

	// -- Execute upstream fetch with shared retry
	const result = await fetchWithRetry(
		targetUrlString,
		fetchOptions,
		proxyPool!,
		"relay",
	);

	if (result.errorClassification) {
		logRelayEvent({
			method,
			url: requestUrl,
			status: result.errorClassification.status,
			durationMs: Math.round(performance.now() - startTime),
			error: result.errorClassification.message,
			targetUrl: targetUrlString,
			ip: clientIP,
		});
		return createErrorResponse(result.errorClassification);
	}

	const relayedResponse = createRelayResponse(result.response!);

	logRelayEvent({
		method,
		url: requestUrl,
		status: relayedResponse.status,
		durationMs: Math.round(performance.now() - startTime),
		targetUrl: targetUrlString,
		ip: clientIP,
	});

	return relayedResponse;
}

// --- Main Router -------------------------------------------------------------

export interface RouterOptions {
	isWebSocketSupported?: boolean;
	getTestApiHtml?: () => string | Promise<string>;
}

export async function handleRequest(
	req: Request,
	env: RouterEnv,
	clientIP: string,
	options: RouterOptions = {},
): Promise<Response | undefined> {
	initGlobals(env);
	const url = new URL(req.url);

	// Static routes
	if (url.pathname === "/health") return handleHealth();
	if (url.pathname === "/docs") return handleDocs(options.isWebSocketSupported ?? false);
	if (url.pathname === "/test" && options.getTestApiHtml) {
		const html = await options.getTestApiHtml();
		return new Response(html, {
			status: 200,
			headers: { "Content-Type": "text/html; charset=utf-8" },
		});
	}
	if (url.pathname === "/" && req.method === "GET" && !req.headers.get("x-relay-target")) {
		return handleIndex();
	}

	// AI proxy routes -- OpenAI-compatible API
	if (url.pathname === "/v1/chat/completions") {
		if (req.method === "OPTIONS") return createCorsPreflightResponse();
		if (req.method !== "POST") return new Response("Method Not Allowed", { status: 405 });
		const authErr = requireAuth(req, env);
		if (authErr) return authErr;
		try {
			const body = await req.json();
			const sessionId = crypto.randomUUID();
			return handleChatCompletion(body, proxyPool!, sessionPool!, sessionId);
		} catch {
			return new Response(
				JSON.stringify({ error: { message: "Invalid JSON body", type: "invalid_request_error" } }),
				{ status: 400, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
			);
		}
	}

	// AI proxy routes -- Anthropic-compatible API
	if (url.pathname === "/v1/messages") {
		if (req.method === "OPTIONS") return createCorsPreflightResponse();
		if (req.method !== "POST") return new Response("Method Not Allowed", { status: 405 });
		const authErr = requireAuth(req, env);
		if (authErr) return authErr;
		try {
			const body = await req.json();
			const sessionId = crypto.randomUUID();
			const anthropicVersion = req.headers.get("anthropic-version") ?? undefined;
			return handleAnthropicMessages(body, proxyPool!, sessionPool!, sessionId, undefined, anthropicVersion);
		} catch {
			return new Response(
				JSON.stringify({
					type: "error",
					error: { message: "Invalid JSON body", type: "invalid_request_error" },
				}),
				{ status: 400, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
			);
		}
	}

	if (url.pathname === "/v1/models" && req.method === "GET") {
		const authErr = requireAuth(req, env);
		if (authErr) return authErr;
		const models = listModels().map((id) => ({
			id,
			object: "model",
			created: Math.floor(Date.now() / 1000),
			owned_by: "edge-proxy",
			features: ["prompt_caching"],
		}));
		return new Response(
			JSON.stringify({
				object: "list",
				data: models,
			}),
			{
				status: 200,
				headers: {
					"Content-Type": "application/json",
					...getCorsHeaders(),
				},
			},
		);
	}

	// WebSocket upgrade check (Bun specific - worker/vercel should handle their own rejection if needed)
	if (
		req.method === "GET" &&
		req.headers.get("upgrade")?.toLowerCase() === "websocket"
	) {
		if (!options.isWebSocketSupported) {
			return new Response(
				JSON.stringify({
					error: true,
					code: "UNSUPPORTED",
					message: "WebSocket relay is not supported on this deployment",
				}),
				{
					status: 400,
					headers: {
						"Content-Type": "application/json",
						...getCorsHeaders(),
					},
				},
			);
		}
		// Return undefined to let Bun handle the upgrade in its fetch method
		return undefined;
	}

	// Generic HTTP relay
	return handleRelay(req, env, clientIP);
}

// Ensure proxyPool is available for index.ts to use proxyPool.tryLoad()
export function getSharedProxyPool() {
	if (!proxyPool) {
		proxyPool = new ProxyPool();
		sessionPool = new SessionProxyPool(proxyPool);
		sessionPool.setFailureThreshold(3);
	}
	return proxyPool;
}