/**
 * Routes BROKER traffic through the operator's proxy — and nothing else.
 *
 * Scope is deliberate: TopstepX REST + its SignalR hub, Tradovate REST + its
 * websocket, and the Yahoo quote lookups go through the proxy so each instance
 * can present its own IP to the firms. The master link, reporter, catalog sync
 * and backup push stay direct — the control channel must keep working when the
 * proxy dies, and there is no setGlobalDispatcher here for exactly that
 * reason. (Corollary: never call the master through axios — axios defaults
 * carry the proxy agents. Master calls use fetch, which stays untouched.)
 *
 * Configured by the `proxy_url` setting: http://, https://, socks5:// or
 * socks5h:// with optional user:pass. Read once per process — changing it
 * requires a restart, which the settings UI says out loud. Blank = direct.
 *
 * Also home of the broker HTTP timeout (applyBrokerHttpDefaults): axios waits
 * forever by default, and one broker request that never answers — a
 * maintenance window that accepts the connection and goes silent — used to
 * wedge a re-login or sync await for the life of the process. Same scoping
 * argument as the proxy: every axios call here is broker/quote traffic, so the
 * process default is the scoped choice. It covers axios only; websockets and
 * the SignalR hub keep their own liveness handling in the clients.
 *
 * Both defaults are applied when this module loads. Every broker client
 * imports it, and that matters: each server bundle (instrumentation.ts, the
 * route handlers) can carry its own copy of axios, and a copy that never had
 * the defaults applied would dial the brokers direct, with no timeout.
 */

import axios from 'axios';
import { ProxyAgent, type Dispatcher } from 'undici';
import { socksDispatcher } from 'fetch-socks';
import { HttpProxyAgent } from 'http-proxy-agent';
import { HttpsProxyAgent } from 'https-proxy-agent';
import { SocksProxyAgent } from 'socks-proxy-agent';
import type { Agent } from 'node:http';
import { getSetting } from './db';

const SCHEMES = ['http:', 'https:', 'socks5:', 'socks5h:'] as const;

interface ProxyState {
    url: URL | null;
    dispatcher: Dispatcher | null;
    httpAgent: Agent | null;
    httpsAgent: Agent | null;
}

// HMR-safe, and the "read once per process" contract lives here.
const g = globalThis as typeof globalThis & { __outboundProxy?: ProxyState };

function state(): ProxyState {
    if (g.__outboundProxy) return g.__outboundProxy;

    const s: ProxyState = { url: null, dispatcher: null, httpAgent: null, httpsAgent: null };
    g.__outboundProxy = s;

    const raw = getSetting('proxy_url')?.trim();
    if (!raw) return s;

    let url: URL;
    try {
        url = new URL(raw);
    } catch {
        // Not echoed: the value carries the proxy's user:password.
        console.error('[proxy] proxy_url is not a URL — trading DIRECT');
        return s;
    }
    if (!SCHEMES.includes(url.protocol as (typeof SCHEMES)[number])) {
        console.error(`[proxy] proxy_url scheme must be one of ${SCHEMES.join(' ')} — trading DIRECT: ${url.protocol}`);
        return s;
    }

    // A literal '%' in the user or password (one not starting a %XX escape)
    // makes decodeURIComponent throw — here, and inside every proxy library
    // below. Escape it so the password is used as typed. This now runs when
    // the module loads, where a throw would fail every route that imports it.
    const escapeStray = (part: string) => part.replace(/%(?![0-9A-Fa-f]{2})/g, '%25');
    url.username = escapeStray(url.username);
    url.password = escapeStray(url.password);

    try {
        const socks = url.protocol.startsWith('socks');
        if (socks) {
            const dispatcher = socksDispatcher({
                type: 5,
                host: url.hostname,
                port: Number(url.port || 1080),
                userId: url.username ? decodeURIComponent(url.username) : undefined,
                password: url.password ? decodeURIComponent(url.password) : undefined,
            });
            const agent = new SocksProxyAgent(url);
            s.dispatcher = dispatcher;
            s.httpAgent = agent;
            s.httpsAgent = agent;
        } else {
            const dispatcher = new ProxyAgent(url.href);
            const httpAgent = new HttpProxyAgent(url);
            const httpsAgent = new HttpsProxyAgent(url);
            s.dispatcher = dispatcher;
            s.httpAgent = httpAgent;
            s.httpsAgent = httpsAgent;
        }
    } catch (err) {
        // All or nothing — nothing is kept until every piece is built: half a
        // proxy (REST proxied, sockets direct) would be worse than the
        // documented bad-setting behavior.
        console.error(`[proxy] proxy_url could not be set up — trading DIRECT: ${err instanceof Error ? err.message : String(err)}`);
        return s;
    }
    s.url = url;
    console.log(`[proxy] broker traffic will use ${url.protocol}//${url.host} (master link stays direct)`);
    return s;
}

export function getProxyUrl(): string | null {
    const { url } = state();
    return url ? url.href : null;
}

/** Puts the proxy under every axios call. All axios usage in this app is
 *  broker/quote traffic (TopstepX, Tradovate REST, contract resolver), so the
 *  process-wide default is the scoped choice, not a global one. Idempotent;
 *  runs when this module loads and again first in the getClients() bootstrap.
 *
 *  "Already applied" is judged on the axios defaults themselves, not a
 *  process-wide flag: the proxy state is shared through globalThis, but each
 *  bundle's copy of axios has its own defaults, and a global flag set by the
 *  first copy would leave every other one dialling direct. */
export function applyBrokerProxy(): void {
    const s = state();
    if (!s.url || axios.defaults.httpsAgent === s.httpsAgent) return;
    axios.defaults.proxy = false; // agents own the routing; ignore env HTTP(S)_PROXY handling
    axios.defaults.httpAgent = s.httpAgent!;
    axios.defaults.httpsAgent = s.httpsAgent!;
}

/** Idle limit for one broker HTTP request. axios applies it as a socket
 *  inactivity timeout, so it bounds a server that has gone silent, not a
 *  big report that is still streaming. Nothing legitimate comes close: the
 *  Tradovate report endpoints answer with a p-ticket and are polled (each
 *  poll its own short request, already capped at 60s per call), logins and
 *  REST calls answer in seconds. A per-call `timeout` still overrides it.
 *
 *  The clock starts once the socket has connected — a connect that never
 *  completes is left to the OS connect timeout. Calls that can't wait that
 *  long (the Tradovate login and renewal) add an AbortSignal of their own. */
export const BROKER_HTTP_TIMEOUT_MS = 60_000;

/** Gives axios a timeout unless one is already set (axios's own default, 0,
 *  means wait forever). Idempotent; runs when this module loads and at the
 *  top of the getClients() bootstrap. Timeouts surface as ECONNABORTED, which
 *  the Tradovate report fetch already retries as transient. */
export function applyBrokerHttpDefaults(): void {
    if (!axios.defaults.timeout) axios.defaults.timeout = BROKER_HTTP_TIMEOUT_MS;
}

// At load, so no broker request from this bundle can go out before them. The
// proxy is skipped during `next build`: the build imports route modules to
// collect page data, and it dials nothing that would need one. Nothing may
// throw out of here: a module that fails to load takes every route that
// imports it (the whole trading side) down with it.
applyBrokerHttpDefaults();
try {
    if (process.env.NEXT_PHASE !== 'phase-production-build') applyBrokerProxy();
} catch (err) {
    console.error(`[proxy] could not apply proxy_url at load: ${err instanceof Error ? err.message : String(err)}`);
}

/** A websocket to a BROKER endpoint: the built-in (undici) WebSocket, dialled
 *  through the proxy when one is set. The master link keeps using plain
 *  `new WebSocket(...)` — do not use this for it. */
export function brokerWebSocket(wsUrl: string): WebSocket {
    const { dispatcher } = state();
    if (!dispatcher) return new WebSocket(wsUrl);
    // The runtime accepts { dispatcher } fine; only the DOM lib type doesn't.
    return new (WebSocket as unknown as new (u: string, o: object) => WebSocket)(wsUrl, { dispatcher });
}

/** A `ws`-package constructor with the proxy agent baked in, for SignalR's
 *  `withUrl({ WebSocket })` option. undefined = no proxy, let SignalR use its
 *  own require('ws'). */
export function signalrWebSocket(): unknown {
    const s = state();
    if (!s.httpsAgent) return undefined;
    const agent = s.httpsAgent;
    // eslint-disable-next-line @typescript-eslint/no-require-imports
    const WS = require('ws') as new (address: string, protocols?: unknown, options?: object) => unknown;

    return class ProxiedWebSocket extends (WS as new (...args: never[]) => object) {
        constructor(address: string, protocols?: unknown, options?: Record<string, unknown>) {
            // ws also allows (address, options) — normalize before merging.
            if (protocols && typeof protocols === 'object' && !Array.isArray(protocols)) {
                options = protocols as Record<string, unknown>;
                protocols = undefined;
            }
            super(...[address, protocols, { ...(options ?? {}), agent }] as never[]);
        }
    };
}