/**
 * 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.
 */

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;
    applied: boolean;
}

// 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, applied: false };
    g.__outboundProxy = s;

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

    let url: URL;
    try {
        url = new URL(raw);
    } catch {
        console.error(`[proxy] proxy_url is not a URL — trading DIRECT: ${raw}`);
        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;
    }

    const socks = url.protocol.startsWith('socks');
    if (socks) {
        s.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.httpAgent = agent;
        s.httpsAgent = agent;
    } else {
        s.dispatcher = new ProxyAgent(url.href);
        s.httpAgent = new HttpProxyAgent(url);
        s.httpsAgent = new HttpsProxyAgent(url);
    }
    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;
 *  called first in the getClients() bootstrap. */
export function applyBrokerProxy(): void {
    const s = state();
    if (s.applied || !s.url) return;
    s.applied = true;
    axios.defaults.proxy = false; // agents own the routing; ignore env HTTP(S)_PROXY handling
    axios.defaults.httpAgent = s.httpAgent!;
    axios.defaults.httpsAgent = s.httpsAgent!;
}

/** 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[]);
        }
    };
}