/**
 * Matrix network sniffer.
 *
 * Watches every request to matrix.redditspace.com made by chat.reddit.com,
 * captures method/URL/body for both request and response, and writes the
 * sequence to data/matrix-sniff-<timestamp>.json when you exit (Ctrl-C).
 *
 * Usage:
 *   tsx scripts/matrix-sniff.ts
 *
 * Then in the browser that pops up: log in if needed → click "Start chat"
 * → pick a recipient → send a message → come back here and press Ctrl-C.
 *
 * The script does NOT initiate any Matrix calls itself. It only observes
 * what the UI sends, so there's no risk of an accidental outbound message.
 */

import fs from 'fs';
import path from 'path';
import { chromium, type Request, type Response } from 'playwright';
import { createLogger } from '../src/utils/logger.js';

const SESSION_DIR = path.resolve(process.cwd(), './data/browser-session');
const OUT_DIR = path.resolve(process.cwd(), './data');
const MATRIX_HOST_RE = /matrix\.(redditspace|reddit)\.com$/i;

interface CapturedCall {
  index: number;
  startedAt: string;
  method: string;
  url: string;
  pathLabel: string;
  requestHeaders: Record<string, string>;
  requestBody: string | null;
  requestBodyJson: unknown | null;
  responseStatus: number | null;
  responseHeaders: Record<string, string> | null;
  responseBody: string | null;
  responseBodyJson: unknown | null;
  durationMs: number | null;
}

/** Best-effort short label so the live log is readable. */
function labelFor(method: string, urlStr: string): string {
  try {
    const url = new URL(urlStr);
    // Strip /_matrix/client/v3 prefix for readability.
    let p = url.pathname.replace(/^\/_matrix\/(client|media)\/(v3|v1)/, '');
    // Truncate long IDs in path segments.
    p = p
      .split('/')
      .map((seg) => (seg.length > 24 ? seg.slice(0, 12) + '…' + seg.slice(-6) : seg))
      .join('/');
    return `${method} ${p}`;
  } catch {
    return `${method} ${urlStr}`;
  }
}

function safeParseJson(s: string | null): unknown | null {
  if (!s) return null;
  try {
    return JSON.parse(s);
  } catch {
    return null;
  }
}

async function main() {
  const logger = createLogger();

  if (!fs.existsSync(OUT_DIR)) fs.mkdirSync(OUT_DIR, { recursive: true });
  const outFile = path.join(OUT_DIR, `matrix-sniff-${new Date().toISOString().replace(/[:.]/g, '-')}.json`);

  logger.info('[sniff] launching browser (using persistent session)...');
  const context = await chromium.launchPersistentContext(SESSION_DIR, {
    headless: false,
    viewport: { width: 1280, height: 800 },
  });

  const calls: CapturedCall[] = [];
  // Map request → index so we can hydrate it when the response arrives.
  const reqIndex = new WeakMap<Request, number>();
  const reqStart = new WeakMap<Request, number>();

  let serial = 0;

  const onRequest = (request: Request) => {
    try {
      const u = new URL(request.url());
      if (!MATRIX_HOST_RE.test(u.hostname)) return;
    } catch {
      return;
    }
    const idx = serial++;
    reqIndex.set(request, idx);
    reqStart.set(request, Date.now());
    const body = request.postData();
    const call: CapturedCall = {
      index: idx,
      startedAt: new Date().toISOString(),
      method: request.method(),
      url: request.url(),
      pathLabel: labelFor(request.method(), request.url()),
      requestHeaders: scrubHeaders(request.headers()),
      requestBody: body ?? null,
      requestBodyJson: safeParseJson(body ?? null),
      responseStatus: null,
      responseHeaders: null,
      responseBody: null,
      responseBodyJson: null,
      durationMs: null,
    };
    calls[idx] = call;
    logger.info(`[sniff] #${idx} → ${call.pathLabel}`);
    if (body && body.length < 600) {
      logger.info(`        req body: ${body}`);
    } else if (body) {
      logger.info(`        req body: ${body.length}B (truncated in log; full saved to file)`);
    }
  };

  const onResponse = async (response: Response) => {
    const request = response.request();
    const idx = reqIndex.get(request);
    if (idx === undefined) return;
    const call = calls[idx];
    if (!call) return;

    call.responseStatus = response.status();
    call.responseHeaders = scrubHeaders(response.headers());
    const started = reqStart.get(request);
    call.durationMs = started ? Date.now() - started : null;

    // Only capture text bodies, and skip large binaries.
    const ct = (response.headers()['content-type'] || '').toLowerCase();
    if (ct.includes('json') || ct.includes('text')) {
      try {
        const text = await response.text();
        if (text.length <= 100_000) {
          call.responseBody = text;
          call.responseBodyJson = safeParseJson(text);
        } else {
          call.responseBody = `[truncated: ${text.length}B ${ct}]`;
        }
      } catch (err) {
        call.responseBody = `[read error: ${(err as Error).message}]`;
      }
    } else if (ct) {
      call.responseBody = `[binary: ${ct}]`;
    }

    logger.info(`[sniff] #${idx} ← ${call.responseStatus} (${call.durationMs}ms)`);
  };

  context.on('request', onRequest);
  context.on('response', onResponse);

  const page = context.pages()[0] ?? (await context.newPage());
  await page.goto('https://chat.reddit.com/', { waitUntil: 'domcontentloaded' });

  logger.info('');
  logger.info('═══════════════════════════════════════════════════════════');
  logger.info(' Ready. In the browser:');
  logger.info('   1. Click "Start chat" (or the + icon)');
  logger.info('   2. Pick a recipient and send a short message');
  logger.info('   3. Come back here and press Ctrl-C to save & exit.');
  logger.info('═══════════════════════════════════════════════════════════');
  logger.info('');

  const flush = async () => {
    logger.info(`[sniff] writing ${calls.length} calls to ${outFile}`);
    fs.writeFileSync(outFile, JSON.stringify({ capturedAt: new Date().toISOString(), calls }, null, 2));
    try {
      await context.close();
    } catch {
      /* ignore */
    }
  };

  // Save on Ctrl-C.
  process.on('SIGINT', async () => {
    logger.info('[sniff] SIGINT — flushing...');
    await flush();
    process.exit(0);
  });

  // Also save if the user closes the browser window.
  context.on('close', async () => {
    logger.info('[sniff] browser closed — flushing...');
    await flush();
    process.exit(0);
  });
}

/**
 * Remove the bearer token before writing to disk — the captured JSON file
 * is going to sit in the repo's data dir, no need to leave creds in it.
 */
function scrubHeaders(headers: Record<string, string>): Record<string, string> {
  const out: Record<string, string> = {};
  for (const [k, v] of Object.entries(headers)) {
    if (k.toLowerCase() === 'authorization') {
      out[k] = v.toLowerCase().startsWith('bearer ') ? 'Bearer <redacted>' : '<redacted>';
    } else if (k.toLowerCase() === 'cookie') {
      out[k] = '<redacted>';
    } else {
      out[k] = v;
    }
  }
  return out;
}

main().catch((err) => {
  console.error('FATAL:', err);
  process.exit(1);
});