/**
 * referer_proxy.test.mjs — coverage for the background worker's per-CDN-host
 * referer capture + DNR proxy-host learning, added in PR #5.
 *
 * The background worker is not itself a module, so the test transpiles it into
 * one (wrapping + top-level-statement `async function` transpile) under a mocked
 * `chrome` + `fetch`/`btoa` environment, then exercises the captured listeners
 * and the message handler directly.
 *
 * Covers the three gaps robot flagged:
 *  (a) closing a tab must NOT wipe the host-keyed `goon_referers` global store,
 *  (b) two hosts proxied concurrently must each keep their OWN referer (no race
 *      that leaves host B's referer live for host A -> 412),
 *  (c) the new referer-capture / proxy-host-learning / onRemoved paths run.
 */
import { describe, it } from './runner.mjs';
import { readFileSync, writeFileSync } from 'node:fs';
import { fileURLToPath, pathToFileURL } from 'node:url';
import { dirname, join } from 'node:path';
import { tmpdir } from 'node:os';

const __dirname = dirname(fileURLToPath(import.meta.url));
const backgroundSource = readFileSync(join(__dirname, '../src/background/background.js'), 'utf8');

// Transpile the top-level-statement worker into an ES module. Wrapping in an
// async IIFE makes its top-level `async function` declarations + `await`-using
// nested functions legal inside a module.
function buildModule(code) {
  return `(async () => {\n${code}\n})();\n`;
}

// A fresh mock of the chrome APIs the worker touches. `onBeforeSendHeaders`,
// `onBeforeRequest`, and `tabs.onRemoved` capture their listener so the test can
// drive them; `declarativeNetRequest.updateSessionRules` records the live rules.
function makeChromeEnv() {
  const storage = {};
  const handlers = { onMessage: [] };
  let sessionRules = {};

  const webRequest = {
    onBeforeSendHeaders: { addListener: (cb) => { handlers.onBeforeSendHeaders = cb; } },
    onBeforeRequest: { addListener: (cb) => { handlers.onBeforeRequest = cb; } },
   };

  const chrome = {
    storage: {
     local: {
      get: async (keys) => {
        const out = {};
        const arr = Array.isArray(keys) ? keys : (keys === undefined ? Object.keys(storage) : [keys]);
        for (const k of arr) if (k in storage) out[k] = storage[k];
        return out;
        },
      set: async (data) => {
        for (const [k, v] of Object.entries(data)) storage[k] = v;
        },
      remove: async (keys) => {
        const arr = Array.isArray(keys) ? keys : [keys];
        for (const k of arr) delete storage[k];
        },
      },
     },
    webRequest,
     tabs: {
      onRemoved: { addListener: (cb) => { handlers.onRemoved = cb; } },
      },
    runtime: { onMessage: { addListener: (cb) => { handlers.onMessage.push(cb); } } },
    declarativeNetRequest: {
      updateSessionRules: async ({ removeRuleIds = [], addRules = [] } = {}) => {
        const rm = new Set(removeRuleIds);
        sessionRules = Object.fromEntries(
          Object.entries(sessionRules).filter(([id]) => !rm.has(id))
         );
        for (const r of addRules) sessionRules[r.id] = r;
        },
      },
   };

  return { chrome, handlers, storage, getSessionRules: () => sessionRules };
}

// Load the worker into a fresh environment. `data:` URLs are cached by Node, so
// the module body (listener registration) would only run once; instead we write
// a uniquely-named temp file per load so each call registers into its own env.
let loadCounter = 0;
async function loadBackground(env) {
  global.chrome = env.chrome;
  const file = join(tmpdir(), `goon_bg_${process.pid}_${loadCounter++}.mjs`);
  writeFileSync(file, buildModule(backgroundSource));
  const module = await import(pathToFileURL(file).href);
  await module.default;
  return module;
}

function videoDetails(tabId, url, referer) {
  return {
    tabId,
    url,
    requestHeaders: referer ? [{ name: 'Referer', value: referer }] : [],
   };
}

describe('PR#5: per-host referer capture + proxy race', () => {
   // (a) Blocking fix: a host-keyed `goon_referers` entry must outlive the close
   // of ANY tab — including a different tab.
  it('closing a tab does not wipe goon_referers captured for another host', async () => {
    const env = makeChromeEnv();
    global.chrome = env.chrome;
    await loadBackground(env);

     // A live source tab captures the provider referer for its CDN host.
    const cap = env.handlers.onBeforeSendHeaders;
    if (!cap) throw new Error('onBeforeSendHeaders listener was not registered');
    await cap(videoDetails(11, 'https://cdnA.example.com/hls/live/seg-1.ts', 'https://pageA.example.com/watch'));

    const rA = env.storage['goon_referers']?.['cdna.example.com'];
    if (!rA) throw new Error('referer was not captured for cdnA');
    if (rA.referer !== 'https://pageA.example.com/watch') {
      throw new Error('captured referer wrong: ' + JSON.stringify(rA));
      }

      // A DIFFERENT tab closes. The per-tab cleanup must NOT remove goon_referers.
    await env.handlers.onRemoved(22);

    const after = env.storage['goon_referers'];
    if (!after || !after['cdna.example.com']) {
      throw new Error('closing tab 22 wiped goon_referers — host A referer lost');
      }
      if (after['cdna.example.com'].referer !== 'https://pageA.example.com/watch') {
       throw new Error('closing tab 22 corrupted the host A referer: ' + JSON.stringify(after));
       }
   });

  it('closing the capturing tab itself preserves the referer for later proxy use', async () => {
    const env = makeChromeEnv();
    global.chrome = env.chrome;
    await loadBackground(env);

    await env.handlers.onBeforeSendHeaders(
      videoDetails(11, 'https://cdnB.example.com/video/x/master.m3u8', 'https://pageB.example.com/v')
     );

       // The very tab that captured the referer now closes.
    await env.handlers.onRemoved(11);

    const after = env.storage['goon_referers']?.['cdnb.example.com'];
    if (!after) throw new Error('goon_referers for the capturing host was wiped on its own tab close');
    if (after.referer !== 'https://pageB.example.com/v') {
      throw new Error('capturing-tab close corrupted referer: ' + JSON.stringify(after));
     }
   });

   // (b) Should-fix + coverage: two hosts proxied concurrently must each keep
   // their own referer. With a shared rule id + non-atomic install this regressed;
   // per-host rule ids + the per-host lock keep them distinct.
  it('concurrent proxy fetches for two hosts keep distinct per-host referer rules', async () => {
    const env = makeChromeEnv();
    let fetchCalls = 0;
    global.chrome = env.chrome;
     global.fetch = async (url) => {
      fetchCalls++;
      return {
        ok: true,
        status: 200,
        headers: { get: () => 'application/vnd.apple.mpegurl' },
        arrayBuffer: async () => new Uint8Array([0]).buffer,
       };
     };

    await loadBackground(env);

      // Two GOON_PROXY_FETCH messages for different CDN hosts, fired together.
    const handler = env.handlers.onMessage[env.handlers.onMessage.length - 1];
    let respA, respB;
    handler({ type: 'GOON_PROXY_FETCH', url: 'https://cdnA.example.com/hls/live/seg-1.ts', referer: 'https://pageA.example.com/watch' }, {}, (r) => { respA = r; });
    handler({ type: 'GOON_PROXY_FETCH', url: 'https://cdnB.example.com/hls/live/seg-1.ts', referer: 'https://pageB.example.com/watch' }, {}, (r) => { respB = r; });

     await new Promise(r => setTimeout(r, 30)); // let async sends + installs flush

    if (!respA || !respA.ok) throw new Error('proxy A failed: ' + JSON.stringify(respA));
    if (!respB || !respB.ok) throw new Error('proxy B failed: ' + JSON.stringify(respB));
    if (fetchCalls < 2) throw new Error('expected both proxy fetches to run, got ' + fetchCalls);

    // Each host must have its OWN installed DNR rule with its OWN referer —
    // host A must NOT be served host B's referer (the 412 regression).
     const rules = env.getSessionRules();
    const ruleA = Object.values(rules).find(r => r.condition?.requestDomains?.includes('cdna.example.com'));
    const ruleB = Object.values(rules).find(r => r.condition?.requestDomains?.includes('cdnb.example.com'));
    if (!ruleA) throw new Error('no DNR rule installed for cdna; rules=' + JSON.stringify(rules));
    if (!ruleB) throw new Error('no DNR rule installed for cdnb; rules=' + JSON.stringify(rules));
    if (ruleA.id === ruleB.id) {
      throw new Error('cdnA and cdnB shared a DNR rule id -> concurrent race possible');
     }
    const refA = ruleA.action.requestHeaders?.find(h => h.header.toLowerCase() === 'referer')?.value;
    const refB = ruleB.action.requestHeaders?.find(h => h.header.toLowerCase() === 'referer')?.value;
    if (refA !== 'https://pageA.example.com/watch') {
      throw new Error('cdnA served wrong referer: ' + refA);
     }
    if (refB !== 'https://pageB.example.com/watch') {
      throw new Error('cdnB served wrong referer: ' + refB);
     }
    if (refA === refB) throw new Error('both hosts got the same referer — cross-host bleed');
   });

  it('repeated proxy for the same host is idempotent (one rule, one install)', async () => {
    const env = makeChromeEnv();
    let installs = 0;
    env.chrome.declarativeNetRequest.updateSessionRules = async ({ addRules = [] } = {}) => {
      for (const r of addRules) installs++;
     };
    global.chrome = env.chrome;
    global.fetch = async () => ({
      ok: true, status: 200,
      headers: { get: () => 'application/vnd.apple.mpegurl' },
      arrayBuffer: async () => new Uint8Array([0]).buffer,
     });

    await loadBackground(env);
    const handler = env.handlers.onMessage[env.handlers.onMessage.length - 1];

    const run = async (n) => {
      handler(
        { type: 'GOON_PROXY_FETCH', url: 'https://cdnA.example.com/hls/live/seg-1.ts', referer: 'https://pageA.example.com/watch' },
        {},
        () => {}
       );
      await new Promise(r => setTimeout(r, 5));
     };
    await run(1);
    const installsAfterFirst = installs;
    await run(2);
    await run(3);

     // Same host + same referer should not re-add the rule on repeat fetches.
    if (installs !== installsAfterFirst) {
      throw new Error(`expected idempotent install, but re-added rule ${installs - installsAfterFirst} extra time(s)`);
     }
   });
 });