#!/usr/bin/env node
// prep-chrome — make the browser look like a clean, default browser before we film it.
//
//   node bin/prep-chrome.mjs [--dir ~/.chrome-cdp]
//
// `reel` films the WINDOW, so Chrome's own furniture is in every frame: the tab
// strip, the URL bar, the bookmarks bar, and whatever theme the profile happens
// to wear. A tutorial should be shot in a browser that looks like the viewer's,
// not like ours — someone else's bookmarks and a purple theme read as "this was
// recorded on a person's laptop", which is exactly the impression to avoid.
//
// These are PROFILE preferences, not command-line flags — Chrome has no switch
// for either — so they are patched in the Preferences JSON. That is only safe
// while Chrome is CLOSED: it holds prefs in memory and rewrites the file on exit,
// so editing a running profile is silently undone the moment it quits.

import { execFileSync } from "node:child_process";
import { existsSync, readFileSync, writeFileSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";

const i = process.argv.indexOf("--dir");
const DIR = i === -1 ? join(homedir(), ".chrome-cdp") : process.argv[i + 1];
const PREFS = join(DIR, "Default", "Preferences");

try { execFileSync("pkill", ["-f", `user-data-dir=${DIR}`]); } catch {}
await new Promise((r) => setTimeout(r, 1500));   // let it flush and exit

if (!existsSync(PREFS)) {
  console.error(`no profile at ${PREFS}`);
  process.exit(1);
}

const p = JSON.parse(readFileSync(PREFS, "utf8"));

// Bookmarks bar off — someone's bookmarks have no place in a product tutorial.
p.bookmark_bar = { ...(p.bookmark_bar || {}), show_on_all_tabs: false };

// Default theme. A custom theme is an installed extension plus a pinned set of
// colours; clearing both is what actually returns Chrome to stock, and either one
// alone leaves the window tinted.
if (p.extensions?.theme) p.extensions.theme = { id: "", use_system: false };
delete p.browser?.theme;
p.browser = { ...(p.browser || {}), theme: { user_color_scheme: 0 } };
delete p.autogenerated?.theme;

writeFileSync(PREFS, JSON.stringify(p));
console.log(`✓ ${DIR}: bookmarks bar off, default theme`);