const assert = require('assert');
const fs = require('fs');
const path = require('path');

const root = path.resolve(__dirname, '..');
const canvasHtml = fs.readFileSync(path.join(root, 'frontend', 'canvas.html'), 'utf8');
const serverPy = fs.readFileSync(path.join(root, 'backend', 'server.py'), 'utf8');

assert(
  canvasHtml.includes('src="/canvas-helpers.js"'),
  'canvas.html should request the canvas helper script from /canvas-helpers.js'
);
assert(
  serverPy.includes("@app.route('/canvas-helpers.js')"),
  'backend/server.py should serve /canvas-helpers.js'
);
assert(
  serverPy.includes("send_from_directory(FRONTEND_DIR, 'canvas-helpers.js')") ||
    serverPy.includes('send_from_directory(FRONTEND_DIR, "canvas-helpers.js")'),
  'the /canvas-helpers.js route should serve frontend/canvas-helpers.js'
);
assert(
  serverPy.includes('def no_cache_response(response):'),
  'canvas assets should use an explicit no-cache response helper'
);
assert(
  serverPy.includes('Cache-Control') && serverPy.includes('no-store'),
  'canvas routes should prevent stale browser caches while the editor is changing'
);