const { test } = require('node:test');
const assert = require('node:assert/strict');
const fs = require('node:fs/promises');
const path = require('node:path');

let modulePromise;

async function loadCitationModule() {
  if (!modulePromise) {
    modulePromise = fs.readFile(path.join(__dirname, '..', 'public', 'js', 'assistant', 'citations.js'), 'utf8')
      .then((source) => import('data:text/javascript;charset=utf-8,' + encodeURIComponent(source)));
  }
  return modulePromise;
}

test('mhchem inline delimiters render as KaTeX without eating ordinary backslash prose', async () => {
  const { renderAssistantMarkdown } = await loadCitationModule();
  const expressions = [];
  const katex = {
    renderToString(expr, opts) {
      expressions.push({ expr, display: opts.displayMode });
      return '<span class="katex">' + expr + '</span>';
    }
  };
  const html = renderAssistantMarkdown('Base deficit \\ce{HCO3-} and \\pu{37 C}; a plain \\ce without braces stays text.', [], { katex });
  assert.deepEqual(expressions, [{ expr: '\\ce{HCO3-}', display: false }, { expr: '\\pu{37 C}', display: false }]);
  assert.match(html, /<span class="katex">\\ce{HCO3-}<\/span>/);
  assert.match(html, /<span class="katex">\\pu{37 C}<\/span>/);
  assert.match(html, /without braces stays text/);
});

test('without KaTeX the mhchem source stays literal and escaped', async () => {
  const { renderAssistantMarkdown } = await loadCitationModule();
  const html = renderAssistantMarkdown('Base deficit \\ce{HCO3-}.', []);
  assert.match(html, /\\ce\{HCO3-\}/);
  assert.doesNotMatch(html, /katex/);
});

test('mhchem inside fenced code blocks is never rendered', async () => {
  const { renderAssistantMarkdown } = await loadCitationModule();
  const katex = { renderToString() { throw new Error('code block sent to KaTeX'); } };
  const html = renderAssistantMarkdown('```md\n\\ce{H2O} stays literal\n```', [], { katex });
  assert.match(html, /\\ce\{H2O\}/);
  assert.doesNotMatch(html, /katex/);
});