import { readFileSync } from 'node:fs';
import { join } from 'node:path';
import { describe, expect, it } from 'vitest';

const projectRoot = process.cwd();
const indexSource = readFileSync(join(projectRoot, 'src/index.ts'), 'utf8');
const html = readFileSync(join(projectRoot, 'index.html'), 'utf8');

const escapeRegex = (value: string) => value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');

const hasClass = (className: string, tagName?: string) => {
  const tagPattern = tagName ? `<${tagName}\\b[^>]*` : '<[a-z][^>]*';
  return new RegExp(
    `${tagPattern}class="[^"]*\\b${escapeRegex(className)}\\b[^"]*"`,
    'i'
  ).test(html);
};

const hasId = (id: string) => new RegExp(`\\bid="${escapeRegex(id)}"`, 'i').test(html);

const hasTag = (tagName: string) =>
  new RegExp(`<${escapeRegex(tagName)}(?:\\s|>|/)`, 'i').test(html);

const selectorExists = (selector: string) => {
  const idSelector = /^#(?<id>[\w-]+)$/.exec(selector);
  if (idSelector?.groups?.id) {
    return hasId(idSelector.groups.id);
  }

  const classSelector = /^\.([\w-]+)$/.exec(selector);
  if (classSelector?.[1]) {
    return hasClass(classSelector[1]);
  }

  const tagClassSelector = /^(?<tagName>[a-z]+)\.(?<className>[\w-]+)$/.exec(selector);
  if (tagClassSelector?.groups) {
    return hasClass(tagClassSelector.groups.className, tagClassSelector.groups.tagName);
  }

  if (/^[a-z]+$/.test(selector)) {
    return hasTag(selector);
  }

  throw new Error(`Unsupported selector contract syntax: ${selector}`);
};

describe('index DOM selector contract', () => {
  it('keeps every boot-time required selector target present in index.html', () => {
    const selectors = Array.from(
      indexSource.matchAll(/queryRequiredElements?\(\s*'([^']+)'\s*,/g),
      (match) => match[1]
    );

    expect(selectors.length).toBeGreaterThan(0);
    expect(selectors.filter((selector) => !selectorExists(selector))).toEqual([]);
  });

  it('keeps the three color swatches expected by the palette UI', () => {
    const colorSwatchCount = Array.from(
      html.matchAll(/class="[^"]*\bcolor-swatch\b[^"]*"/g)
    ).length;

    expect(colorSwatchCount).toBe(3);
  });
});