import { describe, expect, it } from "vitest";
import { readFileSync, readdirSync, statSync } from "node:fs";
import path from "node:path";

/** Every .css file under src/ (src/styles, src/app/globals.css, and any other). */
function cssFiles(dir: string): string[] {
  return readdirSync(dir).flatMap((name) => {
    const full = path.join(dir, name);
    if (statSync(full).isDirectory()) return cssFiles(full);
    return full.endsWith(".css") ? [full] : [];
  });
}

/** Rules whose selector targets a disabled state and whose opacity is below 1. */
function fadedDisabledRules(source: string): string[] {
  const text = source.replace(/\/\*[\s\S]*?\*\//g, "");
  const found: string[] = [];
  // Innermost blocks only: the selector text runs back to the previous brace,
  // so rules nested inside @media or @supports are scanned too.
  for (const m of text.matchAll(/([^{}]+)\{([^{}]*)\}/g)) {
    const selector = m[1].trim();
    if (!/:disabled|\[disabled\]|\[aria-disabled(="true")?\]/.test(selector)) continue;
    for (const o of m[2].matchAll(/(?:^|;|\s)opacity\s*:\s*([\d.]+)(%?)/g)) {
      const value = parseFloat(o[1]) / (o[2] ? 100 : 1);
      if (value < 1) found.push(`${selector} { opacity: ${o[1]}${o[2]} }`);
    }
  }
  return found;
}

describe("disabled buttons are never faded", () => {
  const root = path.resolve(__dirname, "../src");
  const files = cssFiles(root);

  it("finds the stylesheets, globals.css included", () => {
    expect(files.some((f) => f.endsWith(path.join("app", "globals.css")))).toBe(true);
    expect(files.some((f) => f.endsWith(path.join("styles", "signin.css")))).toBe(true);
  });

  it("the scanner catches a faded disabled rule", () => {
    expect(fadedDisabledRules(".a:disabled { opacity: .5; }")).toHaveLength(1);
    expect(fadedDisabledRules("@media (x) { .a[disabled] { color: red; opacity: 40% } }")).toHaveLength(1);
    expect(fadedDisabledRules(".a:disabled { opacity: 1; }")).toHaveLength(0);
    expect(fadedDisabledRules(".a:hover { opacity: .5; }")).toHaveLength(0);
  });

  for (const file of files) {
    it(`${path.relative(root, file)} has no :disabled rule with opacity below 1`, () => {
      expect(fadedDisabledRules(readFileSync(file, "utf8"))).toEqual([]);
    });
  }
});